[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 07:16:33 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:
> bcl5980 wrote:
> > 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
> mul nuw x, c?
yeah


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

https://reviews.llvm.org/D123453



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