main.go

     1  // Copyright 2009 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 gc
     6  
     7  import (
     8  	"bufio"
     9  	"bytes"
    10  	"cmd/compile/internal/base"
    11  	"cmd/compile/internal/coverage"
    12  	"cmd/compile/internal/deadlocals"
    13  	"cmd/compile/internal/dwarfgen"
    14  	"cmd/compile/internal/escape"
    15  	"cmd/compile/internal/inline"
    16  	"cmd/compile/internal/inline/interleaved"
    17  	"cmd/compile/internal/ir"
    18  	"cmd/compile/internal/logopt"
    19  	"cmd/compile/internal/loopvar"
    20  	"cmd/compile/internal/noder"
    21  	"cmd/compile/internal/pgoir"
    22  	"cmd/compile/internal/pkginit"
    23  	"cmd/compile/internal/reflectdata"
    24  	"cmd/compile/internal/rttype"
    25  	"cmd/compile/internal/ssa"
    26  	"cmd/compile/internal/ssagen"
    27  	"cmd/compile/internal/staticinit"
    28  	"cmd/compile/internal/typecheck"
    29  	"cmd/compile/internal/types"
    30  	"cmd/internal/dwarf"
    31  	"cmd/internal/obj"
    32  	"cmd/internal/objabi"
    33  	"cmd/internal/src"
    34  	"cmd/internal/telemetry/counter"
    35  	"flag"
    36  	"fmt"
    37  	"internal/buildcfg"
    38  	"log"
    39  	"os"
    40  	"runtime"
    41  )
    42  
    43  // handlePanic ensures that we print out an "internal compiler error" for any panic
    44  // or runtime exception during front-end compiler processing (unless there have
    45  // already been some compiler errors). It may also be invoked from the explicit panic in
    46  // hcrash(), in which case, we pass the panic on through.
    47  func handlePanic() {
    48  	if err := recover(); err != nil {
    49  		if err == "-h" {
    50  			// Force real panic now with -h option (hcrash) - the error
    51  			// information will have already been printed.
    52  			panic(err)
    53  		}
    54  		base.Fatalf("panic: %v", err)
    55  	}
    56  }
    57  
    58  // Main parses flags and Go source files specified in the command-line
    59  // arguments, type-checks the parsed Go package, compiles functions to machine
    60  // code, and finally writes the compiled package definition to disk.
    61  func Main(archInit func(*ssagen.ArchInfo)) {
    62  	base.Timer.Start("fe", "init")
    63  	counter.Open()
    64  	counter.Inc("compile/invocations")
    65  
    66  	defer handlePanic()
    67  
    68  	archInit(&ssagen.Arch)
    69  
    70  	base.Ctxt = obj.Linknew(ssagen.Arch.LinkArch)
    71  	base.Ctxt.DiagFunc = base.Errorf
    72  	base.Ctxt.DiagFlush = base.FlushErrors
    73  	base.Ctxt.Bso = bufio.NewWriter(os.Stdout)
    74  
    75  	// UseBASEntries is preferred because it shaves about 2% off build time, but LLDB, dsymutil, and dwarfdump
    76  	// on Darwin don't support it properly, especially since macOS 10.14 (Mojave).  This is exposed as a flag
    77  	// to allow testing with LLVM tools on Linux, and to help with reporting this bug to the LLVM project.
    78  	// See bugs 31188 and 21945 (CLs 170638, 98075, 72371).
    79  	base.Ctxt.UseBASEntries = base.Ctxt.Headtype != objabi.Hdarwin
    80  
    81  	base.DebugSSA = ssa.PhaseOption
    82  	base.ParseFlags()
    83  
    84  	if os.Getenv("GOGC") == "" { // GOGC set disables starting heap adjustment
    85  		// More processors will use more heap, but assume that more memory is available.
    86  		// So 1 processor -> 40MB, 4 -> 64MB, 12 -> 128MB
    87  		base.AdjustStartingHeap(uint64(32+8*base.Flag.LowerC) << 20)
    88  	}
    89  
    90  	types.LocalPkg = types.NewPkg(base.Ctxt.Pkgpath, "")
    91  
    92  	// pseudo-package, for scoping
    93  	types.BuiltinPkg = types.NewPkg("go.builtin", "") // TODO(gri) name this package go.builtin?
    94  	types.BuiltinPkg.Prefix = "go:builtin"
    95  
    96  	// pseudo-package, accessed by import "unsafe"
    97  	types.UnsafePkg = types.NewPkg("unsafe", "unsafe")
    98  
    99  	// Pseudo-package that contains the compiler's builtin
   100  	// declarations for package runtime. These are declared in a
   101  	// separate package to avoid conflicts with package runtime's
   102  	// actual declarations, which may differ intentionally but
   103  	// insignificantly.
   104  	ir.Pkgs.Runtime = types.NewPkg("go.runtime", "runtime")
   105  	ir.Pkgs.Runtime.Prefix = "runtime"
   106  
   107  	if buildcfg.Experiment.SwissMap {
   108  		// Pseudo-package that contains the compiler's builtin
   109  		// declarations for maps.
   110  		ir.Pkgs.InternalMaps = types.NewPkg("go.internal/runtime/maps", "internal/runtime/maps")
   111  		ir.Pkgs.InternalMaps.Prefix = "internal/runtime/maps"
   112  	}
   113  
   114  	// pseudo-packages used in symbol tables
   115  	ir.Pkgs.Itab = types.NewPkg("go.itab", "go.itab")
   116  	ir.Pkgs.Itab.Prefix = "go:itab"
   117  
   118  	// pseudo-package used for methods with anonymous receivers
   119  	ir.Pkgs.Go = types.NewPkg("go", "")
   120  
   121  	// pseudo-package for use with code coverage instrumentation.
   122  	ir.Pkgs.Coverage = types.NewPkg("go.coverage", "runtime/coverage")
   123  	ir.Pkgs.Coverage.Prefix = "runtime/coverage"
   124  
   125  	// Record flags that affect the build result. (And don't
   126  	// record flags that don't, since that would cause spurious
   127  	// changes in the binary.)
   128  	dwarfgen.RecordFlags("B", "N", "l", "msan", "race", "asan", "shared", "dynlink", "dwarf", "dwarflocationlists", "dwarfbasentries", "smallframes", "spectre")
   129  
   130  	if !base.EnableTrace && base.Flag.LowerT {
   131  		log.Fatalf("compiler not built with support for -t")
   132  	}
   133  
   134  	// Enable inlining (after RecordFlags, to avoid recording the rewritten -l).  For now:
   135  	//	default: inlining on.  (Flag.LowerL == 1)
   136  	//	-l: inlining off  (Flag.LowerL == 0)
   137  	//	-l=2, -l=3: inlining on again, with extra debugging (Flag.LowerL > 1)
   138  	if base.Flag.LowerL <= 1 {
   139  		base.Flag.LowerL = 1 - base.Flag.LowerL
   140  	}
   141  
   142  	if base.Flag.SmallFrames {
   143  		ir.MaxStackVarSize = 128 * 1024
   144  		ir.MaxImplicitStackVarSize = 16 * 1024
   145  	}
   146  
   147  	if base.Flag.Dwarf {
   148  		base.Ctxt.DebugInfo = dwarfgen.Info
   149  		base.Ctxt.GenAbstractFunc = dwarfgen.AbstractFunc
   150  		base.Ctxt.DwFixups = obj.NewDwarfFixupTable(base.Ctxt)
   151  	} else {
   152  		// turn off inline generation if no dwarf at all
   153  		base.Flag.GenDwarfInl = 0
   154  		base.Ctxt.Flag_locationlists = false
   155  	}
   156  	if base.Ctxt.Flag_locationlists && len(base.Ctxt.Arch.DWARFRegisters) == 0 {
   157  		log.Fatalf("location lists requested but register mapping not available on %v", base.Ctxt.Arch.Name)
   158  	}
   159  
   160  	types.ParseLangFlag()
   161  
   162  	symABIs := ssagen.NewSymABIs()
   163  	if base.Flag.SymABIs != "" {
   164  		symABIs.ReadSymABIs(base.Flag.SymABIs)
   165  	}
   166  
   167  	if objabi.LookupPkgSpecial(base.Ctxt.Pkgpath).NoInstrument {
   168  		base.Flag.Race = false
   169  		base.Flag.MSan = false
   170  		base.Flag.ASan = false
   171  	}
   172  
   173  	ssagen.Arch.LinkArch.Init(base.Ctxt)
   174  	startProfile()
   175  	if base.Flag.Race || base.Flag.MSan || base.Flag.ASan {
   176  		base.Flag.Cfg.Instrumenting = true
   177  	}
   178  	if base.Flag.Dwarf {
   179  		dwarf.EnableLogging(base.Debug.DwarfInl != 0)
   180  	}
   181  	if base.Debug.SoftFloat != 0 {
   182  		ssagen.Arch.SoftFloat = true
   183  	}
   184  
   185  	if base.Flag.JSON != "" { // parse version,destination from json logging optimization.
   186  		logopt.LogJsonOption(base.Flag.JSON)
   187  	}
   188  
   189  	ir.EscFmt = escape.Fmt
   190  	ir.IsIntrinsicCall = ssagen.IsIntrinsicCall
   191  	inline.SSADumpInline = ssagen.DumpInline
   192  	ssagen.InitEnv()
   193  	ssagen.InitTables()
   194  
   195  	types.PtrSize = ssagen.Arch.LinkArch.PtrSize
   196  	types.RegSize = ssagen.Arch.LinkArch.RegSize
   197  	types.MaxWidth = ssagen.Arch.MAXWIDTH
   198  
   199  	typecheck.Target = new(ir.Package)
   200  
   201  	base.AutogeneratedPos = makePos(src.NewFileBase("<autogenerated>", "<autogenerated>"), 1, 0)
   202  
   203  	typecheck.InitUniverse()
   204  	typecheck.InitRuntime()
   205  	rttype.Init()
   206  
   207  	// Parse and typecheck input.
   208  	noder.LoadPackage(flag.Args())
   209  
   210  	// As a convenience to users (toolchain maintainers, in particular),
   211  	// when compiling a package named "main", we default the package
   212  	// path to "main" if the -p flag was not specified.
   213  	if base.Ctxt.Pkgpath == obj.UnlinkablePkg && types.LocalPkg.Name == "main" {
   214  		base.Ctxt.Pkgpath = "main"
   215  		types.LocalPkg.Path = "main"
   216  		types.LocalPkg.Prefix = "main"
   217  	}
   218  
   219  	dwarfgen.RecordPackageName()
   220  
   221  	// Prepare for backend processing.
   222  	ssagen.InitConfig()
   223  
   224  	// Apply coverage fixups, if applicable.
   225  	coverage.Fixup()
   226  
   227  	// Read profile file and build profile-graph and weighted-call-graph.
   228  	base.Timer.Start("fe", "pgo-load-profile")
   229  	var profile *pgoir.Profile
   230  	if base.Flag.PgoProfile != "" {
   231  		var err error
   232  		profile, err = pgoir.New(base.Flag.PgoProfile)
   233  		if err != nil {
   234  			log.Fatalf("%s: PGO error: %v", base.Flag.PgoProfile, err)
   235  		}
   236  	}
   237  
   238  	// Interleaved devirtualization and inlining.
   239  	base.Timer.Start("fe", "devirtualize-and-inline")
   240  	interleaved.DevirtualizeAndInlinePackage(typecheck.Target, profile)
   241  
   242  	noder.MakeWrappers(typecheck.Target) // must happen after inlining
   243  
   244  	// Get variable capture right in for loops.
   245  	var transformed []loopvar.VarAndLoop
   246  	for _, fn := range typecheck.Target.Funcs {
   247  		transformed = append(transformed, loopvar.ForCapture(fn)...)
   248  	}
   249  	ir.CurFunc = nil
   250  
   251  	// Build init task, if needed.
   252  	pkginit.MakeTask()
   253  
   254  	// Generate ABI wrappers. Must happen before escape analysis
   255  	// and doesn't benefit from dead-coding or inlining.
   256  	symABIs.GenABIWrappers()
   257  
   258  	deadlocals.Funcs(typecheck.Target.Funcs)
   259  
   260  	// Escape analysis.
   261  	// Required for moving heap allocations onto stack,
   262  	// which in turn is required by the closure implementation,
   263  	// which stores the addresses of stack variables into the closure.
   264  	// If the closure does not escape, it needs to be on the stack
   265  	// or else the stack copier will not update it.
   266  	// Large values are also moved off stack in escape analysis;
   267  	// because large values may contain pointers, it must happen early.
   268  	base.Timer.Start("fe", "escapes")
   269  	escape.Funcs(typecheck.Target.Funcs)
   270  
   271  	loopvar.LogTransformations(transformed)
   272  
   273  	// Collect information for go:nowritebarrierrec
   274  	// checking. This must happen before transforming closures during Walk
   275  	// We'll do the final check after write barriers are
   276  	// inserted.
   277  	if base.Flag.CompilingRuntime {
   278  		ssagen.EnableNoWriteBarrierRecCheck()
   279  	}
   280  
   281  	ir.CurFunc = nil
   282  
   283  	reflectdata.WriteBasicTypes()
   284  
   285  	// Compile top-level declarations.
   286  	//
   287  	// There are cyclic dependencies between all of these phases, so we
   288  	// need to iterate all of them until we reach a fixed point.
   289  	base.Timer.Start("be", "compilefuncs")
   290  	for nextFunc, nextExtern := 0, 0; ; {
   291  		reflectdata.WriteRuntimeTypes()
   292  
   293  		if nextExtern < len(typecheck.Target.Externs) {
   294  			switch n := typecheck.Target.Externs[nextExtern]; n.Op() {
   295  			case ir.ONAME:
   296  				dumpGlobal(n)
   297  			case ir.OLITERAL:
   298  				dumpGlobalConst(n)
   299  			case ir.OTYPE:
   300  				reflectdata.NeedRuntimeType(n.Type())
   301  			}
   302  			nextExtern++
   303  			continue
   304  		}
   305  
   306  		if nextFunc < len(typecheck.Target.Funcs) {
   307  			enqueueFunc(typecheck.Target.Funcs[nextFunc])
   308  			nextFunc++
   309  			continue
   310  		}
   311  
   312  		// The SSA backend supports using multiple goroutines, so keep it
   313  		// as late as possible to maximize how much work we can batch and
   314  		// process concurrently.
   315  		if len(compilequeue) != 0 {
   316  			compileFunctions(profile)
   317  			continue
   318  		}
   319  
   320  		// Finalize DWARF inline routine DIEs, then explicitly turn off
   321  		// further DWARF inlining generation to avoid problems with
   322  		// generated method wrappers.
   323  		//
   324  		// Note: The DWARF fixup code for inlined calls currently doesn't
   325  		// allow multiple invocations, so we intentionally run it just
   326  		// once after everything else. Worst case, some generated
   327  		// functions have slightly larger DWARF DIEs.
   328  		if base.Ctxt.DwFixups != nil {
   329  			base.Ctxt.DwFixups.Finalize(base.Ctxt.Pkgpath, base.Debug.DwarfInl != 0)
   330  			base.Ctxt.DwFixups = nil
   331  			base.Flag.GenDwarfInl = 0
   332  			continue // may have called reflectdata.TypeLinksym (#62156)
   333  		}
   334  
   335  		break
   336  	}
   337  
   338  	base.Timer.AddEvent(int64(len(typecheck.Target.Funcs)), "funcs")
   339  
   340  	if base.Flag.CompilingRuntime {
   341  		// Write barriers are now known. Check the call graph.
   342  		ssagen.NoWriteBarrierRecCheck()
   343  	}
   344  
   345  	// Add keep relocations for global maps.
   346  	if base.Debug.WrapGlobalMapCtl != 1 {
   347  		staticinit.AddKeepRelocations()
   348  	}
   349  
   350  	// Write object data to disk.
   351  	base.Timer.Start("be", "dumpobj")
   352  	dumpdata()
   353  	base.Ctxt.NumberSyms()
   354  	dumpobj()
   355  	if base.Flag.AsmHdr != "" {
   356  		dumpasmhdr()
   357  	}
   358  
   359  	ssagen.CheckLargeStacks()
   360  	typecheck.CheckFuncStack()
   361  
   362  	if len(compilequeue) != 0 {
   363  		base.Fatalf("%d uncompiled functions", len(compilequeue))
   364  	}
   365  
   366  	logopt.FlushLoggedOpts(base.Ctxt, base.Ctxt.Pkgpath)
   367  	base.ExitIfErrors()
   368  
   369  	base.FlushErrors()
   370  	base.Timer.Stop()
   371  
   372  	if base.Flag.Bench != "" {
   373  		if err := writebench(base.Flag.Bench); err != nil {
   374  			log.Fatalf("cannot write benchmark data: %v", err)
   375  		}
   376  	}
   377  }
   378  
   379  func writebench(filename string) error {
   380  	f, err := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0666)
   381  	if err != nil {
   382  		return err
   383  	}
   384  
   385  	var buf bytes.Buffer
   386  	fmt.Fprintln(&buf, "commit:", buildcfg.Version)
   387  	fmt.Fprintln(&buf, "goos:", runtime.GOOS)
   388  	fmt.Fprintln(&buf, "goarch:", runtime.GOARCH)
   389  	base.Timer.Write(&buf, "BenchmarkCompile:"+base.Ctxt.Pkgpath+":")
   390  
   391  	n, err := f.Write(buf.Bytes())
   392  	if err != nil {
   393  		return err
   394  	}
   395  	if n != buf.Len() {
   396  		panic("bad writer")
   397  	}
   398  
   399  	return f.Close()
   400  }
   401  
   402  func makePos(b *src.PosBase, line, col uint) src.XPos {
   403  	return base.Ctxt.PosTable.XPos(src.MakePos(b, line, col))
   404  }
   405
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