cmd/compile: remove funcdepth variables

There were only two large classes of use for these variables:

1) Testing "funcdepth != 0" or "funcdepth > 0", which is equivalent to
checking "Curfn != nil".

2) In oldname, detecting whether a closure variable has been created
for the current function, which can be handled by instead testing
"n.Name.Curfn != Curfn".

Lastly, merge funcstart into funchdr, since it's only called once, and
it better matches up with funcbody now.

Passes toolstash-check.

Change-Id: I8fe159a9d37ef7debc4cd310354cea22a8b23394
Reviewed-on: https://go-review.googlesource.com/99076
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/compile/internal/gc/bimport.go

@@ -178,8 +178,8 @@ func Import(imp *types.Pkg, in *bufio.Reader) {
 		}
 		i0 = i
 
-		if funcdepth != 0 {
-			p.formatErrorf("unexpected Funcdepth %d", funcdepth)
+		if Curfn != nil {
+			p.formatErrorf("unexpected Curfn %v", Curfn)
 		}
 
 		// Note: In the original code, funchdr and funcbody are called for

src/cmd/compile/internal/gc/closure.go

@@ -16,7 +16,6 @@ func (p *noder) funcLit(expr *syntax.FuncLit) *Node {
 	n := p.nod(expr, OCLOSURE, nil, nil)
 	n.Func.SetIsHiddenClosure(Curfn != nil)
 	n.Func.Ntype = ntype
-	n.Func.Depth = funcdepth
 	n.Func.Outerfunc = Curfn
 
 	old := p.funchdr(n)
@@ -220,8 +219,6 @@ func makeclosure(func_ *Node) *Node {
 	xfunc.Func.Nname.Name.Param.Ntype = xtype
 	xfunc.Func.Nname.Name.Defn = xfunc
 	declare(xfunc.Func.Nname, PFUNC)
-	xfunc.Func.Nname.Name.Funcdepth = func_.Func.Depth
-	xfunc.Func.Depth = func_.Func.Depth
 	xfunc.Func.Endlineno = func_.Func.Endlineno
 	if Ctxt.Flag_dynlink {
 		makefuncsym(xfunc.Func.Nname.Sym)

src/cmd/compile/internal/gc/dcl.go

@@ -128,7 +128,6 @@ func declare(n *Node, ctxt Class) {
 	s.Lastlineno = lineno
 	s.Def = asTypesNode(n)
 	n.Name.Vargen = int32(gen)
-	n.Name.Funcdepth = funcdepth
 	n.SetClass(ctxt)
 
 	autoexport(n, ctxt)
@@ -160,7 +159,7 @@ func variter(vl []*Node, t *Node, el []*Node) []*Node {
 			declare(v, dclcontext)
 			v.Name.Param.Ntype = t
 			v.Name.Defn = as2
-			if funcdepth > 0 {
+			if Curfn != nil {
 				init = append(init, nod(ODCL, v, nil))
 			}
 		}
@@ -183,8 +182,8 @@ func variter(vl []*Node, t *Node, el []*Node) []*Node {
 		declare(v, dclcontext)
 		v.Name.Param.Ntype = t
 
-		if e != nil || funcdepth > 0 || isblank(v) {
-			if funcdepth > 0 {
+		if e != nil || Curfn != nil || isblank(v) {
+			if Curfn != nil {
 				init = append(init, nod(ODCL, v, nil))
 			}
 			e = nod(OAS, v, e)
@@ -276,7 +275,7 @@ func oldname(s *types.Sym) *Node {
 		return newnoname(s)
 	}
 
-	if Curfn != nil && n.Op == ONAME && n.Name.Funcdepth > 0 && n.Name.Funcdepth != funcdepth {
+	if Curfn != nil && n.Op == ONAME && n.Name.Curfn != nil && n.Name.Curfn != Curfn {
 		// Inner func is referring to var in outer func.
 		//
 		// TODO(rsc): If there is an outer variable x and we
@@ -284,7 +283,7 @@ func oldname(s *types.Sym) *Node {
 		// the := it looks like a reference to the outer x so we'll
 		// make x a closure variable unnecessarily.
 		c := n.Name.Param.Innermost
-		if c == nil || c.Name.Funcdepth != funcdepth {
+		if c == nil || c.Name.Curfn != Curfn {
 			// Do not have a closure var for the active closure yet; make one.
 			c = newname(s)
 			c.SetClass(PAUTOHEAP)
@@ -292,7 +291,6 @@ func oldname(s *types.Sym) *Node {
 			c.SetIsddd(n.Isddd())
 			c.Name.Defn = n
 			c.SetAddable(false)
-			c.Name.Funcdepth = funcdepth
 
 			// Link into list of active closure variables.
 			// Popped from list in func closurebody.
@@ -384,12 +382,14 @@ func ifacedcl(n *Node) {
 // returns in auto-declaration context.
 func funchdr(n *Node) {
 	// change the declaration context from extern to auto
-	if funcdepth == 0 && dclcontext != PEXTERN {
+	if Curfn == nil && dclcontext != PEXTERN {
 		Fatalf("funchdr: dclcontext = %d", dclcontext)
 	}
 
 	dclcontext = PAUTO
-	funcstart(n)
+	types.Markdcl()
+	funcstack = append(funcstack, Curfn)
+	Curfn = n
 
 	if n.Func.Nname != nil {
 		funcargs(n.Func.Nname.Name.Param.Ntype)
@@ -523,16 +523,6 @@ func funcargs2(t *types.Type) {
 }
 
 var funcstack []*Node // stack of previous values of Curfn
-var funcdepth int32   // len(funcstack) during parsing, but then forced to be the same later during compilation
-
-// start the function.
-// called before funcargs; undone at end of funcbody.
-func funcstart(n *Node) {
-	types.Markdcl()
-	funcstack = append(funcstack, Curfn)
-	funcdepth++
-	Curfn = n
-}
 
 // finish the body.
 // called in auto-declaration context.
@@ -544,8 +534,7 @@ func funcbody() {
 	}
 	types.Popdcl()
 	funcstack, Curfn = funcstack[:len(funcstack)-1], funcstack[len(funcstack)-1]
-	funcdepth--
-	if funcdepth == 0 {
+	if Curfn == nil {
 		dclcontext = PEXTERN
 	}
 }

src/cmd/compile/internal/gc/fmt.go

@@ -436,13 +436,6 @@ func (n *Node) jconv(s fmt.State, flag FmtFlag) {
 		fmt.Fprintf(s, " colas(%v)", n.Colas())
 	}
 
-	if n.Name != nil && n.Name.Funcdepth != 0 {
-		fmt.Fprintf(s, " f(%d)", n.Name.Funcdepth)
-	}
-	if n.Func != nil && n.Func.Depth != 0 {
-		fmt.Fprintf(s, " ff(%d)", n.Func.Depth)
-	}
-
 	switch n.Esc {
 	case EscUnknown:
 		break

src/cmd/compile/internal/gc/pgen.go

@@ -204,13 +204,11 @@ func funccompile(fn *Node) {
 	}
 
 	dclcontext = PAUTO
-	funcdepth = fn.Func.Depth + 1
 	Curfn = fn
 
 	compile(fn)
 
 	Curfn = nil
-	funcdepth = 0
 	dclcontext = PEXTERN
 }
 

src/cmd/compile/internal/gc/sizeof_test.go

@@ -22,8 +22,8 @@ func TestSizeof(t *testing.T) {
 		_32bit uintptr     // size on 32bit platforms
 		_64bit uintptr     // size on 64bit platforms
 	}{
-		{Func{}, 132, 232},
-		{Name{}, 36, 56},
+		{Func{}, 128, 232},
+		{Name{}, 32, 56},
 		{Param{}, 28, 56},
 		{Node{}, 76, 128},
 	}

src/cmd/compile/internal/gc/syntax.go

@@ -242,7 +242,6 @@ type Name struct {
 	Param     *Param     // additional fields for ONAME, OTYPE
 	Decldepth int32      // declaration loop depth, increased for every loop or label
 	Vargen    int32      // unique name for ONAME within a function.  Function outputs are numbered starting at one.
-	Funcdepth int32
 
 	used  bool // for variable declared and not used error
 	flags bitset8
@@ -433,7 +432,6 @@ type Func struct {
 
 	Inl     Nodes // copy of the body for use in inlining
 	InlCost int32
-	Depth   int32
 
 	Label int32 // largest auto-generated label in this function
 

src/cmd/compile/internal/gc/walk.go

@@ -3868,9 +3868,6 @@ func wrapCall(n *Node, init *Nodes) *Node {
 		args = append(args, a.Left)
 	}
 
-	oldfn := Curfn
-	Curfn = nil
-
 	wrapCall_prgen++
 	sym := lookupN("wrap·", wrapCall_prgen)
 	fn := dclfunc(sym, t)
@@ -3885,7 +3882,6 @@ func wrapCall(n *Node, init *Nodes) *Node {
 	fn = typecheck(fn, Etop)
 	typecheckslice(fn.Nbody.Slice(), Etop)
 	xtop = append(xtop, fn)
-	Curfn = oldfn
 
 	a = nod(OCALL, nil, nil)
 	a.Left = fn.Func.Nname