[PATCH] D150755: [GlobalIsel][x86] Legalize G_CTPOP and G_CTLZ II

Wed May 17 07:58:37 PDT 2023

RKSimon added a comment.

In D150755#4349879 <https://reviews.llvm.org/D150755#4349879>, @tschuett wrote:

> I was also unsure about the availability, but Wikipedia claims:
> https://en.wikipedia.org/wiki/X86_Bit_manipulation_instruction_set
>
> ABM is implemented by SSE4.2 and ABM is popcount and lzcnt.

Don't trust wikipedia - it might be that all SSE4.2 cpus are known to support ABM as well, but its not under the same feature flags inside llvm (or the same cpuid bits on actual cpus), and AMD in fact support it with older cpus.

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https://reviews.llvm.org/D150755