[LLVMdev] stack alignment (again)
dalej at apple.com
Fri Mar 28 17:23:41 PDT 2008
On Mar 28, 2008, at 5:17 PM, Chuck Rose III wrote:
> Hola LLVMers,
> I was curious about the state of stack alignment on x86. I noticed
> there are a few bugs outstanding on the issue. I recently added
> some code which had the effect of throwing an extra function
> parameter on our stack at runtime, a 4 byte pointer.
> Esp is now not 16-byte aligned, so instructions like unpcklps xmm1,
> dword ptr [eps] cause grief. My AllocaInstr instructions are told
> to be 16 byte aligned, so the addition of a 4-byte parameter
> shouldn’t have changed alignment on the objects.
> The unpcklps instruction is coming from an ExtractElementInst or
> InsertElementInst. I can always hard code these by cyling my
> vectors to memory and doing things one scalar at a time, though perf
> will suffer. I’ll try it Monday to see if it gets rid of the
> alignment sensitive instructions.
> I’m noticing this under windows via JIT. I’m going to check to see
> if my mac has similar issues.
The stack on MacOS is supposed to be kept 16-byte aligned.
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the llvm-dev