[LLVMdev] Win64 bugs

Peter Shugalev peter at shugalev.com
Fri Jul 31 01:20:37 PDT 2009

>> Though the most problematic stuff is the lack of 'shadow zone' support
>> in Win64 ABI. Or maybe I haven't figured out how to turn this on. In
>> Win64 any function can treat 32 bytes of stack (RSP+08h..RSP+28h just
>> after the call instruction) as scratch data. VC++ compiler stores
>> arguments passed in registers there. In debug builds this doesn't get
>> optimized away.
> Wow, that's really strange... I'm pretty sure that simply isn't implemented.

Another side effect is function with more that four arguments. It won't
work if LLVM/VC++ code is mixed. That's again because of abscence of
32-byte gap between stack top and arguments.

int main () {
	printf ( "%d %d %d %d\n", 1, 2, 3, 4 );
	return 0;

1 2 3 0

Any ideas on how hard would it be to fix?

Best Regards
Peter Shugalev

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