Fix optimize memory.copy: check size for side effect as well #3072
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MaxGraey
changed the title
kripken
reviewed
Aug 23, 2020
| if (!EffectAnalyzer(getPassOptions(), features, memCopy->dest) | ||
| .hasSideEffects() && | ||
| !EffectAnalyzer(getPassOptions(), features, memCopy->size) | ||
| .hasSideEffects() && |
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how about just checking for side effects on memCopy itself? that would be shorter and handle all the cases.
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In this case:
(memory.copy ;; nop
(local.get $dst)
(local.get $dst)
(local.get $sz)
)will not reduced to nop. I don't know why
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I guess it's because MemoryCopy just don't properly handle by EffectAnalyzer? It just use this:
void visitMemoryCopy(MemoryCopy* curr) {
readsMemory = true;
writesMemory = true;
if (!ignoreImplicitTraps) {
implicitTrap = true;
}
}
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Oh, yes, that makes sense. It doesn't know it doesn't read/write in this case.
kripken
approved these changes
Aug 23, 2020
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Fix issue found by fuzzer: #3038 (comment)