[webkit-changes] [WebKit/WebKit] 5f1ac6: Preserve sign of NaN operands in fsub{32, 64}
Commit Queue
noreply at github.com
Fri Feb 16 23:04:14 PST 2024
Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 5f1ac6454783b0c77f1dc789965e7a097e948771
https://github.com/WebKit/WebKit/commit/5f1ac6454783b0c77f1dc789965e7a097e948771
Author: Marcus Plutowski <marcus_plutowski at apple.com>
Date: 2024-02-16 (Fri, 16 Feb 2024)
Changed paths:
A JSTests/wasm/stress/fsub-nan-copysign.js
M Source/JavaScriptCore/wasm/WasmBBQJIT.cpp
Log Message:
-----------
Preserve sign of NaN operands in fsub{32,64}
https://bugs.webkit.org/show_bug.cgi?id=269509
rdar://120780768
Reviewed by Justin Michaud and Yusuke Suzuki.
Negating a NaN operand for fsub is incorrect, as IEEE defines the result
of an arithmetic operation with a NaN parameter as the NaN itself
(without modification). This is observable when a copysign operation is
done on the result, as copysign itself is exempt from that restriction
and can thus detect the improper negation.
By checking whether the operand is a NaN before negating we avoid this
issue.
* JSTests/wasm/stress/fsub-nan-copysign.js: Added.
* Source/JavaScriptCore/wasm/WasmBBQJIT.cpp:
(JSC::Wasm::BBQJITImpl::BBQJIT::addF32Sub):
(JSC::Wasm::BBQJITImpl::BBQJIT::addF64Sub):
Canonical link: https://commits.webkit.org/274910@main
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