1 files changed, 398 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/typecheck/func.go b/src/cmd/compile/internal/typecheck/func.go
new file mode 100644
index 0000000000..4675de6cad
--- /dev/null
+++ b/src/cmd/compile/internal/typecheck/func.go
@@ -0,0 +1,398 @@
+// 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 typecheck
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/types"
+
+	"fmt"
+)
+
+// package all the arguments that match a ... T parameter into a []T.
+func MakeDotArgs(typ *types.Type, args []ir.Node) ir.Node {
+	var n ir.Node
+	if len(args) == 0 {
+		n = NodNil()
+		n.SetType(typ)
+	} else {
+		lit := ir.NewCompLitExpr(base.Pos, ir.OCOMPLIT, ir.TypeNode(typ).(ir.Ntype), nil)
+		lit.List.Append(args...)
+		lit.SetImplicit(true)
+		n = lit
+	}
+
+	n = Expr(n)
+	if n.Type() == nil {
+		base.Fatalf("mkdotargslice: typecheck failed")
+	}
+	return n
+}
+
+// FixVariadicCall rewrites calls to variadic functions to use an
+// explicit ... argument if one is not already present.
+func FixVariadicCall(call *ir.CallExpr) {
+	fntype := call.X.Type()
+	if !fntype.IsVariadic() || call.IsDDD {
+		return
+	}
+
+	vi := fntype.NumParams() - 1
+	vt := fntype.Params().Field(vi).Type
+
+	args := call.Args
+	extra := args[vi:]
+	slice := MakeDotArgs(vt, extra)
+	for i := range extra {
+		extra[i] = nil // allow GC
+	}
+
+	call.Args.Set(append(args[:vi], slice))
+	call.IsDDD = true
+}
+
+// ClosureType returns the struct type used to hold all the information
+// needed in the closure for clo (clo must be a OCLOSURE node).
+// The address of a variable of the returned type can be cast to a func.
+func ClosureType(clo *ir.ClosureExpr) *types.Type {
+	// Create closure in the form of a composite literal.
+	// supposing the closure captures an int i and a string s
+	// and has one float64 argument and no results,
+	// the generated code looks like:
+	//
+	//	clos = &struct{.F uintptr; i *int; s *string}{func.1, &i, &s}
+	//
+	// The use of the struct provides type information to the garbage
+	// collector so that it can walk the closure. We could use (in this case)
+	// [3]unsafe.Pointer instead, but that would leave the gc in the dark.
+	// The information appears in the binary in the form of type descriptors;
+	// the struct is unnamed so that closures in multiple packages with the
+	// same struct type can share the descriptor.
+	fields := []*ir.Field{
+		ir.NewField(base.Pos, Lookup(".F"), nil, types.Types[types.TUINTPTR]),
+	}
+	for _, v := range clo.Func.ClosureVars {
+		typ := v.Type()
+		if !v.Byval() {
+			typ = types.NewPtr(typ)
+		}
+		fields = append(fields, ir.NewField(base.Pos, v.Sym(), nil, typ))
+	}
+	typ := NewStructType(fields)
+	typ.SetNoalg(true)
+	return typ
+}
+
+// PartialCallType returns the struct type used to hold all the information
+// needed in the closure for n (n must be a OCALLPART node).
+// The address of a variable of the returned type can be cast to a func.
+func PartialCallType(n *ir.CallPartExpr) *types.Type {
+	t := NewStructType([]*ir.Field{
+		ir.NewField(base.Pos, Lookup("F"), nil, types.Types[types.TUINTPTR]),
+		ir.NewField(base.Pos, Lookup("R"), nil, n.X.Type()),
+	})
+	t.SetNoalg(true)
+	return t
+}
+
+// CaptureVars is called in a separate phase after all typechecking is done.
+// It decides whether each variable captured by a closure should be captured
+// by value or by reference.
+// We use value capturing for values <= 128 bytes that are never reassigned
+// after capturing (effectively constant).
+func CaptureVars(fn *ir.Func) {
+	lno := base.Pos
+	base.Pos = fn.Pos()
+	cvars := fn.ClosureVars
+	out := cvars[:0]
+	for _, v := range cvars {
+		if v.Type() == nil {
+			// If v.Type is nil, it means v looked like it
+			// was going to be used in the closure, but
+			// isn't. This happens in struct literals like
+			// s{f: x} where we can't distinguish whether
+			// f is a field identifier or expression until
+			// resolving s.
+			continue
+		}
+		out = append(out, v)
+
+		// type check the & of closed variables outside the closure,
+		// so that the outer frame also grabs them and knows they escape.
+		types.CalcSize(v.Type())
+
+		var outer ir.Node
+		outer = v.Outer
+		outermost := v.Defn.(*ir.Name)
+
+		// out parameters will be assigned to implicitly upon return.
+		if outermost.Class_ != ir.PPARAMOUT && !outermost.Name().Addrtaken() && !outermost.Name().Assigned() && v.Type().Width <= 128 {
+			v.SetByval(true)
+		} else {
+			outermost.Name().SetAddrtaken(true)
+			outer = NodAddr(outer)
+		}
+
+		if base.Flag.LowerM > 1 {
+			var name *types.Sym
+			if v.Curfn != nil && v.Curfn.Nname != nil {
+				name = v.Curfn.Sym()
+			}
+			how := "ref"
+			if v.Byval() {
+				how = "value"
+			}
+			base.WarnfAt(v.Pos(), "%v capturing by %s: %v (addr=%v assign=%v width=%d)", name, how, v.Sym(), outermost.Name().Addrtaken(), outermost.Name().Assigned(), int32(v.Type().Width))
+		}
+
+		outer = Expr(outer)
+		fn.ClosureEnter.Append(outer)
+	}
+
+	fn.ClosureVars = out
+	base.Pos = lno
+}
+
+// typecheckclosure typechecks an OCLOSURE node. It also creates the named
+// function associated with the closure.
+// TODO: This creation of the named function should probably really be done in a
+// separate pass from type-checking.
+func typecheckclosure(clo *ir.ClosureExpr, top int) {
+	fn := clo.Func
+	// Set current associated iota value, so iota can be used inside
+	// function in ConstSpec, see issue #22344
+	if x := getIotaValue(); x >= 0 {
+		fn.Iota = x
+	}
+
+	fn.ClosureType = check(fn.ClosureType, ctxType)
+	clo.SetType(fn.ClosureType.Type())
+	fn.SetClosureCalled(top&ctxCallee != 0)
+
+	// Do not typecheck fn twice, otherwise, we will end up pushing
+	// fn to Target.Decls multiple times, causing initLSym called twice.
+	// See #30709
+	if fn.Typecheck() == 1 {
+		return
+	}
+
+	for _, ln := range fn.ClosureVars {
+		n := ln.Defn
+		if !n.Name().Captured() {
+			n.Name().SetCaptured(true)
+			if n.Name().Decldepth == 0 {
+				base.Fatalf("typecheckclosure: var %v does not have decldepth assigned", n)
+			}
+
+			// Ignore assignments to the variable in straightline code
+			// preceding the first capturing by a closure.
+			if n.Name().Decldepth == decldepth {
+				n.Name().SetAssigned(false)
+			}
+		}
+	}
+
+	fn.Nname.SetSym(closurename(ir.CurFunc))
+	ir.MarkFunc(fn.Nname)
+	Func(fn)
+
+	// Type check the body now, but only if we're inside a function.
+	// At top level (in a variable initialization: curfn==nil) we're not
+	// ready to type check code yet; we'll check it later, because the
+	// underlying closure function we create is added to Target.Decls.
+	if ir.CurFunc != nil && clo.Type() != nil {
+		oldfn := ir.CurFunc
+		ir.CurFunc = fn
+		olddd := decldepth
+		decldepth = 1
+		Stmts(fn.Body)
+		decldepth = olddd
+		ir.CurFunc = oldfn
+	}
+
+	Target.Decls = append(Target.Decls, fn)
+}
+
+// Lazy typechecking of imported bodies. For local functions, caninl will set ->typecheck
+// because they're a copy of an already checked body.
+func ImportedBody(fn *ir.Func) {
+	lno := ir.SetPos(fn.Nname)
+
+	ImportBody(fn)
+
+	// typecheckinl is only for imported functions;
+	// their bodies may refer to unsafe as long as the package
+	// was marked safe during import (which was checked then).
+	// the ->inl of a local function has been typechecked before caninl copied it.
+	pkg := fnpkg(fn.Nname)
+
+	if pkg == types.LocalPkg || pkg == nil {
+		return // typecheckinl on local function
+	}
+
+	if base.Flag.LowerM > 2 || base.Debug.Export != 0 {
+		fmt.Printf("typecheck import [%v] %L { %v }\n", fn.Sym(), fn, ir.Nodes(fn.Inl.Body))
+	}
+
+	savefn := ir.CurFunc
+	ir.CurFunc = fn
+	Stmts(fn.Inl.Body)
+	ir.CurFunc = savefn
+
+	// During expandInline (which imports fn.Func.Inl.Body),
+	// declarations are added to fn.Func.Dcl by funcHdr(). Move them
+	// to fn.Func.Inl.Dcl for consistency with how local functions
+	// behave. (Append because typecheckinl may be called multiple
+	// times.)
+	fn.Inl.Dcl = append(fn.Inl.Dcl, fn.Dcl...)
+	fn.Dcl = nil
+
+	base.Pos = lno
+}
+
+// Get the function's package. For ordinary functions it's on the ->sym, but for imported methods
+// the ->sym can be re-used in the local package, so peel it off the receiver's type.
+func fnpkg(fn *ir.Name) *types.Pkg {
+	if ir.IsMethod(fn) {
+		// method
+		rcvr := fn.Type().Recv().Type
+
+		if rcvr.IsPtr() {
+			rcvr = rcvr.Elem()
+		}
+		if rcvr.Sym() == nil {
+			base.Fatalf("receiver with no sym: [%v] %L  (%v)", fn.Sym(), fn, rcvr)
+		}
+		return rcvr.Sym().Pkg
+	}
+
+	// non-method
+	return fn.Sym().Pkg
+}
+
+// CaptureVarsComplete is set to true when the capturevars phase is done.
+var CaptureVarsComplete bool
+
+// closurename generates a new unique name for a closure within
+// outerfunc.
+func closurename(outerfunc *ir.Func) *types.Sym {
+	outer := "glob."
+	prefix := "func"
+	gen := &globClosgen
+
+	if outerfunc != nil {
+		if outerfunc.OClosure != nil {
+			prefix = ""
+		}
+
+		outer = ir.FuncName(outerfunc)
+
+		// There may be multiple functions named "_". In those
+		// cases, we can't use their individual Closgens as it
+		// would lead to name clashes.
+		if !ir.IsBlank(outerfunc.Nname) {
+			gen = &outerfunc.Closgen
+		}
+	}
+
+	*gen++
+	return Lookup(fmt.Sprintf("%s.%s%d", outer, prefix, *gen))
+}
+
+// globClosgen is like Func.Closgen, but for the global scope.
+var globClosgen int32
+
+// makepartialcall returns a DCLFUNC node representing the wrapper function (*-fm) needed
+// for partial calls.
+func makepartialcall(dot *ir.SelectorExpr, t0 *types.Type, meth *types.Sym) *ir.Func {
+	rcvrtype := dot.X.Type()
+	sym := ir.MethodSymSuffix(rcvrtype, meth, "-fm")
+
+	if sym.Uniq() {
+		return sym.Def.(*ir.Func)
+	}
+	sym.SetUniq(true)
+
+	savecurfn := ir.CurFunc
+	saveLineNo := base.Pos
+	ir.CurFunc = nil
+
+	// Set line number equal to the line number where the method is declared.
+	var m *types.Field
+	if lookdot0(meth, rcvrtype, &m, false) == 1 && m.Pos.IsKnown() {
+		base.Pos = m.Pos
+	}
+	// Note: !m.Pos.IsKnown() happens for method expressions where
+	// the method is implicitly declared. The Error method of the
+	// built-in error type is one such method.  We leave the line
+	// number at the use of the method expression in this
+	// case. See issue 29389.
+
+	tfn := ir.NewFuncType(base.Pos, nil,
+		NewFuncParams(t0.Params(), true),
+		NewFuncParams(t0.Results(), false))
+
+	fn := DeclFunc(sym, tfn)
+	fn.SetDupok(true)
+	fn.SetNeedctxt(true)
+
+	// Declare and initialize variable holding receiver.
+	cr := ir.NewClosureRead(rcvrtype, types.Rnd(int64(types.PtrSize), int64(rcvrtype.Align)))
+	ptr := NewName(Lookup(".this"))
+	Declare(ptr, ir.PAUTO)
+	ptr.SetUsed(true)
+	var body []ir.Node
+	if rcvrtype.IsPtr() || rcvrtype.IsInterface() {
+		ptr.SetType(rcvrtype)
+		body = append(body, ir.NewAssignStmt(base.Pos, ptr, cr))
+	} else {
+		ptr.SetType(types.NewPtr(rcvrtype))
+		body = append(body, ir.NewAssignStmt(base.Pos, ptr, NodAddr(cr)))
+	}
+
+	call := ir.NewCallExpr(base.Pos, ir.OCALL, ir.NewSelectorExpr(base.Pos, ir.OXDOT, ptr, meth), nil)
+	call.Args.Set(ir.ParamNames(tfn.Type()))
+	call.IsDDD = tfn.Type().IsVariadic()
+	if t0.NumResults() != 0 {
+		ret := ir.NewReturnStmt(base.Pos, nil)
+		ret.Results = []ir.Node{call}
+		body = append(body, ret)
+	} else {
+		body = append(body, call)
+	}
+
+	fn.Body.Set(body)
+	FinishFuncBody()
+
+	Func(fn)
+	// Need to typecheck the body of the just-generated wrapper.
+	// typecheckslice() requires that Curfn is set when processing an ORETURN.
+	ir.CurFunc = fn
+	Stmts(fn.Body)
+	sym.Def = fn
+	Target.Decls = append(Target.Decls, fn)
+	ir.CurFunc = savecurfn
+	base.Pos = saveLineNo
+
+	return fn
+}
+
+func typecheckpartialcall(n ir.Node, sym *types.Sym) *ir.CallPartExpr {
+	switch n.Op() {
+	case ir.ODOTINTER, ir.ODOTMETH:
+		break
+
+	default:
+		base.Fatalf("invalid typecheckpartialcall")
+	}
+	dot := n.(*ir.SelectorExpr)
+
+	// Create top-level function.
+	fn := makepartialcall(dot, dot.Type(), sym)
+	fn.SetWrapper(true)
+
+	return ir.NewCallPartExpr(dot.Pos(), dot.X, dot.Selection, fn)
+}