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Differential D38890

[X86] Add FeatureSlowBTMem to Haswell, Broadwell, Skylake, Cannonlake, and Knights Landing CPUs.
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Authored by craig.topper on Oct 13 2017, 9:23 AM.

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RKSimon
zvi
gadi.haber
Commits
rGa1f9c9dd8be5: [X86] Add FeatureSlowBTMem to Haswell, Broadwell, Skylake, Cannonlake, and…
rL315859: [X86] Add FeatureSlowBTMem to Haswell, Broadwell, Skylake, Cannonlake, and…
Summary

I see nothing in Agner Fog's tables to indicate that this improved between Ivy Bridge and Haswell. It's also set for all Atom CPUs so I assume KNL should have it too.

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rL LLVM

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craig.topper created this revision.Oct 13 2017, 9:23 AM
craig.topper added reviewers: RKSimon, zvi.Oct 13 2017, 9:23 AM
craig.topper added a subscriber: llvm-commits.
RKSimon added a reviewer: gadi.haber.Oct 13 2017, 10:29 AM
gadi.haber edited edge metadata.Oct 15 2017, 4:52 AM

Yes. The X86 Bit Test is known to run slowly on all X86 CPUs.

gadi.haber accepted this revision.Oct 15 2017, 7:23 AM
This revision is now accepted and ready to land.Oct 15 2017, 7:23 AM
Closed by commit rL315859: [X86] Add FeatureSlowBTMem to Haswell, Broadwell, Skylake, Cannonlake, and… (authored by ctopper). · Explain WhyOct 15 2017, 9:41 AM
This revision was automatically updated to reflect the committed changes.

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llvm/
trunk/
lib/
Target/
X86/
19 lines

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llvm/trunk/lib/Target/X86/X86.td

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