[PATCH] D112085: [DAGCombiner] fold bit-hack form of usubsat
Sanjay Patel via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Tue Oct 19 11:13:13 PDT 2021
spatel added inline comments.
================
Comment at: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:6020
+ if (TLI.isOperationLegal(ISD::USUBSAT, VT))
+ if (SDValue V = foldAndToUsubsat(N, DAG))
----------------
RKSimon wrote:
> If we could use hasOperation then AVX1 should be able to match this for 256-bit integers as well.
Yes - that's how I had drafted this initially, but I noticed potential regressions with extra uses.
But extra-use patterns on something like this might be too rare to worry about.
I'll add some more tests and update.
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https://reviews.llvm.org/D112085/new/
https://reviews.llvm.org/D112085
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