WebAssembly / WebAssembly/binaryen

Improving Precompute performance

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interpreter
Dominant language
WebAssembly
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Merged PRs (30d)
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Description

Running on the binary from Google Sheets,

BINARYEN_CORES=1 perf record bin/wasm-opt binary.wasm -all --precompute --no-validation

(1 core to avoid noise from multithreading; validation disabled to focus on the optimization)

The top item from perf report is

     7.41%  wasm-opt  libbinaryen.so        [.] wasm::Type::isRef() const

Reading the code, I can't see an obvious reason for that slowness.

@tlively You mentioned some lock you might look into with wasm::Type - is this related? I don't seem to see a lock taken here though.

My only other guess is that this may just be called many times, and by not being in a header, it isn't getting inlined.

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Research direction

Reproduce the profile with bin/wasm-opt and the BINARYEN_CORES=1 perf record command using --precompute and --no-validation. Start by examining wasm::Type::isRef() const and the surrounding wasm::Type implementation, then use perf report to determine whether call frequency, missing inlining, or another factor accounts for the cost. Done means identifying and addressing the performance cause with measurements showing an improvement.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp, wasm
Domain
compilers, performance
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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