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| author | Sanjay Patel <spatel@rotateright.com> | 2017-04-12 18:39:53 +0000 |
|---|---|---|
| committer | Sanjay Patel <spatel@rotateright.com> | 2017-04-12 18:39:53 +0000 |
| commit | 6e410189421190343a742c8e7513ef10f53fc0f0 (patch) | |
| tree | 95e8d79fd710bb1f6fcbfde00445e0b668a91e06 /llvm/docs/LangRef.rst | |
| parent | 8b459c24f34c6772bd637090b118859b154d5da3 (diff) | |
| download | bcm5719-llvm-6e410189421190343a742c8e7513ef10f53fc0f0.tar.gz bcm5719-llvm-6e410189421190343a742c8e7513ef10f53fc0f0.zip | |
[InstCombine] fix wrong undef handling when converting select to shuffle
As discussed in:
https://bugs.llvm.org/show_bug.cgi?id=32486
...the canonicalization of vector select to shufflevector does not hold up
when undef elements are present in the condition vector.
Try to make the undef handling clear in the code and the LangRef.
Differential Revision: https://reviews.llvm.org/D31980
llvm-svn: 300092
Diffstat (limited to 'llvm/docs/LangRef.rst')
| -rw-r--r-- | llvm/docs/LangRef.rst | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst index 363847af0a8..b452ec03041 100644 --- a/llvm/docs/LangRef.rst +++ b/llvm/docs/LangRef.rst @@ -7071,9 +7071,10 @@ Semantics: The elements of the two input vectors are numbered from left to right across both of the vectors. The shuffle mask operand specifies, for each element of the result vector, which element of the two input vectors the -result element gets. The element selector may be undef (meaning "don't -care") and the second operand may be undef if performing a shuffle from -only one vector. +result element gets. If the shuffle mask is undef, the result vector is +undef. If any element of the mask operand is undef, that element of the +result is undef. If the shuffle mask selects an undef element from one +of the input vectors, the resulting element is undef. Example: """""""" |
