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Sanjay Patel
3f985a3da1
This reverses instcombine's demanded bits' transform which always tries to clear bits in constants. As noted in PR35792 and shown in the test diffs: https://bugs.llvm.org/show_bug.cgi?id=35792 ...we can do better in codegen by trying to form -1. The x86 sub test shows a missed opportunity. I did investigate changing instcombine's behavior, but it would be more work to change canonicalization in IR. Clearing bits / shrinking constants can allow killing instructions, so we'd have to figure out how to not regress those cases. Differential Revision: https://reviews.llvm.org/D42986 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@324839 91177308-0d34-0410-b5e6-96231b3b80d8
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