[release/7.0] Allow SIMD-returning calls as arguments #74520
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As of this change we handle all relevant ABI scenarios.
1) Windows x64:
- SIMD8: returned and passed as "TYP_LONG", fine.
- SIMD12 / SIMD16 / SIMD32: returned and passed via a return buffer, fine.
2) Unix x64:
- SIMD8: returned and passed in one FP register, fine.
- SIMD12 / SIMD16, Vector4: returned and passed in two FP registers, fine.
- SIMD16, Vector128 / SIMD32: returned and passed via a return buffer, fine.
3) x86:
- SIMD8: can be returned via two registers or a return buffer (and is always passed on stack), both are fine.
- SIMD12/SIMD16/SIMD32: returned via a return buffer, passed on stack, fine.
4) ARM64:
- SIMD8, Vector2: returned in two FP registers (and passed as such or "TYP_LONG" under Windows varargs), fine.
- SIMD8, Vector64: returned in one FP register, can be passed as such or as "TYP_LONG" under Windows varargs.
The latter case is now handled correctly in "Lowering::LowerArg".
- SIMD12: returned in three FP registers, passed as such or in two integer registers under Windows varargs, fine.
- SIMD16, Vector4: returned in four FP registers, passed as such, or in two integer registers under Windows varargs, fine.
- SIMD16, Vector128: returned in one FP register, passed as such, or in two integer registers under Windows varargs, fine
(morph will decompose the varargs case into a `FIELD_LIST` via a temp).
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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch Issue DetailsBackport of #74184 to release/7.0 /cc @BruceForstall @SingleAccretion Customer ImpactTestingRiskIMPORTANT: Is this backport for a servicing release? If so and this change touches code that ships in a NuGet package, please make certain that you have added any necessary package authoring and gotten it explicitly reviewed.
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Nit: I think the observable symptom of this is silent bad performance; the optimized code will fix hit an
This is a regression from 6.0, caused by a combination of forward substitution and |
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Can we please get an approval, @jeffschwMSFT ? |
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@BruceForstall I reran the failed tests. Once all tests pass, please merge. |
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@carlossanlop all tests are green. It is good to merge. |
Backport of #74184 to release/7.0
/cc @BruceForstall @SingleAccretion
Customer Impact
Possible silent bad codegen for code involving SIMD types.
Testing
Normal CI testing including SuperPMI replay/asmdiffs
Risk
low