Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: e9b6a4f065464e3dadd1babad90d364987c58d4f
https://github.com/WebKit/WebKit/commit/e9b6a4f065464e3dadd1babad90d364987c58d4f
Author: Sosuke Suzuki <[email protected]>
Date: 2026-01-22 (Thu, 22 Jan 2026)
Changed paths:
M Source/JavaScriptCore/assembler/MacroAssemblerX86_64.cpp
Log Message:
-----------
[JSC] Use movaps instead of vmovaps in probe trampoline on non-AVX x86_64
https://bugs.webkit.org/show_bug.cgi?id=306004
Reviewed by Yusuke Suzuki.
304684@main to changed to unify the SIMD and non-SIMD probe trampolines into
a single trampoline that always uses vmovaps to save/restore the full
128-bit XMM registers.
This is correct on macOS where all x86_64 CPUs support AVX, but breaks on
Linux and Windows where pre-AVX x86_64 CPUs still exist. On these CPUs,
executing vmovaps causes SIGILL.
Fix this by providing two trampolines on non-Darwin platforms:
- ctiMasmProbeTrampoline: uses movaps (SSE, always available on x86_64)
- ctiMasmProbeTrampolineAVX: uses vmovaps (requires AVX)
MacroAssembler::probe() selects the appropriate trampoline at JIT compile
time based on supportsAVX(). On macOS, the behavior is unchanged.
The Probe::State memory layout remains the same since both movaps and
vmovaps operate on the full 128-bit XMM register width.
* Source/JavaScriptCore/assembler/MacroAssemblerX86_64.cpp:
(JSC::MacroAssembler::probe):
Canonical link: https://commits.webkit.org/306002@main
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