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