[PATCH] D154953: [InstSimplify] Remove the remainder loop if we know the mask is always true

[Noah Goldstein via Phabricator via llvm-commits]

goldstein.w.n added inline comments.


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Comment at: llvm/lib/Analysis/InstructionSimplify.cpp:1283
+    const APInt *RemC;
+    if (match(Op0, m_Power2(RemC))) {
+      KnownBits Known = computeKnownBits(Op1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
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move the match of Op0 against a constant to before the far more expensive `isKnownToBeAPowerOfTwo` check on Op1.


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Comment at: llvm/lib/Analysis/InstructionSimplify.cpp:1288
+        return ConstantInt::getNullValue(Op0->getType());
+    }
+  }
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Since we are already here, might as well also add an `else if(Known.getMinValue().ugt(*RemC)) { return Op0; }`

Proofs: https://alive2.llvm.org/ce/z/FkTMoy


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D154953/new/

https://reviews.llvm.org/D154953