Let GenTreeCopyOrReload handle scenarios when FEATURE_MULTIREG_RET is disabled #82451
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ghost
assigned 
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@dotnet/jit-contrib @tannergooding |
tannergooding
approved these changes
Feb 22, 2023
SingleAccretion
approved these changes
Feb 22, 2023
src/coreclr/jit/gentree.h
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| @@ -8039,17 +8039,14 @@ struct GenTreePutArgSplit : public GenTreePutArgStk | |||
| // Represents GT_COPY or GT_RELOAD node | |||
| // | |||
| // As it turns out, these are only needed on targets that happen to have multi-reg returns. | |||
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| // As it turns out, these are only needed on targets that happen to have multi-reg returns. | |
| // Needed to support multi-reg ops. |
src/coreclr/jit/gentree.h
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| @@ -8039,17 +8039,14 @@ struct GenTreePutArgSplit : public GenTreePutArgStk | |||
| // Represents GT_COPY or GT_RELOAD node | |||
| // | |||
| // As it turns out, these are only needed on targets that happen to have multi-reg returns. | |||
| // However, they are actually needed on any target that has any multi-reg ops. It is just | |||
| // coincidence that those are the same (and there isn't a FEATURE_MULTIREG_OPS). | |||
| // However, they are actually needed on any target that has any multi-reg ops. | |||
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| // However, they are actually needed on any target that has any multi-reg ops. |
Otherwise the comments contradict themselves:
... are only needed on targets that happen to have multi-reg returns ...
... are actually needed on any target that has any multi-reg ops ...
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/azp run runtime-coreclr superpmi-diffs |
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/azp run runtime-coreclr superpmi-replay |
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Currently Windows ABI doesn't allow to split the result and return it in multiple registers. However, in #66551, we exposed an API that will let us return the result in multiple registers. The ABI doesn't allow us to do, but since
DivRemadded in #66551 is an intrinsic, we should continue to let the instruction return the result in multiple registers. Thanks @tannergooding for helping me understand this concept.GenTreeCopyOrReloadhad special code to handle scenario whenFEATURE_MULTIREG_RETwas allowed (on unix x64/arm64 and windows arm64) but this was breaking withDivRemsupport. The fix is to haveGenTreeCopyOrReloadalso handle scenarios whenFEATURE_MULTIREG_RETis disabled.Fixes: #82397