JIT: Disallow using float callee saves in x64 functions with patchpoints#127158
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jakobbotsch merged 3 commits intodotnet:mainfrom Apr 21, 2026
Merged
JIT: Disallow using float callee saves in x64 functions with patchpoints#127158jakobbotsch merged 3 commits intodotnet:mainfrom
jakobbotsch merged 3 commits intodotnet:mainfrom
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We do not restore these in the OSR methods so using these registers currently relies on the unwinder. We will have transitioning that does not use the unwinder soon so just disable using these registers. Since patchpoints only appear in tier0 methods it is not a big deal to avoid using these registers.
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Pull request overview
This PR updates the x64 JIT register allocator to avoid allocating floating-point callee-saved registers in methods that contain patchpoints, addressing OSR transition semantics where these registers are not restored by the OSR method.
Changes:
- In
LinearScaninitialization for AMD64, mask outRBM_FLT_CALLEE_SAVEDfrom the available float/double register sets when the method has patchpoints (including partial compilation patchpoints).
tannergooding
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Apr 20, 2026
This was referenced Apr 20, 2026
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/azp run runtime-coreclr superpmi-diffs |
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Azure Pipelines successfully started running 1 pipeline(s). |
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FYI @AndyAyersMS @dotnet/jit-contrib |
kg
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Apr 21, 2026
kg
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Apr 21, 2026
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We do not restore these in the OSR methods so using these registers currently relies on the unwinder. We will have transitioning that does not use the unwinder soon so just disable using these registers. Since patchpoints only appear in tier0 methods it is not a big deal to avoid using these registers.