[PATCH] D30137: [InstCombine] shrink truncated insertelement with constant operand

[Sanjay Patel via Phabricator via llvm-commits]

spatel created this revision.
Herald added a subscriber: mcrosier.

This is the 2nd part of solving:
http://lists.llvm.org/pipermail/llvm-dev/2017-February/110293.html

https://reviews.llvm.org/D30123 would move the trunc ahead of the shuffle, and this will move the trunc ahead of the insertelement. I'm assuming that we're ok transforming insertelement insts in general (unlike shufflevector) since those are simple ops that any target should handle.

I neglected to include FP truncate in https://reviews.llvm.org/D30123, so if this looks correct, I can update that patch to do a similar conversion or make a follow-up patch for that.


https://reviews.llvm.org/D30137

Files:
  lib/Transforms/InstCombine/InstCombineCasts.cpp
  test/Transforms/InstCombine/vector-casts.ll

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