diff options
Diffstat (limited to 'src/cmd/8l/pass.c')
| -rw-r--r-- | src/cmd/8l/pass.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/src/cmd/8l/pass.c b/src/cmd/8l/pass.c index b900a5f79..9034fdf3a 100644 --- a/src/cmd/8l/pass.c +++ b/src/cmd/8l/pass.c @@ -527,10 +527,18 @@ dostkoff(void) p = appendp(p); // save frame size in DX p->as = AMOVL; p->to.type = D_DX; - /* 160 comes from 3 calls (3*8) 4 safes (4*8) and 104 guard */ p->from.type = D_CONST; - if(autoffset+160+cursym->text->to.offset2 > 4096) - p->from.offset = (autoffset+160) & ~7LL; + + // If we ask for more stack, we'll get a minimum of StackMin bytes. + // We need a stack frame large enough to hold the top-of-stack data, + // the function arguments+results, our caller's PC, our frame, + // a word for the return PC of the next call, and then the StackLimit bytes + // that must be available on entry to any function called from a function + // that did a stack check. If StackMin is enough, don't ask for a specific + // amount: then we can use the custom functions and save a few + // instructions. + if(StackTop + cursym->text->to.offset2 + PtrSize + autoffset + PtrSize + StackLimit >= StackMin) + p->from.offset = (autoffset+7) & ~7LL; p = appendp(p); // save arg size in AX p->as = AMOVL; |