1 files changed, 144 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/pkginit/init.go b/src/cmd/compile/internal/pkginit/init.go
new file mode 100644
index 0000000..40f1408
--- /dev/null
+++ b/src/cmd/compile/internal/pkginit/init.go
@@ -0,0 +1,144 @@
+// 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
+}