[bmi2] Add lzcnt and bmi target attributes #2888
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* When dynamic dispatching to bmi2 add lzcnt and bmi to the TARGET_ATTRIBUTE. * Centralize the bmi2 TARGET_ATTRIBUTE definition to BMI2_TARGET_ATTRIBUTE so we can change it in the future. * Only enable bmi2 when both bmi1 & bmi2 are supported. There shouldn't be any cases where bmi2 is supported but bmi1 isn't. But, since we are using the instruction we should check bmi1 as well.
Cyan4973
approved these changes
Dec 1, 2021
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TARGET_ATTRIBUTE.
BMI2_TARGET_ATTRIBUTE so we can change it in the future.
be any cases where bmi2 is supported but bmi1 isn't. But, since we are
using the instruction we should check bmi1 as well.
I measure +3-4% performance on gcc-11.1.0 on my Intel i9-9900k, and neutral with clang-13.0.0. But, I'm pretty sure thats just noise. I measure neutral performance on my devserver with our internal gcc and clang builds.
Fixes Issue #2814.