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More altivec intrinsics #1443

Merged
merged 4 commits into from
Jul 3, 2023
Merged

More altivec intrinsics #1443

merged 4 commits into from
Jul 3, 2023

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lu-zero
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@lu-zero lu-zero commented Jun 25, 2023

vec_xl contains an ugly workaround since copy_nonoverlapping is not correctly inlined.

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rustbot commented Jun 25, 2023

r? @Amanieu

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Amanieu commented Jun 29, 2023

The inlining issue happens because the PowerPC LLVM backend doesn't implement TargetTransformInfo::areInlineCompatible, so the default implementation is used which only allows inlining if the target features for the caller and callee match exactly. The target-specific specialized implementation typically allows inlining if the callee has a subset of the target feature of the caller.

Note that inline(always) skips this check, so this could be one way to make copy_nonoverlapping work in this case (you'd have to modify the standard library though).

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lu-zero commented Jun 30, 2023

We could have inline(always) for std::intrinsics and document the pitfall in case other architectures have the same problem.
It is probably a good idea to discuss with LLVM upstream about adding a complete areInlineCompatible for this arch as well...

@lu-zero lu-zero mentioned this pull request Jun 30, 2023
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nikic commented Jun 30, 2023

@Amanieu I believe https://reviews.llvm.org/D150396 will not allow inlining with incompatible target features even if alwaysinline is specified.

bors added a commit to rust-lang-ci/rust that referenced this pull request Jul 1, 2023
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Auto merge of rust-lang#113194 - lu-zero:intrinsics-inline, r=thomcc
6b06fdf 
Mark wrapped intrinsics as inline(always)

This should mitigate having the inliner decide not to inline when the architecture is lacking an implementation of
TargetTransformInfo::areInlineCompatible aware of the target features (e.g. PowerPC as today).

See rust-lang/stdarch#1443 (comment)
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Amanieu commented Jul 3, 2023

Considering the upcoming LLVM changes, I think it's fine to merge with the current workaround. Ideally we'll want a proper implementation of areInlineCompatible in the future.

@Amanieu Amanieu merged commit a4cde4a into rust-lang:master Jul 3, 2023
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thomcc pushed a commit to tcdi/postgrestd that referenced this pull request Aug 24, 2023
@bors
Auto merge of #113194 - lu-zero:intrinsics-inline, r=thomcc
27ad775 
Mark wrapped intrinsics as inline(always)

This should mitigate having the inliner decide not to inline when the architecture is lacking an implementation of
TargetTransformInfo::areInlineCompatible aware of the target features (e.g. PowerPC as today).

See rust-lang/stdarch#1443 (comment)
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