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bmeurer authored
Port the baseline implementation of Object.prototype.isPrototypeOf to the CodeStubAssembler, sharing the existing prototype chain lookup logic with the instanceof / OrdinaryHasInstance implementation. Based on that, do the same in TurboFan, introducing a new JSHasInPrototypeChain operator, which encapsulates the central prototype chain walk logic. This speeds up Object.prototype.isPrototypeOf by more than a factor of four, so that the code A.prototype.isPrototypeOf(a) is now performance-wise on par with a instanceof A for the case where A is a regular constructor function and a is an instance of A. Since instanceof does more than just the fundamental prototype chain lookup, it was discovered in Node core that O.p.isPrototypeOf would be a more appropriate alternative for certain sanity checks, since it's less vulnerable to monkey-patching. In addition, the Object builtin would also avoid the performance-cliff associated with instanceof (due to the Symbol.hasInstance hook), as for example hit by https://github.com/nodejs/node/pull/13403#issuecomment-305915874. The main blocker was the missing performance of isPrototypeOf, since it was still a JS builtin backed by a runtime call. This CL also adds more test coverage for the Object.prototype.isPrototypeOf builtin, especially when called from optimized code. CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_chromium_rel_ng BUG=v8:5269,v8:5989,v8:6483 R=jgruber@chromium.org Review-Url: https://codereview.chromium.org/2934893002 Cr-Commit-Position: refs/heads/master@{#45925}
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