[release/6.0] Fix SIMD temp register interference #58990
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On Windows/x86, if a call returns a SIMD8 in two registers (eax, edx), and needs to be assembled and stored into a single SIMD register, AND we don't have the SSE41 ABI available (because the hardware doesn't support it, or we specifically disable it), then we need a temporary register. In the failure case, the target register and temporary register were the same, and then interfered with each other. The fix is to force the temporary register to be different from the target register. Fixes #58899
ghost
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area-CodeGen-coreclr
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Tagging subscribers to this area: @JulieLeeMSFT Issue DetailsBackport of #58914 to release/6.0 /cc @BruceForstall Customer ImpactTestingRisk
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Contributor
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@kunalspathak @dotnet/jit-contrib PTAL: backport of very simple fix |
Contributor
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@jeffschwMSFT PTAL |
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Backport of #58914 to release/6.0
/cc @BruceForstall
Customer Impact
On Windows/x86, on machines without SSE41 available, certain calls to functions returning a Vector2 type (8-byte SIMD type) will generate bad code and corrupt the function return value.
Testing
Running the previously failing repro case, SuperPMI asm diffs, normal CI testing.
Risk
Very low.