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[dev.power64] liblink: fix lost branch target 

A recent commit lost the branch target in the really-big-stack
case of splitstack, causing an infinite loop stack preempt
case.  Revive the branch target.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/157790044
This commit is contained in:
Austin Clements 2014-10-27 17:19:41 -04:00
parent 5a653089ef
commit 6be0c8a566
1 changed files with 5 additions and 2 deletions
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7
src/liblink/obj9.c
View File

@ -703,7 +703,7 @@ addstacksplit(Link *ctxt, LSym *cursym)
static Prog*
stacksplit(Link *ctxt, Prog *p, int32 framesize, int noctxt)
{
Prog *q1;
Prog *q, *q1;
// MOVD g_stackguard(g), R3
p = appendp(ctxt, p);
@ -716,6 +716,7 @@ stacksplit(Link *ctxt, Prog *p, int32 framesize, int noctxt)
p->to.type = D_REG;
p->to.reg = 3;
q = nil;
if(framesize <= StackSmall) {
// small stack: SP < stackguard
// CMP stackguard, SP
@ -766,7 +767,7 @@ stacksplit(Link *ctxt, Prog *p, int32 framesize, int noctxt)
p->to.type = D_CONST;
p->to.offset = StackPreempt;
p = appendp(ctxt, p);
q = p = appendp(ctxt, p);
p->as = ABEQ;
p->to.type = D_BRANCH;
@ -812,6 +813,8 @@ stacksplit(Link *ctxt, Prog *p, int32 framesize, int noctxt)
p->from.offset = D_LR;
p->to.type = D_REG;
p->to.reg = 5;
if(q)
q->pcond = p;
// BL runtime.morestack(SB)
p = appendp(ctxt, p);