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Re: [PATCH] x86: fix CVT{,T}PD2PI insns


>>> On 27.06.19 at 11:03,  wrote:
> With just an "m" constraint misaligned memory operands won't be forced
> into a register, and hence cause #GP. So far this was guaranteed only
> in the case that CVT{,T}PD2DQ were chosen (which looks to be the case on
> x86-64 only).
> 
> Instead of switching the second alternative to Bm, use just m on the
> first and replace nonimmediate_operand by vector_operand.

While doing this and the others where I'm also replacing Bm by uses of
vector_operand, I've started wondering whether Bm couldn't (and then
shouldn't) be dropped altogether, replacing it everywhere by "m"
combined with vector_operand (or vector_memory_operand when
register operands aren't allowed anyway).

Furthermore there's an issue with Bm and vector_memory_operand:
Whether alignment gets enforced depends on TARGET_AVX. However,
just like the two insns in question here, the SHA ones too don't have
VEX-encoded equivalents, and hence require alignment enforced even
with -mavx. Together with the above I wonder whether Bm shouldn't
be re-purposed to express this special requirement.

Jan



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