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| author | Sanjay Patel <spatel@rotateright.com> | 2019-02-05 22:58:45 +0000 |
|---|---|---|
| committer | Sanjay Patel <spatel@rotateright.com> | 2019-02-05 22:58:45 +0000 |
| commit | cddb1e54697d0eed7329f4bee8878802b388ab29 (patch) | |
| tree | d3f16fedd30c8ccf6cccf18b5f099d84f78e120a /llvm/test/Transforms | |
| parent | 1b8df427121e3d7edf5cfaf0f3e3550ed2091d62 (diff) | |
| download | bcm5719-llvm-cddb1e54697d0eed7329f4bee8878802b388ab29.tar.gz bcm5719-llvm-cddb1e54697d0eed7329f4bee8878802b388ab29.zip | |
[InstCombine] limit extracting shuffle transform based on uses
As discussed in D53037, this can lead to worse codegen, and we
don't generally expect the backend to be able to optimize
arbitrary shuffles. If there's only one use of the 1st shuffle,
that means it's getting removed, so that should always be
safe.
llvm-svn: 353235
Diffstat (limited to 'llvm/test/Transforms')
| -rw-r--r-- | llvm/test/Transforms/InstCombine/vec_shuffle.ll | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/llvm/test/Transforms/InstCombine/vec_shuffle.ll b/llvm/test/Transforms/InstCombine/vec_shuffle.ll index 401bcee4991..aae337d0de3 100644 --- a/llvm/test/Transforms/InstCombine/vec_shuffle.ll +++ b/llvm/test/Transforms/InstCombine/vec_shuffle.ll @@ -195,7 +195,7 @@ define <4 x i8> @extract_subvector_of_shuffle_undefs_types(<2 x i8> %x, <2 x i8> ret <4 x i8> %extract_subv } -; FIXME: Extra uses are not ok - we should only do the transform when we can eliminate an instruction. +; Extra uses are not ok - we only do the transform when we can eliminate an instruction. declare void @use_v5i8(<5 x i8>) @@ -203,7 +203,7 @@ define <4 x i8> @extract_subvector_of_shuffle_extra_use(<2 x i8> %x, <2 x i8> %y ; CHECK-LABEL: @extract_subvector_of_shuffle_extra_use( ; CHECK-NEXT: [[SHUF:%.*]] = shufflevector <2 x i8> [[X:%.*]], <2 x i8> [[Y:%.*]], <5 x i32> <i32 undef, i32 2, i32 0, i32 1, i32 0> ; CHECK-NEXT: call void @use_v5i8(<5 x i8> [[SHUF]]) -; CHECK-NEXT: [[EXTRACT_SUBV:%.*]] = shufflevector <2 x i8> [[X]], <2 x i8> [[Y]], <4 x i32> <i32 undef, i32 2, i32 0, i32 undef> +; CHECK-NEXT: [[EXTRACT_SUBV:%.*]] = shufflevector <5 x i8> [[SHUF]], <5 x i8> undef, <4 x i32> <i32 0, i32 1, i32 2, i32 undef> ; CHECK-NEXT: ret <4 x i8> [[EXTRACT_SUBV]] ; %shuf = shufflevector <2 x i8> %x, <2 x i8> %y, <5 x i32> <i32 undef, i32 2, i32 0, i32 1, i32 0> |
