35269f77f8
BytecodeLabels for forward jumps may create a dead basic block if their corresponding jump was elided (due to it dead code elimination). We can avoid generating such dead basic blocks by skipping the label bind when no corresponding jump has been observed. This works because all jumps except JumpLoop are forward jumps, so we only have to special case one Bind for loop headers to bind unconditionally. Since Binds are now conditional on a jump existing, we can no longer rely on using Bind to get the current offset (e.g. at the beginning of a try block). Instead, we now expose the current offset in the bytecode array writer. Conveniently, this means that we can be a bit smarter about basic blocks around these statements. As a drive-by, remove the unused Bind(target,label) function. Bug: chromium:934166 Change-Id: I532aa452fb083560d07b90da99caca0b1d082aa3 Reviewed-on: https://chromium-review.googlesource.com/c/1488763 Commit-Queue: Leszek Swirski <leszeks@chromium.org> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org> Cr-Commit-Position: refs/heads/master@{#59942}
19 lines
579 B
JavaScript
19 lines
579 B
JavaScript
// Copyright 2019 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Flags: --allow-natives-syntax
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{
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for(let i = 0; i < 10; ++i){
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try{
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// Carefully constructed by a fuzzer to use a new register for s(), whose
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// write is dead due to the unconditional throw after s()=N, but which is
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// read in the ({...g}) call, which therefore must also be marked dead and
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// elided.
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with(f&&g&&(s()=N)({...g})){}
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} catch {}
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%OptimizeOsr();
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}
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}
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