Fix up hijacking on x86 (preserve async continuation register) #123084
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Tagging subscribers to this area: @agocke, @MichalStrehovsky, @jkotas |
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Pull request overview
This pull request attempts to fix GC hijacking on x86 to preserve the ECX register during garbage collection, as it may contain an async continuation according to the CLR ABI. The PR adds the PTFF_SAVE_RCX flag definition and includes it in the register save flags for two hijack handlers.
Changes:
- Adds
PTFF_SAVE_RCXconstant definition in i386/AsmMacros.inc - Updates
_RhpGcProbeHijack@0to include PTFF_SAVE_RCX in its register save flags - Updates
_RhpGcStressHijack@0to include PTFF_SAVE_RCX in its register save flags
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.
| File | Description |
|---|---|
| src/coreclr/nativeaot/Runtime/i386/AsmMacros.inc | Adds PTFF_SAVE_RCX flag constant (0x00000200h) for saving ECX register during hijack |
| src/coreclr/nativeaot/Runtime/i386/GcProbe.asm | Updates two hijack functions to include PTFF_SAVE_RCX in their save flags when waiting for GC |
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
jkotas
reviewed
Jan 12, 2026
VSadov
reviewed
Jan 13, 2026
6 tasks
3 tasks
jkotas
reviewed
Jan 15, 2026
jkotas
approved these changes
Jan 15, 2026
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Flag ecx (see async calling convention) during GC as it might contain an async continuation.
Contributes to #122492.