func.go

     1  // Copyright 2015 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 ssa
     6  
     7  import (
     8  	"cmd/compile/internal/abi"
     9  	"cmd/compile/internal/base"
    10  	"cmd/compile/internal/ir"
    11  	"cmd/compile/internal/typecheck"
    12  	"cmd/compile/internal/types"
    13  	"cmd/internal/obj"
    14  	"cmd/internal/src"
    15  	"fmt"
    16  	"math"
    17  	"strings"
    18  )
    19  
    20  // A Func represents a Go func declaration (or function literal) and its body.
    21  // This package compiles each Func independently.
    22  // Funcs are single-use; a new Func must be created for every compiled function.
    23  type Func struct {
    24  	Config *Config     // architecture information
    25  	Cache  *Cache      // re-usable cache
    26  	fe     Frontend    // frontend state associated with this Func, callbacks into compiler frontend
    27  	pass   *pass       // current pass information (name, options, etc.)
    28  	Name   string      // e.g. NewFunc or (*Func).NumBlocks (no package prefix)
    29  	Type   *types.Type // type signature of the function.
    30  	Blocks []*Block    // unordered set of all basic blocks (note: not indexable by ID)
    31  	Entry  *Block      // the entry basic block
    32  
    33  	bid idAlloc // block ID allocator
    34  	vid idAlloc // value ID allocator
    35  
    36  	HTMLWriter     *HTMLWriter    // html writer, for debugging
    37  	PrintOrHtmlSSA bool           // true if GOSSAFUNC matches, true even if fe.Log() (spew phase results to stdout) is false.  There's an odd dependence on this in debug.go for method logf.
    38  	ruleMatches    map[string]int // number of times countRule was called during compilation for any given string
    39  	ABI0           *abi.ABIConfig // A copy, for no-sync access
    40  	ABI1           *abi.ABIConfig // A copy, for no-sync access
    41  	ABISelf        *abi.ABIConfig // ABI for function being compiled
    42  	ABIDefault     *abi.ABIConfig // ABI for rtcall and other no-parsed-signature/pragma functions.
    43  
    44  	scheduled   bool  // Values in Blocks are in final order
    45  	laidout     bool  // Blocks are ordered
    46  	NoSplit     bool  // true if function is marked as nosplit.  Used by schedule check pass.
    47  	dumpFileSeq uint8 // the sequence numbers of dump file. (%s_%02d__%s.dump", funcname, dumpFileSeq, phaseName)
    48  	IsPgoHot    bool
    49  	DeferReturn *Block // avoid creating more than one deferreturn if there's multiple calls to deferproc-etc.
    50  
    51  	// when register allocation is done, maps value ids to locations
    52  	RegAlloc []Location
    53  
    54  	// temporary registers allocated to rare instructions
    55  	tempRegs map[ID]*Register
    56  
    57  	// map from LocalSlot to set of Values that we want to store in that slot.
    58  	NamedValues map[LocalSlot][]*Value
    59  	// Names is a copy of NamedValues.Keys. We keep a separate list
    60  	// of keys to make iteration order deterministic.
    61  	Names []*LocalSlot
    62  	// Canonicalize root/top-level local slots, and canonicalize their pieces.
    63  	// Because LocalSlot pieces refer to their parents with a pointer, this ensures that equivalent slots really are equal.
    64  	CanonicalLocalSlots  map[LocalSlot]*LocalSlot
    65  	CanonicalLocalSplits map[LocalSlotSplitKey]*LocalSlot
    66  
    67  	// RegArgs is a slice of register-memory pairs that must be spilled and unspilled in the uncommon path of function entry.
    68  	RegArgs []Spill
    69  	// OwnAux describes parameters and results for this function.
    70  	OwnAux *AuxCall
    71  	// CloSlot holds the compiler-synthesized name (".closureptr")
    72  	// where we spill the closure pointer for range func bodies.
    73  	CloSlot *ir.Name
    74  
    75  	freeValues *Value // free Values linked by argstorage[0].  All other fields except ID are 0/nil.
    76  	freeBlocks *Block // free Blocks linked by succstorage[0].b.  All other fields except ID are 0/nil.
    77  
    78  	cachedPostorder  []*Block   // cached postorder traversal
    79  	cachedIdom       []*Block   // cached immediate dominators
    80  	cachedSdom       SparseTree // cached dominator tree
    81  	cachedLoopnest   *loopnest  // cached loop nest information
    82  	cachedLineStarts *xposmap   // cached map/set of xpos to integers
    83  
    84  	auxmap    auxmap             // map from aux values to opaque ids used by CSE
    85  	constants map[int64][]*Value // constants cache, keyed by constant value; users must check value's Op and Type
    86  }
    87  
    88  type LocalSlotSplitKey struct {
    89  	parent *LocalSlot
    90  	Off    int64       // offset of slot in N
    91  	Type   *types.Type // type of slot
    92  }
    93  
    94  // NewFunc returns a new, empty function object.
    95  // Caller must reset cache before calling NewFunc.
    96  func (c *Config) NewFunc(fe Frontend, cache *Cache) *Func {
    97  	return &Func{
    98  		fe:     fe,
    99  		Config: c,
   100  		Cache:  cache,
   101  
   102  		NamedValues:          make(map[LocalSlot][]*Value),
   103  		CanonicalLocalSlots:  make(map[LocalSlot]*LocalSlot),
   104  		CanonicalLocalSplits: make(map[LocalSlotSplitKey]*LocalSlot),
   105  		OwnAux:               &AuxCall{},
   106  	}
   107  }
   108  
   109  // NumBlocks returns an integer larger than the id of any Block in the Func.
   110  func (f *Func) NumBlocks() int {
   111  	return f.bid.num()
   112  }
   113  
   114  // NumValues returns an integer larger than the id of any Value in the Func.
   115  func (f *Func) NumValues() int {
   116  	return f.vid.num()
   117  }
   118  
   119  // NameABI returns the function name followed by comma and the ABI number.
   120  // This is intended for use with GOSSAFUNC and HTML dumps, and differs from
   121  // the linker's "<1>" convention because "<" and ">" require shell quoting
   122  // and are not legal file names (for use with GOSSADIR) on Windows.
   123  func (f *Func) NameABI() string {
   124  	return FuncNameABI(f.Name, f.ABISelf.Which())
   125  }
   126  
   127  // FuncNameABI returns n followed by a comma and the value of a.
   128  // This is a separate function to allow a single point encoding
   129  // of the format, which is used in places where there's not a Func yet.
   130  func FuncNameABI(n string, a obj.ABI) string {
   131  	return fmt.Sprintf("%s,%d", n, a)
   132  }
   133  
   134  // newSparseSet returns a sparse set that can store at least up to n integers.
   135  func (f *Func) newSparseSet(n int) *sparseSet {
   136  	return f.Cache.allocSparseSet(n)
   137  }
   138  
   139  // retSparseSet returns a sparse set to the config's cache of sparse
   140  // sets to be reused by f.newSparseSet.
   141  func (f *Func) retSparseSet(ss *sparseSet) {
   142  	f.Cache.freeSparseSet(ss)
   143  }
   144  
   145  // newSparseMap returns a sparse map that can store at least up to n integers.
   146  func (f *Func) newSparseMap(n int) *sparseMap {
   147  	return f.Cache.allocSparseMap(n)
   148  }
   149  
   150  // retSparseMap returns a sparse map to the config's cache of sparse
   151  // sets to be reused by f.newSparseMap.
   152  func (f *Func) retSparseMap(ss *sparseMap) {
   153  	f.Cache.freeSparseMap(ss)
   154  }
   155  
   156  // newSparseMapPos returns a sparse map that can store at least up to n integers.
   157  func (f *Func) newSparseMapPos(n int) *sparseMapPos {
   158  	return f.Cache.allocSparseMapPos(n)
   159  }
   160  
   161  // retSparseMapPos returns a sparse map to the config's cache of sparse
   162  // sets to be reused by f.newSparseMapPos.
   163  func (f *Func) retSparseMapPos(ss *sparseMapPos) {
   164  	f.Cache.freeSparseMapPos(ss)
   165  }
   166  
   167  // newPoset returns a new poset from the internal cache
   168  func (f *Func) newPoset() *poset {
   169  	if len(f.Cache.scrPoset) > 0 {
   170  		po := f.Cache.scrPoset[len(f.Cache.scrPoset)-1]
   171  		f.Cache.scrPoset = f.Cache.scrPoset[:len(f.Cache.scrPoset)-1]
   172  		return po
   173  	}
   174  	return newPoset()
   175  }
   176  
   177  // retPoset returns a poset to the internal cache
   178  func (f *Func) retPoset(po *poset) {
   179  	f.Cache.scrPoset = append(f.Cache.scrPoset, po)
   180  }
   181  
   182  func (f *Func) localSlotAddr(slot LocalSlot) *LocalSlot {
   183  	a, ok := f.CanonicalLocalSlots[slot]
   184  	if !ok {
   185  		a = new(LocalSlot)
   186  		*a = slot // don't escape slot
   187  		f.CanonicalLocalSlots[slot] = a
   188  	}
   189  	return a
   190  }
   191  
   192  func (f *Func) SplitString(name *LocalSlot) (*LocalSlot, *LocalSlot) {
   193  	ptrType := types.NewPtr(types.Types[types.TUINT8])
   194  	lenType := types.Types[types.TINT]
   195  	// Split this string up into two separate variables.
   196  	p := f.SplitSlot(name, ".ptr", 0, ptrType)
   197  	l := f.SplitSlot(name, ".len", ptrType.Size(), lenType)
   198  	return p, l
   199  }
   200  
   201  func (f *Func) SplitInterface(name *LocalSlot) (*LocalSlot, *LocalSlot) {
   202  	n := name.N
   203  	u := types.Types[types.TUINTPTR]
   204  	t := types.NewPtr(types.Types[types.TUINT8])
   205  	// Split this interface up into two separate variables.
   206  	sfx := ".itab"
   207  	if n.Type().IsEmptyInterface() {
   208  		sfx = ".type"
   209  	}
   210  	c := f.SplitSlot(name, sfx, 0, u) // see comment in typebits.Set
   211  	d := f.SplitSlot(name, ".data", u.Size(), t)
   212  	return c, d
   213  }
   214  
   215  func (f *Func) SplitSlice(name *LocalSlot) (*LocalSlot, *LocalSlot, *LocalSlot) {
   216  	ptrType := types.NewPtr(name.Type.Elem())
   217  	lenType := types.Types[types.TINT]
   218  	p := f.SplitSlot(name, ".ptr", 0, ptrType)
   219  	l := f.SplitSlot(name, ".len", ptrType.Size(), lenType)
   220  	c := f.SplitSlot(name, ".cap", ptrType.Size()+lenType.Size(), lenType)
   221  	return p, l, c
   222  }
   223  
   224  func (f *Func) SplitComplex(name *LocalSlot) (*LocalSlot, *LocalSlot) {
   225  	s := name.Type.Size() / 2
   226  	var t *types.Type
   227  	if s == 8 {
   228  		t = types.Types[types.TFLOAT64]
   229  	} else {
   230  		t = types.Types[types.TFLOAT32]
   231  	}
   232  	r := f.SplitSlot(name, ".real", 0, t)
   233  	i := f.SplitSlot(name, ".imag", t.Size(), t)
   234  	return r, i
   235  }
   236  
   237  func (f *Func) SplitInt64(name *LocalSlot) (*LocalSlot, *LocalSlot) {
   238  	var t *types.Type
   239  	if name.Type.IsSigned() {
   240  		t = types.Types[types.TINT32]
   241  	} else {
   242  		t = types.Types[types.TUINT32]
   243  	}
   244  	if f.Config.BigEndian {
   245  		return f.SplitSlot(name, ".hi", 0, t), f.SplitSlot(name, ".lo", t.Size(), types.Types[types.TUINT32])
   246  	}
   247  	return f.SplitSlot(name, ".hi", t.Size(), t), f.SplitSlot(name, ".lo", 0, types.Types[types.TUINT32])
   248  }
   249  
   250  func (f *Func) SplitStruct(name *LocalSlot, i int) *LocalSlot {
   251  	st := name.Type
   252  	return f.SplitSlot(name, st.FieldName(i), st.FieldOff(i), st.FieldType(i))
   253  }
   254  func (f *Func) SplitArray(name *LocalSlot) *LocalSlot {
   255  	n := name.N
   256  	at := name.Type
   257  	if at.NumElem() != 1 {
   258  		base.FatalfAt(n.Pos(), "bad array size")
   259  	}
   260  	et := at.Elem()
   261  	return f.SplitSlot(name, "[0]", 0, et)
   262  }
   263  
   264  func (f *Func) SplitSlot(name *LocalSlot, sfx string, offset int64, t *types.Type) *LocalSlot {
   265  	lssk := LocalSlotSplitKey{name, offset, t}
   266  	if als, ok := f.CanonicalLocalSplits[lssk]; ok {
   267  		return als
   268  	}
   269  	// Note: the _ field may appear several times.  But
   270  	// have no fear, identically-named but distinct Autos are
   271  	// ok, albeit maybe confusing for a debugger.
   272  	ls := f.fe.SplitSlot(name, sfx, offset, t)
   273  	f.CanonicalLocalSplits[lssk] = &ls
   274  	return &ls
   275  }
   276  
   277  // newValue allocates a new Value with the given fields and places it at the end of b.Values.
   278  func (f *Func) newValue(op Op, t *types.Type, b *Block, pos src.XPos) *Value {
   279  	var v *Value
   280  	if f.freeValues != nil {
   281  		v = f.freeValues
   282  		f.freeValues = v.argstorage[0]
   283  		v.argstorage[0] = nil
   284  	} else {
   285  		ID := f.vid.get()
   286  		if int(ID) < len(f.Cache.values) {
   287  			v = &f.Cache.values[ID]
   288  			v.ID = ID
   289  		} else {
   290  			v = &Value{ID: ID}
   291  		}
   292  	}
   293  	v.Op = op
   294  	v.Type = t
   295  	v.Block = b
   296  	if notStmtBoundary(op) {
   297  		pos = pos.WithNotStmt()
   298  	}
   299  	v.Pos = pos
   300  	b.Values = append(b.Values, v)
   301  	return v
   302  }
   303  
   304  // newValueNoBlock allocates a new Value with the given fields.
   305  // The returned value is not placed in any block.  Once the caller
   306  // decides on a block b, it must set b.Block and append
   307  // the returned value to b.Values.
   308  func (f *Func) newValueNoBlock(op Op, t *types.Type, pos src.XPos) *Value {
   309  	var v *Value
   310  	if f.freeValues != nil {
   311  		v = f.freeValues
   312  		f.freeValues = v.argstorage[0]
   313  		v.argstorage[0] = nil
   314  	} else {
   315  		ID := f.vid.get()
   316  		if int(ID) < len(f.Cache.values) {
   317  			v = &f.Cache.values[ID]
   318  			v.ID = ID
   319  		} else {
   320  			v = &Value{ID: ID}
   321  		}
   322  	}
   323  	v.Op = op
   324  	v.Type = t
   325  	v.Block = nil // caller must fix this.
   326  	if notStmtBoundary(op) {
   327  		pos = pos.WithNotStmt()
   328  	}
   329  	v.Pos = pos
   330  	return v
   331  }
   332  
   333  // LogStat writes a string key and int value as a warning in a
   334  // tab-separated format easily handled by spreadsheets or awk.
   335  // file names, lines, and function names are included to provide enough (?)
   336  // context to allow item-by-item comparisons across runs.
   337  // For example:
   338  // awk 'BEGIN {FS="\t"} $3~/TIME/{sum+=$4} END{print "t(ns)=",sum}' t.log
   339  func (f *Func) LogStat(key string, args ...interface{}) {
   340  	value := ""
   341  	for _, a := range args {
   342  		value += fmt.Sprintf("\t%v", a)
   343  	}
   344  	n := "missing_pass"
   345  	if f.pass != nil {
   346  		n = strings.ReplaceAll(f.pass.name, " ", "_")
   347  	}
   348  	f.Warnl(f.Entry.Pos, "\t%s\t%s%s\t%s", n, key, value, f.Name)
   349  }
   350  
   351  // unCacheLine removes v from f's constant cache "line" for aux,
   352  // resets v.InCache when it is found (and removed),
   353  // and returns whether v was found in that line.
   354  func (f *Func) unCacheLine(v *Value, aux int64) bool {
   355  	vv := f.constants[aux]
   356  	for i, cv := range vv {
   357  		if v == cv {
   358  			vv[i] = vv[len(vv)-1]
   359  			vv[len(vv)-1] = nil
   360  			f.constants[aux] = vv[0 : len(vv)-1]
   361  			v.InCache = false
   362  			return true
   363  		}
   364  	}
   365  	return false
   366  }
   367  
   368  // unCache removes v from f's constant cache.
   369  func (f *Func) unCache(v *Value) {
   370  	if v.InCache {
   371  		aux := v.AuxInt
   372  		if f.unCacheLine(v, aux) {
   373  			return
   374  		}
   375  		if aux == 0 {
   376  			switch v.Op {
   377  			case OpConstNil:
   378  				aux = constNilMagic
   379  			case OpConstSlice:
   380  				aux = constSliceMagic
   381  			case OpConstString:
   382  				aux = constEmptyStringMagic
   383  			case OpConstInterface:
   384  				aux = constInterfaceMagic
   385  			}
   386  			if aux != 0 && f.unCacheLine(v, aux) {
   387  				return
   388  			}
   389  		}
   390  		f.Fatalf("unCached value %s not found in cache, auxInt=0x%x, adjusted aux=0x%x", v.LongString(), v.AuxInt, aux)
   391  	}
   392  }
   393  
   394  // freeValue frees a value. It must no longer be referenced or have any args.
   395  func (f *Func) freeValue(v *Value) {
   396  	if v.Block == nil {
   397  		f.Fatalf("trying to free an already freed value")
   398  	}
   399  	if v.Uses != 0 {
   400  		f.Fatalf("value %s still has %d uses", v, v.Uses)
   401  	}
   402  	if len(v.Args) != 0 {
   403  		f.Fatalf("value %s still has %d args", v, len(v.Args))
   404  	}
   405  	// Clear everything but ID (which we reuse).
   406  	id := v.ID
   407  	if v.InCache {
   408  		f.unCache(v)
   409  	}
   410  	*v = Value{}
   411  	v.ID = id
   412  	v.argstorage[0] = f.freeValues
   413  	f.freeValues = v
   414  }
   415  
   416  // NewBlock allocates a new Block of the given kind and places it at the end of f.Blocks.
   417  func (f *Func) NewBlock(kind BlockKind) *Block {
   418  	var b *Block
   419  	if f.freeBlocks != nil {
   420  		b = f.freeBlocks
   421  		f.freeBlocks = b.succstorage[0].b
   422  		b.succstorage[0].b = nil
   423  	} else {
   424  		ID := f.bid.get()
   425  		if int(ID) < len(f.Cache.blocks) {
   426  			b = &f.Cache.blocks[ID]
   427  			b.ID = ID
   428  		} else {
   429  			b = &Block{ID: ID}
   430  		}
   431  	}
   432  	b.Kind = kind
   433  	b.Func = f
   434  	b.Preds = b.predstorage[:0]
   435  	b.Succs = b.succstorage[:0]
   436  	b.Values = b.valstorage[:0]
   437  	f.Blocks = append(f.Blocks, b)
   438  	f.invalidateCFG()
   439  	return b
   440  }
   441  
   442  func (f *Func) freeBlock(b *Block) {
   443  	if b.Func == nil {
   444  		f.Fatalf("trying to free an already freed block")
   445  	}
   446  	// Clear everything but ID (which we reuse).
   447  	id := b.ID
   448  	*b = Block{}
   449  	b.ID = id
   450  	b.succstorage[0].b = f.freeBlocks
   451  	f.freeBlocks = b
   452  }
   453  
   454  // NewValue0 returns a new value in the block with no arguments and zero aux values.
   455  func (b *Block) NewValue0(pos src.XPos, op Op, t *types.Type) *Value {
   456  	v := b.Func.newValue(op, t, b, pos)
   457  	v.AuxInt = 0
   458  	v.Args = v.argstorage[:0]
   459  	return v
   460  }
   461  
   462  // NewValue0I returns a new value in the block with no arguments and an auxint value.
   463  func (b *Block) NewValue0I(pos src.XPos, op Op, t *types.Type, auxint int64) *Value {
   464  	v := b.Func.newValue(op, t, b, pos)
   465  	v.AuxInt = auxint
   466  	v.Args = v.argstorage[:0]
   467  	return v
   468  }
   469  
   470  // NewValue0A returns a new value in the block with no arguments and an aux value.
   471  func (b *Block) NewValue0A(pos src.XPos, op Op, t *types.Type, aux Aux) *Value {
   472  	v := b.Func.newValue(op, t, b, pos)
   473  	v.AuxInt = 0
   474  	v.Aux = aux
   475  	v.Args = v.argstorage[:0]
   476  	return v
   477  }
   478  
   479  // NewValue0IA returns a new value in the block with no arguments and both an auxint and aux values.
   480  func (b *Block) NewValue0IA(pos src.XPos, op Op, t *types.Type, auxint int64, aux Aux) *Value {
   481  	v := b.Func.newValue(op, t, b, pos)
   482  	v.AuxInt = auxint
   483  	v.Aux = aux
   484  	v.Args = v.argstorage[:0]
   485  	return v
   486  }
   487  
   488  // NewValue1 returns a new value in the block with one argument and zero aux values.
   489  func (b *Block) NewValue1(pos src.XPos, op Op, t *types.Type, arg *Value) *Value {
   490  	v := b.Func.newValue(op, t, b, pos)
   491  	v.AuxInt = 0
   492  	v.Args = v.argstorage[:1]
   493  	v.argstorage[0] = arg
   494  	arg.Uses++
   495  	return v
   496  }
   497  
   498  // NewValue1I returns a new value in the block with one argument and an auxint value.
   499  func (b *Block) NewValue1I(pos src.XPos, op Op, t *types.Type, auxint int64, arg *Value) *Value {
   500  	v := b.Func.newValue(op, t, b, pos)
   501  	v.AuxInt = auxint
   502  	v.Args = v.argstorage[:1]
   503  	v.argstorage[0] = arg
   504  	arg.Uses++
   505  	return v
   506  }
   507  
   508  // NewValue1A returns a new value in the block with one argument and an aux value.
   509  func (b *Block) NewValue1A(pos src.XPos, op Op, t *types.Type, aux Aux, arg *Value) *Value {
   510  	v := b.Func.newValue(op, t, b, pos)
   511  	v.AuxInt = 0
   512  	v.Aux = aux
   513  	v.Args = v.argstorage[:1]
   514  	v.argstorage[0] = arg
   515  	arg.Uses++
   516  	return v
   517  }
   518  
   519  // NewValue1IA returns a new value in the block with one argument and both an auxint and aux values.
   520  func (b *Block) NewValue1IA(pos src.XPos, op Op, t *types.Type, auxint int64, aux Aux, arg *Value) *Value {
   521  	v := b.Func.newValue(op, t, b, pos)
   522  	v.AuxInt = auxint
   523  	v.Aux = aux
   524  	v.Args = v.argstorage[:1]
   525  	v.argstorage[0] = arg
   526  	arg.Uses++
   527  	return v
   528  }
   529  
   530  // NewValue2 returns a new value in the block with two arguments and zero aux values.
   531  func (b *Block) NewValue2(pos src.XPos, op Op, t *types.Type, arg0, arg1 *Value) *Value {
   532  	v := b.Func.newValue(op, t, b, pos)
   533  	v.AuxInt = 0
   534  	v.Args = v.argstorage[:2]
   535  	v.argstorage[0] = arg0
   536  	v.argstorage[1] = arg1
   537  	arg0.Uses++
   538  	arg1.Uses++
   539  	return v
   540  }
   541  
   542  // NewValue2A returns a new value in the block with two arguments and one aux values.
   543  func (b *Block) NewValue2A(pos src.XPos, op Op, t *types.Type, aux Aux, arg0, arg1 *Value) *Value {
   544  	v := b.Func.newValue(op, t, b, pos)
   545  	v.AuxInt = 0
   546  	v.Aux = aux
   547  	v.Args = v.argstorage[:2]
   548  	v.argstorage[0] = arg0
   549  	v.argstorage[1] = arg1
   550  	arg0.Uses++
   551  	arg1.Uses++
   552  	return v
   553  }
   554  
   555  // NewValue2I returns a new value in the block with two arguments and an auxint value.
   556  func (b *Block) NewValue2I(pos src.XPos, op Op, t *types.Type, auxint int64, arg0, arg1 *Value) *Value {
   557  	v := b.Func.newValue(op, t, b, pos)
   558  	v.AuxInt = auxint
   559  	v.Args = v.argstorage[:2]
   560  	v.argstorage[0] = arg0
   561  	v.argstorage[1] = arg1
   562  	arg0.Uses++
   563  	arg1.Uses++
   564  	return v
   565  }
   566  
   567  // NewValue2IA returns a new value in the block with two arguments and both an auxint and aux values.
   568  func (b *Block) NewValue2IA(pos src.XPos, op Op, t *types.Type, auxint int64, aux Aux, arg0, arg1 *Value) *Value {
   569  	v := b.Func.newValue(op, t, b, pos)
   570  	v.AuxInt = auxint
   571  	v.Aux = aux
   572  	v.Args = v.argstorage[:2]
   573  	v.argstorage[0] = arg0
   574  	v.argstorage[1] = arg1
   575  	arg0.Uses++
   576  	arg1.Uses++
   577  	return v
   578  }
   579  
   580  // NewValue3 returns a new value in the block with three arguments and zero aux values.
   581  func (b *Block) NewValue3(pos src.XPos, op Op, t *types.Type, arg0, arg1, arg2 *Value) *Value {
   582  	v := b.Func.newValue(op, t, b, pos)
   583  	v.AuxInt = 0
   584  	v.Args = v.argstorage[:3]
   585  	v.argstorage[0] = arg0
   586  	v.argstorage[1] = arg1
   587  	v.argstorage[2] = arg2
   588  	arg0.Uses++
   589  	arg1.Uses++
   590  	arg2.Uses++
   591  	return v
   592  }
   593  
   594  // NewValue3I returns a new value in the block with three arguments and an auxint value.
   595  func (b *Block) NewValue3I(pos src.XPos, op Op, t *types.Type, auxint int64, arg0, arg1, arg2 *Value) *Value {
   596  	v := b.Func.newValue(op, t, b, pos)
   597  	v.AuxInt = auxint
   598  	v.Args = v.argstorage[:3]
   599  	v.argstorage[0] = arg0
   600  	v.argstorage[1] = arg1
   601  	v.argstorage[2] = arg2
   602  	arg0.Uses++
   603  	arg1.Uses++
   604  	arg2.Uses++
   605  	return v
   606  }
   607  
   608  // NewValue3A returns a new value in the block with three argument and an aux value.
   609  func (b *Block) NewValue3A(pos src.XPos, op Op, t *types.Type, aux Aux, arg0, arg1, arg2 *Value) *Value {
   610  	v := b.Func.newValue(op, t, b, pos)
   611  	v.AuxInt = 0
   612  	v.Aux = aux
   613  	v.Args = v.argstorage[:3]
   614  	v.argstorage[0] = arg0
   615  	v.argstorage[1] = arg1
   616  	v.argstorage[2] = arg2
   617  	arg0.Uses++
   618  	arg1.Uses++
   619  	arg2.Uses++
   620  	return v
   621  }
   622  
   623  // NewValue4 returns a new value in the block with four arguments and zero aux values.
   624  func (b *Block) NewValue4(pos src.XPos, op Op, t *types.Type, arg0, arg1, arg2, arg3 *Value) *Value {
   625  	v := b.Func.newValue(op, t, b, pos)
   626  	v.AuxInt = 0
   627  	v.Args = []*Value{arg0, arg1, arg2, arg3}
   628  	arg0.Uses++
   629  	arg1.Uses++
   630  	arg2.Uses++
   631  	arg3.Uses++
   632  	return v
   633  }
   634  
   635  // NewValue4I returns a new value in the block with four arguments and auxint value.
   636  func (b *Block) NewValue4I(pos src.XPos, op Op, t *types.Type, auxint int64, arg0, arg1, arg2, arg3 *Value) *Value {
   637  	v := b.Func.newValue(op, t, b, pos)
   638  	v.AuxInt = auxint
   639  	v.Args = []*Value{arg0, arg1, arg2, arg3}
   640  	arg0.Uses++
   641  	arg1.Uses++
   642  	arg2.Uses++
   643  	arg3.Uses++
   644  	return v
   645  }
   646  
   647  // constVal returns a constant value for c.
   648  func (f *Func) constVal(op Op, t *types.Type, c int64, setAuxInt bool) *Value {
   649  	if f.constants == nil {
   650  		f.constants = make(map[int64][]*Value)
   651  	}
   652  	vv := f.constants[c]
   653  	for _, v := range vv {
   654  		if v.Op == op && v.Type.Compare(t) == types.CMPeq {
   655  			if setAuxInt && v.AuxInt != c {
   656  				panic(fmt.Sprintf("cached const %s should have AuxInt of %d", v.LongString(), c))
   657  			}
   658  			return v
   659  		}
   660  	}
   661  	var v *Value
   662  	if setAuxInt {
   663  		v = f.Entry.NewValue0I(src.NoXPos, op, t, c)
   664  	} else {
   665  		v = f.Entry.NewValue0(src.NoXPos, op, t)
   666  	}
   667  	f.constants[c] = append(vv, v)
   668  	v.InCache = true
   669  	return v
   670  }
   671  
   672  // These magic auxint values let us easily cache non-numeric constants
   673  // using the same constants map while making collisions unlikely.
   674  // These values are unlikely to occur in regular code and
   675  // are easy to grep for in case of bugs.
   676  const (
   677  	constSliceMagic       = 1122334455
   678  	constInterfaceMagic   = 2233445566
   679  	constNilMagic         = 3344556677
   680  	constEmptyStringMagic = 4455667788
   681  )
   682  
   683  // ConstBool returns an int constant representing its argument.
   684  func (f *Func) ConstBool(t *types.Type, c bool) *Value {
   685  	i := int64(0)
   686  	if c {
   687  		i = 1
   688  	}
   689  	return f.constVal(OpConstBool, t, i, true)
   690  }
   691  func (f *Func) ConstInt8(t *types.Type, c int8) *Value {
   692  	return f.constVal(OpConst8, t, int64(c), true)
   693  }
   694  func (f *Func) ConstInt16(t *types.Type, c int16) *Value {
   695  	return f.constVal(OpConst16, t, int64(c), true)
   696  }
   697  func (f *Func) ConstInt32(t *types.Type, c int32) *Value {
   698  	return f.constVal(OpConst32, t, int64(c), true)
   699  }
   700  func (f *Func) ConstInt64(t *types.Type, c int64) *Value {
   701  	return f.constVal(OpConst64, t, c, true)
   702  }
   703  func (f *Func) ConstFloat32(t *types.Type, c float64) *Value {
   704  	return f.constVal(OpConst32F, t, int64(math.Float64bits(float64(float32(c)))), true)
   705  }
   706  func (f *Func) ConstFloat64(t *types.Type, c float64) *Value {
   707  	return f.constVal(OpConst64F, t, int64(math.Float64bits(c)), true)
   708  }
   709  
   710  func (f *Func) ConstSlice(t *types.Type) *Value {
   711  	return f.constVal(OpConstSlice, t, constSliceMagic, false)
   712  }
   713  func (f *Func) ConstInterface(t *types.Type) *Value {
   714  	return f.constVal(OpConstInterface, t, constInterfaceMagic, false)
   715  }
   716  func (f *Func) ConstNil(t *types.Type) *Value {
   717  	return f.constVal(OpConstNil, t, constNilMagic, false)
   718  }
   719  func (f *Func) ConstEmptyString(t *types.Type) *Value {
   720  	v := f.constVal(OpConstString, t, constEmptyStringMagic, false)
   721  	v.Aux = StringToAux("")
   722  	return v
   723  }
   724  func (f *Func) ConstOffPtrSP(t *types.Type, c int64, sp *Value) *Value {
   725  	v := f.constVal(OpOffPtr, t, c, true)
   726  	if len(v.Args) == 0 {
   727  		v.AddArg(sp)
   728  	}
   729  	return v
   730  }
   731  
   732  func (f *Func) Frontend() Frontend                                  { return f.fe }
   733  func (f *Func) Warnl(pos src.XPos, msg string, args ...interface{}) { f.fe.Warnl(pos, msg, args...) }
   734  func (f *Func) Logf(msg string, args ...interface{})                { f.fe.Logf(msg, args...) }
   735  func (f *Func) Log() bool                                           { return f.fe.Log() }
   736  
   737  func (f *Func) Fatalf(msg string, args ...interface{}) {
   738  	stats := "crashed"
   739  	if f.Log() {
   740  		f.Logf("  pass %s end %s\n", f.pass.name, stats)
   741  		printFunc(f)
   742  	}
   743  	if f.HTMLWriter != nil {
   744  		f.HTMLWriter.WritePhase(f.pass.name, fmt.Sprintf("%s <span class=\"stats\">%s</span>", f.pass.name, stats))
   745  		f.HTMLWriter.flushPhases()
   746  	}
   747  	f.fe.Fatalf(f.Entry.Pos, msg, args...)
   748  }
   749  
   750  // postorder returns the reachable blocks in f in a postorder traversal.
   751  func (f *Func) postorder() []*Block {
   752  	if f.cachedPostorder == nil {
   753  		f.cachedPostorder = postorder(f)
   754  	}
   755  	return f.cachedPostorder
   756  }
   757  
   758  func (f *Func) Postorder() []*Block {
   759  	return f.postorder()
   760  }
   761  
   762  // Idom returns a map from block ID to the immediate dominator of that block.
   763  // f.Entry.ID maps to nil. Unreachable blocks map to nil as well.
   764  func (f *Func) Idom() []*Block {
   765  	if f.cachedIdom == nil {
   766  		f.cachedIdom = dominators(f)
   767  	}
   768  	return f.cachedIdom
   769  }
   770  
   771  // Sdom returns a sparse tree representing the dominator relationships
   772  // among the blocks of f.
   773  func (f *Func) Sdom() SparseTree {
   774  	if f.cachedSdom == nil {
   775  		f.cachedSdom = newSparseTree(f, f.Idom())
   776  	}
   777  	return f.cachedSdom
   778  }
   779  
   780  // loopnest returns the loop nest information for f.
   781  func (f *Func) loopnest() *loopnest {
   782  	if f.cachedLoopnest == nil {
   783  		f.cachedLoopnest = loopnestfor(f)
   784  	}
   785  	return f.cachedLoopnest
   786  }
   787  
   788  // invalidateCFG tells f that its CFG has changed.
   789  func (f *Func) invalidateCFG() {
   790  	f.cachedPostorder = nil
   791  	f.cachedIdom = nil
   792  	f.cachedSdom = nil
   793  	f.cachedLoopnest = nil
   794  }
   795  
   796  // DebugHashMatch returns
   797  //
   798  //	base.DebugHashMatch(this function's package.name)
   799  //
   800  // for use in bug isolation.  The return value is true unless
   801  // environment variable GOCOMPILEDEBUG=gossahash=X is set, in which case "it depends on X".
   802  // See [base.DebugHashMatch] for more information.
   803  func (f *Func) DebugHashMatch() bool {
   804  	if !base.HasDebugHash() {
   805  		return true
   806  	}
   807  	sym := f.fe.Func().Sym()
   808  	return base.DebugHashMatchPkgFunc(sym.Pkg.Path, sym.Name)
   809  }
   810  
   811  func (f *Func) spSb() (sp, sb *Value) {
   812  	initpos := src.NoXPos // These are originally created with no position in ssa.go; if they are optimized out then recreated, should be the same.
   813  	for _, v := range f.Entry.Values {
   814  		if v.Op == OpSB {
   815  			sb = v
   816  		}
   817  		if v.Op == OpSP {
   818  			sp = v
   819  		}
   820  		if sb != nil && sp != nil {
   821  			return
   822  		}
   823  	}
   824  	if sb == nil {
   825  		sb = f.Entry.NewValue0(initpos.WithNotStmt(), OpSB, f.Config.Types.Uintptr)
   826  	}
   827  	if sp == nil {
   828  		sp = f.Entry.NewValue0(initpos.WithNotStmt(), OpSP, f.Config.Types.Uintptr)
   829  	}
   830  	return
   831  }
   832  
   833  // useFMA allows targeted debugging w/ GOFMAHASH
   834  // If you have an architecture-dependent FP glitch, this will help you find it.
   835  func (f *Func) useFMA(v *Value) bool {
   836  	if base.FmaHash == nil {
   837  		return true
   838  	}
   839  	return base.FmaHash.MatchPos(v.Pos, nil)
   840  }
   841  
   842  // NewLocal returns a new anonymous local variable of the given type.
   843  func (f *Func) NewLocal(pos src.XPos, typ *types.Type) *ir.Name {
   844  	nn := typecheck.TempAt(pos, f.fe.Func(), typ) // Note: adds new auto to fn.Dcl list
   845  	nn.SetNonMergeable(true)
   846  	return nn
   847  }
   848  
   849  // IsMergeCandidate returns true if variable n could participate in
   850  // stack slot merging. For now we're restricting the set to things to
   851  // items larger than what CanSSA would allow (approximateky, we disallow things
   852  // marked as open defer slots so as to avoid complicating liveness
   853  // analysis.
   854  func IsMergeCandidate(n *ir.Name) bool {
   855  	if base.Debug.MergeLocals == 0 ||
   856  		base.Flag.N != 0 ||
   857  		n.Class != ir.PAUTO ||
   858  		n.Type().Size() <= int64(3*types.PtrSize) ||
   859  		n.Addrtaken() ||
   860  		n.NonMergeable() ||
   861  		n.OpenDeferSlot() {
   862  		return false
   863  	}
   864  	return true
   865  }
   866
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