Current File : //data/old/usr/lib/golang/src/cmd/compile/internal/pkginit/init.go
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package pkginit
import (
"cmd/compile/internal/base"
"cmd/compile/internal/ir"
"cmd/compile/internal/objw"
"cmd/compile/internal/staticinit"
"cmd/compile/internal/typecheck"
"cmd/compile/internal/types"
"cmd/internal/obj"
"cmd/internal/src"
)
// MakeInit creates a synthetic init function to handle any
// package-scope initialization statements.
//
// TODO(mdempsky): Move into noder, so that the types2-based frontends
// can use Info.InitOrder instead.
func MakeInit() {
nf := initOrder(typecheck.Target.Decls)
if len(nf) == 0 {
return
}
// Make a function that contains all the initialization statements.
base.Pos = nf[0].Pos() // prolog/epilog gets line number of first init stmt
initializers := typecheck.Lookup("init")
fn := typecheck.DeclFunc(initializers, ir.NewFuncType(base.Pos, nil, nil, nil))
for _, dcl := range typecheck.InitTodoFunc.Dcl {
dcl.Curfn = fn
}
fn.Dcl = append(fn.Dcl, typecheck.InitTodoFunc.Dcl...)
typecheck.InitTodoFunc.Dcl = nil
// Suppress useless "can inline" diagnostics.
// Init functions are only called dynamically.
fn.SetInlinabilityChecked(true)
fn.Body = nf
typecheck.FinishFuncBody()
typecheck.Func(fn)
ir.WithFunc(fn, func() {
typecheck.Stmts(nf)
})
typecheck.Target.Decls = append(typecheck.Target.Decls, fn)
// Prepend to Inits, so it runs first, before any user-declared init
// functions.
typecheck.Target.Inits = append([]*ir.Func{fn}, typecheck.Target.Inits...)
if typecheck.InitTodoFunc.Dcl != nil {
// We only generate temps using InitTodoFunc if there
// are package-scope initialization statements, so
// something's weird if we get here.
base.Fatalf("InitTodoFunc still has declarations")
}
typecheck.InitTodoFunc = nil
}
// Task makes and returns an initialization record for the package.
// See runtime/proc.go:initTask for its layout.
// The 3 tasks for initialization are:
// 1) Initialize all of the packages the current package depends on.
// 2) Initialize all the variables that have initializers.
// 3) Run any init functions.
func Task() *ir.Name {
var deps []*obj.LSym // initTask records for packages the current package depends on
var fns []*obj.LSym // functions to call for package initialization
// Find imported packages with init tasks.
for _, pkg := range typecheck.Target.Imports {
n := typecheck.Resolve(ir.NewIdent(base.Pos, pkg.Lookup(".inittask")))
if n.Op() == ir.ONONAME {
continue
}
if n.Op() != ir.ONAME || n.(*ir.Name).Class != ir.PEXTERN {
base.Fatalf("bad inittask: %v", n)
}
deps = append(deps, n.(*ir.Name).Linksym())
}
// Record user init functions.
for _, fn := range typecheck.Target.Inits {
if fn.Sym().Name == "init" {
// Synthetic init function for initialization of package-scope
// variables. We can use staticinit to optimize away static
// assignments.
s := staticinit.Schedule{
Plans: make(map[ir.Node]*staticinit.Plan),
Temps: make(map[ir.Node]*ir.Name),
}
for _, n := range fn.Body {
s.StaticInit(n)
}
fn.Body = s.Out
ir.WithFunc(fn, func() {
typecheck.Stmts(fn.Body)
})
if len(fn.Body) == 0 {
fn.Body = []ir.Node{ir.NewBlockStmt(src.NoXPos, nil)}
}
}
// Skip init functions with empty bodies.
if len(fn.Body) == 1 {
if stmt := fn.Body[0]; stmt.Op() == ir.OBLOCK && len(stmt.(*ir.BlockStmt).List) == 0 {
continue
}
}
fns = append(fns, fn.Nname.Linksym())
}
if len(deps) == 0 && len(fns) == 0 && types.LocalPkg.Name != "main" && types.LocalPkg.Name != "runtime" {
return nil // nothing to initialize
}
// Make an .inittask structure.
sym := typecheck.Lookup(".inittask")
task := typecheck.NewName(sym)
task.SetType(types.Types[types.TUINT8]) // fake type
task.Class = ir.PEXTERN
sym.Def = task
lsym := task.Linksym()
ot := 0
ot = objw.Uintptr(lsym, ot, 0) // state: not initialized yet
ot = objw.Uintptr(lsym, ot, uint64(len(deps)))
ot = objw.Uintptr(lsym, ot, uint64(len(fns)))
for _, d := range deps {
ot = objw.SymPtr(lsym, ot, d, 0)
}
for _, f := range fns {
ot = objw.SymPtr(lsym, ot, f, 0)
}
// An initTask has pointers, but none into the Go heap.
// It's not quite read only, the state field must be modifiable.
objw.Global(lsym, int32(ot), obj.NOPTR)
return task
}
Mini Shell