From: Russ Cox <rsc@golang.org>
Date: Mon, 25 Feb 2013 17:13:47 +0000 (-0500)
Subject: cmd/gc: emit explicit type information for local variables
X-Git-Tag: go1.1rc2~864
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=1d5dc4fd481ae5ccebe1be0091a88b9343fe0904;p=gostls13.git

cmd/gc: emit explicit type information for local variables

The type information is (and for years has been) included
as an extra field in the address chunk of an instruction.
Unfortunately, suppose there is a string at a+24(FP) and
we have an instruction reading its length. It will say:

        MOVQ x+32(FP), AX

and the type of *that* argument is int (not slice), because
it is the length being read. This confuses the picture seen
by debuggers and now, worse, by the garbage collector.

Instead of attaching the type information to all uses,
emit an explicit list of TYPE instructions with the information.
The TYPE instructions are no-ops whose only role is to
provide an address to attach type information to.

For example, this function:

        func f(x, y, z int) (a, b string) {
                return
        }

now compiles into:

        --- prog list "f" ---
        0000 (/Users/rsc/x.go:3) TEXT    f+0(SB),$0-56
        0001 (/Users/rsc/x.go:3) LOCALS  ,
        0002 (/Users/rsc/x.go:3) TYPE    x+0(FP){int},$8
        0003 (/Users/rsc/x.go:3) TYPE    y+8(FP){int},$8
        0004 (/Users/rsc/x.go:3) TYPE    z+16(FP){int},$8
        0005 (/Users/rsc/x.go:3) TYPE    a+24(FP){string},$16
        0006 (/Users/rsc/x.go:3) TYPE    b+40(FP){string},$16
        0007 (/Users/rsc/x.go:3) MOVQ    $0,b+40(FP)
        0008 (/Users/rsc/x.go:3) MOVQ    $0,b+48(FP)
        0009 (/Users/rsc/x.go:3) MOVQ    $0,a+24(FP)
        0010 (/Users/rsc/x.go:3) MOVQ    $0,a+32(FP)
        0011 (/Users/rsc/x.go:4) RET     ,

The { } show the formerly hidden type information.
The { } syntax is used when printing from within the gc compiler.
It is not accepted by the assemblers.

The same type information is now included on global variables:

0055 (/Users/rsc/x.go:15) GLOBL   slice+0(SB){[]string},$24(AL*0)

This more accurate type information fixes a bug in the
garbage collector's precise heap collection.

The linker only cares about globals right now, but having the
local information should make things a little nicer for Carl
in the future.

Fixes #4907.

R=ken2
CC=golang-dev
https://golang.org/cl/7395056
---

diff --git a/src/cmd/5g/ggen.c b/src/cmd/5g/ggen.c
index 679354da9a..de1671bb6f 100644
--- a/src/cmd/5g/ggen.c
+++ b/src/cmd/5g/ggen.c
@@ -28,6 +28,9 @@ void
 markautoused(Prog* p)
 {
 	for (; p; p = p->link) {
+		if (p->as == ATYPE)
+			continue;
+
 		if (p->from.name == D_AUTO && p->from.node)
 			p->from.node->used = 1;
 
@@ -40,12 +43,21 @@ markautoused(Prog* p)
 void
 fixautoused(Prog* p)
 {
-	for (; p; p = p->link) {
+	Prog **lp;
+
+	for (lp=&p; (p=*lp) != P; ) {
+		if (p->as == ATYPE && p->from.node && p->from.name == D_AUTO && !p->from.node->used) {
+			*lp = p->link;
+			continue;
+		}
+
 		if (p->from.name == D_AUTO && p->from.node)
 			p->from.offset += p->from.node->stkdelta;
 
 		if (p->to.name == D_AUTO && p->to.node)
 			p->to.offset += p->to.node->stkdelta;
+
+		lp = &p->link;
 	}
 }
 
diff --git a/src/cmd/5g/gsubr.c b/src/cmd/5g/gsubr.c
index ce5ae422e0..38c4a92006 100644
--- a/src/cmd/5g/gsubr.c
+++ b/src/cmd/5g/gsubr.c
@@ -192,15 +192,16 @@ gjmp(Prog *to)
 }
 
 void
-ggloblnod(Node *nam, int32 width)
+ggloblnod(Node *nam)
 {
 	Prog *p;
 
 	p = gins(AGLOBL, nam, N);
 	p->lineno = nam->lineno;
+	p->from.gotype = ngotype(nam);
 	p->to.sym = S;
 	p->to.type = D_CONST;
-	p->to.offset = width;
+	p->to.offset = nam->type->width;
 	if(nam->readonly)
 		p->reg = RODATA;
 	if(nam->type != T && !haspointers(nam->type))
diff --git a/src/cmd/5g/list.c b/src/cmd/5g/list.c
index 9f67f79f43..6c3f1d7449 100644
--- a/src/cmd/5g/list.c
+++ b/src/cmd/5g/list.c
@@ -196,7 +196,10 @@ Dconv(Fmt *fp)
 //		goto conv;
 	}
 conv:
-	return fmtstrcpy(fp, str);
+	fmtstrcpy(fp, str);
+	if(a->gotype)
+		fmtprint(fp, "{%s}", a->gotype->name);
+	return 0;
 }
 
 int
diff --git a/src/cmd/5g/peep.c b/src/cmd/5g/peep.c
index c729a64661..b6202a882c 100644
--- a/src/cmd/5g/peep.c
+++ b/src/cmd/5g/peep.c
@@ -76,6 +76,8 @@ peep(void)
 		case AGLOBL:
 		case ANAME:
 		case ASIGNAME:
+		case ALOCALS:
+		case ATYPE:
 			p = p->link;
 		}
 	}
diff --git a/src/cmd/5g/reg.c b/src/cmd/5g/reg.c
index da80f32a4b..0667531ebf 100644
--- a/src/cmd/5g/reg.c
+++ b/src/cmd/5g/reg.c
@@ -248,6 +248,8 @@ regopt(Prog *firstp)
 		case AGLOBL:
 		case ANAME:
 		case ASIGNAME:
+		case ALOCALS:
+		case ATYPE:
 			continue;
 		}
 		r = rega();
diff --git a/src/cmd/5l/5.out.h b/src/cmd/5l/5.out.h
index 1ffe9dc85e..4aef8a27f4 100644
--- a/src/cmd/5l/5.out.h
+++ b/src/cmd/5l/5.out.h
@@ -198,6 +198,7 @@ enum	as
 	
 	AUSEFIELD,
 	ALOCALS,
+	ATYPE,
 
 	ALAST,
 };
diff --git a/src/cmd/5l/obj.c b/src/cmd/5l/obj.c
index c9e38dc389..14b1ea7aae 100644
--- a/src/cmd/5l/obj.c
+++ b/src/cmd/5l/obj.c
@@ -578,6 +578,10 @@ loop:
 		pc++;
 		break;
 
+	case ATYPE:
+		pc++;
+		goto loop;
+
 	case ATEXT:
 		if(cursym != nil && cursym->text) {
 			histtoauto();
diff --git a/src/cmd/5l/span.c b/src/cmd/5l/span.c
index fd30e91a52..a5afa02e79 100644
--- a/src/cmd/5l/span.c
+++ b/src/cmd/5l/span.c
@@ -833,6 +833,7 @@ buildop(void)
 		case ALOCALS:
 		case ACASE:
 		case ABCASE:
+		case ATYPE:
 			break;
 		case AADDF:
 			oprange[AADDD] = oprange[r];
diff --git a/src/cmd/6g/ggen.c b/src/cmd/6g/ggen.c
index 10c116d623..23bb5093f0 100644
--- a/src/cmd/6g/ggen.c
+++ b/src/cmd/6g/ggen.c
@@ -25,6 +25,9 @@ void
 markautoused(Prog* p)
 {
 	for (; p; p = p->link) {
+		if (p->as == ATYPE)
+			continue;
+
 		if (p->from.type == D_AUTO && p->from.node)
 			p->from.node->used = 1;
 
@@ -35,14 +38,22 @@ markautoused(Prog* p)
 
 // Fixup instructions after compactframe has moved all autos around.
 void
-fixautoused(Prog* p)
+fixautoused(Prog *p)
 {
-	for (; p; p = p->link) {
+	Prog **lp;
+
+	for (lp=&p; (p=*lp) != P; ) {
+		if (p->as == ATYPE && p->from.node && p->from.type == D_AUTO && !p->from.node->used) {
+			*lp = p->link;
+			continue;
+		}
 		if (p->from.type == D_AUTO && p->from.node)
 			p->from.offset += p->from.node->stkdelta;
 
 		if (p->to.type == D_AUTO && p->to.node)
 			p->to.offset += p->to.node->stkdelta;
+
+		lp = &p->link;
 	}
 }
 
diff --git a/src/cmd/6g/gsubr.c b/src/cmd/6g/gsubr.c
index 34965126e8..fc5407a1f3 100644
--- a/src/cmd/6g/gsubr.c
+++ b/src/cmd/6g/gsubr.c
@@ -190,15 +190,16 @@ gjmp(Prog *to)
 }
 
 void
-ggloblnod(Node *nam, int32 width)
+ggloblnod(Node *nam)
 {
 	Prog *p;
 
 	p = gins(AGLOBL, nam, N);
 	p->lineno = nam->lineno;
+	p->from.gotype = ngotype(nam);
 	p->to.sym = S;
 	p->to.type = D_CONST;
-	p->to.offset = width;
+	p->to.offset = nam->type->width;
 	if(nam->readonly)
 		p->from.scale = RODATA;
 	if(nam->type != T && !haspointers(nam->type))
@@ -1179,10 +1180,8 @@ naddr(Node *n, Addr *a, int canemitcode)
 
 	case ONAME:
 		a->etype = 0;
-		if(n->type != T) {
+		if(n->type != T)
 			a->etype = simtype[n->type->etype];
-			a->gotype = ngotype(n);
-		}
 		a->offset = n->xoffset;
 		a->sym = n->sym;
 		a->node = n->orig;
diff --git a/src/cmd/6g/list.c b/src/cmd/6g/list.c
index d84cceffb8..9d27a6a097 100644
--- a/src/cmd/6g/list.c
+++ b/src/cmd/6g/list.c
@@ -161,7 +161,10 @@ brk:
 		strcat(str, s);
 	}
 conv:
-	return fmtstrcpy(fp, str);
+	fmtstrcpy(fp, str);
+	if(a->gotype)
+		fmtprint(fp, "{%s}", a->gotype->name);
+	return 0;
 }
 
 static	char*	regstr[] =
diff --git a/src/cmd/6g/peep.c b/src/cmd/6g/peep.c
index 070077f105..569655786a 100644
--- a/src/cmd/6g/peep.c
+++ b/src/cmd/6g/peep.c
@@ -132,6 +132,8 @@ peep(void)
 		case AGLOBL:
 		case ANAME:
 		case ASIGNAME:
+		case ALOCALS:
+		case ATYPE:
 			p = p->link;
 		}
 	}
diff --git a/src/cmd/6g/reg.c b/src/cmd/6g/reg.c
index bb8e09c642..e1188a2353 100644
--- a/src/cmd/6g/reg.c
+++ b/src/cmd/6g/reg.c
@@ -224,6 +224,8 @@ regopt(Prog *firstp)
 		case AGLOBL:
 		case ANAME:
 		case ASIGNAME:
+		case ALOCALS:
+		case ATYPE:
 			continue;
 		}
 		r = rega();
diff --git a/src/cmd/6l/6.out.h b/src/cmd/6l/6.out.h
index d348c1304e..805b3fc6f2 100644
--- a/src/cmd/6l/6.out.h
+++ b/src/cmd/6l/6.out.h
@@ -759,6 +759,7 @@ enum	as
 	
 	AUSEFIELD,
 	ALOCALS,
+	ATYPE,
 
 	ALAST
 };
diff --git a/src/cmd/6l/obj.c b/src/cmd/6l/obj.c
index e90a66e5dc..10e4a98601 100644
--- a/src/cmd/6l/obj.c
+++ b/src/cmd/6l/obj.c
@@ -590,6 +590,10 @@ loop:
 		cursym->locals = p->to.offset;
 		pc++;
 		goto loop;
+	
+	case ATYPE:
+		pc++;
+		goto loop;
 
 	case ATEXT:
 		s = p->from.sym;
diff --git a/src/cmd/6l/optab.c b/src/cmd/6l/optab.c
index 21b4784353..a163e6faab 100644
--- a/src/cmd/6l/optab.c
+++ b/src/cmd/6l/optab.c
@@ -1318,6 +1318,7 @@ Optab optab[] =
 
 	{ AUSEFIELD,	ynop,	Px, 0,0 },
 	{ ALOCALS },
+	{ ATYPE },
 
 	{ AEND },
 	0
diff --git a/src/cmd/8g/ggen.c b/src/cmd/8g/ggen.c
index e8d6747c4a..70148106c4 100644
--- a/src/cmd/8g/ggen.c
+++ b/src/cmd/8g/ggen.c
@@ -27,6 +27,9 @@ void
 markautoused(Prog* p)
 {
 	for (; p; p = p->link) {
+		if (p->as == ATYPE)
+			continue;
+
 		if (p->from.type == D_AUTO && p->from.node)
 			p->from.node->used = 1;
 
@@ -39,12 +42,21 @@ markautoused(Prog* p)
 void
 fixautoused(Prog* p)
 {
-	for (; p; p = p->link) {
+	Prog **lp;
+
+	for (lp=&p; (p=*lp) != P; ) {
+		if (p->as == ATYPE && p->from.node && p->from.type == D_AUTO && !p->from.node->used) {
+			*lp = p->link;
+			continue;
+		}
+
 		if (p->from.type == D_AUTO && p->from.node)
 			p->from.offset += p->from.node->stkdelta;
 
 		if (p->to.type == D_AUTO && p->to.node)
 			p->to.offset += p->to.node->stkdelta;
+
+		lp = &p->link;
 	}
 }
 
diff --git a/src/cmd/8g/gsubr.c b/src/cmd/8g/gsubr.c
index 3650d34a05..c4c184bb9a 100644
--- a/src/cmd/8g/gsubr.c
+++ b/src/cmd/8g/gsubr.c
@@ -191,15 +191,16 @@ gjmp(Prog *to)
 }
 
 void
-ggloblnod(Node *nam, int32 width)
+ggloblnod(Node *nam)
 {
 	Prog *p;
 
 	p = gins(AGLOBL, nam, N);
 	p->lineno = nam->lineno;
+	p->from.gotype = ngotype(nam);
 	p->to.sym = S;
 	p->to.type = D_CONST;
-	p->to.offset = width;
+	p->to.offset = nam->type->width;
 	if(nam->readonly)
 		p->from.scale = RODATA;
 	if(nam->type != T && !haspointers(nam->type))
@@ -2260,7 +2261,6 @@ naddr(Node *n, Addr *a, int canemitcode)
 			a->etype = simtype[n->type->etype];
 			dowidth(n->type);
 			a->width = n->type->width;
-			a->gotype = ngotype(n);
 		}
 		a->offset = n->xoffset;
 		a->sym = n->sym;
diff --git a/src/cmd/8g/list.c b/src/cmd/8g/list.c
index 7ed1c119d5..ec02ba5c5c 100644
--- a/src/cmd/8g/list.c
+++ b/src/cmd/8g/list.c
@@ -158,7 +158,10 @@ brk:
 		strcat(str, s);
 	}
 conv:
-	return fmtstrcpy(fp, str);
+	fmtstrcpy(fp, str);
+	if(a->gotype)
+		fmtprint(fp, "{%s}", a->gotype->name);
+	return 0;
 }
 
 static	char*	regstr[] =
diff --git a/src/cmd/8g/peep.c b/src/cmd/8g/peep.c
index ccf7dcd339..e5a3149cf1 100644
--- a/src/cmd/8g/peep.c
+++ b/src/cmd/8g/peep.c
@@ -126,6 +126,8 @@ peep(void)
 		case AGLOBL:
 		case ANAME:
 		case ASIGNAME:
+		case ALOCALS:
+		case ATYPE:
 			p = p->link;
 		}
 	}
diff --git a/src/cmd/8g/reg.c b/src/cmd/8g/reg.c
index e96336b702..c1f51c0a41 100644
--- a/src/cmd/8g/reg.c
+++ b/src/cmd/8g/reg.c
@@ -195,6 +195,8 @@ regopt(Prog *firstp)
 		case AGLOBL:
 		case ANAME:
 		case ASIGNAME:
+		case ALOCALS:
+		case ATYPE:
 			continue;
 		}
 		r = rega();
diff --git a/src/cmd/8l/8.out.h b/src/cmd/8l/8.out.h
index ae1397dd8d..3868899560 100644
--- a/src/cmd/8l/8.out.h
+++ b/src/cmd/8l/8.out.h
@@ -569,6 +569,7 @@ enum	as
 	
 	AUSEFIELD,
 	ALOCALS,
+	ATYPE,
 
 	ALAST
 };
diff --git a/src/cmd/8l/obj.c b/src/cmd/8l/obj.c
index bd5684a350..dcb8390b97 100644
--- a/src/cmd/8l/obj.c
+++ b/src/cmd/8l/obj.c
@@ -600,6 +600,10 @@ loop:
 		pc++;
 		goto loop;
 
+	case ATYPE:
+		pc++;
+		goto loop;
+
 	case ATEXT:
 		s = p->from.sym;
 		if(s->text != nil) {
diff --git a/src/cmd/8l/optab.c b/src/cmd/8l/optab.c
index 3ccdbfd226..79d7b39f00 100644
--- a/src/cmd/8l/optab.c
+++ b/src/cmd/8l/optab.c
@@ -963,6 +963,7 @@ Optab optab[] =
 
 	{ AUSEFIELD,	ynop,	Px, 0,0 },
 	{ ALOCALS },
+	{ ATYPE },
 
 	0
 };
diff --git a/src/cmd/gc/closure.c b/src/cmd/gc/closure.c
index 3e65e0dd2c..78b73d847c 100644
--- a/src/cmd/gc/closure.c
+++ b/src/cmd/gc/closure.c
@@ -13,7 +13,7 @@
 void
 closurehdr(Node *ntype)
 {
-	Node *n, *name, *a, *orig;
+	Node *n, *name, *a;
 	NodeList *l;
 
 	n = nod(OCLOSURE, N, N);
@@ -43,11 +43,8 @@ closurehdr(Node *ntype)
 	}
 	for(l=n->rlist; l; l=l->next) {
 		name = l->n->left;
-		if(name) {
-			orig = name->orig;  // preserve the meaning of orig == N (anonymous PPARAMOUT)
+		if(name)
 			name = newname(name->sym);
-			name->orig = orig;
-		}
 		ntype->rlist = list(ntype->rlist, nod(ODCLFIELD, name, l->n->right));
 	}
 }
diff --git a/src/cmd/gc/dcl.c b/src/cmd/gc/dcl.c
index c4990df072..aa2489d9a1 100644
--- a/src/cmd/gc/dcl.c
+++ b/src/cmd/gc/dcl.c
@@ -640,8 +640,7 @@ funcargs(Node *nt)
 			// give it a name so escape analysis has nodes to work with
 			snprint(namebuf, sizeof(namebuf), "~anon%d", gen++);
 			n->left = newname(lookup(namebuf));
-			n->left->orig = N;  // signal that the original was absent
-
+			// TODO: n->left->missing = 1;
 		} 
 
 		n->left->op = ONAME;
@@ -815,7 +814,7 @@ structfield(Node *n)
 		break;
 	}
 
-	if(n->left && n->left->op == ONAME && n->left->orig != N) {
+	if(n->left && n->left->op == ONAME) {
 		f->nname = n->left;
 		f->embedded = n->embedded;
 		f->sym = f->nname->sym;
@@ -1177,6 +1176,7 @@ functype(Node *this, NodeList *in, NodeList *out)
 {
 	Type *t;
 	NodeList *rcvr;
+	Sym *s;
 
 	t = typ(TFUNC);
 
@@ -1194,7 +1194,12 @@ functype(Node *this, NodeList *in, NodeList *out)
 		t->thistuple = 1;
 	t->outtuple = count(out);
 	t->intuple = count(in);
-	t->outnamed = t->outtuple > 0 && out->n->left != N && out->n->left->orig != N;
+	t->outnamed = 0;
+	if(t->outtuple > 0 && out->n->left != N && out->n->left->orig != N) {
+		s = out->n->left->orig->sym;
+		if(s != S && s->name[0] != '~')
+			t->outnamed = 1;
+	}
 
 	return t;
 }
diff --git a/src/cmd/gc/fmt.c b/src/cmd/gc/fmt.c
index bae66e0772..5d37ac0fd5 100644
--- a/src/cmd/gc/fmt.c
+++ b/src/cmd/gc/fmt.c
@@ -723,12 +723,15 @@ typefmt(Fmt *fp, Type *t)
 		if(!(fp->flags&FmtShort)) {
 			s = t->sym;
 
-			// Take the name from the original, lest we substituted it with .anon%d
-			if ((fmtmode == FErr || fmtmode == FExp) && t->nname != N)
-				if(t->nname->orig != N)
+			// Take the name from the original, lest we substituted it with ~anon%d
+			if ((fmtmode == FErr || fmtmode == FExp) && t->nname != N) {
+				if(t->nname->orig != N) {
 					s = t->nname->orig->sym;
-				else 
+					if(s != S && s->name[0] == '~')
+						s = S;
+				} else 
 					s = S;
+			}
 			
 			if(s != S && !t->embedded) {
 				if(t->funarg)
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index 68a0563aac..05d942b419 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -271,7 +271,6 @@ struct	Node
 
 	// most nodes
 	Type*	type;
-	Type*	realtype;	// as determined by typecheck
 	Node*	orig;		// original form, for printing, and tracking copies of ONAMEs
 
 	// func
@@ -1438,7 +1437,7 @@ void	gdata(Node*, Node*, int);
 void	gdatacomplex(Node*, Mpcplx*);
 void	gdatastring(Node*, Strlit*);
 void	genembedtramp(Type*, Type*, Sym*, int iface);
-void	ggloblnod(Node *nam, int32 width);
+void	ggloblnod(Node *nam);
 void	ggloblsym(Sym *s, int32 width, int dupok, int rodata);
 Prog*	gjmp(Prog*);
 void	gused(Node*);
diff --git a/src/cmd/gc/obj.c b/src/cmd/gc/obj.c
index 94f1c65c96..b87d35b7bd 100644
--- a/src/cmd/gc/obj.c
+++ b/src/cmd/gc/obj.c
@@ -59,7 +59,7 @@ dumpglobls(void)
 			continue;
 		dowidth(n->type);
 
-		ggloblnod(n, n->type->width);
+		ggloblnod(n);
 	}
 
 	for(l=funcsyms; l; l=l->next) {
diff --git a/src/cmd/gc/pgen.c b/src/cmd/gc/pgen.c
index f4894e468e..6f732b991e 100644
--- a/src/cmd/gc/pgen.c
+++ b/src/cmd/gc/pgen.c
@@ -14,11 +14,12 @@ compile(Node *fn)
 {
 	Plist *pl;
 	Node nod1, *n;
-	Prog *plocals, *ptxt;
+	Prog *plocals, *ptxt, *p, *p1;
 	int32 lno;
 	Type *t;
 	Iter save;
 	vlong oldstksize;
+	NodeList *l;
 
 	if(newproc == N) {
 		newproc = sysfunc("newproc");
@@ -92,12 +93,25 @@ compile(Node *fn)
 	for(t=curfn->paramfld; t; t=t->down)
 		gtrack(tracksym(t->type));
 
+	for(l=fn->dcl; l; l=l->next) {
+		n = l->n;
+		if(n->op != ONAME) // might be OTYPE or OLITERAL
+			continue;
+		switch(n->class) {
+		case PAUTO:
+		case PPARAM:
+		case PPARAMOUT:
+			nodconst(&nod1, types[TUINTPTR], l->n->type->width);
+			p = gins(ATYPE, l->n, &nod1);
+			p->from.gotype = ngotype(l->n);
+			break;
+		}
+	}
+
 	genlist(curfn->enter);
 
 	retpc = nil;
 	if(hasdefer || curfn->exit) {
-		Prog *p1;
-
 		p1 = gjmp(nil);
 		retpc = gjmp(nil);
 		patch(p1, pc);
diff --git a/src/cmd/gc/subr.c b/src/cmd/gc/subr.c
index 323d4f3922..db8b170145 100644
--- a/src/cmd/gc/subr.c
+++ b/src/cmd/gc/subr.c
@@ -3555,10 +3555,8 @@ umagic(Magic *m)
 Sym*
 ngotype(Node *n)
 {
-	if(n->sym != S && n->realtype != T)
-	if(strncmp(n->sym->name, "autotmp_", 8) != 0)
-		return typenamesym(n->realtype);
-
+	if(n->type != T)
+		return typenamesym(n->type);
 	return S;
 }
 
diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c
index 6b750384c0..ac90baafd2 100644
--- a/src/cmd/gc/typecheck.c
+++ b/src/cmd/gc/typecheck.c
@@ -296,7 +296,6 @@ typecheck1(Node **np, int top)
 		}
 
 		typecheckdef(n);
-		n->realtype = n->type;
 		if(n->op == ONONAME)
 			goto error;
 	}
diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index c79339ca77..de2105ed39 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -2217,6 +2217,8 @@ paramstoheap(Type **argin, int out)
 	nn = nil;
 	for(t = structfirst(&savet, argin); t != T; t = structnext(&savet)) {
 		v = t->nname;
+		if(v && v->sym && v->sym->name[0] == '~')
+			v = N;
 		if(v == N && out && hasdefer) {
 			// Defer might stop a panic and show the
 			// return values as they exist at the time of panic.