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golang compile

· 3 min read

golang 的 lex和parse 在src\cmd\compile\internal\gc\main.go开始

核心步骤

  • parseFiles lex and parse
  • typecheck 语法树的遍历做类型检查
  • ssa

之后会经过link 连接和加载器ld

func Main(archInit func(*Arch)) {
    	lines := parseFiles(flag.Args())  // lex and parse
        ...
        	typecheckok = true

	// Process top-level declarations in phases.

	// Phase 1: const, type, and names and types of funcs.
	//   This will gather all the information about types
	//   and methods but doesn't depend on any of it.
	//
	//   We also defer type alias declarations until phase 2
	//   to avoid cycles like #18640.
	//   TODO(gri) Remove this again once we have a fix for #25838.

	// Don't use range--typecheck can add closures to xtop.
	timings.Start("fe", "typecheck", "top1")
	for i := 0; i < len(xtop); i++ {
		n := xtop[i]
		if op := n.Op; op != ODCL && op != OAS && op != OAS2 && (op != ODCLTYPE || !n.Left.Name.Param.Alias) {
			xtop[i] = typecheck(n, ctxStmt)
		}
	}

	// Phase 2: Variable assignments.
	//   To check interface assignments, depends on phase 1.

	// Don't use range--typecheck can add closures to xtop.
	timings.Start("fe", "typecheck", "top2")
	for i := 0; i < len(xtop); i++ {
		n := xtop[i]
		if op := n.Op; op == ODCL || op == OAS || op == OAS2 || op == ODCLTYPE && n.Left.Name.Param.Alias {
			xtop[i] = typecheck(n, ctxStmt)
		}
	}

	// Phase 3: Type check function bodies.
	// Don't use range--typecheck can add closures to xtop.
	timings.Start("fe", "typecheck", "func")
	var fcount int64
	for i := 0; i < len(xtop); i++ {
		n := xtop[i]
		if op := n.Op; op == ODCLFUNC || op == OCLOSURE {
			Curfn = n
			decldepth = 1
			saveerrors()
			typecheckslice(Curfn.Nbody.Slice(), ctxStmt)
			checkreturn(Curfn)
			if nerrors != 0 {
				Curfn.Nbody.Set(nil) // type errors; do not compile
			}
			// Now that we've checked whether n terminates,
			// we can eliminate some obviously dead code.
			deadcode(Curfn)
			fcount++
		}
	}
	// With all types checked, it's now safe to verify map keys. One single
	// check past phase 9 isn't sufficient, as we may exit with other errors
	// before then, thus skipping map key errors.
}
(gdb) bt
#0  cmd/go/internal/load.LoadImport (path=..., srcDir=..., parent=0xc000147200, stk=0xc0001db698, importPos=..., mode=1, ~r6=<optimized out>) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:530
#1  0x000000000079fa1b in cmd/go/internal/load.(*Package).load (p=0xc000147200, stk=0xc0001db698, bp=0xc0001b8a80, err=...) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:1707
#2  0x0000000000799827 in cmd/go/internal/load.loadImport (pre=0x0, path=..., srcDir=..., parent=0xc000146d80, stk=0xc0001db698, importPos=..., mode=1, ~r7=<optimized out>)
    at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:578
#3  0x000000000079890a in cmd/go/internal/load.LoadImport (path=..., srcDir=..., parent=0xc000146d80, stk=0xc0001db698, importPos=..., mode=1, ~r6=<optimized out>) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:531
#4  0x000000000079fa1b in cmd/go/internal/load.(*Package).load (p=0xc000146d80, stk=0xc0001db698, bp=0xc0001b8700, err=...) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:1707
#5  0x0000000000799827 in cmd/go/internal/load.loadImport (pre=0x0, path=..., srcDir=..., parent=0xc000146900, stk=0xc0001db698, importPos=..., mode=1, ~r7=<optimized out>)
    at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:578
#6  0x000000000079890a in cmd/go/internal/load.LoadImport (path=..., srcDir=..., parent=0xc000146900, stk=0xc0001cf698, importPos=..., mode=1, ~r6=<optimized out>) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:531
#7  0x000000000079fa1b in cmd/go/internal/load.(*Package).load (p=0xc000146900, stk=0xc0001db698, bp=0xc0001b8380, err=...) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:1707
#8  0x00000000007a4c66 in cmd/go/internal/load.GoFilesPackage (gofiles=..., ~r1=<optimized out>) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:2230
#9  0x00000000007a3c54 in cmd/go/internal/load.PackagesAndErrors (patterns=..., ~r1=...) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:2056
#10 0x00000000007a417d in cmd/go/internal/load.PackagesForBuild (args=..., ~r1=...) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:2123
#11 0x0000000000842528 in cmd/go/internal/work.runBuild (cmd=<optimized out>, args=...) at /home/dinosaur/newgo/go/src/cmd/go/internal/work/build.go:348
#12 0x0000000000932219 in main.main () at /home/dinosaur/newgo/go/src/cmd/go/main.go:189