1984901 - Demo at https://thatopen.github.io/engine_web-ifc/demo/ spends 600ms around BT Alloc and 200ms around SimpleAlloc

Status: NEW

(Core :: JavaScript Engine: JIT, defect, P2)

Description

[Mayank Bansal]

go to https://thatopen.github.io/engine_web-ifc/demo/
change gridsize to 600
Click on "Run Code"

BT: https://share.firefox.dev/3HPE2P8 / https://share.firefox.dev/4lTb532 (600ms)
SA: https://share.firefox.dev/41TlSTr (200ms)

Comment 1

[Jan de Mooij [:jandem]]

We spend a lot of time under trySplitAcrossHotcode and computeRequirement for some Wasm functions. Likely a very large function with a long live range with many uses. It'd be interesting to take a closer look at this to see what's happening exactly.

The register allocator optimizations last year probably improved this a lot but it didn't fix all the slowness in the allocator.

Comment 2

[Nicolas B. Pierron [:nbp]]

(In reply to Mayank Bansal from comment #0)

BT: https://share.firefox.dev/3HPE2P8 / https://share.firefox.dev/4lTb532 (600ms)
SA: https://share.firefox.dev/41TlSTr (200ms)

Focusing on js::wasm::ModuleGenerator::locallyCompileCurrentTask:

BT: Backtracking Allocator takes 71% of the compilation time. (this is quite high even for the backtracking allocator)
SA: Simple Allocator takes 9.7% of the compilation time.