On Wed, Nov 20, 2013 at 11:28 AM, H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> wrote:
>>
>> .section .fixup,"ax"
>> 11: lea (%rdx,%rcx,8),%rcx
>> 12: movl %ecx,%edx /* ecx is zerorest also */
>
> -> Even if %rdx+%rcx*8 > 2^32 we end up truncating at 12: -- not that it
> matters, since both arguments are prototyped as "unsigned" and therefore
> the C compiler is supposed to guarantee the upper 32 bits are ignored.
Ahh. That was the one I thought was broken, but yes, while the upper
bits of %rcx are calculated and not zeroed, they end up not actually
getting used. So yeah, I'll believe it's correct.
Linus
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