Source file src/cmd/compile/internal/noder/reader.go

     1  // Copyright 2021 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package noder
     6  
     7  import (
     8  	"encoding/hex"
     9  	"fmt"
    10  	"go/constant"
    11  	"internal/buildcfg"
    12  	"internal/pkgbits"
    13  	"path/filepath"
    14  	"strings"
    15  
    16  	"cmd/compile/internal/base"
    17  	"cmd/compile/internal/dwarfgen"
    18  	"cmd/compile/internal/inline"
    19  	"cmd/compile/internal/inline/interleaved"
    20  	"cmd/compile/internal/ir"
    21  	"cmd/compile/internal/objw"
    22  	"cmd/compile/internal/reflectdata"
    23  	"cmd/compile/internal/staticinit"
    24  	"cmd/compile/internal/typecheck"
    25  	"cmd/compile/internal/types"
    26  	"cmd/internal/hash"
    27  	"cmd/internal/obj"
    28  	"cmd/internal/objabi"
    29  	"cmd/internal/src"
    30  )
    31  
    32  // This file implements cmd/compile backend's reader for the Unified
    33  // IR export data.
    34  
    35  // A pkgReader reads Unified IR export data.
    36  type pkgReader struct {
    37  	pkgbits.PkgDecoder
    38  
    39  	// Indices for encoded things; lazily populated as needed.
    40  	//
    41  	// Note: Objects (i.e., ir.Names) are lazily instantiated by
    42  	// populating their types.Sym.Def; see objReader below.
    43  
    44  	posBases []*src.PosBase
    45  	pkgs     []*types.Pkg
    46  	typs     []*types.Type
    47  
    48  	// offset for rewriting the given (absolute!) index into the output,
    49  	// but bitwise inverted so we can detect if we're missing the entry
    50  	// or not.
    51  	newindex []index
    52  }
    53  
    54  func newPkgReader(pr pkgbits.PkgDecoder) *pkgReader {
    55  	return &pkgReader{
    56  		PkgDecoder: pr,
    57  
    58  		posBases: make([]*src.PosBase, pr.NumElems(pkgbits.SectionPosBase)),
    59  		pkgs:     make([]*types.Pkg, pr.NumElems(pkgbits.SectionPkg)),
    60  		typs:     make([]*types.Type, pr.NumElems(pkgbits.SectionType)),
    61  
    62  		newindex: make([]index, pr.TotalElems()),
    63  	}
    64  }
    65  
    66  // A pkgReaderIndex compactly identifies an index (and its
    67  // corresponding dictionary) within a package's export data.
    68  type pkgReaderIndex struct {
    69  	pr        *pkgReader
    70  	idx       index
    71  	dict      *readerDict
    72  	methodSym *types.Sym
    73  
    74  	synthetic func(pos src.XPos, r *reader)
    75  }
    76  
    77  func (pri pkgReaderIndex) asReader(k pkgbits.SectionKind, marker pkgbits.SyncMarker) *reader {
    78  	if pri.synthetic != nil {
    79  		return &reader{synthetic: pri.synthetic}
    80  	}
    81  
    82  	r := pri.pr.newReader(k, pri.idx, marker)
    83  	r.dict = pri.dict
    84  	r.methodSym = pri.methodSym
    85  	return r
    86  }
    87  
    88  func (pr *pkgReader) newReader(k pkgbits.SectionKind, idx index, marker pkgbits.SyncMarker) *reader {
    89  	return &reader{
    90  		Decoder: pr.NewDecoder(k, idx, marker),
    91  		p:       pr,
    92  	}
    93  }
    94  
    95  // A reader provides APIs for reading an individual element.
    96  type reader struct {
    97  	pkgbits.Decoder
    98  
    99  	p *pkgReader
   100  
   101  	dict *readerDict
   102  
   103  	// funcLitGen is a counter for closure names.
   104  	funcLitGen int
   105  	// rangeLitGen is a counter for range func closure names.
   106  	rangeLitGen int
   107  
   108  	// TODO(mdempsky): The state below is all specific to reading
   109  	// function bodies. It probably makes sense to split it out
   110  	// separately so that it doesn't take up space in every reader
   111  	// instance.
   112  
   113  	curfn       *ir.Func
   114  	locals      []*ir.Name
   115  	closureVars []*ir.Name
   116  
   117  	// funarghack is used during inlining to suppress setting
   118  	// Field.Nname to the inlined copies of the parameters. This is
   119  	// necessary because we reuse the same types.Type as the original
   120  	// function, and most of the compiler still relies on field.Nname to
   121  	// find parameters/results.
   122  	funarghack bool
   123  
   124  	// methodSym is the name of method's name, if reading a method.
   125  	// It's nil if reading a normal function or closure body.
   126  	methodSym *types.Sym
   127  
   128  	// dictParam is the .dict param, if any.
   129  	dictParam *ir.Name
   130  
   131  	// synthetic is a callback function to construct a synthetic
   132  	// function body. It's used for creating the bodies of function
   133  	// literals used to curry arguments to shaped functions.
   134  	synthetic func(pos src.XPos, r *reader)
   135  
   136  	// scopeVars is a stack tracking the number of variables declared in
   137  	// the current function at the moment each open scope was opened.
   138  	scopeVars         []int
   139  	marker            dwarfgen.ScopeMarker
   140  	lastCloseScopePos src.XPos
   141  
   142  	// === details for handling inline body expansion ===
   143  
   144  	// If we're reading in a function body because of inlining, this is
   145  	// the call that we're inlining for.
   146  	inlCaller    *ir.Func
   147  	inlCall      *ir.CallExpr
   148  	inlFunc      *ir.Func
   149  	inlTreeIndex int
   150  	inlPosBases  map[*src.PosBase]*src.PosBase
   151  
   152  	// suppressInlPos tracks whether position base rewriting for
   153  	// inlining should be suppressed. See funcLit.
   154  	suppressInlPos int
   155  
   156  	delayResults bool
   157  
   158  	// Label to return to.
   159  	retlabel *types.Sym
   160  }
   161  
   162  // A readerDict represents an instantiated "compile-time dictionary,"
   163  // used for resolving any derived types needed for instantiating a
   164  // generic object.
   165  //
   166  // A compile-time dictionary can either be "shaped" or "non-shaped."
   167  // Shaped compile-time dictionaries are only used for instantiating
   168  // shaped type definitions and function bodies, while non-shaped
   169  // compile-time dictionaries are used for instantiating runtime
   170  // dictionaries.
   171  type readerDict struct {
   172  	shaped bool // whether this is a shaped dictionary
   173  
   174  	// baseSym is the symbol for the object this dictionary belongs to.
   175  	// If the object is an instantiated function or defined type, then
   176  	// baseSym is the mangled symbol, including any type arguments.
   177  	baseSym *types.Sym
   178  
   179  	// For non-shaped dictionaries, shapedObj is a reference to the
   180  	// corresponding shaped object (always a function or defined type).
   181  	shapedObj *ir.Name
   182  
   183  	// targs holds the implicit and explicit type arguments in use for
   184  	// reading the current object. For example:
   185  	//
   186  	//	func F[T any]() {
   187  	//		type X[U any] struct { t T; u U }
   188  	//		var _ X[string]
   189  	//	}
   190  	//
   191  	//	var _ = F[int]
   192  	//
   193  	// While instantiating F[int], we need to in turn instantiate
   194  	// X[string]. [int] and [string] are explicit type arguments for F
   195  	// and X, respectively; but [int] is also the implicit type
   196  	// arguments for X.
   197  	//
   198  	// (As an analogy to function literals, explicits are the function
   199  	// literal's formal parameters, while implicits are variables
   200  	// captured by the function literal.)
   201  	targs []*types.Type
   202  
   203  	// implicits counts how many of types within targs are implicit type
   204  	// arguments; the rest are explicit.
   205  	implicits int
   206  	// receivers counts how many of types within targs are receiver type
   207  	// arguments; they are explicit.
   208  	receivers int
   209  
   210  	derived      []derivedInfo // reloc index of the derived type's descriptor
   211  	derivedTypes []*types.Type // slice of previously computed derived types
   212  
   213  	// These slices correspond to entries in the runtime dictionary.
   214  	typeParamMethodExprs []readerMethodExprInfo
   215  	subdicts             []objInfo
   216  	rtypes               []typeInfo
   217  	itabs                []itabInfo
   218  }
   219  
   220  type readerMethodExprInfo struct {
   221  	typeParamIdx int
   222  	method       *types.Sym
   223  }
   224  
   225  func setType(n ir.Node, typ *types.Type) {
   226  	n.SetType(typ)
   227  	n.SetTypecheck(1)
   228  }
   229  
   230  func setValue(name *ir.Name, val constant.Value) {
   231  	name.SetVal(val)
   232  	name.Defn = nil
   233  }
   234  
   235  // @@@ Positions
   236  
   237  // pos reads a position from the bitstream.
   238  func (r *reader) pos() src.XPos {
   239  	return base.Ctxt.PosTable.XPos(r.pos0())
   240  }
   241  
   242  // origPos reads a position from the bitstream, and returns both the
   243  // original raw position and an inlining-adjusted position.
   244  func (r *reader) origPos() (origPos, inlPos src.XPos) {
   245  	r.suppressInlPos++
   246  	origPos = r.pos()
   247  	r.suppressInlPos--
   248  	inlPos = r.inlPos(origPos)
   249  	return
   250  }
   251  
   252  func (r *reader) pos0() src.Pos {
   253  	r.Sync(pkgbits.SyncPos)
   254  	if !r.Bool() {
   255  		return src.NoPos
   256  	}
   257  
   258  	posBase := r.posBase()
   259  	line := r.Uint()
   260  	col := r.Uint()
   261  	return src.MakePos(posBase, line, col)
   262  }
   263  
   264  // posBase reads a position base from the bitstream.
   265  func (r *reader) posBase() *src.PosBase {
   266  	return r.inlPosBase(r.p.posBaseIdx(r.Reloc(pkgbits.SectionPosBase)))
   267  }
   268  
   269  // posBaseIdx returns the specified position base, reading it first if
   270  // needed.
   271  func (pr *pkgReader) posBaseIdx(idx index) *src.PosBase {
   272  	if b := pr.posBases[idx]; b != nil {
   273  		return b
   274  	}
   275  
   276  	r := pr.newReader(pkgbits.SectionPosBase, idx, pkgbits.SyncPosBase)
   277  	var b *src.PosBase
   278  
   279  	absFilename := r.String()
   280  	filename := absFilename
   281  
   282  	// For build artifact stability, the export data format only
   283  	// contains the "absolute" filename as returned by objabi.AbsFile.
   284  	// However, some tests (e.g., test/run.go's asmcheck tests) expect
   285  	// to see the full, original filename printed out. Re-expanding
   286  	// "$GOROOT" to buildcfg.GOROOT is a close-enough approximation to
   287  	// satisfy this.
   288  	//
   289  	// The export data format only ever uses slash paths
   290  	// (for cross-operating-system reproducible builds),
   291  	// but error messages need to use native paths (backslash on Windows)
   292  	// as if they had been specified on the command line.
   293  	// (The go command always passes native paths to the compiler.)
   294  	const dollarGOROOT = "$GOROOT"
   295  	if buildcfg.GOROOT != "" && strings.HasPrefix(filename, dollarGOROOT) {
   296  		filename = filepath.FromSlash(buildcfg.GOROOT + filename[len(dollarGOROOT):])
   297  	}
   298  
   299  	if r.Bool() {
   300  		b = src.NewFileBase(filename, absFilename)
   301  	} else {
   302  		pos := r.pos0()
   303  		line := r.Uint()
   304  		col := r.Uint()
   305  		b = src.NewLinePragmaBase(pos, filename, absFilename, line, col)
   306  	}
   307  
   308  	pr.posBases[idx] = b
   309  	return b
   310  }
   311  
   312  // inlPosBase returns the inlining-adjusted src.PosBase corresponding
   313  // to oldBase, which must be a non-inlined position. When not
   314  // inlining, this is just oldBase.
   315  func (r *reader) inlPosBase(oldBase *src.PosBase) *src.PosBase {
   316  	if index := oldBase.InliningIndex(); index >= 0 {
   317  		base.Fatalf("oldBase %v already has inlining index %v", oldBase, index)
   318  	}
   319  
   320  	if r.inlCall == nil || r.suppressInlPos != 0 {
   321  		return oldBase
   322  	}
   323  
   324  	if newBase, ok := r.inlPosBases[oldBase]; ok {
   325  		return newBase
   326  	}
   327  
   328  	newBase := src.NewInliningBase(oldBase, r.inlTreeIndex)
   329  	r.inlPosBases[oldBase] = newBase
   330  	return newBase
   331  }
   332  
   333  // inlPos returns the inlining-adjusted src.XPos corresponding to
   334  // xpos, which must be a non-inlined position. When not inlining, this
   335  // is just xpos.
   336  func (r *reader) inlPos(xpos src.XPos) src.XPos {
   337  	pos := base.Ctxt.PosTable.Pos(xpos)
   338  	pos.SetBase(r.inlPosBase(pos.Base()))
   339  	return base.Ctxt.PosTable.XPos(pos)
   340  }
   341  
   342  // @@@ Packages
   343  
   344  // pkg reads a package reference from the bitstream.
   345  func (r *reader) pkg() *types.Pkg {
   346  	r.Sync(pkgbits.SyncPkg)
   347  	return r.p.pkgIdx(r.Reloc(pkgbits.SectionPkg))
   348  }
   349  
   350  // pkgIdx returns the specified package from the export data, reading
   351  // it first if needed.
   352  func (pr *pkgReader) pkgIdx(idx index) *types.Pkg {
   353  	if pkg := pr.pkgs[idx]; pkg != nil {
   354  		return pkg
   355  	}
   356  
   357  	pkg := pr.newReader(pkgbits.SectionPkg, idx, pkgbits.SyncPkgDef).doPkg()
   358  	pr.pkgs[idx] = pkg
   359  	return pkg
   360  }
   361  
   362  // doPkg reads a package definition from the bitstream.
   363  func (r *reader) doPkg() *types.Pkg {
   364  	path := r.String()
   365  	switch path {
   366  	case "":
   367  		path = r.p.PkgPath()
   368  	case "builtin":
   369  		return types.BuiltinPkg
   370  	case "unsafe":
   371  		return types.UnsafePkg
   372  	}
   373  
   374  	name := r.String()
   375  
   376  	pkg := types.NewPkg(path, "")
   377  
   378  	if pkg.Name == "" {
   379  		pkg.Name = name
   380  	} else {
   381  		base.Assertf(pkg.Name == name, "package %q has name %q, but want %q", pkg.Path, pkg.Name, name)
   382  	}
   383  
   384  	return pkg
   385  }
   386  
   387  // @@@ Types
   388  
   389  func (r *reader) typ() *types.Type {
   390  	return r.typWrapped(true)
   391  }
   392  
   393  // typWrapped is like typ, but allows suppressing generation of
   394  // unnecessary wrappers as a compile-time optimization.
   395  func (r *reader) typWrapped(wrapped bool) *types.Type {
   396  	return r.p.typIdx(r.typInfo(), r.dict, wrapped)
   397  }
   398  
   399  func (r *reader) typInfo() typeInfo {
   400  	r.Sync(pkgbits.SyncType)
   401  	if r.Bool() {
   402  		return typeInfo{idx: index(r.Len()), derived: true}
   403  	}
   404  	return typeInfo{idx: r.Reloc(pkgbits.SectionType), derived: false}
   405  }
   406  
   407  // typListIdx returns a list of the specified types, resolving derived
   408  // types within the given dictionary.
   409  func (pr *pkgReader) typListIdx(infos []typeInfo, dict *readerDict) []*types.Type {
   410  	typs := make([]*types.Type, len(infos))
   411  	for i, info := range infos {
   412  		typs[i] = pr.typIdx(info, dict, true)
   413  	}
   414  	return typs
   415  }
   416  
   417  // typIdx returns the specified type. If info specifies a derived
   418  // type, it's resolved within the given dictionary. If wrapped is
   419  // true, then method wrappers will be generated, if appropriate.
   420  func (pr *pkgReader) typIdx(info typeInfo, dict *readerDict, wrapped bool) *types.Type {
   421  	idx := info.idx
   422  	var where **types.Type
   423  	if info.derived {
   424  		where = &dict.derivedTypes[idx]
   425  		idx = dict.derived[idx].idx
   426  	} else {
   427  		where = &pr.typs[idx]
   428  	}
   429  
   430  	if typ := *where; typ != nil {
   431  		return typ
   432  	}
   433  
   434  	r := pr.newReader(pkgbits.SectionType, idx, pkgbits.SyncTypeIdx)
   435  	r.dict = dict
   436  
   437  	typ := r.doTyp()
   438  	if typ == nil {
   439  		base.Fatalf("doTyp returned nil for info=%v", info)
   440  	}
   441  
   442  	// For recursive type declarations involving interfaces and aliases,
   443  	// above r.doTyp() call may have already set pr.typs[idx], so just
   444  	// double check and return the type.
   445  	//
   446  	// Example:
   447  	//
   448  	//     type F = func(I)
   449  	//
   450  	//     type I interface {
   451  	//         m(F)
   452  	//     }
   453  	//
   454  	// The writer writes data types in following index order:
   455  	//
   456  	//     0: func(I)
   457  	//     1: I
   458  	//     2: interface{m(func(I))}
   459  	//
   460  	// The reader resolves it in following index order:
   461  	//
   462  	//     0 -> 1 -> 2 -> 0 -> 1
   463  	//
   464  	// and can divide in logically 2 steps:
   465  	//
   466  	//  - 0 -> 1     : first time the reader reach type I,
   467  	//                 it creates new named type with symbol I.
   468  	//
   469  	//  - 2 -> 0 -> 1: the reader ends up reaching symbol I again,
   470  	//                 now the symbol I was setup in above step, so
   471  	//                 the reader just return the named type.
   472  	//
   473  	// Now, the functions called return, the pr.typs looks like below:
   474  	//
   475  	//  - 0 -> 1 -> 2 -> 0 : [<T> I <T>]
   476  	//  - 0 -> 1 -> 2      : [func(I) I <T>]
   477  	//  - 0 -> 1           : [func(I) I interface { "".m(func("".I)) }]
   478  	//
   479  	// The idx 1, corresponding with type I was resolved successfully
   480  	// after r.doTyp() call.
   481  
   482  	if prev := *where; prev != nil {
   483  		return prev
   484  	}
   485  
   486  	if wrapped {
   487  		// Only cache if we're adding wrappers, so that other callers that
   488  		// find a cached type know it was wrapped.
   489  		*where = typ
   490  
   491  		r.needWrapper(typ)
   492  	}
   493  
   494  	if !typ.IsUntyped() {
   495  		types.CheckSize(typ)
   496  	}
   497  
   498  	return typ
   499  }
   500  
   501  func (r *reader) doTyp() *types.Type {
   502  	switch tag := pkgbits.CodeType(r.Code(pkgbits.SyncType)); tag {
   503  	default:
   504  		panic(fmt.Sprintf("unexpected type: %v", tag))
   505  
   506  	case pkgbits.TypeBasic:
   507  		return *basics[r.Len()]
   508  
   509  	case pkgbits.TypeNamed:
   510  		obj := r.obj()
   511  		assert(obj.Op() == ir.OTYPE)
   512  		return obj.Type()
   513  
   514  	case pkgbits.TypeTypeParam:
   515  		return r.dict.targs[r.Len()]
   516  
   517  	case pkgbits.TypeArray:
   518  		len := int64(r.Uint64())
   519  		return types.NewArray(r.typ(), len)
   520  	case pkgbits.TypeChan:
   521  		dir := dirs[r.Len()]
   522  		return types.NewChan(r.typ(), dir)
   523  	case pkgbits.TypeMap:
   524  		return types.NewMap(r.typ(), r.typ())
   525  	case pkgbits.TypePointer:
   526  		return types.NewPtr(r.typ())
   527  	case pkgbits.TypeSignature:
   528  		return r.signature(nil)
   529  	case pkgbits.TypeSlice:
   530  		return types.NewSlice(r.typ())
   531  	case pkgbits.TypeStruct:
   532  		return r.structType()
   533  	case pkgbits.TypeInterface:
   534  		return r.interfaceType()
   535  	case pkgbits.TypeUnion:
   536  		return r.unionType()
   537  	}
   538  }
   539  
   540  func (r *reader) unionType() *types.Type {
   541  	// In the types1 universe, we only need to handle value types.
   542  	// Impure interfaces (i.e., interfaces with non-trivial type sets
   543  	// like "int | string") can only appear as type parameter bounds,
   544  	// and this is enforced by the types2 type checker.
   545  	//
   546  	// However, type unions can still appear in pure interfaces if the
   547  	// type union is equivalent to "any". E.g., typeparam/issue52124.go
   548  	// declares variables with the type "interface { any | int }".
   549  	//
   550  	// To avoid needing to represent type unions in types1 (since we
   551  	// don't have any uses for that today anyway), we simply fold them
   552  	// to "any".
   553  
   554  	// TODO(mdempsky): Restore consistency check to make sure folding to
   555  	// "any" is safe. This is unfortunately tricky, because a pure
   556  	// interface can reference impure interfaces too, including
   557  	// cyclically (#60117).
   558  	if false {
   559  		pure := false
   560  		for i, n := 0, r.Len(); i < n; i++ {
   561  			_ = r.Bool() // tilde
   562  			term := r.typ()
   563  			if term.IsEmptyInterface() {
   564  				pure = true
   565  			}
   566  		}
   567  		if !pure {
   568  			base.Fatalf("impure type set used in value type")
   569  		}
   570  	}
   571  
   572  	return types.Types[types.TINTER]
   573  }
   574  
   575  func (r *reader) interfaceType() *types.Type {
   576  	nmethods, nembeddeds := r.Len(), r.Len()
   577  	implicit := nmethods == 0 && nembeddeds == 1 && r.Bool()
   578  	assert(!implicit) // implicit interfaces only appear in constraints
   579  
   580  	fields := make([]*types.Field, nmethods+nembeddeds)
   581  	methods, embeddeds := fields[:nmethods], fields[nmethods:]
   582  
   583  	for i := range methods {
   584  		methods[i] = types.NewField(r.pos(), r.selector(), r.signature(types.FakeRecv()))
   585  	}
   586  	for i := range embeddeds {
   587  		embeddeds[i] = types.NewField(src.NoXPos, nil, r.typ())
   588  	}
   589  
   590  	if len(fields) == 0 {
   591  		return types.Types[types.TINTER] // empty interface
   592  	}
   593  	return types.NewInterface(fields)
   594  }
   595  
   596  func (r *reader) structType() *types.Type {
   597  	fields := make([]*types.Field, r.Len())
   598  	for i := range fields {
   599  		field := types.NewField(r.pos(), r.selector(), r.typ())
   600  		field.Note = r.String()
   601  		if r.Bool() {
   602  			field.Embedded = 1
   603  		}
   604  		fields[i] = field
   605  	}
   606  	return types.NewStruct(fields)
   607  }
   608  
   609  func (r *reader) signature(recv *types.Field) *types.Type {
   610  	r.Sync(pkgbits.SyncSignature)
   611  
   612  	params := r.params()
   613  	results := r.params()
   614  	if r.Bool() { // variadic
   615  		params[len(params)-1].SetIsDDD(true)
   616  	}
   617  
   618  	return types.NewSignature(recv, params, results)
   619  }
   620  
   621  func (r *reader) params() []*types.Field {
   622  	r.Sync(pkgbits.SyncParams)
   623  	params := make([]*types.Field, r.Len())
   624  	for i := range params {
   625  		params[i] = r.param()
   626  	}
   627  	return params
   628  }
   629  
   630  func (r *reader) param() *types.Field {
   631  	r.Sync(pkgbits.SyncParam)
   632  	return types.NewField(r.pos(), r.localIdent(), r.typ())
   633  }
   634  
   635  // @@@ Objects
   636  
   637  // objReader maps qualified identifiers (represented as *types.Sym) to
   638  // a pkgReader and corresponding index that can be used for reading
   639  // that object's definition.
   640  var objReader = map[*types.Sym]pkgReaderIndex{}
   641  
   642  // obj reads an instantiated object reference from the bitstream.
   643  func (r *reader) obj() ir.Node {
   644  	return r.p.objInstIdx(r.objInfo(), r.dict, false)
   645  }
   646  
   647  // objInfo reads an instantiated object reference from the bitstream
   648  // and returns the encoded reference to it, without instantiating it.
   649  func (r *reader) objInfo() objInfo {
   650  	r.Sync(pkgbits.SyncObject)
   651  	if r.Version().Has(pkgbits.DerivedFuncInstance) {
   652  		assert(!r.Bool())
   653  	}
   654  	idx := r.Reloc(pkgbits.SectionObj)
   655  
   656  	explicits := make([]typeInfo, r.Len())
   657  	for i := range explicits {
   658  		explicits[i] = r.typInfo()
   659  	}
   660  
   661  	return objInfo{idx, explicits}
   662  }
   663  
   664  // objInstIdx returns the encoded, instantiated object. If shaped is
   665  // true, then the shaped variant of the object is returned instead.
   666  func (pr *pkgReader) objInstIdx(info objInfo, dict *readerDict, shaped bool) ir.Node {
   667  	explicits := pr.typListIdx(info.explicits, dict)
   668  
   669  	var implicits []*types.Type
   670  	if dict != nil {
   671  		implicits = dict.targs
   672  	}
   673  
   674  	return pr.objIdx(info.idx, implicits, explicits, shaped)
   675  }
   676  
   677  // objIdx returns the specified object, instantiated with the given
   678  // type arguments, if any.
   679  // If shaped is true, then the shaped variant of the object is returned
   680  // instead.
   681  func (pr *pkgReader) objIdx(idx index, implicits, explicits []*types.Type, shaped bool) ir.Node {
   682  	n, err := pr.objIdxMayFail(idx, implicits, explicits, shaped)
   683  	if err != nil {
   684  		base.Fatalf("%v", err)
   685  	}
   686  	return n
   687  }
   688  
   689  // objIdxMayFail is equivalent to objIdx, but returns an error rather than
   690  // failing the build if this object requires type arguments and the incorrect
   691  // number of type arguments were passed.
   692  //
   693  // Other sources of internal failure (such as duplicate definitions) still fail
   694  // the build.
   695  func (pr *pkgReader) objIdxMayFail(idx index, implicits, explicits []*types.Type, shaped bool) (ir.Node, error) {
   696  	rname := pr.newReader(pkgbits.SectionName, idx, pkgbits.SyncObject1)
   697  	_, sym := rname.qualifiedIdent()
   698  	tag := pkgbits.CodeObj(rname.Code(pkgbits.SyncCodeObj))
   699  
   700  	if tag == pkgbits.ObjStub {
   701  		assert(!sym.IsBlank())
   702  		switch sym.Pkg {
   703  		case types.BuiltinPkg, types.UnsafePkg:
   704  			return sym.Def.(ir.Node), nil
   705  		}
   706  		if pri, ok := objReader[sym]; ok {
   707  			return pri.pr.objIdxMayFail(pri.idx, nil, explicits, shaped)
   708  		}
   709  		if sym.Pkg.Path == "runtime" {
   710  			return typecheck.LookupRuntime(sym.Name), nil
   711  		}
   712  		base.Fatalf("unresolved stub: %v", sym)
   713  	}
   714  
   715  	dict, err := pr.objDictIdx(sym, idx, implicits, explicits, shaped)
   716  	if err != nil {
   717  		return nil, err
   718  	}
   719  
   720  	sym = dict.baseSym
   721  	if !sym.IsBlank() && sym.Def != nil {
   722  		return sym.Def.(*ir.Name), nil
   723  	}
   724  
   725  	r := pr.newReader(pkgbits.SectionObj, idx, pkgbits.SyncObject1)
   726  	rext := pr.newReader(pkgbits.SectionObjExt, idx, pkgbits.SyncObject1)
   727  
   728  	r.dict = dict
   729  	rext.dict = dict
   730  
   731  	do := func(op ir.Op, hasTParams bool) *ir.Name {
   732  		pos := r.pos()
   733  		setBasePos(pos)
   734  		if hasTParams {
   735  			r.typeParamNames()
   736  		}
   737  
   738  		name := ir.NewDeclNameAt(pos, op, sym)
   739  		name.Class = ir.PEXTERN // may be overridden later
   740  		if !sym.IsBlank() {
   741  			if sym.Def != nil {
   742  				base.FatalfAt(name.Pos(), "already have a definition for %v", name)
   743  			}
   744  			assert(sym.Def == nil)
   745  			sym.Def = name
   746  		}
   747  		return name
   748  	}
   749  
   750  	switch tag {
   751  	default:
   752  		panic("unexpected object")
   753  
   754  	case pkgbits.ObjAlias:
   755  		name := do(ir.OTYPE, false)
   756  
   757  		if r.Version().Has(pkgbits.AliasTypeParamNames) {
   758  			r.typeParamNames()
   759  		}
   760  
   761  		// Clumsy dance: the r.typ() call here might recursively find this
   762  		// type alias name, before we've set its type (#66873). So we
   763  		// temporarily clear sym.Def and then restore it later, if still
   764  		// unset.
   765  		hack := sym.Def == name
   766  		if hack {
   767  			sym.Def = nil
   768  		}
   769  		typ := r.typ()
   770  		if hack {
   771  			if sym.Def != nil {
   772  				name = sym.Def.(*ir.Name)
   773  				assert(types.IdenticalStrict(name.Type(), typ))
   774  				return name, nil
   775  			}
   776  			sym.Def = name
   777  		}
   778  
   779  		setType(name, typ)
   780  		name.SetAlias(true)
   781  		return name, nil
   782  
   783  	case pkgbits.ObjConst:
   784  		name := do(ir.OLITERAL, false)
   785  		typ := r.typ()
   786  		val := FixValue(typ, r.Value())
   787  		setType(name, typ)
   788  		setValue(name, val)
   789  		return name, nil
   790  
   791  	case pkgbits.ObjFunc:
   792  		npos := r.pos()
   793  		setBasePos(npos)
   794  
   795  		var sel *types.Sym
   796  		var recv *types.Field
   797  		if r.Version().Has(pkgbits.GenericMethods) && r.Bool() {
   798  			sel = r.selector()
   799  			r.recvTypeParamNames()
   800  			recv = r.param()
   801  		} else {
   802  			if sym.Name == "init" {
   803  				sym = Renameinit()
   804  			}
   805  		}
   806  		r.typeParamNames()
   807  		typ := r.signature(recv)
   808  		fpos := r.pos()
   809  
   810  		fn := ir.NewFunc(fpos, npos, sym, typ)
   811  		if r.hasTypeParams() && r.dict.shaped {
   812  			typ.SetHasShape(true)
   813  		}
   814  
   815  		name := fn.Nname
   816  		if !sym.IsBlank() {
   817  			if sym.Def != nil {
   818  				base.FatalfAt(name.Pos(), "already have a definition for %v", name)
   819  			}
   820  			assert(sym.Def == nil)
   821  			sym.Def = name
   822  		}
   823  
   824  		if r.hasTypeParams() {
   825  			name.Func.SetDupok(true)
   826  			if r.dict.shaped {
   827  				setType(name, shapeSig(name.Func, r.dict))
   828  			} else {
   829  				todoDicts = append(todoDicts, func() {
   830  					r.dict.shapedObj = pr.objIdx(idx, implicits, explicits, true).(*ir.Name)
   831  				})
   832  			}
   833  		}
   834  
   835  		rext.funcExt(name, sel)
   836  		return name, nil
   837  
   838  	case pkgbits.ObjType:
   839  		name := do(ir.OTYPE, true)
   840  		typ := types.NewNamed(name)
   841  		setType(name, typ)
   842  		if r.hasTypeParams() && r.dict.shaped {
   843  			typ.SetHasShape(true)
   844  		}
   845  
   846  		// Important: We need to do this before SetUnderlying.
   847  		rext.typeExt(name)
   848  
   849  		// We need to defer CheckSize until we've called SetUnderlying to
   850  		// handle recursive types.
   851  		types.DeferCheckSize()
   852  		typ.SetUnderlying(r.typWrapped(false))
   853  		types.ResumeCheckSize()
   854  
   855  		if r.hasTypeParams() && !r.dict.shaped {
   856  			todoDicts = append(todoDicts, func() {
   857  				r.dict.shapedObj = pr.objIdx(idx, implicits, explicits, true).(*ir.Name)
   858  			})
   859  		}
   860  
   861  		methods := make([]*types.Field, r.Len())
   862  		for i := range methods {
   863  			methods[i] = r.method(rext)
   864  		}
   865  		if len(methods) != 0 {
   866  			typ.SetMethods(methods)
   867  		}
   868  
   869  		if !r.dict.shaped {
   870  			r.needWrapper(typ)
   871  		}
   872  
   873  		return name, nil
   874  
   875  	case pkgbits.ObjVar:
   876  		name := do(ir.ONAME, false)
   877  		setType(name, r.typ())
   878  		rext.varExt(name)
   879  		return name, nil
   880  	}
   881  }
   882  
   883  // mangle shapes the non-shaped symbol sym under the current dictionary.
   884  func (dict *readerDict) mangle(sym *types.Sym) *types.Sym {
   885  	if !dict.hasTypeParams() {
   886  		return sym
   887  	}
   888  
   889  	var buf strings.Builder
   890  	// If sym is a locally defined generic type, we need the suffix to
   891  	// stay at the end after mangling so that types/fmt.go can strip it
   892  	// out again when writing the type's runtime descriptor (#54456).
   893  	n0, vsuff := types.SplitVargenSuffix(sym.Name)
   894  	n1, msuff := types.SplitMethSuffix(sym.Name)
   895  
   896  	// Methods are never locally defined.
   897  	var n string
   898  	assert(vsuff == "" || msuff == "")
   899  	if vsuff != "" {
   900  		n = n0
   901  	} else {
   902  		n = n1
   903  	}
   904  
   905  	var j int
   906  	assert(dict.implicits == 0 || dict.receivers == 0)
   907  	if msuff != "" {
   908  		j = dict.receivers // consume receiver type arguments
   909  	} else {
   910  		j = len(dict.targs) // consume all type arguments
   911  	}
   912  
   913  	// put type arguments inside parenthesis; (*T)[int] -> (*T[int])
   914  	n, ok := strings.CutSuffix(n, ")")
   915  
   916  	// type arguments, if any
   917  	buf.WriteString(n)
   918  	if j > 0 {
   919  		buf.WriteByte('[')
   920  		for i := 0; i < j; i++ {
   921  			if i > 0 {
   922  				if i == dict.implicits {
   923  					buf.WriteByte(';')
   924  				} else {
   925  					buf.WriteByte(',')
   926  				}
   927  			}
   928  			buf.WriteString(dict.targs[i].LinkString())
   929  		}
   930  		buf.WriteByte(']')
   931  	}
   932  
   933  	if ok {
   934  		buf.WriteString(")")
   935  	}
   936  
   937  	buf.WriteString(vsuff)
   938  	buf.WriteString(msuff)
   939  
   940  	// method arguments, if any
   941  	if msuff != "" {
   942  		buf.WriteByte('[')
   943  		for i := j; i < len(dict.targs); i++ {
   944  			if i > j {
   945  				buf.WriteByte(',')
   946  			}
   947  			buf.WriteString(dict.targs[i].LinkString())
   948  		}
   949  		buf.WriteByte(']')
   950  	}
   951  
   952  	return sym.Pkg.Lookup(buf.String())
   953  }
   954  
   955  // Shapify returns the shape type for targ.
   956  //
   957  // If basic is true, then the type argument is used to instantiate a
   958  // type parameter whose constraint is a basic interface.
   959  func Shapify(targ *types.Type, basic bool) *types.Type {
   960  	if targ.Kind() == types.TFORW {
   961  		if targ.IsFullyInstantiated() {
   962  			// For recursive instantiated type argument, it may  still be a TFORW
   963  			// when shapifying happens. If we don't have targ's underlying type,
   964  			// shapify won't work. The worst case is we end up not reusing code
   965  			// optimally in some tricky cases.
   966  			if base.Debug.Shapify != 0 {
   967  				base.Warn("skipping shaping of recursive type %v", targ)
   968  			}
   969  			if targ.HasShape() {
   970  				return targ
   971  			}
   972  		} else {
   973  			base.Fatalf("%v is missing its underlying type", targ)
   974  		}
   975  	}
   976  	// For fully instantiated shape interface type, use it as-is. Otherwise, the instantiation
   977  	// involved recursive generic interface may cause mismatching in function signature, see issue #65362.
   978  	if targ.Kind() == types.TINTER && targ.IsFullyInstantiated() && targ.HasShape() {
   979  		return targ
   980  	}
   981  
   982  	// When a pointer type is used to instantiate a type parameter
   983  	// constrained by a basic interface, we know the pointer's element
   984  	// type can't matter to the generated code. In this case, we can use
   985  	// an arbitrary pointer type as the shape type. (To match the
   986  	// non-unified frontend, we use `*byte`.)
   987  	//
   988  	// Otherwise, we simply use the type's underlying type as its shape.
   989  	//
   990  	// TODO(mdempsky): It should be possible to do much more aggressive
   991  	// shaping still; e.g., collapsing all pointer-shaped types into a
   992  	// common type, collapsing scalars of the same size/alignment into a
   993  	// common type, recursively shaping the element types of composite
   994  	// types, and discarding struct field names and tags. However, we'll
   995  	// need to start tracking how type parameters are actually used to
   996  	// implement some of these optimizations.
   997  	under := targ.Underlying()
   998  	if basic && targ.IsPtr() && !targ.Elem().NotInHeap() {
   999  		under = types.NewPtr(types.Types[types.TUINT8])
  1000  	}
  1001  
  1002  	// Hash long type names to bound symbol name length seen by users,
  1003  	// particularly for large protobuf structs (#65030).
  1004  	uls := under.LinkString()
  1005  	if base.Debug.MaxShapeLen != 0 &&
  1006  		len(uls) > base.Debug.MaxShapeLen {
  1007  		h := hash.Sum32([]byte(uls))
  1008  		uls = hex.EncodeToString(h[:])
  1009  	}
  1010  
  1011  	sym := types.ShapePkg.Lookup(uls)
  1012  	if sym.Def == nil {
  1013  		name := ir.NewDeclNameAt(under.Pos(), ir.OTYPE, sym)
  1014  		typ := types.NewNamed(name)
  1015  		typ.SetUnderlying(under)
  1016  		sym.Def = typed(typ, name)
  1017  	}
  1018  	res := sym.Def.Type()
  1019  	assert(res.IsShape())
  1020  	assert(res.HasShape())
  1021  	return res
  1022  }
  1023  
  1024  // objDictIdx reads and returns the specified object dictionary.
  1025  func (pr *pkgReader) objDictIdx(sym *types.Sym, idx index, implicits, explicits []*types.Type, shaped bool) (*readerDict, error) {
  1026  	r := pr.newReader(pkgbits.SectionObjDict, idx, pkgbits.SyncObject1)
  1027  
  1028  	dict := readerDict{
  1029  		shaped: shaped,
  1030  	}
  1031  
  1032  	nimplicits := r.Len()
  1033  	nreceivers := 0
  1034  	if r.Version().Has(pkgbits.GenericMethods) {
  1035  		nreceivers = r.Len()
  1036  	}
  1037  	nexplicits := r.Len() + nreceivers
  1038  
  1039  	if nimplicits > len(implicits) || nexplicits != len(explicits) {
  1040  		return nil, fmt.Errorf("%v has %v+%v params, but instantiated with %v+%v args", sym, nimplicits, nexplicits, len(implicits), len(explicits))
  1041  	}
  1042  
  1043  	dict.targs = append(implicits[:nimplicits:nimplicits], explicits...)
  1044  	dict.implicits = nimplicits
  1045  	dict.receivers = nreceivers
  1046  
  1047  	// Within the compiler, we can just skip over the type parameters.
  1048  	for range dict.targs[dict.implicits:] {
  1049  		// Skip past bounds without actually evaluating them.
  1050  		r.typInfo()
  1051  	}
  1052  
  1053  	dict.derived = make([]derivedInfo, r.Len())
  1054  	dict.derivedTypes = make([]*types.Type, len(dict.derived))
  1055  	for i := range dict.derived {
  1056  		dict.derived[i] = derivedInfo{idx: r.Reloc(pkgbits.SectionType)}
  1057  		if r.Version().Has(pkgbits.DerivedInfoNeeded) {
  1058  			assert(!r.Bool())
  1059  		}
  1060  	}
  1061  
  1062  	// Runtime dictionary information; private to the compiler.
  1063  
  1064  	// If any type argument is already shaped, then we're constructing a
  1065  	// shaped object, even if not explicitly requested (i.e., calling
  1066  	// objIdx with shaped==true). This can happen with instantiating
  1067  	// types that are referenced within a function body.
  1068  	for _, targ := range dict.targs {
  1069  		if targ.HasShape() {
  1070  			dict.shaped = true
  1071  			break
  1072  		}
  1073  	}
  1074  
  1075  	// And if we're constructing a shaped object, then shapify all type
  1076  	// arguments.
  1077  	for i, targ := range dict.targs {
  1078  		basic := r.Bool()
  1079  		if dict.shaped {
  1080  			dict.targs[i] = Shapify(targ, basic)
  1081  		}
  1082  	}
  1083  
  1084  	dict.baseSym = dict.mangle(sym)
  1085  
  1086  	dict.typeParamMethodExprs = make([]readerMethodExprInfo, r.Len())
  1087  	for i := range dict.typeParamMethodExprs {
  1088  		typeParamIdx := r.Len()
  1089  		method := r.selector()
  1090  
  1091  		dict.typeParamMethodExprs[i] = readerMethodExprInfo{typeParamIdx, method}
  1092  	}
  1093  
  1094  	dict.subdicts = make([]objInfo, r.Len())
  1095  	for i := range dict.subdicts {
  1096  		dict.subdicts[i] = r.objInfo()
  1097  	}
  1098  
  1099  	dict.rtypes = make([]typeInfo, r.Len())
  1100  	for i := range dict.rtypes {
  1101  		dict.rtypes[i] = r.typInfo()
  1102  	}
  1103  
  1104  	dict.itabs = make([]itabInfo, r.Len())
  1105  	for i := range dict.itabs {
  1106  		dict.itabs[i] = itabInfo{typ: r.typInfo(), iface: r.typInfo()}
  1107  	}
  1108  
  1109  	return &dict, nil
  1110  }
  1111  
  1112  func (r *reader) recvTypeParamNames() {
  1113  	r.Sync(pkgbits.SyncTypeParamNames)
  1114  
  1115  	for range r.dict.targs[r.dict.implicits : r.dict.implicits+r.dict.receivers] {
  1116  		r.pos()
  1117  		r.localIdent()
  1118  	}
  1119  }
  1120  
  1121  func (r *reader) typeParamNames() {
  1122  	r.Sync(pkgbits.SyncTypeParamNames)
  1123  
  1124  	for range r.dict.targs[r.dict.implicits+r.dict.receivers:] {
  1125  		r.pos()
  1126  		r.localIdent()
  1127  	}
  1128  }
  1129  
  1130  func (r *reader) method(rext *reader) *types.Field {
  1131  	r.Sync(pkgbits.SyncMethod)
  1132  	npos := r.pos()
  1133  	sym := r.selector()
  1134  	r.typeParamNames()
  1135  	recv := r.param()
  1136  	typ := r.signature(recv)
  1137  
  1138  	fpos := r.pos()
  1139  	fn := ir.NewFunc(fpos, npos, ir.MethodSym(recv.Type, sym), typ)
  1140  	name := fn.Nname
  1141  
  1142  	if r.hasTypeParams() {
  1143  		name.Func.SetDupok(true)
  1144  		if r.dict.shaped {
  1145  			typ = shapeSig(name.Func, r.dict)
  1146  			setType(name, typ)
  1147  		}
  1148  	}
  1149  
  1150  	rext.funcExt(name, sym)
  1151  
  1152  	meth := types.NewField(name.Func.Pos(), sym, typ)
  1153  	meth.Nname = name
  1154  	meth.SetNointerface(name.Func.Pragma&ir.Nointerface != 0)
  1155  
  1156  	return meth
  1157  }
  1158  
  1159  func (r *reader) qualifiedIdent() (pkg *types.Pkg, sym *types.Sym) {
  1160  	r.Sync(pkgbits.SyncSym)
  1161  	pkg = r.pkg()
  1162  	if name := r.String(); name != "" {
  1163  		sym = pkg.Lookup(name)
  1164  	}
  1165  	return
  1166  }
  1167  
  1168  func (r *reader) localIdent() *types.Sym {
  1169  	r.Sync(pkgbits.SyncLocalIdent)
  1170  	pkg := r.pkg()
  1171  	if name := r.String(); name != "" {
  1172  		return pkg.Lookup(name)
  1173  	}
  1174  	return nil
  1175  }
  1176  
  1177  func (r *reader) selector() *types.Sym {
  1178  	r.Sync(pkgbits.SyncSelector)
  1179  	pkg := r.pkg()
  1180  	name := r.String()
  1181  	if types.IsExported(name) {
  1182  		pkg = types.LocalPkg
  1183  	}
  1184  	return pkg.Lookup(name)
  1185  }
  1186  
  1187  func (r *reader) hasTypeParams() bool {
  1188  	return r.dict.hasTypeParams()
  1189  }
  1190  
  1191  func (dict *readerDict) hasTypeParams() bool {
  1192  	return dict != nil && len(dict.targs) != 0
  1193  }
  1194  
  1195  // @@@ Compiler extensions
  1196  
  1197  func (r *reader) funcExt(name *ir.Name, method *types.Sym) {
  1198  	r.Sync(pkgbits.SyncFuncExt)
  1199  
  1200  	fn := name.Func
  1201  
  1202  	// XXX: Workaround because linker doesn't know how to copy Pos.
  1203  	if !fn.Pos().IsKnown() {
  1204  		fn.SetPos(name.Pos())
  1205  	}
  1206  
  1207  	// Normally, we only compile local functions, which saves redundant compilation work.
  1208  	// n.Defn is not nil for local functions, and is nil for imported function. But for
  1209  	// generic functions, we might have an instantiation that no other package has seen before.
  1210  	// So we need to be conservative and compile it again.
  1211  	//
  1212  	// That's why name.Defn is set here, so ir.VisitFuncsBottomUp can analyze function.
  1213  	// TODO(mdempsky,cuonglm): find a cleaner way to handle this.
  1214  	if name.Sym().Pkg == types.LocalPkg || r.hasTypeParams() {
  1215  		name.Defn = fn
  1216  	}
  1217  
  1218  	fn.Pragma = r.pragmaFlag()
  1219  	r.linkname(name)
  1220  
  1221  	if buildcfg.GOARCH == "wasm" {
  1222  		importmod := r.String()
  1223  		importname := r.String()
  1224  		exportname := r.String()
  1225  
  1226  		if importmod != "" && importname != "" {
  1227  			fn.WasmImport = &ir.WasmImport{
  1228  				Module: importmod,
  1229  				Name:   importname,
  1230  			}
  1231  		}
  1232  		if exportname != "" {
  1233  			if method != nil {
  1234  				base.ErrorfAt(fn.Pos(), 0, "cannot use //go:wasmexport on a method")
  1235  			}
  1236  			fn.WasmExport = &ir.WasmExport{Name: exportname}
  1237  		}
  1238  	}
  1239  
  1240  	if r.Bool() {
  1241  		assert(name.Defn == nil)
  1242  
  1243  		fn.ABI = obj.ABI(r.Uint64())
  1244  
  1245  		// Escape analysis.
  1246  		for _, f := range name.Type().RecvParams() {
  1247  			f.Note = r.String()
  1248  		}
  1249  
  1250  		if r.Bool() {
  1251  			fn.Inl = &ir.Inline{
  1252  				Cost:            int32(r.Len()),
  1253  				CanDelayResults: r.Bool(),
  1254  			}
  1255  			if buildcfg.Experiment.NewInliner {
  1256  				fn.Inl.Properties = r.String()
  1257  			}
  1258  		}
  1259  	} else {
  1260  		r.addBody(name.Func, method)
  1261  	}
  1262  	r.Sync(pkgbits.SyncEOF)
  1263  }
  1264  
  1265  func (r *reader) typeExt(name *ir.Name) {
  1266  	r.Sync(pkgbits.SyncTypeExt)
  1267  
  1268  	typ := name.Type()
  1269  
  1270  	if r.hasTypeParams() {
  1271  		// Mark type as fully instantiated to ensure the type descriptor is written
  1272  		// out as DUPOK and method wrappers are generated even for imported types.
  1273  		typ.SetIsFullyInstantiated(true)
  1274  		// HasShape should be set if any type argument is or has a shape type.
  1275  		for _, targ := range r.dict.targs {
  1276  			if targ.HasShape() {
  1277  				typ.SetHasShape(true)
  1278  				break
  1279  			}
  1280  		}
  1281  	}
  1282  
  1283  	name.SetPragma(r.pragmaFlag())
  1284  
  1285  	typecheck.SetBaseTypeIndex(typ, r.Int64(), r.Int64())
  1286  }
  1287  
  1288  func (r *reader) varExt(name *ir.Name) {
  1289  	r.Sync(pkgbits.SyncVarExt)
  1290  	r.linkname(name)
  1291  }
  1292  
  1293  func (r *reader) linkname(name *ir.Name) {
  1294  	assert(name.Op() == ir.ONAME)
  1295  	r.Sync(pkgbits.SyncLinkname)
  1296  
  1297  	if idx := r.Int64(); idx >= 0 {
  1298  		lsym := name.Linksym()
  1299  		lsym.SymIdx = int32(idx)
  1300  		lsym.Set(obj.AttrIndexed, true)
  1301  	} else {
  1302  		linkname := r.String()
  1303  		std := r.Bool()
  1304  		sym := name.Sym()
  1305  		sym.Linkname = linkname
  1306  		if sym.Pkg == types.LocalPkg && linkname != "" {
  1307  			// Mark linkname in the current package. We don't mark the
  1308  			// ones that are imported and propagated (e.g. through
  1309  			// inlining or instantiation, which are marked in their
  1310  			// corresponding packages). So we can tell in which package
  1311  			// the linkname is used (pulled), and the linker can
  1312  			// make a decision for allowing or disallowing it.
  1313  			if std {
  1314  				sym.Linksym().Set(obj.AttrLinknameStd, true)
  1315  			} else {
  1316  				sym.Linksym().Set(obj.AttrLinkname, true)
  1317  			}
  1318  		}
  1319  	}
  1320  }
  1321  
  1322  func (r *reader) pragmaFlag() ir.PragmaFlag {
  1323  	r.Sync(pkgbits.SyncPragma)
  1324  	return ir.PragmaFlag(r.Int())
  1325  }
  1326  
  1327  // @@@ Function bodies
  1328  
  1329  // bodyReader tracks where the serialized IR for a local or imported,
  1330  // generic function's body can be found.
  1331  var bodyReader = map[*ir.Func]pkgReaderIndex{}
  1332  
  1333  // importBodyReader tracks where the serialized IR for an imported,
  1334  // static (i.e., non-generic) function body can be read.
  1335  var importBodyReader = map[*types.Sym]pkgReaderIndex{}
  1336  
  1337  // bodyReaderFor returns the pkgReaderIndex for reading fn's
  1338  // serialized IR, and whether one was found.
  1339  func bodyReaderFor(fn *ir.Func) (pri pkgReaderIndex, ok bool) {
  1340  	if fn.Nname.Defn != nil {
  1341  		pri, ok = bodyReader[fn]
  1342  		base.AssertfAt(ok, base.Pos, "must have bodyReader for %v", fn) // must always be available
  1343  	} else {
  1344  		pri, ok = importBodyReader[fn.Sym()]
  1345  	}
  1346  	return
  1347  }
  1348  
  1349  // todoDicts holds the list of dictionaries that still need their
  1350  // runtime dictionary objects constructed.
  1351  var todoDicts []func()
  1352  
  1353  // todoBodies holds the list of function bodies that still need to be
  1354  // constructed.
  1355  var todoBodies []*ir.Func
  1356  
  1357  // addBody reads a function body reference from the element bitstream,
  1358  // and associates it with fn.
  1359  func (r *reader) addBody(fn *ir.Func, method *types.Sym) {
  1360  	// addBody should only be called for local functions or imported
  1361  	// generic functions; see comment in funcExt.
  1362  	assert(fn.Nname.Defn != nil)
  1363  
  1364  	idx := r.Reloc(pkgbits.SectionBody)
  1365  
  1366  	pri := pkgReaderIndex{r.p, idx, r.dict, method, nil}
  1367  	bodyReader[fn] = pri
  1368  
  1369  	if r.curfn == nil {
  1370  		todoBodies = append(todoBodies, fn)
  1371  		return
  1372  	}
  1373  
  1374  	pri.funcBody(fn)
  1375  }
  1376  
  1377  func (pri pkgReaderIndex) funcBody(fn *ir.Func) {
  1378  	r := pri.asReader(pkgbits.SectionBody, pkgbits.SyncFuncBody)
  1379  	panicking := true
  1380  	defer func() {
  1381  		if panicking {
  1382  			// TODO not sure what the best way to print in this context is.
  1383  			// If code panics in unified IR reading, you want *something* like this.
  1384  			// Whoever ends up debugging the next unified IR failure, please
  1385  			// improve this (base.Warnf?) if you can figure out how.
  1386  			fmt.Printf("****** panic traversed funcBody of %v\n", fn)
  1387  		}
  1388  	}()
  1389  	r.funcBody(fn)
  1390  	panicking = false
  1391  
  1392  }
  1393  
  1394  // funcBody reads a function body definition from the element
  1395  // bitstream, and populates fn with it.
  1396  func (r *reader) funcBody(fn *ir.Func) {
  1397  	r.curfn = fn
  1398  	r.closureVars = fn.ClosureVars
  1399  	if len(r.closureVars) != 0 && r.hasTypeParams() {
  1400  		r.dictParam = r.closureVars[len(r.closureVars)-1] // dictParam is last; see reader.funcLit
  1401  	}
  1402  
  1403  	ir.WithFunc(fn, func() {
  1404  		r.declareParams()
  1405  
  1406  		if r.syntheticBody(fn.Pos()) {
  1407  			return
  1408  		}
  1409  
  1410  		if !r.Bool() {
  1411  			return
  1412  		}
  1413  
  1414  		body := r.stmts()
  1415  		if body == nil {
  1416  			body = []ir.Node{typecheck.Stmt(ir.NewBlockStmt(src.NoXPos, nil))}
  1417  		}
  1418  		fn.Body = body
  1419  		fn.Endlineno = r.pos()
  1420  	})
  1421  
  1422  	r.marker.WriteTo(fn)
  1423  }
  1424  
  1425  // syntheticBody adds a synthetic body to r.curfn if appropriate, and
  1426  // reports whether it did.
  1427  func (r *reader) syntheticBody(pos src.XPos) bool {
  1428  	if r.synthetic != nil {
  1429  		r.synthetic(pos, r)
  1430  		return true
  1431  	}
  1432  
  1433  	// If this function has type parameters and isn't shaped, then we
  1434  	// just tail call its corresponding shaped variant.
  1435  	if r.hasTypeParams() && !r.dict.shaped {
  1436  		r.callShaped(pos)
  1437  		return true
  1438  	}
  1439  
  1440  	return false
  1441  }
  1442  
  1443  // callShaped emits a tail call to r.shapedFn, passing along the
  1444  // arguments to the current function.
  1445  func (r *reader) callShaped(pos src.XPos) {
  1446  	shapedObj := r.dict.shapedObj
  1447  	assert(shapedObj != nil)
  1448  
  1449  	var shapedFn ir.Node
  1450  	if r.methodSym == nil {
  1451  		// Instantiating a generic function; shapedObj is the shaped function itself.
  1452  		assert(shapedObj.Op() == ir.ONAME && shapedObj.Class == ir.PFUNC)
  1453  		shapedFn = shapedObj
  1454  	} else {
  1455  		// Instantiating a generic type's method; shapedObj is the shaped method itself
  1456  		// if the method is generic — else, it is the shaped type declaring the method.
  1457  		shapedFn = shapedMethodExpr(pos, shapedObj, r.methodSym)
  1458  	}
  1459  
  1460  	params := r.syntheticArgs()
  1461  
  1462  	// Construct the arguments list: receiver (if any), then runtime
  1463  	// dictionary, and finally normal parameters.
  1464  	//
  1465  	// Note: For simplicity, shaped methods are added as normal methods
  1466  	// on their shaped types. So existing code (e.g., packages ir and
  1467  	// typecheck) expects the shaped type to appear as the receiver
  1468  	// parameter (or first parameter, as a method expression). Hence
  1469  	// putting the dictionary parameter after that is the least invasive
  1470  	// solution at the moment.
  1471  	var args ir.Nodes
  1472  	if r.methodSym != nil {
  1473  		args.Append(params[0])
  1474  		params = params[1:]
  1475  	}
  1476  	args.Append(typecheck.Expr(ir.NewAddrExpr(pos, r.p.dictNameOf(r.dict))))
  1477  	args.Append(params...)
  1478  
  1479  	r.syntheticTailCall(pos, shapedFn, args)
  1480  }
  1481  
  1482  // syntheticArgs returns the recvs and params arguments passed to the
  1483  // current function.
  1484  func (r *reader) syntheticArgs() ir.Nodes {
  1485  	sig := r.curfn.Nname.Type()
  1486  	return ir.ToNodes(r.curfn.Dcl[:sig.NumRecvs()+sig.NumParams()])
  1487  }
  1488  
  1489  // syntheticTailCall emits a tail call to fn, passing the given
  1490  // arguments list.
  1491  func (r *reader) syntheticTailCall(pos src.XPos, fn ir.Node, args ir.Nodes) {
  1492  	// Mark the function as a wrapper so it doesn't show up in stack
  1493  	// traces.
  1494  	r.curfn.SetWrapper(true)
  1495  
  1496  	call := typecheck.Call(pos, fn, args, fn.Type().IsVariadic()).(*ir.CallExpr)
  1497  
  1498  	var stmt ir.Node
  1499  	if fn.Type().NumResults() != 0 {
  1500  		stmt = typecheck.Stmt(ir.NewReturnStmt(pos, []ir.Node{call}))
  1501  	} else {
  1502  		stmt = call
  1503  	}
  1504  	r.curfn.Body.Append(stmt)
  1505  }
  1506  
  1507  // dictNameOf returns the runtime dictionary corresponding to dict.
  1508  func (pr *pkgReader) dictNameOf(dict *readerDict) *ir.Name {
  1509  	pos := base.AutogeneratedPos
  1510  
  1511  	// Check that we only instantiate runtime dictionaries with real types.
  1512  	base.AssertfAt(!dict.shaped, pos, "runtime dictionary of shaped object %v", dict.baseSym)
  1513  
  1514  	sym := dict.baseSym.Pkg.Lookup(objabi.GlobalDictPrefix + "." + dict.baseSym.Name)
  1515  	if sym.Def != nil {
  1516  		return sym.Def.(*ir.Name)
  1517  	}
  1518  
  1519  	name := ir.NewNameAt(pos, sym, dict.varType())
  1520  	name.Class = ir.PEXTERN
  1521  	sym.Def = name // break cycles with mutual subdictionaries
  1522  
  1523  	lsym := name.Linksym()
  1524  	ot := 0
  1525  
  1526  	assertOffset := func(section string, offset int) {
  1527  		base.AssertfAt(ot == offset*types.PtrSize, pos, "writing section %v at offset %v, but it should be at %v*%v", section, ot, offset, types.PtrSize)
  1528  	}
  1529  
  1530  	assertOffset("type param method exprs", dict.typeParamMethodExprsOffset())
  1531  	for _, info := range dict.typeParamMethodExprs {
  1532  		typeParam := dict.targs[info.typeParamIdx]
  1533  		method := typecheck.NewMethodExpr(pos, typeParam, info.method)
  1534  
  1535  		rsym := method.FuncName().Linksym()
  1536  		assert(rsym.ABI() == obj.ABIInternal) // must be ABIInternal; see ir.OCFUNC in ssagen/ssa.go
  1537  
  1538  		ot = objw.SymPtr(lsym, ot, rsym, 0)
  1539  	}
  1540  
  1541  	assertOffset("subdictionaries", dict.subdictsOffset())
  1542  	for _, info := range dict.subdicts {
  1543  		explicits := pr.typListIdx(info.explicits, dict)
  1544  
  1545  		// Careful: Due to subdictionary cycles, name may not be fully
  1546  		// initialized yet.
  1547  		name := pr.objDictName(info.idx, dict.targs, explicits)
  1548  
  1549  		ot = objw.SymPtr(lsym, ot, name.Linksym(), 0)
  1550  	}
  1551  
  1552  	assertOffset("rtypes", dict.rtypesOffset())
  1553  	for _, info := range dict.rtypes {
  1554  		typ := pr.typIdx(info, dict, true)
  1555  		ot = objw.SymPtr(lsym, ot, reflectdata.TypeLinksym(typ), 0)
  1556  
  1557  		// TODO(mdempsky): Double check this.
  1558  		reflectdata.MarkTypeUsedInInterface(typ, lsym)
  1559  	}
  1560  
  1561  	// For each (typ, iface) pair, we write the *runtime.itab pointer
  1562  	// for the pair. For pairs that don't actually require an itab
  1563  	// (i.e., typ is an interface, or iface is an empty interface), we
  1564  	// write a nil pointer instead. This is wasteful, but rare in
  1565  	// practice (e.g., instantiating a type parameter with an interface
  1566  	// type).
  1567  	assertOffset("itabs", dict.itabsOffset())
  1568  	for _, info := range dict.itabs {
  1569  		typ := pr.typIdx(info.typ, dict, true)
  1570  		iface := pr.typIdx(info.iface, dict, true)
  1571  
  1572  		if !typ.IsInterface() && iface.IsInterface() && !iface.IsEmptyInterface() {
  1573  			ot = objw.SymPtr(lsym, ot, reflectdata.ITabLsym(typ, iface), 0)
  1574  		} else {
  1575  			ot += types.PtrSize
  1576  		}
  1577  
  1578  		// TODO(mdempsky): Double check this.
  1579  		reflectdata.MarkTypeUsedInInterface(typ, lsym)
  1580  		reflectdata.MarkTypeUsedInInterface(iface, lsym)
  1581  	}
  1582  
  1583  	objw.Global(lsym, int32(ot), obj.DUPOK|obj.RODATA)
  1584  
  1585  	return name
  1586  }
  1587  
  1588  // typeParamMethodExprsOffset returns the offset of the runtime
  1589  // dictionary's type parameter method expressions section, in words.
  1590  func (dict *readerDict) typeParamMethodExprsOffset() int {
  1591  	return 0
  1592  }
  1593  
  1594  // subdictsOffset returns the offset of the runtime dictionary's
  1595  // subdictionary section, in words.
  1596  func (dict *readerDict) subdictsOffset() int {
  1597  	return dict.typeParamMethodExprsOffset() + len(dict.typeParamMethodExprs)
  1598  }
  1599  
  1600  // rtypesOffset returns the offset of the runtime dictionary's rtypes
  1601  // section, in words.
  1602  func (dict *readerDict) rtypesOffset() int {
  1603  	return dict.subdictsOffset() + len(dict.subdicts)
  1604  }
  1605  
  1606  // itabsOffset returns the offset of the runtime dictionary's itabs
  1607  // section, in words.
  1608  func (dict *readerDict) itabsOffset() int {
  1609  	return dict.rtypesOffset() + len(dict.rtypes)
  1610  }
  1611  
  1612  // numWords returns the total number of words that comprise dict's
  1613  // runtime dictionary variable.
  1614  func (dict *readerDict) numWords() int64 {
  1615  	return int64(dict.itabsOffset() + len(dict.itabs))
  1616  }
  1617  
  1618  // varType returns the type of dict's runtime dictionary variable.
  1619  func (dict *readerDict) varType() *types.Type {
  1620  	return types.NewArray(types.Types[types.TUINTPTR], dict.numWords())
  1621  }
  1622  
  1623  func (r *reader) declareParams() {
  1624  	r.curfn.DeclareParams(!r.funarghack)
  1625  
  1626  	for _, name := range r.curfn.Dcl {
  1627  		if name.Sym().Name == dictParamName {
  1628  			r.dictParam = name
  1629  			continue
  1630  		}
  1631  
  1632  		r.addLocal(name)
  1633  	}
  1634  }
  1635  
  1636  func (r *reader) addLocal(name *ir.Name) {
  1637  	if r.synthetic == nil {
  1638  		r.Sync(pkgbits.SyncAddLocal)
  1639  		if r.p.SyncMarkers() {
  1640  			want := r.Int()
  1641  			if have := len(r.locals); have != want {
  1642  				base.FatalfAt(name.Pos(), "locals table has desynced")
  1643  			}
  1644  		}
  1645  		r.varDictIndex(name)
  1646  	}
  1647  
  1648  	r.locals = append(r.locals, name)
  1649  }
  1650  
  1651  func (r *reader) useLocal() *ir.Name {
  1652  	r.Sync(pkgbits.SyncUseObjLocal)
  1653  	if r.Bool() {
  1654  		return r.locals[r.Len()]
  1655  	}
  1656  	return r.closureVars[r.Len()]
  1657  }
  1658  
  1659  func (r *reader) openScope() {
  1660  	r.Sync(pkgbits.SyncOpenScope)
  1661  	pos := r.pos()
  1662  
  1663  	if base.Flag.Dwarf {
  1664  		r.scopeVars = append(r.scopeVars, len(r.curfn.Dcl))
  1665  		r.marker.Push(pos)
  1666  	}
  1667  }
  1668  
  1669  func (r *reader) closeScope() {
  1670  	r.Sync(pkgbits.SyncCloseScope)
  1671  	r.lastCloseScopePos = r.pos()
  1672  
  1673  	r.closeAnotherScope()
  1674  }
  1675  
  1676  // closeAnotherScope is like closeScope, but it reuses the same mark
  1677  // position as the last closeScope call. This is useful for "for" and
  1678  // "if" statements, as their implicit blocks always end at the same
  1679  // position as an explicit block.
  1680  func (r *reader) closeAnotherScope() {
  1681  	r.Sync(pkgbits.SyncCloseAnotherScope)
  1682  
  1683  	if base.Flag.Dwarf {
  1684  		scopeVars := r.scopeVars[len(r.scopeVars)-1]
  1685  		r.scopeVars = r.scopeVars[:len(r.scopeVars)-1]
  1686  
  1687  		// Quirkish: noder decides which scopes to keep before
  1688  		// typechecking, whereas incremental typechecking during IR
  1689  		// construction can result in new autotemps being allocated. To
  1690  		// produce identical output, we ignore autotemps here for the
  1691  		// purpose of deciding whether to retract the scope.
  1692  		//
  1693  		// This is important for net/http/fcgi, because it contains:
  1694  		//
  1695  		//	var body io.ReadCloser
  1696  		//	if len(content) > 0 {
  1697  		//		body, req.pw = io.Pipe()
  1698  		//	} else { … }
  1699  		//
  1700  		// Notably, io.Pipe is inlinable, and inlining it introduces a ~R0
  1701  		// variable at the call site.
  1702  		//
  1703  		// Noder does not preserve the scope where the io.Pipe() call
  1704  		// resides, because it doesn't contain any declared variables in
  1705  		// source. So the ~R0 variable ends up being assigned to the
  1706  		// enclosing scope instead.
  1707  		//
  1708  		// However, typechecking this assignment also introduces
  1709  		// autotemps, because io.Pipe's results need conversion before
  1710  		// they can be assigned to their respective destination variables.
  1711  		//
  1712  		// TODO(mdempsky): We should probably just keep all scopes, and
  1713  		// let dwarfgen take care of pruning them instead.
  1714  		retract := true
  1715  		for _, n := range r.curfn.Dcl[scopeVars:] {
  1716  			if !n.AutoTemp() {
  1717  				retract = false
  1718  				break
  1719  			}
  1720  		}
  1721  
  1722  		if retract {
  1723  			// no variables were declared in this scope, so we can retract it.
  1724  			r.marker.Unpush()
  1725  		} else {
  1726  			r.marker.Pop(r.lastCloseScopePos)
  1727  		}
  1728  	}
  1729  }
  1730  
  1731  // @@@ Statements
  1732  
  1733  func (r *reader) stmt() ir.Node {
  1734  	return block(r.stmts())
  1735  }
  1736  
  1737  func block(stmts []ir.Node) ir.Node {
  1738  	switch len(stmts) {
  1739  	case 0:
  1740  		return nil
  1741  	case 1:
  1742  		return stmts[0]
  1743  	default:
  1744  		return ir.NewBlockStmt(stmts[0].Pos(), stmts)
  1745  	}
  1746  }
  1747  
  1748  func (r *reader) stmts() ir.Nodes {
  1749  	assert(ir.CurFunc == r.curfn)
  1750  	var res ir.Nodes
  1751  
  1752  	r.Sync(pkgbits.SyncStmts)
  1753  	for {
  1754  		tag := codeStmt(r.Code(pkgbits.SyncStmt1))
  1755  		if tag == stmtEnd {
  1756  			r.Sync(pkgbits.SyncStmtsEnd)
  1757  			return res
  1758  		}
  1759  
  1760  		if n := r.stmt1(tag, &res); n != nil {
  1761  			res.Append(typecheck.Stmt(n))
  1762  		}
  1763  	}
  1764  }
  1765  
  1766  func (r *reader) stmt1(tag codeStmt, out *ir.Nodes) ir.Node {
  1767  	var label *types.Sym
  1768  	if n := len(*out); n > 0 {
  1769  		if ls, ok := (*out)[n-1].(*ir.LabelStmt); ok {
  1770  			label = ls.Label
  1771  		}
  1772  	}
  1773  
  1774  	switch tag {
  1775  	default:
  1776  		panic("unexpected statement")
  1777  
  1778  	case stmtAssign:
  1779  		pos := r.pos()
  1780  		names, lhs := r.assignList()
  1781  		rhs := r.multiExpr()
  1782  
  1783  		if len(rhs) == 0 {
  1784  			for _, name := range names {
  1785  				as := ir.NewAssignStmt(pos, name, nil)
  1786  				as.PtrInit().Append(ir.NewDecl(pos, ir.ODCL, name))
  1787  				out.Append(typecheck.Stmt(as))
  1788  			}
  1789  			return nil
  1790  		}
  1791  
  1792  		if len(lhs) == 1 && len(rhs) == 1 {
  1793  			n := ir.NewAssignStmt(pos, lhs[0], rhs[0])
  1794  			n.Def = r.initDefn(n, names)
  1795  			return n
  1796  		}
  1797  
  1798  		n := ir.NewAssignListStmt(pos, ir.OAS2, lhs, rhs)
  1799  		n.Def = r.initDefn(n, names)
  1800  		return n
  1801  
  1802  	case stmtAssignOp:
  1803  		op := r.op()
  1804  		lhs := r.expr()
  1805  		pos := r.pos()
  1806  		rhs := r.expr()
  1807  		return ir.NewAssignOpStmt(pos, op, lhs, rhs)
  1808  
  1809  	case stmtIncDec:
  1810  		op := r.op()
  1811  		lhs := r.expr()
  1812  		pos := r.pos()
  1813  		n := ir.NewAssignOpStmt(pos, op, lhs, ir.NewOne(pos, lhs.Type()))
  1814  		n.IncDec = true
  1815  		return n
  1816  
  1817  	case stmtBlock:
  1818  		out.Append(r.blockStmt()...)
  1819  		return nil
  1820  
  1821  	case stmtBranch:
  1822  		pos := r.pos()
  1823  		op := r.op()
  1824  		sym := r.optLabel()
  1825  		return ir.NewBranchStmt(pos, op, sym)
  1826  
  1827  	case stmtCall:
  1828  		pos := r.pos()
  1829  		op := r.op()
  1830  		call := r.expr()
  1831  		stmt := ir.NewGoDeferStmt(pos, op, call)
  1832  		if op == ir.ODEFER {
  1833  			x := r.optExpr()
  1834  			if x != nil {
  1835  				stmt.DeferAt = x.(ir.Expr)
  1836  			}
  1837  		}
  1838  		return stmt
  1839  
  1840  	case stmtExpr:
  1841  		return r.expr()
  1842  
  1843  	case stmtFor:
  1844  		return r.forStmt(label)
  1845  
  1846  	case stmtIf:
  1847  		return r.ifStmt()
  1848  
  1849  	case stmtLabel:
  1850  		pos := r.pos()
  1851  		sym := r.label()
  1852  		return ir.NewLabelStmt(pos, sym)
  1853  
  1854  	case stmtReturn:
  1855  		pos := r.pos()
  1856  		results := r.multiExpr()
  1857  		return ir.NewReturnStmt(pos, results)
  1858  
  1859  	case stmtSelect:
  1860  		return r.selectStmt(label)
  1861  
  1862  	case stmtSend:
  1863  		pos := r.pos()
  1864  		ch := r.expr()
  1865  		value := r.expr()
  1866  		return ir.NewSendStmt(pos, ch, value)
  1867  
  1868  	case stmtSwitch:
  1869  		return r.switchStmt(label)
  1870  	}
  1871  }
  1872  
  1873  func (r *reader) assignList() ([]*ir.Name, []ir.Node) {
  1874  	lhs := make([]ir.Node, r.Len())
  1875  	var names []*ir.Name
  1876  
  1877  	for i := range lhs {
  1878  		expr, def := r.assign()
  1879  		lhs[i] = expr
  1880  		if def {
  1881  			names = append(names, expr.(*ir.Name))
  1882  		}
  1883  	}
  1884  
  1885  	return names, lhs
  1886  }
  1887  
  1888  // assign returns an assignee expression. It also reports whether the
  1889  // returned expression is a newly declared variable.
  1890  func (r *reader) assign() (ir.Node, bool) {
  1891  	switch tag := codeAssign(r.Code(pkgbits.SyncAssign)); tag {
  1892  	default:
  1893  		panic("unhandled assignee expression")
  1894  
  1895  	case assignBlank:
  1896  		return typecheck.AssignExpr(ir.BlankNode), false
  1897  
  1898  	case assignDef:
  1899  		pos := r.pos()
  1900  		setBasePos(pos) // test/fixedbugs/issue49767.go depends on base.Pos being set for the r.typ() call here, ugh
  1901  		name := r.curfn.NewLocal(pos, r.localIdent(), r.typ())
  1902  		r.addLocal(name)
  1903  		return name, true
  1904  
  1905  	case assignExpr:
  1906  		return r.expr(), false
  1907  	}
  1908  }
  1909  
  1910  func (r *reader) blockStmt() []ir.Node {
  1911  	r.Sync(pkgbits.SyncBlockStmt)
  1912  	r.openScope()
  1913  	stmts := r.stmts()
  1914  	r.closeScope()
  1915  	return stmts
  1916  }
  1917  
  1918  func (r *reader) forStmt(label *types.Sym) ir.Node {
  1919  	r.Sync(pkgbits.SyncForStmt)
  1920  
  1921  	r.openScope()
  1922  
  1923  	if r.Bool() {
  1924  		pos := r.pos()
  1925  		rang := ir.NewRangeStmt(pos, nil, nil, nil, nil, false)
  1926  		rang.Label = label
  1927  
  1928  		names, lhs := r.assignList()
  1929  		if len(lhs) >= 1 {
  1930  			rang.Key = lhs[0]
  1931  			if len(lhs) >= 2 {
  1932  				rang.Value = lhs[1]
  1933  			}
  1934  		}
  1935  		rang.Def = r.initDefn(rang, names)
  1936  
  1937  		rang.X = r.expr()
  1938  		if rang.X.Type().IsMap() {
  1939  			rang.RType = r.rtype(pos)
  1940  		}
  1941  		if rang.Key != nil && !ir.IsBlank(rang.Key) {
  1942  			rang.KeyTypeWord, rang.KeySrcRType = r.convRTTI(pos)
  1943  		}
  1944  		if rang.Value != nil && !ir.IsBlank(rang.Value) {
  1945  			rang.ValueTypeWord, rang.ValueSrcRType = r.convRTTI(pos)
  1946  		}
  1947  
  1948  		rang.Body = r.blockStmt()
  1949  		rang.DistinctVars = r.Bool()
  1950  		r.closeAnotherScope()
  1951  
  1952  		return rang
  1953  	}
  1954  
  1955  	pos := r.pos()
  1956  	init := r.stmt()
  1957  	cond := r.optExpr()
  1958  	post := r.stmt()
  1959  	body := r.blockStmt()
  1960  	perLoopVars := r.Bool()
  1961  	r.closeAnotherScope()
  1962  
  1963  	if ir.IsConst(cond, constant.Bool) && !ir.BoolVal(cond) {
  1964  		return init // simplify "for init; false; post { ... }" into "init"
  1965  	}
  1966  
  1967  	stmt := ir.NewForStmt(pos, init, cond, post, body, perLoopVars)
  1968  	stmt.Label = label
  1969  	return stmt
  1970  }
  1971  
  1972  func (r *reader) ifStmt() ir.Node {
  1973  	r.Sync(pkgbits.SyncIfStmt)
  1974  	r.openScope()
  1975  	pos := r.pos()
  1976  	init := r.stmts()
  1977  	cond := r.expr()
  1978  	staticCond := r.Int()
  1979  	var then, els []ir.Node
  1980  	if staticCond >= 0 {
  1981  		then = r.blockStmt()
  1982  	} else {
  1983  		r.lastCloseScopePos = r.pos()
  1984  	}
  1985  	if staticCond <= 0 {
  1986  		els = r.stmts()
  1987  	}
  1988  	r.closeAnotherScope()
  1989  
  1990  	if staticCond != 0 {
  1991  		// We may have removed a dead return statement, which can trip up
  1992  		// later passes (#62211). To avoid confusion, we instead flatten
  1993  		// the if statement into a block.
  1994  
  1995  		if cond.Op() != ir.OLITERAL {
  1996  			init.Append(typecheck.Stmt(ir.NewAssignStmt(pos, ir.BlankNode, cond))) // for side effects
  1997  		}
  1998  		init.Append(then...)
  1999  		init.Append(els...)
  2000  		return block(init)
  2001  	}
  2002  
  2003  	n := ir.NewIfStmt(pos, cond, then, els)
  2004  	n.SetInit(init)
  2005  	return n
  2006  }
  2007  
  2008  func (r *reader) selectStmt(label *types.Sym) ir.Node {
  2009  	r.Sync(pkgbits.SyncSelectStmt)
  2010  
  2011  	pos := r.pos()
  2012  	clauses := make([]*ir.CommClause, r.Len())
  2013  	for i := range clauses {
  2014  		if i > 0 {
  2015  			r.closeScope()
  2016  		}
  2017  		r.openScope()
  2018  
  2019  		pos := r.pos()
  2020  		comm := r.stmt()
  2021  		body := r.stmts()
  2022  
  2023  		// "case i = <-c: ..." may require an implicit conversion (e.g.,
  2024  		// see fixedbugs/bug312.go). Currently, typecheck throws away the
  2025  		// implicit conversion and relies on it being reinserted later,
  2026  		// but that would lose any explicit RTTI operands too. To preserve
  2027  		// RTTI, we rewrite this as "case tmp := <-c: i = tmp; ...".
  2028  		if as, ok := comm.(*ir.AssignStmt); ok && as.Op() == ir.OAS && !as.Def {
  2029  			if conv, ok := as.Y.(*ir.ConvExpr); ok && conv.Op() == ir.OCONVIFACE {
  2030  				base.AssertfAt(conv.Implicit(), conv.Pos(), "expected implicit conversion: %v", conv)
  2031  
  2032  				recv := conv.X
  2033  				base.AssertfAt(recv.Op() == ir.ORECV, recv.Pos(), "expected receive expression: %v", recv)
  2034  
  2035  				tmp := r.temp(pos, recv.Type())
  2036  
  2037  				// Replace comm with `tmp := <-c`.
  2038  				tmpAs := ir.NewAssignStmt(pos, tmp, recv)
  2039  				tmpAs.Def = true
  2040  				tmpAs.PtrInit().Append(ir.NewDecl(pos, ir.ODCL, tmp))
  2041  				comm = tmpAs
  2042  
  2043  				// Change original assignment to `i = tmp`, and prepend to body.
  2044  				conv.X = tmp
  2045  				body = append([]ir.Node{as}, body...)
  2046  			}
  2047  		}
  2048  
  2049  		// multiExpr will have desugared a comma-ok receive expression
  2050  		// into a separate statement. However, the rest of the compiler
  2051  		// expects comm to be the OAS2RECV statement itself, so we need to
  2052  		// shuffle things around to fit that pattern.
  2053  		if as2, ok := comm.(*ir.AssignListStmt); ok && as2.Op() == ir.OAS2 {
  2054  			init := ir.TakeInit(as2.Rhs[0])
  2055  			base.AssertfAt(len(init) == 1 && init[0].Op() == ir.OAS2RECV, as2.Pos(), "unexpected assignment: %+v", as2)
  2056  
  2057  			comm = init[0]
  2058  			body = append([]ir.Node{as2}, body...)
  2059  		}
  2060  
  2061  		clauses[i] = ir.NewCommStmt(pos, comm, body)
  2062  	}
  2063  	if len(clauses) > 0 {
  2064  		r.closeScope()
  2065  	}
  2066  	n := ir.NewSelectStmt(pos, clauses)
  2067  	n.Label = label
  2068  	return n
  2069  }
  2070  
  2071  func (r *reader) switchStmt(label *types.Sym) ir.Node {
  2072  	r.Sync(pkgbits.SyncSwitchStmt)
  2073  
  2074  	r.openScope()
  2075  	pos := r.pos()
  2076  	init := r.stmt()
  2077  
  2078  	var tag ir.Node
  2079  	var ident *ir.Ident
  2080  	var iface *types.Type
  2081  	if r.Bool() {
  2082  		pos := r.pos()
  2083  		if r.Bool() {
  2084  			ident = ir.NewIdent(r.pos(), r.localIdent())
  2085  		}
  2086  		x := r.expr()
  2087  		iface = x.Type()
  2088  		tag = ir.NewTypeSwitchGuard(pos, ident, x)
  2089  	} else {
  2090  		tag = r.optExpr()
  2091  	}
  2092  
  2093  	clauses := make([]*ir.CaseClause, r.Len())
  2094  	for i := range clauses {
  2095  		if i > 0 {
  2096  			r.closeScope()
  2097  		}
  2098  		r.openScope()
  2099  
  2100  		pos := r.pos()
  2101  		var cases, rtypes []ir.Node
  2102  		if iface != nil {
  2103  			cases = make([]ir.Node, r.Len())
  2104  			if len(cases) == 0 {
  2105  				cases = nil // TODO(mdempsky): Unclear if this matters.
  2106  			}
  2107  			for i := range cases {
  2108  				if r.Bool() { // case nil
  2109  					cases[i] = typecheck.Expr(types.BuiltinPkg.Lookup("nil").Def.(*ir.NilExpr))
  2110  				} else {
  2111  					cases[i] = r.exprType()
  2112  				}
  2113  			}
  2114  		} else {
  2115  			cases = r.exprList()
  2116  
  2117  			// For `switch { case any(true): }` (e.g., issue 3980 in
  2118  			// test/switch.go), the backend still creates a mixed bool/any
  2119  			// comparison, and we need to explicitly supply the RTTI for the
  2120  			// comparison.
  2121  			//
  2122  			// TODO(mdempsky): Change writer.go to desugar "switch {" into
  2123  			// "switch true {", which we already handle correctly.
  2124  			if tag == nil {
  2125  				for i, cas := range cases {
  2126  					if cas.Type().IsEmptyInterface() {
  2127  						for len(rtypes) < i {
  2128  							rtypes = append(rtypes, nil)
  2129  						}
  2130  						rtypes = append(rtypes, reflectdata.TypePtrAt(cas.Pos(), types.Types[types.TBOOL]))
  2131  					}
  2132  				}
  2133  			}
  2134  		}
  2135  
  2136  		clause := ir.NewCaseStmt(pos, cases, nil)
  2137  		clause.RTypes = rtypes
  2138  
  2139  		if ident != nil {
  2140  			name := r.curfn.NewLocal(r.pos(), ident.Sym(), r.typ())
  2141  			r.addLocal(name)
  2142  			clause.Var = name
  2143  			name.Defn = tag
  2144  		}
  2145  
  2146  		clause.Body = r.stmts()
  2147  		clauses[i] = clause
  2148  	}
  2149  	if len(clauses) > 0 {
  2150  		r.closeScope()
  2151  	}
  2152  	r.closeScope()
  2153  
  2154  	n := ir.NewSwitchStmt(pos, tag, clauses)
  2155  	n.Label = label
  2156  	if init != nil {
  2157  		n.SetInit([]ir.Node{init})
  2158  	}
  2159  	return n
  2160  }
  2161  
  2162  func (r *reader) label() *types.Sym {
  2163  	r.Sync(pkgbits.SyncLabel)
  2164  	name := r.String()
  2165  	if r.inlCall != nil && name != "_" {
  2166  		name = fmt.Sprintf("~%s·%d", name, inlgen)
  2167  	}
  2168  	return typecheck.Lookup(name)
  2169  }
  2170  
  2171  func (r *reader) optLabel() *types.Sym {
  2172  	r.Sync(pkgbits.SyncOptLabel)
  2173  	if r.Bool() {
  2174  		return r.label()
  2175  	}
  2176  	return nil
  2177  }
  2178  
  2179  // initDefn marks the given names as declared by defn and populates
  2180  // its Init field with ODCL nodes. It then reports whether any names
  2181  // were so declared, which can be used to initialize defn.Def.
  2182  func (r *reader) initDefn(defn ir.InitNode, names []*ir.Name) bool {
  2183  	if len(names) == 0 {
  2184  		return false
  2185  	}
  2186  
  2187  	init := make([]ir.Node, len(names))
  2188  	for i, name := range names {
  2189  		name.Defn = defn
  2190  		init[i] = ir.NewDecl(name.Pos(), ir.ODCL, name)
  2191  	}
  2192  	defn.SetInit(init)
  2193  	return true
  2194  }
  2195  
  2196  // @@@ Expressions
  2197  
  2198  // expr reads and returns a typechecked expression.
  2199  func (r *reader) expr() (res ir.Node) {
  2200  	defer func() {
  2201  		if res != nil && res.Typecheck() == 0 {
  2202  			base.FatalfAt(res.Pos(), "%v missed typecheck", res)
  2203  		}
  2204  	}()
  2205  
  2206  	switch tag := codeExpr(r.Code(pkgbits.SyncExpr)); tag {
  2207  	default:
  2208  		panic("unhandled expression")
  2209  
  2210  	case exprLocal:
  2211  		return typecheck.Expr(r.useLocal())
  2212  
  2213  	case exprGlobal:
  2214  		// Callee instead of Expr allows builtins
  2215  		// TODO(mdempsky): Handle builtins directly in exprCall, like method calls?
  2216  		return typecheck.Callee(r.obj())
  2217  
  2218  	case exprFuncInst:
  2219  		origPos, pos := r.origPos()
  2220  		wrapperFn, baseFn, dictPtr := r.funcInst(pos)
  2221  		if wrapperFn != nil {
  2222  			return wrapperFn
  2223  		}
  2224  		return r.curry(origPos, false, baseFn, dictPtr, nil)
  2225  
  2226  	case exprConst:
  2227  		pos := r.pos()
  2228  		typ := r.typ()
  2229  		val := FixValue(typ, r.Value())
  2230  		return ir.NewBasicLit(pos, typ, val)
  2231  
  2232  	case exprZero:
  2233  		pos := r.pos()
  2234  		typ := r.typ()
  2235  		return ir.NewZero(pos, typ)
  2236  
  2237  	case exprCompLit:
  2238  		return r.compLit()
  2239  
  2240  	case exprFuncLit:
  2241  		return r.funcLit()
  2242  
  2243  	case exprFieldVal:
  2244  		x := r.expr()
  2245  		pos := r.pos()
  2246  		sym := r.selector()
  2247  
  2248  		return typecheck.XDotField(pos, x, sym)
  2249  
  2250  	case exprMethodVal:
  2251  		recv := r.expr()
  2252  		origPos, pos := r.origPos()
  2253  		wrapperFn, baseFn, dictPtr := r.methodExpr()
  2254  
  2255  		// For simple wrapperFn values, the existing machinery for creating
  2256  		// and deduplicating wrapperFn value wrappers still works fine.
  2257  		if wrapperFn, ok := wrapperFn.(*ir.SelectorExpr); ok && wrapperFn.Op() == ir.OMETHEXPR {
  2258  			// The receiver expression we constructed may have a shape type.
  2259  			// For example, in fixedbugs/issue54343.go, `New[int]()` is
  2260  			// constructed as `New[go.shape.int](&.dict.New[int])`, which
  2261  			// has type `*T[go.shape.int]`, not `*T[int]`.
  2262  			//
  2263  			// However, the method we want to select here is `(*T[int]).M`,
  2264  			// not `(*T[go.shape.int]).M`, so we need to manually convert
  2265  			// the type back so that the OXDOT resolves correctly.
  2266  			//
  2267  			// TODO(mdempsky): Logically it might make more sense for
  2268  			// exprCall to take responsibility for setting a non-shaped
  2269  			// result type, but this is the only place where we care
  2270  			// currently. And only because existing ir.OMETHVALUE backend
  2271  			// code relies on n.X.Type() instead of n.Selection.Recv().Type
  2272  			// (because the latter is types.FakeRecvType() in the case of
  2273  			// interface method values).
  2274  			//
  2275  			if recv.Type().HasShape() {
  2276  				typ := wrapperFn.Type().Param(0).Type
  2277  				if !types.Identical(typ, recv.Type()) {
  2278  					base.FatalfAt(wrapperFn.Pos(), "receiver %L does not match %L", recv, wrapperFn)
  2279  				}
  2280  				recv = typecheck.Expr(ir.NewConvExpr(recv.Pos(), ir.OCONVNOP, typ, recv))
  2281  			}
  2282  
  2283  			n := typecheck.XDotMethod(pos, recv, wrapperFn.Sel, false)
  2284  
  2285  			// As a consistency check here, we make sure "n" selected the
  2286  			// same method (represented by a types.Field) that wrapperFn
  2287  			// selected. However, for anonymous receiver types, there can be
  2288  			// multiple such types.Field instances (#58563). So we may need
  2289  			// to fallback to making sure Sym and Type (including the
  2290  			// receiver parameter's type) match.
  2291  			if n.Selection != wrapperFn.Selection {
  2292  				assert(n.Selection.Sym == wrapperFn.Selection.Sym)
  2293  				assert(types.Identical(n.Selection.Type, wrapperFn.Selection.Type))
  2294  				assert(types.Identical(n.Selection.Type.Recv().Type, wrapperFn.Selection.Type.Recv().Type))
  2295  			}
  2296  
  2297  			wrapper := methodValueWrapper{
  2298  				rcvr:   n.X.Type(),
  2299  				method: n.Selection,
  2300  			}
  2301  
  2302  			if r.importedDef() {
  2303  				haveMethodValueWrappers = append(haveMethodValueWrappers, wrapper)
  2304  			} else {
  2305  				needMethodValueWrappers = append(needMethodValueWrappers, wrapper)
  2306  			}
  2307  			return n
  2308  		}
  2309  
  2310  		// For more complicated method expressions, we construct a
  2311  		// function literal wrapper.
  2312  		return r.curry(origPos, true, baseFn, recv, dictPtr)
  2313  
  2314  	case exprMethodExpr:
  2315  		recv := r.typ()
  2316  
  2317  		implicits := make([]int, r.Len())
  2318  		for i := range implicits {
  2319  			implicits[i] = r.Len()
  2320  		}
  2321  		var deref, addr bool
  2322  		if r.Bool() {
  2323  			deref = true
  2324  		} else if r.Bool() {
  2325  			addr = true
  2326  		}
  2327  
  2328  		origPos, pos := r.origPos()
  2329  		wrapperFn, baseFn, dictPtr := r.methodExpr()
  2330  
  2331  		// If we already have a wrapper and don't need to do anything with
  2332  		// it, we can just return the wrapper directly.
  2333  		//
  2334  		// N.B., we use implicits/deref/addr here as the source of truth
  2335  		// rather than types.Identical, because the latter can be confused
  2336  		// by tricky promoted methods (e.g., typeparam/mdempsky/21.go).
  2337  		if wrapperFn != nil && len(implicits) == 0 && !deref && !addr {
  2338  			if !types.Identical(recv, wrapperFn.Type().Param(0).Type) {
  2339  				base.FatalfAt(pos, "want receiver type %v, but have method %L", recv, wrapperFn)
  2340  			}
  2341  			return wrapperFn
  2342  		}
  2343  
  2344  		// Otherwise, if the wrapper function is a static method
  2345  		// expression (OMETHEXPR) and the receiver type is unshaped, then
  2346  		// we can rely on a statically generated wrapper being available.
  2347  		if method, ok := wrapperFn.(*ir.SelectorExpr); ok && method.Op() == ir.OMETHEXPR && !recv.HasShape() {
  2348  			return typecheck.NewMethodExpr(pos, recv, method.Sel)
  2349  		}
  2350  
  2351  		return r.methodExprWrap(origPos, recv, implicits, deref, addr, baseFn, dictPtr)
  2352  
  2353  	case exprIndex:
  2354  		x := r.expr()
  2355  		pos := r.pos()
  2356  		index := r.expr()
  2357  		n := typecheck.Expr(ir.NewIndexExpr(pos, x, index))
  2358  		switch n.Op() {
  2359  		case ir.OINDEXMAP:
  2360  			n := n.(*ir.IndexExpr)
  2361  			n.RType = r.rtype(pos)
  2362  		}
  2363  		return n
  2364  
  2365  	case exprSlice:
  2366  		x := r.expr()
  2367  		pos := r.pos()
  2368  		var index [3]ir.Node
  2369  		for i := range index {
  2370  			index[i] = r.optExpr()
  2371  		}
  2372  		op := ir.OSLICE
  2373  		if index[2] != nil {
  2374  			op = ir.OSLICE3
  2375  		}
  2376  		return typecheck.Expr(ir.NewSliceExpr(pos, op, x, index[0], index[1], index[2]))
  2377  
  2378  	case exprAssert:
  2379  		x := r.expr()
  2380  		pos := r.pos()
  2381  		typ := r.exprType()
  2382  		srcRType := r.rtype(pos)
  2383  
  2384  		// TODO(mdempsky): Always emit ODYNAMICDOTTYPE for uniformity?
  2385  		if typ, ok := typ.(*ir.DynamicType); ok && typ.Op() == ir.ODYNAMICTYPE {
  2386  			assert := ir.NewDynamicTypeAssertExpr(pos, ir.ODYNAMICDOTTYPE, x, typ.RType)
  2387  			assert.SrcRType = srcRType
  2388  			assert.ITab = typ.ITab
  2389  			return typed(typ.Type(), assert)
  2390  		}
  2391  		return typecheck.Expr(ir.NewTypeAssertExpr(pos, x, typ.Type()))
  2392  
  2393  	case exprUnaryOp:
  2394  		op := r.op()
  2395  		pos := r.pos()
  2396  		x := r.expr()
  2397  
  2398  		switch op {
  2399  		case ir.OADDR:
  2400  			return typecheck.Expr(typecheck.NodAddrAt(pos, x))
  2401  		case ir.ODEREF:
  2402  			return typecheck.Expr(ir.NewStarExpr(pos, x))
  2403  		}
  2404  		return typecheck.Expr(ir.NewUnaryExpr(pos, op, x))
  2405  
  2406  	case exprBinaryOp:
  2407  		op := r.op()
  2408  		x := r.expr()
  2409  		pos := r.pos()
  2410  		y := r.expr()
  2411  
  2412  		switch op {
  2413  		case ir.OANDAND, ir.OOROR:
  2414  			return typecheck.Expr(ir.NewLogicalExpr(pos, op, x, y))
  2415  		case ir.OLSH, ir.ORSH:
  2416  			// Untyped rhs of non-constant shift, e.g. x << 1.0.
  2417  			// If we have a constant value, it must be an int >= 0.
  2418  			if ir.IsConstNode(y) {
  2419  				val := constant.ToInt(y.Val())
  2420  				assert(val.Kind() == constant.Int && constant.Sign(val) >= 0)
  2421  			}
  2422  		}
  2423  		return typecheck.Expr(ir.NewBinaryExpr(pos, op, x, y))
  2424  
  2425  	case exprRecv:
  2426  		x := r.expr()
  2427  		pos := r.pos()
  2428  		for i, n := 0, r.Len(); i < n; i++ {
  2429  			x = Implicit(typecheck.DotField(pos, x, r.Len()))
  2430  		}
  2431  		if r.Bool() { // needs deref
  2432  			x = Implicit(Deref(pos, x.Type().Elem(), x))
  2433  		} else if r.Bool() { // needs addr
  2434  			x = Implicit(Addr(pos, x))
  2435  		}
  2436  		return x
  2437  
  2438  	case exprCall:
  2439  		var fun ir.Node
  2440  		var args ir.Nodes
  2441  		if r.Bool() { // method call
  2442  			recv := r.expr()
  2443  			_, method, dictPtr := r.methodExpr()
  2444  
  2445  			if recv.Type().IsInterface() && method.Op() == ir.OMETHEXPR {
  2446  				method := method.(*ir.SelectorExpr)
  2447  
  2448  				// The compiler backend (e.g., devirtualization) handle
  2449  				// OCALLINTER/ODOTINTER better than OCALLFUNC/OMETHEXPR for
  2450  				// interface calls, so we prefer to continue constructing
  2451  				// calls that way where possible.
  2452  				//
  2453  				// There are also corner cases where semantically it's perhaps
  2454  				// significant; e.g., fixedbugs/issue15975.go, #38634, #52025.
  2455  
  2456  				fun = typecheck.XDotMethod(method.Pos(), recv, method.Sel, true)
  2457  			} else {
  2458  				if recv.Type().IsInterface() {
  2459  					// N.B., this happens currently for typeparam/issue51521.go
  2460  					// and typeparam/typeswitch3.go.
  2461  					if base.Flag.LowerM != 0 {
  2462  						base.WarnfAt(method.Pos(), "imprecise interface call")
  2463  					}
  2464  				}
  2465  
  2466  				fun = method
  2467  				args.Append(recv)
  2468  			}
  2469  			if dictPtr != nil {
  2470  				args.Append(dictPtr)
  2471  			}
  2472  		} else if r.Bool() { // call to instanced function
  2473  			pos := r.pos()
  2474  			_, shapedFn, dictPtr := r.funcInst(pos)
  2475  			fun = shapedFn
  2476  			args.Append(dictPtr)
  2477  		} else {
  2478  			fun = r.expr()
  2479  		}
  2480  		pos := r.pos()
  2481  		args.Append(r.multiExpr()...)
  2482  		dots := r.Bool()
  2483  		n := typecheck.Call(pos, fun, args, dots)
  2484  		switch n.Op() {
  2485  		case ir.OAPPEND:
  2486  			n := n.(*ir.CallExpr)
  2487  			n.RType = r.rtype(pos)
  2488  			// For append(a, b...), we don't need the implicit conversion. The typechecker already
  2489  			// ensured that a and b are both slices with the same base type, or []byte and string.
  2490  			if n.IsDDD {
  2491  				if conv, ok := n.Args[1].(*ir.ConvExpr); ok && conv.Op() == ir.OCONVNOP && conv.Implicit() {
  2492  					n.Args[1] = conv.X
  2493  				}
  2494  			}
  2495  		case ir.OCOPY:
  2496  			n := n.(*ir.BinaryExpr)
  2497  			n.RType = r.rtype(pos)
  2498  		case ir.ODELETE:
  2499  			n := n.(*ir.CallExpr)
  2500  			n.RType = r.rtype(pos)
  2501  		case ir.OUNSAFESLICE:
  2502  			n := n.(*ir.BinaryExpr)
  2503  			n.RType = r.rtype(pos)
  2504  		}
  2505  		return n
  2506  
  2507  	case exprMake:
  2508  		pos := r.pos()
  2509  		typ := r.exprType()
  2510  		extra := r.exprs()
  2511  		n := typecheck.Expr(ir.NewCallExpr(pos, ir.OMAKE, nil, append([]ir.Node{typ}, extra...))).(*ir.MakeExpr)
  2512  		n.RType = r.rtype(pos)
  2513  		return n
  2514  
  2515  	case exprNew:
  2516  		pos := r.pos()
  2517  		if r.Bool() {
  2518  			// new(expr) -> tmp := expr; &tmp
  2519  			x := r.expr()
  2520  			x = typecheck.DefaultLit(x, nil) // See TODO in exprConvert case.
  2521  			var init ir.Nodes
  2522  			addr := ir.NewAddrExpr(pos, r.tempCopy(pos, x, &init))
  2523  			addr.SetInit(init)
  2524  			return typecheck.Expr(addr)
  2525  		}
  2526  		// new(T)
  2527  		return typecheck.Expr(ir.NewUnaryExpr(pos, ir.ONEW, r.exprType()))
  2528  
  2529  	case exprSizeof:
  2530  		return ir.NewUintptr(r.pos(), r.typ().Size())
  2531  
  2532  	case exprAlignof:
  2533  		return ir.NewUintptr(r.pos(), r.typ().Alignment())
  2534  
  2535  	case exprOffsetof:
  2536  		pos := r.pos()
  2537  		typ := r.typ()
  2538  		types.CalcSize(typ)
  2539  
  2540  		var offset int64
  2541  		for i := r.Len(); i >= 0; i-- {
  2542  			field := typ.Field(r.Len())
  2543  			offset += field.Offset
  2544  			typ = field.Type
  2545  		}
  2546  
  2547  		return ir.NewUintptr(pos, offset)
  2548  
  2549  	case exprReshape:
  2550  		typ := r.typ()
  2551  		x := r.expr()
  2552  
  2553  		if types.IdenticalStrict(x.Type(), typ) {
  2554  			return x
  2555  		}
  2556  
  2557  		// Comparison expressions are constructed as "untyped bool" still.
  2558  		//
  2559  		// TODO(mdempsky): It should be safe to reshape them here too, but
  2560  		// maybe it's better to construct them with the proper type
  2561  		// instead.
  2562  		if x.Type() == types.UntypedBool && typ.IsBoolean() {
  2563  			return x
  2564  		}
  2565  
  2566  		base.AssertfAt(x.Type().HasShape() || typ.HasShape(), x.Pos(), "%L and %v are not shape types", x, typ)
  2567  		base.AssertfAt(types.Identical(x.Type(), typ), x.Pos(), "%L is not shape-identical to %v", x, typ)
  2568  
  2569  		// We use ir.HasUniquePos here as a check that x only appears once
  2570  		// in the AST, so it's okay for us to call SetType without
  2571  		// breaking any other uses of it.
  2572  		//
  2573  		// Notably, any ONAMEs should already have the exactly right shape
  2574  		// type and been caught by types.IdenticalStrict above.
  2575  		base.AssertfAt(ir.HasUniquePos(x), x.Pos(), "cannot call SetType(%v) on %L", typ, x)
  2576  
  2577  		if base.Debug.Reshape != 0 {
  2578  			base.WarnfAt(x.Pos(), "reshaping %L to %v", x, typ)
  2579  		}
  2580  
  2581  		x.SetType(typ)
  2582  
  2583  		if call, ok := x.(*ir.CallExpr); ok {
  2584  			call.Reshape = true
  2585  		}
  2586  
  2587  		return x
  2588  
  2589  	case exprConvert:
  2590  		implicit := r.Bool()
  2591  		typ := r.typ()
  2592  		pos := r.pos()
  2593  		typeWord, srcRType := r.convRTTI(pos)
  2594  		dstTypeParam := r.Bool()
  2595  		identical := r.Bool()
  2596  		x := r.expr()
  2597  
  2598  		// TODO(mdempsky): Stop constructing expressions of untyped type.
  2599  		x = typecheck.DefaultLit(x, typ)
  2600  
  2601  		ce := ir.NewConvExpr(pos, ir.OCONV, typ, x)
  2602  		ce.TypeWord, ce.SrcRType = typeWord, srcRType
  2603  		if implicit {
  2604  			ce.SetImplicit(true)
  2605  		}
  2606  		n := typecheck.Expr(ce)
  2607  
  2608  		// Conversions between non-identical, non-empty interfaces always
  2609  		// requires a runtime call, even if they have identical underlying
  2610  		// interfaces. This is because we create separate itab instances
  2611  		// for each unique interface type, not merely each unique
  2612  		// interface shape.
  2613  		//
  2614  		// However, due to shape types, typecheck.Expr might mistakenly
  2615  		// think a conversion between two non-empty interfaces are
  2616  		// identical and set ir.OCONVNOP, instead of ir.OCONVIFACE. To
  2617  		// ensure we update the itab field appropriately, we force it to
  2618  		// ir.OCONVIFACE instead when shape types are involved.
  2619  		//
  2620  		// TODO(mdempsky): Are there other places we might get this wrong?
  2621  		// Should this be moved down into typecheck.{Assign,Convert}op?
  2622  		// This would be a non-issue if itabs were unique for each
  2623  		// *underlying* interface type instead.
  2624  		if !identical {
  2625  			if n, ok := n.(*ir.ConvExpr); ok && n.Op() == ir.OCONVNOP && n.Type().IsInterface() && !n.Type().IsEmptyInterface() && (n.Type().HasShape() || n.X.Type().HasShape()) {
  2626  				n.SetOp(ir.OCONVIFACE)
  2627  			}
  2628  		}
  2629  
  2630  		// spec: "If the type is a type parameter, the constant is converted
  2631  		// into a non-constant value of the type parameter."
  2632  		if dstTypeParam && ir.IsConstNode(n) {
  2633  			// Wrap in an OCONVNOP node to ensure result is non-constant.
  2634  			n = Implicit(ir.NewConvExpr(pos, ir.OCONVNOP, n.Type(), n))
  2635  			n.SetTypecheck(1)
  2636  		}
  2637  		return n
  2638  
  2639  	case exprRuntimeBuiltin:
  2640  		builtin := typecheck.LookupRuntime(r.String())
  2641  		return builtin
  2642  	}
  2643  }
  2644  
  2645  // funcInst reads an instantiated function reference, and returns
  2646  // three (possibly nil) expressions related to it:
  2647  //
  2648  // baseFn is always non-nil: it's either a function of the appropriate
  2649  // type already, or it has an extra dictionary parameter as the first
  2650  // parameter.
  2651  //
  2652  // If dictPtr is non-nil, then it's a dictionary argument that must be
  2653  // passed as the first argument to baseFn.
  2654  //
  2655  // If wrapperFn is non-nil, then it's either the same as baseFn (if
  2656  // dictPtr is nil), or it's semantically equivalent to currying baseFn
  2657  // to pass dictPtr. (wrapperFn is nil when dictPtr is an expression
  2658  // that needs to be computed dynamically.)
  2659  //
  2660  // For callers that are creating a call to the returned function, it's
  2661  // best to emit a call to baseFn, and include dictPtr in the arguments
  2662  // list as appropriate.
  2663  //
  2664  // For callers that want to return the function without invoking it,
  2665  // they may return wrapperFn if it's non-nil; but otherwise, they need
  2666  // to create their own wrapper.
  2667  func (r *reader) funcInst(pos src.XPos) (wrapperFn, baseFn, dictPtr ir.Node) {
  2668  	// Like in methodExpr, I'm pretty sure this isn't needed.
  2669  	var implicits []*types.Type
  2670  	if r.dict != nil {
  2671  		implicits = r.dict.targs
  2672  	}
  2673  
  2674  	if r.Bool() { // dynamic subdictionary
  2675  		idx := r.Len()
  2676  		info := r.dict.subdicts[idx]
  2677  		explicits := r.p.typListIdx(info.explicits, r.dict)
  2678  
  2679  		baseFn = r.p.objIdx(info.idx, implicits, explicits, true).(*ir.Name)
  2680  
  2681  		// TODO(mdempsky): Is there a more robust way to get the
  2682  		// dictionary pointer type here?
  2683  		dictPtrType := baseFn.Type().Param(0).Type
  2684  		dictPtr = typecheck.Expr(ir.NewConvExpr(pos, ir.OCONVNOP, dictPtrType, r.dictWord(pos, r.dict.subdictsOffset()+idx)))
  2685  
  2686  		return
  2687  	}
  2688  
  2689  	info := r.objInfo()
  2690  	explicits := r.p.typListIdx(info.explicits, r.dict)
  2691  
  2692  	wrapperFn = r.p.objIdx(info.idx, implicits, explicits, false).(*ir.Name)
  2693  	baseFn = r.p.objIdx(info.idx, implicits, explicits, true).(*ir.Name)
  2694  
  2695  	dictName := r.p.objDictName(info.idx, implicits, explicits)
  2696  	dictPtr = typecheck.Expr(ir.NewAddrExpr(pos, dictName))
  2697  
  2698  	return
  2699  }
  2700  
  2701  func (pr *pkgReader) objDictName(idx index, implicits, explicits []*types.Type) *ir.Name {
  2702  	rname := pr.newReader(pkgbits.SectionName, idx, pkgbits.SyncObject1)
  2703  	_, sym := rname.qualifiedIdent()
  2704  	tag := pkgbits.CodeObj(rname.Code(pkgbits.SyncCodeObj))
  2705  
  2706  	if tag == pkgbits.ObjStub {
  2707  		assert(!sym.IsBlank())
  2708  		if pri, ok := objReader[sym]; ok {
  2709  			return pri.pr.objDictName(pri.idx, nil, explicits)
  2710  		}
  2711  		base.Fatalf("unresolved stub: %v", sym)
  2712  	}
  2713  
  2714  	dict, err := pr.objDictIdx(sym, idx, implicits, explicits, false)
  2715  	if err != nil {
  2716  		base.Fatalf("%v", err)
  2717  	}
  2718  
  2719  	return pr.dictNameOf(dict)
  2720  }
  2721  
  2722  // curry returns a function literal that calls fun with arg0 and
  2723  // (optionally) arg1, accepting additional arguments to the function
  2724  // literal as necessary to satisfy fun's signature.
  2725  //
  2726  // If nilCheck is true and arg0 is an interface value, then it's
  2727  // checked to be non-nil as an initial step at the point of evaluating
  2728  // the function literal itself.
  2729  func (r *reader) curry(origPos src.XPos, ifaceHack bool, fun ir.Node, arg0, arg1 ir.Node) ir.Node {
  2730  	var captured ir.Nodes
  2731  	captured.Append(fun, arg0)
  2732  	if arg1 != nil {
  2733  		captured.Append(arg1)
  2734  	}
  2735  
  2736  	params, results := syntheticSig(fun.Type())
  2737  	params = params[len(captured)-1:] // skip curried parameters
  2738  	typ := types.NewSignature(nil, params, results)
  2739  
  2740  	addBody := func(pos src.XPos, r *reader, captured []ir.Node) {
  2741  		fun := captured[0]
  2742  
  2743  		var args ir.Nodes
  2744  		args.Append(captured[1:]...)
  2745  		args.Append(r.syntheticArgs()...)
  2746  
  2747  		r.syntheticTailCall(pos, fun, args)
  2748  	}
  2749  
  2750  	return r.syntheticClosure(origPos, typ, ifaceHack, captured, addBody)
  2751  }
  2752  
  2753  // methodExprWrap returns a function literal that changes method's
  2754  // first parameter's type to recv, and uses implicits/deref/addr to
  2755  // select the appropriate receiver parameter to pass to method.
  2756  func (r *reader) methodExprWrap(origPos src.XPos, recv *types.Type, implicits []int, deref, addr bool, method, dictPtr ir.Node) ir.Node {
  2757  	var captured ir.Nodes
  2758  	captured.Append(method)
  2759  
  2760  	params, results := syntheticSig(method.Type())
  2761  
  2762  	// Change first parameter to recv.
  2763  	params[0].Type = recv
  2764  
  2765  	// If we have a dictionary pointer argument to pass, then omit the
  2766  	// underlying method expression's dictionary parameter from the
  2767  	// returned signature too.
  2768  	if dictPtr != nil {
  2769  		captured.Append(dictPtr)
  2770  		params = append(params[:1], params[2:]...)
  2771  	}
  2772  
  2773  	typ := types.NewSignature(nil, params, results)
  2774  
  2775  	addBody := func(pos src.XPos, r *reader, captured []ir.Node) {
  2776  		fn := captured[0]
  2777  		args := r.syntheticArgs()
  2778  
  2779  		// Rewrite first argument based on implicits/deref/addr.
  2780  		{
  2781  			arg := args[0]
  2782  			for _, ix := range implicits {
  2783  				arg = Implicit(typecheck.DotField(pos, arg, ix))
  2784  			}
  2785  			if deref {
  2786  				arg = Implicit(Deref(pos, arg.Type().Elem(), arg))
  2787  			} else if addr {
  2788  				arg = Implicit(Addr(pos, arg))
  2789  			}
  2790  			args[0] = arg
  2791  		}
  2792  
  2793  		// Insert dictionary argument, if provided.
  2794  		if dictPtr != nil {
  2795  			newArgs := make([]ir.Node, len(args)+1)
  2796  			newArgs[0] = args[0]
  2797  			newArgs[1] = captured[1]
  2798  			copy(newArgs[2:], args[1:])
  2799  			args = newArgs
  2800  		}
  2801  
  2802  		r.syntheticTailCall(pos, fn, args)
  2803  	}
  2804  
  2805  	return r.syntheticClosure(origPos, typ, false, captured, addBody)
  2806  }
  2807  
  2808  // syntheticClosure constructs a synthetic function literal for
  2809  // currying dictionary arguments. origPos is the position used for the
  2810  // closure, which must be a non-inlined position. typ is the function
  2811  // literal's signature type.
  2812  //
  2813  // captures is a list of expressions that need to be evaluated at the
  2814  // point of function literal evaluation and captured by the function
  2815  // literal. If ifaceHack is true and captures[1] is an interface type,
  2816  // it's checked to be non-nil after evaluation.
  2817  //
  2818  // addBody is a callback function to populate the function body. The
  2819  // list of captured values passed back has the captured variables for
  2820  // use within the function literal, corresponding to the expressions
  2821  // in captures.
  2822  func (r *reader) syntheticClosure(origPos src.XPos, typ *types.Type, ifaceHack bool, captures ir.Nodes, addBody func(pos src.XPos, r *reader, captured []ir.Node)) ir.Node {
  2823  	// isSafe reports whether n is an expression that we can safely
  2824  	// defer to evaluating inside the closure instead, to avoid storing
  2825  	// them into the closure.
  2826  	//
  2827  	// In practice this is always (and only) the wrappee function.
  2828  	isSafe := func(n ir.Node) bool {
  2829  		if n.Op() == ir.ONAME && n.(*ir.Name).Class == ir.PFUNC {
  2830  			return true
  2831  		}
  2832  		if n.Op() == ir.OMETHEXPR {
  2833  			return true
  2834  		}
  2835  
  2836  		return false
  2837  	}
  2838  
  2839  	fn := r.inlClosureFunc(origPos, typ, ir.OCLOSURE)
  2840  	fn.SetWrapper(true)
  2841  
  2842  	clo := fn.OClosure
  2843  	inlPos := clo.Pos()
  2844  
  2845  	var init ir.Nodes
  2846  	for i, n := range captures {
  2847  		if isSafe(n) {
  2848  			continue // skip capture; can reference directly
  2849  		}
  2850  
  2851  		tmp := r.tempCopy(inlPos, n, &init)
  2852  		ir.NewClosureVar(origPos, fn, tmp)
  2853  
  2854  		// We need to nil check interface receivers at the point of method
  2855  		// value evaluation, ugh.
  2856  		if ifaceHack && i == 1 && n.Type().IsInterface() {
  2857  			check := ir.NewUnaryExpr(inlPos, ir.OCHECKNIL, ir.NewUnaryExpr(inlPos, ir.OITAB, tmp))
  2858  			init.Append(typecheck.Stmt(check))
  2859  		}
  2860  	}
  2861  
  2862  	pri := pkgReaderIndex{synthetic: func(pos src.XPos, r *reader) {
  2863  		captured := make([]ir.Node, len(captures))
  2864  		next := 0
  2865  		for i, n := range captures {
  2866  			if isSafe(n) {
  2867  				captured[i] = n
  2868  			} else {
  2869  				captured[i] = r.closureVars[next]
  2870  				next++
  2871  			}
  2872  		}
  2873  		assert(next == len(r.closureVars))
  2874  
  2875  		addBody(origPos, r, captured)
  2876  	}}
  2877  	bodyReader[fn] = pri
  2878  	pri.funcBody(fn)
  2879  
  2880  	return ir.InitExpr(init, clo)
  2881  }
  2882  
  2883  // syntheticSig duplicates and returns the params and results lists
  2884  // for sig, but renaming anonymous parameters so they can be assigned
  2885  // ir.Names.
  2886  func syntheticSig(sig *types.Type) (params, results []*types.Field) {
  2887  	clone := func(params []*types.Field) []*types.Field {
  2888  		res := make([]*types.Field, len(params))
  2889  		for i, param := range params {
  2890  			// TODO(mdempsky): It would be nice to preserve the original
  2891  			// parameter positions here instead, but at least
  2892  			// typecheck.NewMethodType replaces them with base.Pos, making
  2893  			// them useless. Worse, the positions copied from base.Pos may
  2894  			// have inlining contexts, which we definitely don't want here
  2895  			// (e.g., #54625).
  2896  			res[i] = types.NewField(base.AutogeneratedPos, param.Sym, param.Type)
  2897  			res[i].SetIsDDD(param.IsDDD())
  2898  		}
  2899  		return res
  2900  	}
  2901  
  2902  	return clone(sig.Params()), clone(sig.Results())
  2903  }
  2904  
  2905  func (r *reader) optExpr() ir.Node {
  2906  	if r.Bool() {
  2907  		return r.expr()
  2908  	}
  2909  	return nil
  2910  }
  2911  
  2912  // methodExpr reads a method expression reference, and returns three
  2913  // (possibly nil) expressions related to it:
  2914  //
  2915  // baseFn is always non-nil: it's either a function of the appropriate
  2916  // type already, or it has an extra dictionary parameter as the second
  2917  // parameter (i.e., immediately after the promoted receiver
  2918  // parameter).
  2919  //
  2920  // If dictPtr is non-nil, then it's a dictionary argument that must be
  2921  // passed as the second argument to baseFn.
  2922  //
  2923  // If wrapperFn is non-nil, then it's either the same as baseFn (if
  2924  // dictPtr is nil), or it's semantically equivalent to currying baseFn
  2925  // to pass dictPtr. (wrapperFn is nil when dictPtr is an expression
  2926  // that needs to be computed dynamically.)
  2927  //
  2928  // For callers that are creating a call to the returned method, it's
  2929  // best to emit a call to baseFn, and include dictPtr in the arguments
  2930  // list as appropriate.
  2931  //
  2932  // For callers that want to return a method expression without
  2933  // invoking it, they may return wrapperFn if it's non-nil; but
  2934  // otherwise, they need to create their own wrapper.
  2935  func (r *reader) methodExpr() (wrapperFn, baseFn, dictPtr ir.Node) {
  2936  	recv := r.typ()
  2937  
  2938  	var sig *types.Type
  2939  	generic := r.Version().Has(pkgbits.GenericMethods) && r.Bool()
  2940  	if !generic {
  2941  		// Signature type to return (i.e., recv prepended to the method's
  2942  		// normal parameters list).
  2943  		sig = typecheck.NewMethodType(r.typ(), recv)
  2944  	}
  2945  
  2946  	pos := r.pos()
  2947  	sym := r.selector()
  2948  
  2949  	if r.Bool() { // type parameter method expression
  2950  		idx := r.Len()
  2951  		word := r.dictWord(pos, r.dict.typeParamMethodExprsOffset()+idx)
  2952  
  2953  		// TODO(mdempsky): If the type parameter was instantiated with an
  2954  		// interface type (i.e., embed.IsInterface()), then we could
  2955  		// return the OMETHEXPR instead and save an indirection.
  2956  
  2957  		// We wrote the method expression's entry point PC into the
  2958  		// dictionary, but for Go `func` values we need to return a
  2959  		// closure (i.e., pointer to a structure with the PC as the first
  2960  		// field). Because method expressions don't have any closure
  2961  		// variables, we pun the dictionary entry as the closure struct.
  2962  		fn := typecheck.Expr(ir.NewConvExpr(pos, ir.OCONVNOP, sig, ir.NewAddrExpr(pos, word)))
  2963  		return fn, fn, nil
  2964  	}
  2965  
  2966  	if r.Bool() { // dynamic subdictionary
  2967  		idx := r.Len()
  2968  		info := r.dict.subdicts[idx]
  2969  		explicits := r.p.typListIdx(info.explicits, r.dict)
  2970  
  2971  		shapedObj := r.p.objIdx(info.idx, nil, explicits, true).(*ir.Name)
  2972  		shapedFn := shapedMethodExpr(pos, shapedObj, sym)
  2973  
  2974  		// TODO(mdempsky): Is there a more robust way to get the
  2975  		// dictionary pointer type here?
  2976  		dictPtrType := shapedFn.Type().Param(1).Type
  2977  		dictPtr := typecheck.Expr(ir.NewConvExpr(pos, ir.OCONVNOP, dictPtrType, r.dictWord(pos, r.dict.subdictsOffset()+idx)))
  2978  
  2979  		return nil, shapedFn, dictPtr
  2980  	}
  2981  
  2982  	if r.Bool() { // static dictionary
  2983  		info := r.objInfo()
  2984  		explicits := r.p.typListIdx(info.explicits, r.dict)
  2985  
  2986  		shapedObj := r.p.objIdx(info.idx, nil, explicits, true).(*ir.Name)
  2987  		shapedFn := shapedMethodExpr(pos, shapedObj, sym)
  2988  
  2989  		dict := r.p.objDictName(info.idx, nil, explicits)
  2990  		dictPtr := typecheck.Expr(ir.NewAddrExpr(pos, dict))
  2991  
  2992  		// Check that dictPtr matches shapedFn's dictionary parameter.
  2993  		if !types.Identical(dictPtr.Type(), shapedFn.Type().Param(1).Type) {
  2994  			base.FatalfAt(pos, "dict %L, but shaped method %L", dict, shapedFn)
  2995  		}
  2996  
  2997  		if !generic {
  2998  			// For statically known instantiations, we can take advantage of
  2999  			// the stenciled wrapper.
  3000  			base.AssertfAt(!recv.HasShape(), pos, "shaped receiver %v", recv)
  3001  			wrapperFn := typecheck.NewMethodExpr(pos, recv, sym)
  3002  			base.AssertfAt(types.Identical(sig, wrapperFn.Type()), pos, "wrapper %L does not have type %v", wrapperFn, sig)
  3003  			return wrapperFn, shapedFn, dictPtr
  3004  		} else {
  3005  			// Also statically known, but there is a good amount of existing
  3006  			// machinery downstream which makes assumptions about method
  3007  			// wrapper functions. It's safest not to emit them for now.
  3008  			// TODO(mark): Emit wrapper functions for generic methods.
  3009  			return nil, shapedFn, dictPtr
  3010  		}
  3011  	}
  3012  
  3013  	// Simple method expression; no dictionary needed.
  3014  	base.AssertfAt(!recv.HasShape() || recv.IsInterface(), pos, "shaped receiver %v", recv)
  3015  	fn := typecheck.NewMethodExpr(pos, recv, sym)
  3016  	return fn, fn, nil
  3017  }
  3018  
  3019  // shapedMethodExpr creates an OMETHEXPR for obj using sym.
  3020  //
  3021  // If obj is an OTYPE, it must refer to a generic type. If obj is an ONAME,
  3022  // it must refer to a generic method. In either case, sym.Name must be the
  3023  // unqualified name of the method.
  3024  //
  3025  // For example, given:
  3026  //
  3027  //	package p
  3028  //
  3029  //	type T[P any] struct {}
  3030  //
  3031  //	func (T[P]) m() {}
  3032  //	func (T[P]) n[Q any]() {}
  3033  //
  3034  // then, using S as go.shape.int:
  3035  //   - in T[int].m,      obj is T[S]      and sym.Name is "m".
  3036  //   - in T[int].n[int], obj is T[S].n[S] and sym.Name is "n".
  3037  //
  3038  // Note that we could have pushed dictionaries down to methods in every case,
  3039  // but since non-generic methods will always share the same "type environment"
  3040  // as their defining type, we can optimize by reusing the type's dictionary.
  3041  func shapedMethodExpr(pos src.XPos, obj *ir.Name, sym *types.Sym) ir.Node {
  3042  	if obj.Op() == ir.OTYPE {
  3043  		// non-generic method on generic type
  3044  		typ := obj.Type()
  3045  		assert(typ.HasShape())
  3046  
  3047  		method := func() *types.Field {
  3048  			for _, m := range typ.Methods() {
  3049  				if m.Sym == sym {
  3050  					return m
  3051  				}
  3052  			}
  3053  
  3054  			base.FatalfAt(pos, "failed to find method %v in shaped type %v", sym, typ)
  3055  			panic("unreachable")
  3056  		}()
  3057  
  3058  		return typecheck.NewMethodExpr(pos, method.Type.Recv().Type, sym)
  3059  	} else {
  3060  		// generic method on possibly generic type
  3061  		assert(obj.Op() == ir.ONAME && obj.Class == ir.PFUNC)
  3062  		typ := obj.Type()
  3063  		assert(typ.HasShape())
  3064  
  3065  		// OMETHEXPR assumes that the linker symbol to call looks like "<type sym>.<method sym>".
  3066  		// This works because non-generic method symbols are relative to their type. But generic
  3067  		// methods use fully-qualified names, so this won't work.
  3068  		//
  3069  		// To use OMETHEXPR for generic methods, we craft a dummy field on the type by removing
  3070  		// the qualifier; OMETHEXPR will put it back later.
  3071  		lsym := obj.Linksym().Name
  3072  		// Since the method is generic, we know the method name must be followed by a bracket.
  3073  		// TODO(mark): It's not ideal to rely on string naming here. Find a more robust solution.
  3074  		msym := sym.Pkg.Lookup(lsym[strings.LastIndex(lsym, sym.Name+"["):])
  3075  
  3076  		// Note that the field name here includes the type arguments; while also not ideal, the
  3077  		// types package does not seem to complain.
  3078  		m := types.NewField(obj.Pos(), msym, typ)
  3079  		m.Nname = obj
  3080  
  3081  		n := ir.NewSelectorExpr(pos, ir.OMETHEXPR, ir.TypeNode(typ.Recv().Type), msym)
  3082  		n.Selection = m
  3083  		n.SetType(typecheck.NewMethodType(typ, typ.Recv().Type))
  3084  		n.SetTypecheck(1)
  3085  
  3086  		return n
  3087  	}
  3088  }
  3089  
  3090  func (r *reader) multiExpr() []ir.Node {
  3091  	r.Sync(pkgbits.SyncMultiExpr)
  3092  
  3093  	if r.Bool() { // N:1
  3094  		pos := r.pos()
  3095  		expr := r.expr()
  3096  
  3097  		results := make([]ir.Node, r.Len())
  3098  		as := ir.NewAssignListStmt(pos, ir.OAS2, nil, []ir.Node{expr})
  3099  		as.Def = true
  3100  		for i := range results {
  3101  			tmp := r.temp(pos, r.typ())
  3102  			tmp.Defn = as
  3103  			as.PtrInit().Append(ir.NewDecl(pos, ir.ODCL, tmp))
  3104  			as.Lhs.Append(tmp)
  3105  
  3106  			res := ir.Node(tmp)
  3107  			if r.Bool() {
  3108  				n := ir.NewConvExpr(pos, ir.OCONV, r.typ(), res)
  3109  				n.TypeWord, n.SrcRType = r.convRTTI(pos)
  3110  				n.SetImplicit(true)
  3111  				res = typecheck.Expr(n)
  3112  			}
  3113  			results[i] = res
  3114  		}
  3115  
  3116  		// TODO(mdempsky): Could use ir.InlinedCallExpr instead?
  3117  		results[0] = ir.InitExpr([]ir.Node{typecheck.Stmt(as)}, results[0])
  3118  		return results
  3119  	}
  3120  
  3121  	// N:N
  3122  	exprs := make([]ir.Node, r.Len())
  3123  	if len(exprs) == 0 {
  3124  		return nil
  3125  	}
  3126  	for i := range exprs {
  3127  		exprs[i] = r.expr()
  3128  	}
  3129  	return exprs
  3130  }
  3131  
  3132  // temp returns a new autotemp of the specified type.
  3133  func (r *reader) temp(pos src.XPos, typ *types.Type) *ir.Name {
  3134  	return typecheck.TempAt(pos, r.curfn, typ)
  3135  }
  3136  
  3137  // tempCopy declares and returns a new autotemp initialized to the
  3138  // value of expr.
  3139  func (r *reader) tempCopy(pos src.XPos, expr ir.Node, init *ir.Nodes) *ir.Name {
  3140  	tmp := r.temp(pos, expr.Type())
  3141  
  3142  	init.Append(typecheck.Stmt(ir.NewDecl(pos, ir.ODCL, tmp)))
  3143  
  3144  	assign := ir.NewAssignStmt(pos, tmp, expr)
  3145  	assign.Def = true
  3146  	init.Append(typecheck.Stmt(assign))
  3147  
  3148  	tmp.Defn = assign
  3149  
  3150  	return tmp
  3151  }
  3152  
  3153  func (r *reader) compLit() ir.Node {
  3154  	r.Sync(pkgbits.SyncCompLit)
  3155  	pos := r.pos()
  3156  	typ0 := r.typ()
  3157  
  3158  	typ := typ0
  3159  	if typ.IsPtr() {
  3160  		typ = typ.Elem()
  3161  	}
  3162  	if typ.Kind() == types.TFORW {
  3163  		base.FatalfAt(pos, "unresolved composite literal type: %v", typ)
  3164  	}
  3165  	var rtype ir.Node
  3166  	if typ.IsMap() {
  3167  		rtype = r.rtype(pos)
  3168  	}
  3169  
  3170  	var elems []ir.Node
  3171  	if r.Version().Has(pkgbits.CompactCompLiterals) {
  3172  		n := r.Int()
  3173  		elems = make([]ir.Node, max(n, -n) /* abs(n) */)
  3174  		switch typ.Kind() {
  3175  		default:
  3176  			base.FatalfAt(pos, "unexpected composite literal type: %v", typ)
  3177  		case types.TARRAY:
  3178  			r.arrayElems(n >= 0, elems)
  3179  		case types.TMAP:
  3180  			r.mapElems(elems)
  3181  		case types.TSLICE:
  3182  			r.arrayElems(n >= 0, elems)
  3183  		case types.TSTRUCT:
  3184  			r.structElems(typ, n >= 0, elems)
  3185  		}
  3186  	} else {
  3187  		elems = make([]ir.Node, r.Len())
  3188  		isStruct := typ.Kind() == types.TSTRUCT
  3189  		for i := range elems {
  3190  			elemp := &elems[i]
  3191  			if isStruct {
  3192  				sk := ir.NewStructKeyExpr(r.pos(), typ.Field(r.Len()), nil)
  3193  				*elemp, elemp = sk, &sk.Value
  3194  			} else if r.Bool() {
  3195  				kv := ir.NewKeyExpr(r.pos(), r.expr(), nil)
  3196  				*elemp, elemp = kv, &kv.Value
  3197  			}
  3198  			*elemp = r.expr()
  3199  		}
  3200  	}
  3201  
  3202  	lit := typecheck.Expr(ir.NewCompLitExpr(pos, ir.OCOMPLIT, typ, elems))
  3203  	if rtype != nil {
  3204  		lit := lit.(*ir.CompLitExpr)
  3205  		lit.RType = rtype
  3206  	}
  3207  	if typ0.IsPtr() {
  3208  		lit = typecheck.Expr(typecheck.NodAddrAt(pos, lit))
  3209  		lit.SetType(typ0)
  3210  	}
  3211  	return lit
  3212  }
  3213  
  3214  func (r *reader) arrayElems(valuesOnly bool, elems []ir.Node) {
  3215  	if valuesOnly {
  3216  		for i := range elems {
  3217  			elems[i] = r.expr()
  3218  		}
  3219  		return
  3220  	}
  3221  	// some elements may have a key
  3222  	for i := range elems {
  3223  		if r.Bool() {
  3224  			kv := ir.NewKeyExpr(r.pos(), r.expr(), nil)
  3225  			kv.Value = r.expr()
  3226  			elems[i] = kv
  3227  		} else {
  3228  			elems[i] = r.expr()
  3229  		}
  3230  	}
  3231  }
  3232  
  3233  func (r *reader) mapElems(elems []ir.Node) {
  3234  	// all elements have a key
  3235  	for i := range elems {
  3236  		kv := ir.NewKeyExpr(r.pos(), r.expr(), nil)
  3237  		kv.Value = r.expr()
  3238  		elems[i] = kv
  3239  	}
  3240  }
  3241  
  3242  func (r *reader) structElems(typ *types.Type, valuesOnly bool, elems []ir.Node) {
  3243  	if valuesOnly {
  3244  		for i := range elems {
  3245  			sk := ir.NewStructKeyExpr(r.pos(), typ.Field(i), nil)
  3246  			sk.Value = r.expr()
  3247  			elems[i] = sk
  3248  		}
  3249  		return
  3250  	}
  3251  
  3252  	// all elements have a key
  3253  	for i := range elems {
  3254  		pos := r.pos()
  3255  		var fld *types.Field
  3256  		if n := r.Int(); n < 0 {
  3257  			// embedded field
  3258  			typ := typ // don't modify the original typ
  3259  			for range -n {
  3260  				fld = typ.Field(r.Int())
  3261  				typ = fld.Type
  3262  			}
  3263  		} else { // n >= 0
  3264  			fld = typ.Field(n)
  3265  		}
  3266  		sk := ir.NewStructKeyExpr(pos, fld, nil)
  3267  		sk.Value = r.expr()
  3268  		elems[i] = sk
  3269  	}
  3270  }
  3271  
  3272  func (r *reader) funcLit() ir.Node {
  3273  	r.Sync(pkgbits.SyncFuncLit)
  3274  
  3275  	// The underlying function declaration (including its parameters'
  3276  	// positions, if any) need to remain the original, uninlined
  3277  	// positions. This is because we track inlining-context on nodes so
  3278  	// we can synthesize the extra implied stack frames dynamically when
  3279  	// generating tracebacks, whereas those stack frames don't make
  3280  	// sense *within* the function literal. (Any necessary inlining
  3281  	// adjustments will have been applied to the call expression
  3282  	// instead.)
  3283  	//
  3284  	// This is subtle, and getting it wrong leads to cycles in the
  3285  	// inlining tree, which lead to infinite loops during stack
  3286  	// unwinding (#46234, #54625).
  3287  	//
  3288  	// Note that we *do* want the inline-adjusted position for the
  3289  	// OCLOSURE node, because that position represents where any heap
  3290  	// allocation of the closure is credited (#49171).
  3291  	r.suppressInlPos++
  3292  	origPos := r.pos()
  3293  	sig := r.signature(nil)
  3294  	r.suppressInlPos--
  3295  	why := ir.OCLOSURE
  3296  	if r.Bool() {
  3297  		why = ir.ORANGE
  3298  	}
  3299  
  3300  	fn := r.inlClosureFunc(origPos, sig, why)
  3301  
  3302  	fn.ClosureVars = make([]*ir.Name, 0, r.Len())
  3303  	for len(fn.ClosureVars) < cap(fn.ClosureVars) {
  3304  		// TODO(mdempsky): I think these should be original positions too
  3305  		// (i.e., not inline-adjusted).
  3306  		ir.NewClosureVar(r.pos(), fn, r.useLocal())
  3307  	}
  3308  	if param := r.dictParam; param != nil {
  3309  		// If we have a dictionary parameter, capture it too. For
  3310  		// simplicity, we capture it last and unconditionally.
  3311  		ir.NewClosureVar(param.Pos(), fn, param)
  3312  	}
  3313  
  3314  	r.addBody(fn, nil)
  3315  
  3316  	return fn.OClosure
  3317  }
  3318  
  3319  // inlClosureFunc constructs a new closure function, but correctly
  3320  // handles inlining.
  3321  func (r *reader) inlClosureFunc(origPos src.XPos, sig *types.Type, why ir.Op) *ir.Func {
  3322  	curfn := r.inlCaller
  3323  	if curfn == nil {
  3324  		curfn = r.curfn
  3325  	}
  3326  
  3327  	var gen int
  3328  	if why == ir.ORANGE {
  3329  		r.rangeLitGen++
  3330  		gen = r.rangeLitGen
  3331  	} else {
  3332  		r.funcLitGen++
  3333  		gen = r.funcLitGen
  3334  	}
  3335  
  3336  	// TODO(mdempsky): Remove hard-coding of typecheck.Target.
  3337  	return ir.NewClosureFunc(origPos, r.inlPos(origPos), why, sig, curfn, typecheck.Target, gen)
  3338  }
  3339  
  3340  func (r *reader) exprList() []ir.Node {
  3341  	r.Sync(pkgbits.SyncExprList)
  3342  	return r.exprs()
  3343  }
  3344  
  3345  func (r *reader) exprs() []ir.Node {
  3346  	r.Sync(pkgbits.SyncExprs)
  3347  	nodes := make([]ir.Node, r.Len())
  3348  	if len(nodes) == 0 {
  3349  		return nil // TODO(mdempsky): Unclear if this matters.
  3350  	}
  3351  	for i := range nodes {
  3352  		nodes[i] = r.expr()
  3353  	}
  3354  	return nodes
  3355  }
  3356  
  3357  // dictWord returns an expression to return the specified
  3358  // uintptr-typed word from the dictionary parameter.
  3359  func (r *reader) dictWord(pos src.XPos, idx int) ir.Node {
  3360  	base.AssertfAt(r.dictParam != nil, pos, "expected dictParam in %v", r.curfn)
  3361  	return typecheck.Expr(ir.NewIndexExpr(pos, r.dictParam, ir.NewInt(pos, int64(idx))))
  3362  }
  3363  
  3364  // rttiWord is like dictWord, but converts it to *byte (the type used
  3365  // internally to represent *runtime._type and *runtime.itab).
  3366  func (r *reader) rttiWord(pos src.XPos, idx int) ir.Node {
  3367  	return typecheck.Expr(ir.NewConvExpr(pos, ir.OCONVNOP, types.NewPtr(types.Types[types.TUINT8]), r.dictWord(pos, idx)))
  3368  }
  3369  
  3370  // rtype reads a type reference from the element bitstream, and
  3371  // returns an expression of type *runtime._type representing that
  3372  // type.
  3373  func (r *reader) rtype(pos src.XPos) ir.Node {
  3374  	_, rtype := r.rtype0(pos)
  3375  	return rtype
  3376  }
  3377  
  3378  func (r *reader) rtype0(pos src.XPos) (typ *types.Type, rtype ir.Node) {
  3379  	r.Sync(pkgbits.SyncRType)
  3380  	if r.Bool() { // derived type
  3381  		idx := r.Len()
  3382  		info := r.dict.rtypes[idx]
  3383  		typ = r.p.typIdx(info, r.dict, true)
  3384  		rtype = r.rttiWord(pos, r.dict.rtypesOffset()+idx)
  3385  		return
  3386  	}
  3387  
  3388  	typ = r.typ()
  3389  	rtype = reflectdata.TypePtrAt(pos, typ)
  3390  	return
  3391  }
  3392  
  3393  // varDictIndex populates name.DictIndex if name is a derived type.
  3394  func (r *reader) varDictIndex(name *ir.Name) {
  3395  	if r.Bool() {
  3396  		idx := 1 + r.dict.rtypesOffset() + r.Len()
  3397  		if int(uint16(idx)) != idx {
  3398  			base.FatalfAt(name.Pos(), "DictIndex overflow for %v: %v", name, idx)
  3399  		}
  3400  		name.DictIndex = uint16(idx)
  3401  	}
  3402  }
  3403  
  3404  // itab returns a (typ, iface) pair of types.
  3405  //
  3406  // typRType and ifaceRType are expressions that evaluate to the
  3407  // *runtime._type for typ and iface, respectively.
  3408  //
  3409  // If typ is a concrete type and iface is a non-empty interface type,
  3410  // then itab is an expression that evaluates to the *runtime.itab for
  3411  // the pair. Otherwise, itab is nil.
  3412  func (r *reader) itab(pos src.XPos) (typ *types.Type, typRType ir.Node, iface *types.Type, ifaceRType ir.Node, itab ir.Node) {
  3413  	typ, typRType = r.rtype0(pos)
  3414  	iface, ifaceRType = r.rtype0(pos)
  3415  
  3416  	idx := -1
  3417  	if r.Bool() {
  3418  		idx = r.Len()
  3419  	}
  3420  
  3421  	if !typ.IsInterface() && iface.IsInterface() && !iface.IsEmptyInterface() {
  3422  		if idx >= 0 {
  3423  			itab = r.rttiWord(pos, r.dict.itabsOffset()+idx)
  3424  		} else {
  3425  			base.AssertfAt(!typ.HasShape(), pos, "%v is a shape type", typ)
  3426  			base.AssertfAt(!iface.HasShape(), pos, "%v is a shape type", iface)
  3427  
  3428  			lsym := reflectdata.ITabLsym(typ, iface)
  3429  			itab = typecheck.LinksymAddr(pos, lsym, types.Types[types.TUINT8])
  3430  		}
  3431  	}
  3432  
  3433  	return
  3434  }
  3435  
  3436  // convRTTI returns expressions appropriate for populating an
  3437  // ir.ConvExpr's TypeWord and SrcRType fields, respectively.
  3438  func (r *reader) convRTTI(pos src.XPos) (typeWord, srcRType ir.Node) {
  3439  	r.Sync(pkgbits.SyncConvRTTI)
  3440  	src, srcRType0, dst, dstRType, itab := r.itab(pos)
  3441  	if !dst.IsInterface() {
  3442  		return
  3443  	}
  3444  
  3445  	// See reflectdata.ConvIfaceTypeWord.
  3446  	switch {
  3447  	case dst.IsEmptyInterface():
  3448  		if !src.IsInterface() {
  3449  			typeWord = srcRType0 // direct eface construction
  3450  		}
  3451  	case !src.IsInterface():
  3452  		typeWord = itab // direct iface construction
  3453  	default:
  3454  		typeWord = dstRType // convI2I
  3455  	}
  3456  
  3457  	// See reflectdata.ConvIfaceSrcRType.
  3458  	if !src.IsInterface() {
  3459  		srcRType = srcRType0
  3460  	}
  3461  
  3462  	return
  3463  }
  3464  
  3465  func (r *reader) exprType() ir.Node {
  3466  	r.Sync(pkgbits.SyncExprType)
  3467  	pos := r.pos()
  3468  
  3469  	var typ *types.Type
  3470  	var rtype, itab ir.Node
  3471  
  3472  	if r.Bool() {
  3473  		// non-empty interface
  3474  		typ, rtype, _, _, itab = r.itab(pos)
  3475  		if !typ.IsInterface() {
  3476  			rtype = nil // TODO(mdempsky): Leave set?
  3477  		}
  3478  	} else {
  3479  		typ, rtype = r.rtype0(pos)
  3480  
  3481  		if !r.Bool() { // not derived
  3482  			return ir.TypeNode(typ)
  3483  		}
  3484  	}
  3485  
  3486  	dt := ir.NewDynamicType(pos, rtype)
  3487  	dt.ITab = itab
  3488  	dt = typed(typ, dt).(*ir.DynamicType)
  3489  	if st := dt.ToStatic(); st != nil {
  3490  		return st
  3491  	}
  3492  	return dt
  3493  }
  3494  
  3495  func (r *reader) op() ir.Op {
  3496  	r.Sync(pkgbits.SyncOp)
  3497  	return ir.Op(r.Len())
  3498  }
  3499  
  3500  // @@@ Package initialization
  3501  
  3502  func (r *reader) pkgInit(self *types.Pkg, target *ir.Package) {
  3503  	cgoPragmas := make([][]string, r.Len())
  3504  	for i := range cgoPragmas {
  3505  		cgoPragmas[i] = r.Strings()
  3506  	}
  3507  	target.CgoPragmas = cgoPragmas
  3508  
  3509  	r.pkgInitOrder(target)
  3510  
  3511  	r.pkgDecls(target)
  3512  
  3513  	r.Sync(pkgbits.SyncEOF)
  3514  }
  3515  
  3516  // pkgInitOrder creates a synthetic init function to handle any
  3517  // package-scope initialization statements.
  3518  func (r *reader) pkgInitOrder(target *ir.Package) {
  3519  	initOrder := make([]ir.Node, r.Len())
  3520  	if len(initOrder) == 0 {
  3521  		return
  3522  	}
  3523  
  3524  	// Make a function that contains all the initialization statements.
  3525  	pos := base.AutogeneratedPos
  3526  	base.Pos = pos
  3527  
  3528  	fn := ir.NewFunc(pos, pos, typecheck.Lookup("init"), types.NewSignature(nil, nil, nil))
  3529  	fn.SetIsPackageInit(true)
  3530  	fn.SetInlinabilityChecked(true) // suppress useless "can inline" diagnostics
  3531  
  3532  	typecheck.DeclFunc(fn)
  3533  	r.curfn = fn
  3534  
  3535  	for i := range initOrder {
  3536  		lhs := make([]ir.Node, r.Len())
  3537  		for j := range lhs {
  3538  			lhs[j] = r.obj()
  3539  		}
  3540  		rhs := r.expr()
  3541  		pos := lhs[0].Pos()
  3542  
  3543  		var as ir.Node
  3544  		if len(lhs) == 1 {
  3545  			as = typecheck.Stmt(ir.NewAssignStmt(pos, lhs[0], rhs))
  3546  		} else {
  3547  			as = typecheck.Stmt(ir.NewAssignListStmt(pos, ir.OAS2, lhs, []ir.Node{rhs}))
  3548  		}
  3549  
  3550  		for _, v := range lhs {
  3551  			v.(*ir.Name).Defn = as
  3552  		}
  3553  
  3554  		initOrder[i] = as
  3555  	}
  3556  
  3557  	fn.Body = initOrder
  3558  
  3559  	typecheck.FinishFuncBody()
  3560  	r.curfn = nil
  3561  	r.locals = nil
  3562  
  3563  	// Outline (if legal/profitable) global map inits.
  3564  	staticinit.OutlineMapInits(fn)
  3565  
  3566  	// Split large init function.
  3567  	staticinit.SplitLargeInit(fn)
  3568  
  3569  	target.Inits = append(target.Inits, fn)
  3570  }
  3571  
  3572  func (r *reader) pkgDecls(target *ir.Package) {
  3573  	r.Sync(pkgbits.SyncDecls)
  3574  	for {
  3575  		switch code := codeDecl(r.Code(pkgbits.SyncDecl)); code {
  3576  		default:
  3577  			panic(fmt.Sprintf("unhandled decl: %v", code))
  3578  
  3579  		case declEnd:
  3580  			return
  3581  
  3582  		case declFunc:
  3583  			names := r.pkgObjs(target)
  3584  			assert(len(names) == 1)
  3585  			target.Funcs = append(target.Funcs, names[0].Func)
  3586  
  3587  		case declMethod:
  3588  			typ := r.typ()
  3589  			sym := r.selector()
  3590  
  3591  			method := typecheck.Lookdot1(nil, sym, typ, typ.Methods(), 0)
  3592  			target.Funcs = append(target.Funcs, method.Nname.(*ir.Name).Func)
  3593  
  3594  		case declVar:
  3595  			names := r.pkgObjs(target)
  3596  
  3597  			if n := r.Len(); n > 0 {
  3598  				assert(len(names) == 1)
  3599  				embeds := make([]ir.Embed, n)
  3600  				for i := range embeds {
  3601  					embeds[i] = ir.Embed{Pos: r.pos(), Patterns: r.Strings()}
  3602  				}
  3603  				names[0].Embed = &embeds
  3604  				target.Embeds = append(target.Embeds, names[0])
  3605  			}
  3606  
  3607  		case declOther:
  3608  			r.pkgObjs(target)
  3609  		}
  3610  	}
  3611  }
  3612  
  3613  func (r *reader) pkgObjs(target *ir.Package) []*ir.Name {
  3614  	r.Sync(pkgbits.SyncDeclNames)
  3615  	nodes := make([]*ir.Name, r.Len())
  3616  	for i := range nodes {
  3617  		r.Sync(pkgbits.SyncDeclName)
  3618  
  3619  		name := r.obj().(*ir.Name)
  3620  		nodes[i] = name
  3621  
  3622  		sym := name.Sym()
  3623  		if sym.IsBlank() {
  3624  			continue
  3625  		}
  3626  
  3627  		switch name.Class {
  3628  		default:
  3629  			base.FatalfAt(name.Pos(), "unexpected class: %v", name.Class)
  3630  
  3631  		case ir.PEXTERN:
  3632  			target.Externs = append(target.Externs, name)
  3633  
  3634  		case ir.PFUNC:
  3635  			assert(name.Type().Recv() == nil)
  3636  
  3637  			// TODO(mdempsky): Cleaner way to recognize init?
  3638  			if strings.HasPrefix(sym.Name, "init.") {
  3639  				target.Inits = append(target.Inits, name.Func)
  3640  			}
  3641  		}
  3642  
  3643  		if base.Ctxt.Flag_dynlink && types.LocalPkg.Name == "main" && types.IsExported(sym.Name) && name.Op() == ir.ONAME {
  3644  			assert(!sym.OnExportList())
  3645  			target.PluginExports = append(target.PluginExports, name)
  3646  			sym.SetOnExportList(true)
  3647  		}
  3648  
  3649  		if base.Flag.AsmHdr != "" && (name.Op() == ir.OLITERAL || name.Op() == ir.OTYPE) {
  3650  			assert(!sym.Asm())
  3651  			target.AsmHdrDecls = append(target.AsmHdrDecls, name)
  3652  			sym.SetAsm(true)
  3653  		}
  3654  	}
  3655  
  3656  	return nodes
  3657  }
  3658  
  3659  // @@@ Inlining
  3660  
  3661  // unifiedHaveInlineBody reports whether we have the function body for
  3662  // fn, so we can inline it.
  3663  func unifiedHaveInlineBody(fn *ir.Func) bool {
  3664  	if fn.Inl == nil {
  3665  		return false
  3666  	}
  3667  
  3668  	_, ok := bodyReaderFor(fn)
  3669  	return ok
  3670  }
  3671  
  3672  var inlgen = 0
  3673  
  3674  // unifiedInlineCall implements inline.NewInline by re-reading the function
  3675  // body from its Unified IR export data.
  3676  func unifiedInlineCall(callerfn *ir.Func, call *ir.CallExpr, fn *ir.Func, inlIndex int) *ir.InlinedCallExpr {
  3677  	pri, ok := bodyReaderFor(fn)
  3678  	if !ok {
  3679  		base.FatalfAt(call.Pos(), "cannot inline call to %v: missing inline body", fn)
  3680  	}
  3681  
  3682  	if !fn.Inl.HaveDcl {
  3683  		expandInline(fn, pri)
  3684  	}
  3685  
  3686  	r := pri.asReader(pkgbits.SectionBody, pkgbits.SyncFuncBody)
  3687  
  3688  	tmpfn := ir.NewFunc(fn.Pos(), fn.Nname.Pos(), callerfn.Sym(), fn.Type())
  3689  
  3690  	r.curfn = tmpfn
  3691  
  3692  	r.inlCaller = callerfn
  3693  	r.inlCall = call
  3694  	r.inlFunc = fn
  3695  	r.inlTreeIndex = inlIndex
  3696  	r.inlPosBases = make(map[*src.PosBase]*src.PosBase)
  3697  	r.funarghack = true
  3698  
  3699  	r.closureVars = make([]*ir.Name, len(r.inlFunc.ClosureVars))
  3700  	for i, cv := range r.inlFunc.ClosureVars {
  3701  		// TODO(mdempsky): It should be possible to support this case, but
  3702  		// for now we rely on the inliner avoiding it.
  3703  		if cv.Outer.Curfn != callerfn {
  3704  			base.FatalfAt(call.Pos(), "inlining closure call across frames")
  3705  		}
  3706  		r.closureVars[i] = cv.Outer
  3707  	}
  3708  	if len(r.closureVars) != 0 && r.hasTypeParams() {
  3709  		r.dictParam = r.closureVars[len(r.closureVars)-1] // dictParam is last; see reader.funcLit
  3710  	}
  3711  
  3712  	r.declareParams()
  3713  
  3714  	var inlvars, retvars []*ir.Name
  3715  	{
  3716  		sig := r.curfn.Type()
  3717  		endParams := sig.NumRecvs() + sig.NumParams()
  3718  		endResults := endParams + sig.NumResults()
  3719  
  3720  		inlvars = r.curfn.Dcl[:endParams]
  3721  		retvars = r.curfn.Dcl[endParams:endResults]
  3722  	}
  3723  
  3724  	r.delayResults = fn.Inl.CanDelayResults
  3725  
  3726  	r.retlabel = typecheck.AutoLabel(".i")
  3727  	inlgen++
  3728  
  3729  	init := ir.TakeInit(call)
  3730  
  3731  	// For normal function calls, the function callee expression
  3732  	// may contain side effects. Make sure to preserve these,
  3733  	// if necessary (#42703).
  3734  	if call.Op() == ir.OCALLFUNC {
  3735  		inline.CalleeEffects(&init, call.Fun)
  3736  	}
  3737  
  3738  	var args ir.Nodes
  3739  	if call.Op() == ir.OCALLMETH {
  3740  		base.FatalfAt(call.Pos(), "OCALLMETH missed by typecheck")
  3741  	}
  3742  	args.Append(call.Args...)
  3743  
  3744  	// Create assignment to declare and initialize inlvars.
  3745  	as2 := ir.NewAssignListStmt(call.Pos(), ir.OAS2, ir.ToNodes(inlvars), args)
  3746  	as2.Def = true
  3747  	var as2init ir.Nodes
  3748  	for _, name := range inlvars {
  3749  		if ir.IsBlank(name) {
  3750  			continue
  3751  		}
  3752  		// TODO(mdempsky): Use inlined position of name.Pos() instead?
  3753  		as2init.Append(ir.NewDecl(call.Pos(), ir.ODCL, name))
  3754  		name.Defn = as2
  3755  	}
  3756  	as2.SetInit(as2init)
  3757  	init.Append(typecheck.Stmt(as2))
  3758  
  3759  	if !r.delayResults {
  3760  		// If not delaying retvars, declare and zero initialize the
  3761  		// result variables now.
  3762  		for _, name := range retvars {
  3763  			// TODO(mdempsky): Use inlined position of name.Pos() instead?
  3764  			init.Append(ir.NewDecl(call.Pos(), ir.ODCL, name))
  3765  			ras := ir.NewAssignStmt(call.Pos(), name, nil)
  3766  			init.Append(typecheck.Stmt(ras))
  3767  		}
  3768  	}
  3769  
  3770  	// Add an inline mark just before the inlined body.
  3771  	// This mark is inline in the code so that it's a reasonable spot
  3772  	// to put a breakpoint. Not sure if that's really necessary or not
  3773  	// (in which case it could go at the end of the function instead).
  3774  	// Note issue 28603.
  3775  	init.Append(ir.NewInlineMarkStmt(call.Pos().WithIsStmt(), int64(r.inlTreeIndex)))
  3776  
  3777  	ir.WithFunc(r.curfn, func() {
  3778  		if !r.syntheticBody(call.Pos()) {
  3779  			assert(r.Bool()) // have body
  3780  
  3781  			r.curfn.Body = r.stmts()
  3782  			r.curfn.Endlineno = r.pos()
  3783  		}
  3784  
  3785  		// TODO(mdempsky): This shouldn't be necessary. Inlining might
  3786  		// read in new function/method declarations, which could
  3787  		// potentially be recursively inlined themselves; but we shouldn't
  3788  		// need to read in the non-inlined bodies for the declarations
  3789  		// themselves. But currently it's an easy fix to #50552.
  3790  		readBodies(typecheck.Target, true)
  3791  
  3792  		// Replace any "return" statements within the function body.
  3793  		var edit func(ir.Node) ir.Node
  3794  		edit = func(n ir.Node) ir.Node {
  3795  			if ret, ok := n.(*ir.ReturnStmt); ok {
  3796  				n = typecheck.Stmt(r.inlReturn(ret, retvars))
  3797  			}
  3798  			ir.EditChildren(n, edit)
  3799  			return n
  3800  		}
  3801  		edit(r.curfn)
  3802  	})
  3803  
  3804  	body := r.curfn.Body
  3805  
  3806  	// Reparent any declarations into the caller function.
  3807  	for _, name := range r.curfn.Dcl {
  3808  		name.Curfn = callerfn
  3809  
  3810  		if name.Class != ir.PAUTO {
  3811  			name.SetPos(r.inlPos(name.Pos()))
  3812  			name.SetInlFormal(true)
  3813  			name.Class = ir.PAUTO
  3814  		} else {
  3815  			name.SetInlLocal(true)
  3816  		}
  3817  	}
  3818  	callerfn.Dcl = append(callerfn.Dcl, r.curfn.Dcl...)
  3819  
  3820  	body.Append(ir.NewLabelStmt(call.Pos(), r.retlabel))
  3821  
  3822  	res := ir.NewInlinedCallExpr(call.Pos(), body, ir.ToNodes(retvars))
  3823  	res.SetInit(init)
  3824  	res.SetType(call.Type())
  3825  	res.SetTypecheck(1)
  3826  	res.Reshape = call.Reshape
  3827  
  3828  	// Inlining shouldn't add any functions to todoBodies.
  3829  	assert(len(todoBodies) == 0)
  3830  
  3831  	return res
  3832  }
  3833  
  3834  // inlReturn returns a statement that can substitute for the given
  3835  // return statement when inlining.
  3836  func (r *reader) inlReturn(ret *ir.ReturnStmt, retvars []*ir.Name) *ir.BlockStmt {
  3837  	pos := r.inlCall.Pos()
  3838  
  3839  	block := ir.TakeInit(ret)
  3840  
  3841  	if results := ret.Results; len(results) != 0 {
  3842  		assert(len(retvars) == len(results))
  3843  
  3844  		as2 := ir.NewAssignListStmt(pos, ir.OAS2, ir.ToNodes(retvars), ret.Results)
  3845  
  3846  		if r.delayResults {
  3847  			for _, name := range retvars {
  3848  				// TODO(mdempsky): Use inlined position of name.Pos() instead?
  3849  				block.Append(ir.NewDecl(pos, ir.ODCL, name))
  3850  				name.Defn = as2
  3851  			}
  3852  		}
  3853  
  3854  		block.Append(as2)
  3855  	}
  3856  
  3857  	block.Append(ir.NewBranchStmt(pos, ir.OGOTO, r.retlabel))
  3858  	return ir.NewBlockStmt(pos, block)
  3859  }
  3860  
  3861  // expandInline reads in an extra copy of IR to populate
  3862  // fn.Inl.Dcl.
  3863  func expandInline(fn *ir.Func, pri pkgReaderIndex) {
  3864  	// TODO(mdempsky): Remove this function. It's currently needed by
  3865  	// dwarfgen/dwarf.go:preInliningDcls, which requires fn.Inl.Dcl to
  3866  	// create abstract function DIEs. But we should be able to provide it
  3867  	// with the same information some other way.
  3868  
  3869  	fndcls := len(fn.Dcl)
  3870  	topdcls := len(typecheck.Target.Funcs)
  3871  
  3872  	tmpfn := ir.NewFunc(fn.Pos(), fn.Nname.Pos(), fn.Sym(), fn.Type())
  3873  	tmpfn.ClosureVars = fn.ClosureVars
  3874  
  3875  	{
  3876  		r := pri.asReader(pkgbits.SectionBody, pkgbits.SyncFuncBody)
  3877  
  3878  		// Don't change parameter's Sym/Nname fields.
  3879  		r.funarghack = true
  3880  
  3881  		r.funcBody(tmpfn)
  3882  	}
  3883  
  3884  	// Move tmpfn's params to fn.Inl.Dcl, and reparent under fn.
  3885  	for _, name := range tmpfn.Dcl {
  3886  		name.Curfn = fn
  3887  	}
  3888  	fn.Inl.Dcl = tmpfn.Dcl
  3889  	fn.Inl.HaveDcl = true
  3890  
  3891  	// Double check that we didn't change fn.Dcl by accident.
  3892  	assert(fndcls == len(fn.Dcl))
  3893  
  3894  	// typecheck.Stmts may have added function literals to
  3895  	// typecheck.Target.Decls. Remove them again so we don't risk trying
  3896  	// to compile them multiple times.
  3897  	typecheck.Target.Funcs = typecheck.Target.Funcs[:topdcls]
  3898  }
  3899  
  3900  // @@@ Method wrappers
  3901  //
  3902  // Here we handle constructing "method wrappers," alternative entry
  3903  // points that adapt methods to different calling conventions. Given a
  3904  // user-declared method "func (T) M(i int) bool { ... }", there are a
  3905  // few wrappers we may need to construct:
  3906  //
  3907  //	- Implicit dereferencing. Methods declared with a value receiver T
  3908  //	  are also included in the method set of the pointer type *T, so
  3909  //	  we need to construct a wrapper like "func (recv *T) M(i int)
  3910  //	  bool { return (*recv).M(i) }".
  3911  //
  3912  //	- Promoted methods. If struct type U contains an embedded field of
  3913  //	  type T or *T, we need to construct a wrapper like "func (recv U)
  3914  //	  M(i int) bool { return recv.T.M(i) }".
  3915  //
  3916  //	- Method values. If x is an expression of type T, then "x.M" is
  3917  //	  roughly "tmp := x; func(i int) bool { return tmp.M(i) }".
  3918  //
  3919  // At call sites, we always prefer to call the user-declared method
  3920  // directly, if known, so wrappers are only needed for indirect calls
  3921  // (for example, interface method calls that can't be devirtualized).
  3922  // Consequently, we can save some compile time by skipping
  3923  // construction of wrappers that are never needed.
  3924  //
  3925  // Alternatively, because the linker doesn't care which compilation
  3926  // unit constructed a particular wrapper, we can instead construct
  3927  // them as needed. However, if a wrapper is needed in multiple
  3928  // downstream packages, we may end up needing to compile it multiple
  3929  // times, costing us more compile time and object file size. (We mark
  3930  // the wrappers as DUPOK, so the linker doesn't complain about the
  3931  // duplicate symbols.)
  3932  //
  3933  // The current heuristics we use to balance these trade offs are:
  3934  //
  3935  //	- For a (non-parameterized) defined type T, we construct wrappers
  3936  //	  for *T and any promoted methods on T (and *T) in the same
  3937  //	  compilation unit as the type declaration.
  3938  //
  3939  //	- For a parameterized defined type, we construct wrappers in the
  3940  //	  compilation units in which the type is instantiated. We
  3941  //	  similarly handle wrappers for anonymous types with methods and
  3942  //	  compilation units where their type literals appear in source.
  3943  //
  3944  //	- Method value expressions are relatively uncommon, so we
  3945  //	  construct their wrappers in the compilation units that they
  3946  //	  appear in.
  3947  //
  3948  // Finally, as an opportunistic compile-time optimization, if we know
  3949  // a wrapper was constructed in any imported package's compilation
  3950  // unit, then we skip constructing a duplicate one. However, currently
  3951  // this is only done on a best-effort basis.
  3952  
  3953  // needWrapperTypes lists types for which we may need to generate
  3954  // method wrappers.
  3955  var needWrapperTypes []*types.Type
  3956  
  3957  // haveWrapperTypes lists types for which we know we already have
  3958  // method wrappers, because we found the type in an imported package.
  3959  var haveWrapperTypes []*types.Type
  3960  
  3961  // needMethodValueWrappers lists methods for which we may need to
  3962  // generate method value wrappers.
  3963  var needMethodValueWrappers []methodValueWrapper
  3964  
  3965  // haveMethodValueWrappers lists methods for which we know we already
  3966  // have method value wrappers, because we found it in an imported
  3967  // package.
  3968  var haveMethodValueWrappers []methodValueWrapper
  3969  
  3970  type methodValueWrapper struct {
  3971  	rcvr   *types.Type
  3972  	method *types.Field
  3973  }
  3974  
  3975  // needWrapper records that wrapper methods may be needed at link
  3976  // time.
  3977  func (r *reader) needWrapper(typ *types.Type) {
  3978  	if typ.IsPtr() || typ.IsKind(types.TFORW) {
  3979  		return
  3980  	}
  3981  
  3982  	// Special case: runtime must define error even if imported packages mention it (#29304).
  3983  	forceNeed := typ == types.ErrorType && base.Ctxt.Pkgpath == "runtime"
  3984  
  3985  	// If a type was found in an imported package, then we can assume
  3986  	// that package (or one of its transitive dependencies) already
  3987  	// generated method wrappers for it.
  3988  	if r.importedDef() && !forceNeed {
  3989  		haveWrapperTypes = append(haveWrapperTypes, typ)
  3990  	} else {
  3991  		needWrapperTypes = append(needWrapperTypes, typ)
  3992  	}
  3993  }
  3994  
  3995  // importedDef reports whether r is reading from an imported and
  3996  // non-generic element.
  3997  //
  3998  // If a type was found in an imported package, then we can assume that
  3999  // package (or one of its transitive dependencies) already generated
  4000  // method wrappers for it.
  4001  //
  4002  // Exception: If we're instantiating an imported generic type or
  4003  // function, we might be instantiating it with type arguments not
  4004  // previously seen before.
  4005  //
  4006  // TODO(mdempsky): Distinguish when a generic function or type was
  4007  // instantiated in an imported package so that we can add types to
  4008  // haveWrapperTypes instead.
  4009  func (r *reader) importedDef() bool {
  4010  	return r.p != localPkgReader && !r.hasTypeParams()
  4011  }
  4012  
  4013  // MakeWrappers constructs all wrapper methods needed for the target
  4014  // compilation unit.
  4015  func MakeWrappers(target *ir.Package) {
  4016  	// always generate a wrapper for error.Error (#29304)
  4017  	needWrapperTypes = append(needWrapperTypes, types.ErrorType)
  4018  
  4019  	seen := make(map[string]*types.Type)
  4020  
  4021  	for _, typ := range haveWrapperTypes {
  4022  		wrapType(typ, target, seen, false)
  4023  	}
  4024  	haveWrapperTypes = nil
  4025  
  4026  	for _, typ := range needWrapperTypes {
  4027  		wrapType(typ, target, seen, true)
  4028  	}
  4029  	needWrapperTypes = nil
  4030  
  4031  	for _, wrapper := range haveMethodValueWrappers {
  4032  		wrapMethodValue(wrapper.rcvr, wrapper.method, target, false)
  4033  	}
  4034  	haveMethodValueWrappers = nil
  4035  
  4036  	for _, wrapper := range needMethodValueWrappers {
  4037  		wrapMethodValue(wrapper.rcvr, wrapper.method, target, true)
  4038  	}
  4039  	needMethodValueWrappers = nil
  4040  }
  4041  
  4042  func wrapType(typ *types.Type, target *ir.Package, seen map[string]*types.Type, needed bool) {
  4043  	key := typ.LinkString()
  4044  	if prev := seen[key]; prev != nil {
  4045  		if !types.Identical(typ, prev) {
  4046  			base.Fatalf("collision: types %v and %v have link string %q", typ, prev, key)
  4047  		}
  4048  		return
  4049  	}
  4050  	seen[key] = typ
  4051  
  4052  	if !needed {
  4053  		// Only called to add to 'seen'.
  4054  		return
  4055  	}
  4056  
  4057  	if !typ.IsInterface() {
  4058  		typecheck.CalcMethods(typ)
  4059  	}
  4060  	for _, meth := range typ.AllMethods() {
  4061  		if meth.Sym.IsBlank() || !meth.IsMethod() {
  4062  			base.FatalfAt(meth.Pos, "invalid method: %v", meth)
  4063  		}
  4064  
  4065  		methodWrapper(0, typ, meth, target)
  4066  
  4067  		// For non-interface types, we also want *T wrappers.
  4068  		if !typ.IsInterface() {
  4069  			methodWrapper(1, typ, meth, target)
  4070  
  4071  			// For not-in-heap types, *T is a scalar, not pointer shaped,
  4072  			// so the interface wrappers use **T.
  4073  			if typ.NotInHeap() {
  4074  				methodWrapper(2, typ, meth, target)
  4075  			}
  4076  		}
  4077  	}
  4078  }
  4079  
  4080  func methodWrapper(derefs int, tbase *types.Type, method *types.Field, target *ir.Package) {
  4081  	wrapper := tbase
  4082  	for i := 0; i < derefs; i++ {
  4083  		wrapper = types.NewPtr(wrapper)
  4084  	}
  4085  
  4086  	sym := ir.MethodSym(wrapper, method.Sym)
  4087  	base.Assertf(!sym.Siggen(), "already generated wrapper %v", sym)
  4088  	sym.SetSiggen(true)
  4089  
  4090  	wrappee := method.Type.Recv().Type
  4091  	if types.Identical(wrapper, wrappee) ||
  4092  		!types.IsMethodApplicable(wrapper, method) ||
  4093  		!reflectdata.NeedEmit(tbase) {
  4094  		return
  4095  	}
  4096  
  4097  	// TODO(mdempsky): Use method.Pos instead?
  4098  	pos := base.AutogeneratedPos
  4099  
  4100  	fn := newWrapperFunc(pos, sym, wrapper, method)
  4101  
  4102  	var recv ir.Node = fn.Nname.Type().Recv().Nname.(*ir.Name)
  4103  
  4104  	// For simple *T wrappers around T methods, panicwrap produces a
  4105  	// nicer panic message.
  4106  	if wrapper.IsPtr() && types.Identical(wrapper.Elem(), wrappee) {
  4107  		cond := ir.NewBinaryExpr(pos, ir.OEQ, recv, types.BuiltinPkg.Lookup("nil").Def.(ir.Node))
  4108  		then := []ir.Node{ir.NewCallExpr(pos, ir.OCALL, typecheck.LookupRuntime("panicwrap"), nil)}
  4109  		fn.Body.Append(ir.NewIfStmt(pos, cond, then, nil))
  4110  	}
  4111  
  4112  	// typecheck will add one implicit deref, if necessary,
  4113  	// but not-in-heap types require more for their **T wrappers.
  4114  	for i := 1; i < derefs; i++ {
  4115  		recv = Implicit(ir.NewStarExpr(pos, recv))
  4116  	}
  4117  
  4118  	addTailCall(pos, fn, recv, method)
  4119  
  4120  	finishWrapperFunc(fn, target)
  4121  }
  4122  
  4123  func wrapMethodValue(recvType *types.Type, method *types.Field, target *ir.Package, needed bool) {
  4124  	sym := ir.MethodSymSuffix(recvType, method.Sym, "-fm")
  4125  	if sym.Uniq() {
  4126  		return
  4127  	}
  4128  	sym.SetUniq(true)
  4129  
  4130  	// TODO(mdempsky): Use method.Pos instead?
  4131  	pos := base.AutogeneratedPos
  4132  
  4133  	fn := newWrapperFunc(pos, sym, nil, method)
  4134  	sym.Def = fn.Nname
  4135  
  4136  	// Declare and initialize variable holding receiver.
  4137  	recv := ir.NewHiddenParam(pos, fn, typecheck.Lookup(".this"), recvType)
  4138  
  4139  	if !needed {
  4140  		return
  4141  	}
  4142  
  4143  	addTailCall(pos, fn, recv, method)
  4144  
  4145  	finishWrapperFunc(fn, target)
  4146  }
  4147  
  4148  func newWrapperFunc(pos src.XPos, sym *types.Sym, wrapper *types.Type, method *types.Field) *ir.Func {
  4149  	sig := newWrapperType(wrapper, method)
  4150  	fn := ir.NewFunc(pos, pos, sym, sig)
  4151  	fn.DeclareParams(true)
  4152  	fn.SetDupok(true) // TODO(mdempsky): Leave unset for local, non-generic wrappers?
  4153  
  4154  	return fn
  4155  }
  4156  
  4157  func finishWrapperFunc(fn *ir.Func, target *ir.Package) {
  4158  	ir.WithFunc(fn, func() {
  4159  		typecheck.Stmts(fn.Body)
  4160  	})
  4161  
  4162  	// We generate wrappers after the global inlining pass,
  4163  	// so we're responsible for applying inlining ourselves here.
  4164  	// TODO(prattmic): plumb PGO.
  4165  	interleaved.DevirtualizeAndInlineFunc(fn, nil)
  4166  
  4167  	// The body of wrapper function after inlining may reveal new ir.OMETHVALUE node,
  4168  	// we don't know whether wrapper function has been generated for it or not, so
  4169  	// generate one immediately here.
  4170  	//
  4171  	// Further, after CL 492017, function that construct closures is allowed to be inlined,
  4172  	// even though the closure itself can't be inline. So we also need to visit body of any
  4173  	// closure that we see when visiting body of the wrapper function.
  4174  	ir.VisitFuncAndClosures(fn, func(n ir.Node) {
  4175  		if n, ok := n.(*ir.SelectorExpr); ok && n.Op() == ir.OMETHVALUE {
  4176  			wrapMethodValue(n.X.Type(), n.Selection, target, true)
  4177  		}
  4178  	})
  4179  
  4180  	fn.Nname.Defn = fn
  4181  	target.Funcs = append(target.Funcs, fn)
  4182  }
  4183  
  4184  // newWrapperType returns a copy of the given signature type, but with
  4185  // the receiver parameter type substituted with recvType.
  4186  // If recvType is nil, newWrapperType returns a signature
  4187  // without a receiver parameter.
  4188  func newWrapperType(recvType *types.Type, method *types.Field) *types.Type {
  4189  	clone := func(params []*types.Field) []*types.Field {
  4190  		res := make([]*types.Field, len(params))
  4191  		for i, param := range params {
  4192  			res[i] = types.NewField(param.Pos, param.Sym, param.Type)
  4193  			res[i].SetIsDDD(param.IsDDD())
  4194  		}
  4195  		return res
  4196  	}
  4197  
  4198  	sig := method.Type
  4199  
  4200  	var recv *types.Field
  4201  	if recvType != nil {
  4202  		recv = types.NewField(sig.Recv().Pos, sig.Recv().Sym, recvType)
  4203  	}
  4204  	params := clone(sig.Params())
  4205  	results := clone(sig.Results())
  4206  
  4207  	return types.NewSignature(recv, params, results)
  4208  }
  4209  
  4210  func addTailCall(pos src.XPos, fn *ir.Func, recv ir.Node, method *types.Field) {
  4211  	sig := fn.Nname.Type()
  4212  	args := make([]ir.Node, sig.NumParams())
  4213  	for i, param := range sig.Params() {
  4214  		args[i] = param.Nname.(*ir.Name)
  4215  	}
  4216  
  4217  	dot := typecheck.XDotMethod(pos, recv, method.Sym, true)
  4218  	call := typecheck.Call(pos, dot, args, method.Type.IsVariadic()).(*ir.CallExpr)
  4219  
  4220  	if recv.Type() != nil && recv.Type().IsPtr() && method.Type.Recv().Type.IsPtr() &&
  4221  		method.Embedded != 0 &&
  4222  		(types.IsInterfaceMethod(method.Type) && base.Ctxt.Arch.Name != "wasm" ||
  4223  			!types.IsInterfaceMethod(method.Type) && !unifiedHaveInlineBody(ir.MethodExprName(dot).Func)) &&
  4224  		// TODO: implement wasm indirect tail calls
  4225  		// TODO: do we need the ppc64le/dynlink restriction for interface tail calls?
  4226  		!((base.Ctxt.Arch.Name == "ppc64le" || base.Ctxt.Arch.Name == "ppc64") && base.Ctxt.Flag_dynlink) {
  4227  		if base.Debug.TailCall != 0 {
  4228  			base.WarnfAt(fn.Nname.Type().Recv().Type.Elem().Pos(), "tail call emitted for the method %v wrapper", method.Nname)
  4229  		}
  4230  		// Prefer OTAILCALL to reduce code size (except the case when the called method can be inlined).
  4231  		fn.Body.Append(ir.NewTailCallStmt(pos, call))
  4232  		return
  4233  	}
  4234  
  4235  	fn.SetWrapper(true)
  4236  
  4237  	if method.Type.NumResults() == 0 {
  4238  		fn.Body.Append(call)
  4239  		return
  4240  	}
  4241  
  4242  	ret := ir.NewReturnStmt(pos, nil)
  4243  	ret.Results = []ir.Node{call}
  4244  	fn.Body.Append(ret)
  4245  }
  4246  
  4247  func setBasePos(pos src.XPos) {
  4248  	// Set the position for any error messages we might print (e.g. too large types).
  4249  	base.Pos = pos
  4250  }
  4251  
  4252  // dictParamName is the name of the synthetic dictionary parameter
  4253  // added to shaped functions.
  4254  //
  4255  // N.B., this variable name is known to Delve:
  4256  // https://github.com/go-delve/delve/blob/cb91509630529e6055be845688fd21eb89ae8714/pkg/proc/eval.go#L28
  4257  const dictParamName = typecheck.LocalDictName
  4258  
  4259  // shapeSig returns a copy of fn's signature, except adding a
  4260  // dictionary parameter and promoting the receiver parameter (if any)
  4261  // to a normal parameter.
  4262  //
  4263  // The parameter types.Fields are all copied too, so their Nname
  4264  // fields can be initialized for use by the shape function.
  4265  //
  4266  // All signatures returned by shapeSig are marked as shaped.
  4267  func shapeSig(fn *ir.Func, dict *readerDict) *types.Type {
  4268  	sig := fn.Nname.Type()
  4269  	oldRecv := sig.Recv()
  4270  
  4271  	var recv *types.Field
  4272  	if oldRecv != nil {
  4273  		recv = types.NewField(oldRecv.Pos, oldRecv.Sym, oldRecv.Type)
  4274  	}
  4275  
  4276  	params := make([]*types.Field, 1+sig.NumParams())
  4277  	params[0] = types.NewField(fn.Pos(), fn.Sym().Pkg.Lookup(dictParamName), types.NewPtr(dict.varType()))
  4278  	for i, param := range sig.Params() {
  4279  		d := types.NewField(param.Pos, param.Sym, param.Type)
  4280  		d.SetIsDDD(param.IsDDD())
  4281  		params[1+i] = d
  4282  	}
  4283  
  4284  	results := make([]*types.Field, sig.NumResults())
  4285  	for i, result := range sig.Results() {
  4286  		results[i] = types.NewField(result.Pos, result.Sym, result.Type)
  4287  	}
  4288  
  4289  	typ := types.NewSignature(recv, params, results)
  4290  	typ.SetHasShape(true)
  4291  	return typ
  4292  }
  4293  

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