[PATCH] D123453: [InstCombine] Fold mul nuw+lshr exact to a single multiplication when the latter is a factor

chenglin.bi via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Sat Apr 9 06:44:24 PDT 2022


bcl5980 added inline comments.


================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp:1176
+
+      //  lshr exact (mul nuw x, qc * (1 << ShAmtC)), ShAmtC -> mul nuw, c
+      if (Op0->hasOneUse() && I.isExact()) {
----------------
xbolva00 wrote:
> xbolva00 wrote:
> > mul nuw, c??
> qc is what?
I'm sorry, should be : 
lshr exact (mul nuw x,  c * (1 << ShAmtC)), ShAmtC -> mul nuw, c
I will fix the comment later


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D123453/new/

https://reviews.llvm.org/D123453



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