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Summary

  1. [InstCombine] fold extract+insert into identity shuffle (details)
Commit aff5bee35fb36897dd5414a52c11c14d2f858822 by spatel
[InstCombine] fold extract+insert into identity shuffle
This is similar to the existing fold for splats added with: rL365379
If we can adjust the shuffle mask to include another element in an
identity mask (if it changes vector length, that's an extract/insert
subvector operation in the backend), then that can eliminate
extractelement/insertelement pairs in IR.
All targets are expected to lower shuffles with identity masks
efficiently.
llvm-svn: 371340
The file was modifiedllvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp (diff)
The file was modifiedllvm/test/Transforms/InstCombine/insert-extract-shuffle.ll (diff)