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/bloop"
    12  	"cmd/compile/internal/coverage"
    13  	"cmd/compile/internal/deadlocals"
    14  	"cmd/compile/internal/dwarfgen"
    15  	"cmd/compile/internal/escape"
    16  	"cmd/compile/internal/inline"
    17  	"cmd/compile/internal/inline/interleaved"
    18  	"cmd/compile/internal/ir"
    19  	"cmd/compile/internal/logopt"
    20  	"cmd/compile/internal/loopvar"
    21  	"cmd/compile/internal/noder"
    22  	"cmd/compile/internal/pgoir"
    23  	"cmd/compile/internal/pkginit"
    24  	"cmd/compile/internal/reflectdata"
    25  	"cmd/compile/internal/rttype"
    26  	"cmd/compile/internal/slice"
    27  	"cmd/compile/internal/ssa"
    28  	"cmd/compile/internal/ssagen"
    29  	"cmd/compile/internal/staticinit"
    30  	"cmd/compile/internal/typecheck"
    31  	"cmd/compile/internal/types"
    32  	"cmd/internal/dwarf"
    33  	"cmd/internal/obj"
    34  	"cmd/internal/objabi"
    35  	"cmd/internal/src"
    36  	"cmd/internal/telemetry/counter"
    37  	"flag"
    38  	"fmt"
    39  	"internal/buildcfg"
    40  	"log"
    41  	"os"
    42  	"runtime"
    43  )
    44  
    45  // handlePanic ensures that we print out an "internal compiler error" for any panic
    46  // or runtime exception during front-end compiler processing (unless there have
    47  // already been some compiler errors). It may also be invoked from the explicit panic in
    48  // hcrash(), in which case, we pass the panic on through.
    49  func handlePanic() {
    50  	ir.CloseHTMLWriters()
    51  	noder.CloseHTMLWriters()
    52  	if err := recover(); err != nil {
    53  		if err == "-h" {
    54  			// Force real panic now with -h option (hcrash) - the error
    55  			// information will have already been printed.
    56  			panic(err)
    57  		}
    58  		base.Fatalf("panic: %v", err)
    59  	}
    60  }
    61  
    62  // Main parses flags and Go source files specified in the command-line
    63  // arguments, type-checks the parsed Go package, compiles functions to machine
    64  // code, and finally writes the compiled package definition to disk.
    65  func Main(archInit func(*ssagen.ArchInfo)) {
    66  	base.Timer.Start("fe", "init")
    67  	counter.Open()
    68  	counter.Inc("compile/invocations")
    69  
    70  	defer handlePanic()
    71  
    72  	archInit(&ssagen.Arch)
    73  
    74  	base.Ctxt = obj.Linknew(ssagen.Arch.LinkArch)
    75  	base.Ctxt.DiagFunc = base.Errorf
    76  	base.Ctxt.DiagFlush = base.FlushErrors
    77  	base.Ctxt.Bso = bufio.NewWriter(os.Stdout)
    78  
    79  	// UseBASEntries is preferred because it shaves about 2% off build time, but LLDB, dsymutil, and dwarfdump
    80  	// on Darwin don't support it properly, especially since macOS 10.14 (Mojave).  This is exposed as a flag
    81  	// to allow testing with LLVM tools on Linux, and to help with reporting this bug to the LLVM project.
    82  	// See bugs 31188 and 21945 (CLs 170638, 98075, 72371).
    83  	base.Ctxt.UseBASEntries = base.Ctxt.Headtype != objabi.Hdarwin
    84  
    85  	base.DebugSSA = ssa.PhaseOption
    86  	base.ParseFlags()
    87  
    88  	if flagGCStart := base.Debug.GCStart; flagGCStart > 0 || // explicit flags overrides environment variable disable of GC boost
    89  		os.Getenv("GOGC") == "" && os.Getenv("GOMEMLIMIT") == "" && base.Flag.LowerC != 1 { // explicit GC knobs or no concurrency implies default heap
    90  		startHeapMB := int64(128)
    91  		if flagGCStart > 0 {
    92  			startHeapMB = int64(flagGCStart)
    93  		}
    94  		base.AdjustStartingHeap(uint64(startHeapMB)<<20, 0, 0, 0, base.Debug.GCAdjust == 1)
    95  	}
    96  
    97  	types.LocalPkg = types.NewPkg(base.Ctxt.Pkgpath, "")
    98  
    99  	// pseudo-package, for scoping
   100  	types.BuiltinPkg = types.NewPkg("go.builtin", "") // TODO(gri) name this package go.builtin?
   101  	types.BuiltinPkg.Prefix = "go:builtin"
   102  
   103  	// pseudo-package, accessed by import "unsafe"
   104  	types.UnsafePkg = types.NewPkg("unsafe", "unsafe")
   105  
   106  	// Pseudo-package that contains the compiler's builtin
   107  	// declarations for package runtime. These are declared in a
   108  	// separate package to avoid conflicts with package runtime's
   109  	// actual declarations, which may differ intentionally but
   110  	// insignificantly.
   111  	ir.Pkgs.Runtime = types.NewPkg("go.runtime", "runtime")
   112  	ir.Pkgs.Runtime.Prefix = "runtime"
   113  
   114  	// Pseudo-package that contains the compiler's builtin
   115  	// declarations for maps.
   116  	ir.Pkgs.InternalMaps = types.NewPkg("go.internal/runtime/maps", "internal/runtime/maps")
   117  	ir.Pkgs.InternalMaps.Prefix = "internal/runtime/maps"
   118  
   119  	// pseudo-packages used in symbol tables
   120  	ir.Pkgs.Itab = types.NewPkg("go.itab", "go.itab")
   121  	ir.Pkgs.Itab.Prefix = "go:itab"
   122  
   123  	// pseudo-package used for methods with anonymous receivers
   124  	ir.Pkgs.Go = types.NewPkg("go", "")
   125  
   126  	// pseudo-package for use with code coverage instrumentation.
   127  	ir.Pkgs.Coverage = types.NewPkg("go.coverage", "runtime/coverage")
   128  	ir.Pkgs.Coverage.Prefix = "runtime/coverage"
   129  
   130  	// Record flags that affect the build result. (And don't
   131  	// record flags that don't, since that would cause spurious
   132  	// changes in the binary.)
   133  	dwarfgen.RecordFlags("B", "N", "l", "msan", "race", "asan", "shared", "dynlink", "dwarf", "dwarflocationlists", "dwarfbasentries", "smallframes", "spectre")
   134  
   135  	if !base.EnableTrace && base.Flag.LowerT {
   136  		log.Fatalf("compiler not built with support for -t")
   137  	}
   138  
   139  	// Enable inlining (after RecordFlags, to avoid recording the rewritten -l).  For now:
   140  	//	default: inlining on.  (Flag.LowerL == 1)
   141  	//	-l: inlining off  (Flag.LowerL == 0)
   142  	//	-l=2, -l=3: inlining on again, with extra debugging (Flag.LowerL > 1)
   143  	if base.Flag.LowerL <= 1 {
   144  		base.Flag.LowerL = 1 - base.Flag.LowerL
   145  	}
   146  
   147  	if base.Flag.SmallFrames {
   148  		ir.MaxStackVarSize = 64 * 1024
   149  		ir.MaxImplicitStackVarSize = 16 * 1024
   150  	}
   151  
   152  	if base.Flag.Dwarf {
   153  		base.Ctxt.DebugInfo = dwarfgen.Info
   154  		base.Ctxt.GenAbstractFunc = dwarfgen.AbstractFunc
   155  		base.Ctxt.DwFixups = obj.NewDwarfFixupTable(base.Ctxt)
   156  	} else {
   157  		// turn off inline generation if no dwarf at all
   158  		base.Flag.GenDwarfInl = 0
   159  		base.Ctxt.Flag_locationlists = false
   160  	}
   161  	if base.Ctxt.Flag_locationlists && len(base.Ctxt.Arch.DWARFRegisters) == 0 {
   162  		log.Fatalf("location lists requested but register mapping not available on %v", base.Ctxt.Arch.Name)
   163  	}
   164  
   165  	types.ParseLangFlag()
   166  
   167  	symABIs := ssagen.NewSymABIs()
   168  	if base.Flag.SymABIs != "" {
   169  		symABIs.ReadSymABIs(base.Flag.SymABIs)
   170  	}
   171  
   172  	if objabi.LookupPkgSpecial(base.Ctxt.Pkgpath).NoInstrument {
   173  		base.Flag.Race = false
   174  		base.Flag.MSan = false
   175  		base.Flag.ASan = false
   176  	}
   177  
   178  	ssagen.Arch.LinkArch.Init(base.Ctxt)
   179  	startProfile()
   180  	if base.Flag.Race || base.Flag.MSan || base.Flag.ASan {
   181  		base.Flag.Cfg.Instrumenting = true
   182  	}
   183  	if base.Flag.Dwarf {
   184  		dwarf.EnableLogging(base.Debug.DwarfInl != 0)
   185  	}
   186  	if base.Debug.SoftFloat != 0 {
   187  		ssagen.Arch.SoftFloat = true
   188  	}
   189  
   190  	if base.Flag.JSON != "" { // parse version,destination from json logging optimization.
   191  		logopt.LogJsonOption(base.Flag.JSON)
   192  	}
   193  
   194  	ir.EscFmt = escape.Fmt
   195  	ir.IsIntrinsicCall = ssagen.IsIntrinsicCall
   196  	ir.IsIntrinsicSym = ssagen.IsIntrinsicSym
   197  	inline.SSADumpInline = ssagen.DumpInline
   198  	ssagen.InitEnv()
   199  
   200  	types.PtrSize = ssagen.Arch.LinkArch.PtrSize
   201  	types.RegSize = ssagen.Arch.LinkArch.RegSize
   202  	types.MaxWidth = ssagen.Arch.MAXWIDTH
   203  
   204  	typecheck.Target = new(ir.Package)
   205  
   206  	base.AutogeneratedPos = makePos(src.NewFileBase("<autogenerated>", "<autogenerated>"), 1, 0)
   207  
   208  	typecheck.InitUniverse()
   209  	typecheck.InitRuntime()
   210  	rttype.Init()
   211  
   212  	// Some intrinsics (notably, the simd intrinsics) mention
   213  	// types "eagerly", thus ssagen must be initialized AFTER
   214  	// the type system is ready.
   215  	ssagen.InitTables()
   216  
   217  	// Parse and typecheck input.
   218  	noder.LoadPackage(flag.Args())
   219  
   220  	// As a convenience to users (toolchain maintainers, in particular),
   221  	// when compiling a package named "main", we default the package
   222  	// path to "main" if the -p flag was not specified.
   223  	if base.Ctxt.Pkgpath == obj.UnlinkablePkg && types.LocalPkg.Name == "main" {
   224  		base.Ctxt.Pkgpath = "main"
   225  		types.LocalPkg.Path = "main"
   226  		types.LocalPkg.Prefix = "main"
   227  	}
   228  
   229  	dwarfgen.RecordPackageName()
   230  
   231  	// Prepare for backend processing.
   232  	ssagen.InitConfig()
   233  
   234  	// Apply coverage fixups, if applicable.
   235  	coverage.Fixup()
   236  
   237  	// Read profile file and build profile-graph and weighted-call-graph.
   238  	base.Timer.Start("fe", "pgo-load-profile")
   239  	var profile *pgoir.Profile
   240  	if base.Flag.PgoProfile != "" {
   241  		var err error
   242  		profile, err = pgoir.New(base.Flag.PgoProfile)
   243  		if err != nil {
   244  			log.Fatalf("%s: PGO error: %v", base.Flag.PgoProfile, err)
   245  		}
   246  	}
   247  
   248  	for _, fn := range typecheck.Target.Funcs {
   249  		if ir.MatchAstDump(fn, "start") {
   250  			ir.AstDump(fn, "start, "+ir.FuncName(fn))
   251  		}
   252  	}
   253  
   254  	// Apply bloop markings.
   255  	bloop.Walk(typecheck.Target)
   256  
   257  	// Interleaved devirtualization and inlining.
   258  	base.Timer.Start("fe", "devirtualize-and-inline")
   259  	interleaved.DevirtualizeAndInlinePackage(typecheck.Target, profile)
   260  
   261  	for _, fn := range typecheck.Target.Funcs {
   262  		if ir.MatchAstDump(fn, "devirtualize-and-inline") {
   263  			ir.AstDump(fn, "devirtualize-and-inline, "+ir.FuncName(fn))
   264  		}
   265  	}
   266  
   267  	noder.MakeWrappers(typecheck.Target) // must happen after inlining
   268  
   269  	// Get variable capture right in for loops.
   270  	var transformed []loopvar.VarAndLoop
   271  	for _, fn := range typecheck.Target.Funcs {
   272  		transformed = append(transformed, loopvar.ForCapture(fn)...)
   273  	}
   274  	ir.CurFunc = nil
   275  
   276  	// Build init task, if needed.
   277  	pkginit.MakeTask()
   278  
   279  	// Generate ABI wrappers. Must happen before escape analysis
   280  	// and doesn't benefit from dead-coding or inlining.
   281  	symABIs.GenABIWrappers()
   282  
   283  	deadlocals.Funcs(typecheck.Target.Funcs)
   284  
   285  	// Escape analysis.
   286  	// Required for moving heap allocations onto stack,
   287  	// which in turn is required by the closure implementation,
   288  	// which stores the addresses of stack variables into the closure.
   289  	// If the closure does not escape, it needs to be on the stack
   290  	// or else the stack copier will not update it.
   291  	// Large values are also moved off stack in escape analysis;
   292  	// because large values may contain pointers, it must happen early.
   293  	base.Timer.Start("fe", "escapes")
   294  	escape.Funcs(typecheck.Target.Funcs)
   295  
   296  	slice.Funcs(typecheck.Target.Funcs)
   297  
   298  	loopvar.LogTransformations(transformed)
   299  
   300  	// Collect information for go:nowritebarrierrec
   301  	// checking. This must happen before transforming closures during Walk
   302  	// We'll do the final check after write barriers are
   303  	// inserted.
   304  	if base.Flag.CompilingRuntime {
   305  		ssagen.EnableNoWriteBarrierRecCheck()
   306  	}
   307  
   308  	ir.CurFunc = nil
   309  
   310  	reflectdata.WriteBasicTypes()
   311  
   312  	// Compile top-level declarations.
   313  	//
   314  	// There are cyclic dependencies between all of these phases, so we
   315  	// need to iterate all of them until we reach a fixed point.
   316  	base.Timer.Start("be", "compilefuncs")
   317  	for nextFunc, nextExtern := 0, 0; ; {
   318  		reflectdata.WriteRuntimeTypes()
   319  
   320  		if nextExtern < len(typecheck.Target.Externs) {
   321  			switch n := typecheck.Target.Externs[nextExtern]; n.Op() {
   322  			case ir.ONAME:
   323  				dumpGlobal(n)
   324  			case ir.OLITERAL:
   325  				dumpGlobalConst(n)
   326  			case ir.OTYPE:
   327  				reflectdata.NeedRuntimeType(n.Type())
   328  			}
   329  			nextExtern++
   330  			continue
   331  		}
   332  
   333  		if nextFunc < len(typecheck.Target.Funcs) {
   334  			enqueueFunc(typecheck.Target.Funcs[nextFunc], symABIs)
   335  			nextFunc++
   336  			continue
   337  		}
   338  
   339  		// The SSA backend supports using multiple goroutines, so keep it
   340  		// as late as possible to maximize how much work we can batch and
   341  		// process concurrently.
   342  		if len(compilequeue) != 0 {
   343  			compileFunctions(profile)
   344  			continue
   345  		}
   346  
   347  		// Finalize DWARF inline routine DIEs, then explicitly turn off
   348  		// further DWARF inlining generation to avoid problems with
   349  		// generated method wrappers.
   350  		//
   351  		// Note: The DWARF fixup code for inlined calls currently doesn't
   352  		// allow multiple invocations, so we intentionally run it just
   353  		// once after everything else. Worst case, some generated
   354  		// functions have slightly larger DWARF DIEs.
   355  		if base.Ctxt.DwFixups != nil {
   356  			base.Ctxt.DwFixups.Finalize(base.Ctxt.Pkgpath, base.Debug.DwarfInl != 0)
   357  			base.Ctxt.DwFixups = nil
   358  			base.Flag.GenDwarfInl = 0
   359  			continue // may have called reflectdata.TypeLinksym (#62156)
   360  		}
   361  
   362  		break
   363  	}
   364  
   365  	base.Timer.AddEvent(int64(len(typecheck.Target.Funcs)), "funcs")
   366  
   367  	if base.Flag.CompilingRuntime {
   368  		// Write barriers are now known. Check the call graph.
   369  		ssagen.NoWriteBarrierRecCheck()
   370  	}
   371  
   372  	// Add keep relocations for global maps.
   373  	if base.Debug.WrapGlobalMapCtl != 1 {
   374  		staticinit.AddKeepRelocations()
   375  	}
   376  
   377  	// Write object data to disk.
   378  	base.Timer.Start("be", "dumpobj")
   379  	dumpdata()
   380  	base.Ctxt.NumberSyms()
   381  	dumpobj()
   382  	if base.Flag.AsmHdr != "" {
   383  		dumpasmhdr()
   384  	}
   385  
   386  	ssagen.CheckLargeStacks()
   387  	typecheck.CheckFuncStack()
   388  
   389  	if len(compilequeue) != 0 {
   390  		base.Fatalf("%d uncompiled functions", len(compilequeue))
   391  	}
   392  
   393  	logopt.FlushLoggedOpts(base.Ctxt, base.Ctxt.Pkgpath)
   394  	base.ExitIfErrors()
   395  
   396  	base.FlushErrors()
   397  	base.Timer.Stop()
   398  
   399  	if base.Flag.Bench != "" {
   400  		if err := writebench(base.Flag.Bench); err != nil {
   401  			log.Fatalf("cannot write benchmark data: %v", err)
   402  		}
   403  	}
   404  }
   405  
   406  func writebench(filename string) error {
   407  	f, err := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0666)
   408  	if err != nil {
   409  		return err
   410  	}
   411  
   412  	var buf bytes.Buffer
   413  	fmt.Fprintln(&buf, "commit:", buildcfg.Version)
   414  	fmt.Fprintln(&buf, "goos:", runtime.GOOS)
   415  	fmt.Fprintln(&buf, "goarch:", runtime.GOARCH)
   416  	base.Timer.Write(&buf, "BenchmarkCompile:"+base.Ctxt.Pkgpath+":")
   417  
   418  	n, err := f.Write(buf.Bytes())
   419  	if err != nil {
   420  		return err
   421  	}
   422  	if n != buf.Len() {
   423  		panic("bad writer")
   424  	}
   425  
   426  	return f.Close()
   427  }
   428  
   429  func makePos(b *src.PosBase, line, col uint) src.XPos {
   430  	return base.Ctxt.PosTable.XPos(src.MakePos(b, line, col))
   431  }
   432
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