1488726 - x86: Implement CPU feature detection for bmi1, bmi2, lzcnt

Status: RESOLVED FIXED

(Core :: JavaScript Engine: JIT, enhancement, P3)

Comment 1

[Benjamin Bouvier [:bbouvier] (inactive)]

Attachment: fix.patch

This also refactors cpuid reading so we can pass it specific eax input values, and implements detection for these features accordingly.

I actually wonder if it wouldn't make more sense for Cranelift to do this itself? In the meanwhile, that's an easy thing to implement in Spidermonkey. It's a bit sad we have a few implementations of ReadCPUInfo in tree, but the other ones are part of embedded libraries if I understand correctly.

Comment 2

[Dan Gohman [:sunfish]]

Comment on attachment 9023607 [details] [diff] [review]
fix.patch

Review of attachment 9023607 [details] [diff] [review]:
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Looks good!

Comment 3

[Dan Gohman [:sunfish]]

Cranelift has cranelift-native which can do CPU feature detection, but using SpiderMonkey's has the advantage of using SpiderMonkey's existing command-line flags for enabling/disabling use of various features, like --no-sse3.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/9e6f82773bdc
Implement CPU detection of LZCNT, BMI1, BMI2; r=sunfish

Comment 5

[Daniel Varga [:dvarga]]

https://hg.mozilla.org/mozilla-central/rev/9e6f82773bdc