cmd/gc: fix stkptrsize calculation

I moved the pointer block from one end of the frame
to the other toward the end of working on the last CL,
and of course that made the optimization no longer work.

Now it works again:

0030 (bug361.go:12) DATA    gclocals·0+0(SB)/4,$4
0030 (bug361.go:12) DATA    gclocals·0+4(SB)/4,$3
0030 (bug361.go:12) GLOBL   gclocals·0+0(SB),8,$8

Fixes arm build (this time for sure!).

TBR=golang-dev
CC=cshapiro, golang-dev, iant
https://golang.org/cl/12627044

1 files changed, 4 insertions, 10 deletions

diff --git a/src/cmd/gc/pgen.c b/src/cmd/gc/pgen.c
index ad005a8f92..64b03b341f 100644
--- a/src/cmd/gc/pgen.c
+++ b/src/cmd/gc/pgen.c
@@ -341,7 +341,7 @@ dumpgclocals(Node* fn, Sym *sym)
 		node = ll->n;
 		if(node->class == PAUTO && node->op == ONAME) {
 			if(haspointers(node->type)) {
-				xoffset = node->xoffset + stksize;
+				xoffset = node->xoffset + stkptrsize;
 				walktype1(node->type, &xoffset, bv);
 			}
 		}
@@ -397,7 +397,6 @@ allocauto(Prog* ptxt)
 	NodeList *ll;
 	Node* n;
 	vlong w;
-	vlong ptrlimit;
 
 	if(curfn->dcl == nil) {
 		stksize = 0;
@@ -437,7 +436,7 @@ allocauto(Prog* ptxt)
 
 	// Reassign stack offsets of the locals that are still there.
 	stksize = 0;
-	ptrlimit = -1;
+	stkptrsize = 0;
 	for(ll = curfn->dcl; ll != nil; ll=ll->next) {
 		n = ll->n;
 		if (n->class != PAUTO || n->op != ONAME)
@@ -449,8 +448,8 @@ allocauto(Prog* ptxt)
 			fatal("bad width");
 		stksize += w;
 		stksize = rnd(stksize, n->type->align);
-		if(ptrlimit < 0 && haspointers(n->type))
-			ptrlimit = stksize - w;
+		if(haspointers(n->type))
+			stkptrsize = stksize;
 		if(thechar == '5')
 			stksize = rnd(stksize, widthptr);
 		if(stksize >= (1ULL<<31)) {
@@ -460,11 +459,6 @@ allocauto(Prog* ptxt)
 		n->stkdelta = -stksize - n->xoffset;
 	}
 	stksize = rnd(stksize, widthptr);
-
-	if(ptrlimit < 0)
-		stkptrsize = 0;
-	else
-		stkptrsize = stksize - ptrlimit;
 	stkptrsize = rnd(stkptrsize, widthptr);
 
 	fixautoused(ptxt);