[PATCH] D89821: [SCEV] Match 'zext (trunc A to iB) to iY' as URem.

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev added inline comments.


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Comment at: llvm/lib/Analysis/ScalarEvolution.cpp:12767
+      LHS = Trunc->getOperand();
+      RHS = getConstant(Expr->getType(),
+                        1u << getTypeSizeInBits(Trunc->getType()));
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I think `getPowerOf2` would be a useful utility function in SCEV. Consider factoring out (maybe as separate patch).


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Comment at: llvm/lib/Analysis/ScalarEvolution.cpp:12768
+      RHS = getConstant(Expr->getType(),
+                        1u << getTypeSizeInBits(Trunc->getType()));
+      return true;
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`1u << X` will overflowan become zero if `X > 32`. Consider using APInt.


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Comment at: llvm/unittests/Analysis/ScalarEvolutionTest.cpp:67
+
+  bool matchURem(ScalarEvolution &SE, const SCEV *Expr, const SCEV *&LHS,
+                 const SCEV *&RHS) {
----------------
static?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D89821/new/

https://reviews.llvm.org/D89821