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