[PATCH] D83273: [X86] Remove the feature dependency handling in X86TargetInfo::setFeatureEnabledImpl to a table based lookup in X86TargetParser.cpp

Tue Aug 4 16:26:22 PDT 2020

echristo added a comment.

In D83273#2194842 <https://reviews.llvm.org/D83273#2194842>, @nickdesaulniers wrote:

> In D83273#2194832 <https://reviews.llvm.org/D83273#2194832>, @craig.topper wrote:
>
>> It's a pretty nasty revert in our downstream tree where we have prototyped future ISAs. So I'd like a little time to take a look.
>>
>> @nickdesaulniers what cpu and fetaures are on your command lines. getImpliedDisabledFeatures should only be called if some feature is explicitly being disabled.
>
> Likely, as the kernel is very explicit to disable the use of all FP extensions, see https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/x86/Makefile#n57.  Maybe we could just set fewer flags, but there's still probably room for improvement here, too.

That said, it's a 10% compile time regression for compiling something like the linux kernel or anything that's very explicit what flags they set.

Repository:
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  https://reviews.llvm.org/D83273/new/

https://reviews.llvm.org/D83273