[LLVMdev] [PATCH] Detect Haswell subarchitecture (i.e. using -march=native)

[Tim Northover]

> I think your real problem is that garbage went into ECX instead of 0 and
> caused cpuid to return 0.

Ah, that looks very likely. The value seems to come from "xorl %eax,
%eax" in both good object files, but a previous cpuid in the bad one.

Excellent work Craig, I suspect that would have taken me days to find.

Tim.