1644424 - Constant fold SIMD reduction operators

Status: RESOLVED FIXED

(Core :: JavaScript: WebAssembly, enhancement, P3)

Description

[Lars T Hansen [:lth]]

Constant fold all_true, any_true, bitmask, and extract_lane operators. On at least one occasion I've observed emcc at even -O3 emit code that's not properly folded, and it costs us little to do this.

Comment 1

[Lars T Hansen [:lth]]

Attachment: Bug 1644424 - Constant fold wasm SIMD reductions. r=jseward

In general, we should do constant folding as other optimizations may result
in constants to fold. In addition, emcc has been observed not to fold
SIMD constants in all desirable cases.

Comment 2

[Lars T Hansen [:lth]]

Attachment: Bug 1644424 - Report triggering of SIMD constant folding. r=jseward

Inserts logging (active in DEBUG builds) and adds test cases that check that
the constant folding is triggered in at least trivial cases, cf other
test cases in the same test file.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/83605fde62ee
Constant fold wasm SIMD reductions. r=jseward
https://hg.mozilla.org/integration/autoland/rev/3ce9af6580b2
Report triggering of SIMD constant folding. r=jseward

Comment 4

[Bogdan Tara[:bogdan_tara | bogdant]]

https://hg.mozilla.org/mozilla-central/rev/83605fde62ee
https://hg.mozilla.org/mozilla-central/rev/3ce9af6580b2