[PATCH] D130680: [IntegerDivision][AMDGPU] Use CreateLogicalOr to block poison propagation.

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


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Comment at: llvm/lib/Transforms/Utils/IntegerDivision.cpp:260
   Value *Ret0_2      = Builder.CreateICmpEQ(Dividend, Zero);
-  Value *Ret0_3      = Builder.CreateOr(Ret0_1, Ret0_2);
+  Value *Ret0_3      = Builder.CreateLogicalOr(Ret0_1, Ret0_2);
   Value *Tmp0 = Builder.CreateCall(CTLZ, {Divisor, True});
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I don't think we need this logical or, because both inputs are non-poison with the freeze.


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Comment at: llvm/lib/Transforms/Utils/IntegerDivision.cpp:265
   Value *Ret0_4      = Builder.CreateICmpUGT(SR, MSB);
-  Value *Ret0        = Builder.CreateOr(Ret0_3, Ret0_4);
+  Value *Ret0        = Builder.CreateLogicalOr(Ret0_3, Ret0_4);
   Value *RetDividend = Builder.CreateICmpEQ(SR, MSB);
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We *do* need this one, because Ret0_4 may be poison (through SR).


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Comment at: llvm/lib/Transforms/Utils/IntegerDivision.cpp:268
   Value *RetVal      = Builder.CreateSelect(Ret0, Zero, Dividend);
-  Value *EarlyRet    = Builder.CreateOr(Ret0, RetDividend);
+  Value *EarlyRet    = Builder.CreateLogicalOr(Ret0, RetDividend);
   Builder.CreateCondBr(EarlyRet, End, BB1);
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We also need this one, because RetDividend may be poison (through SR).


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D130680/new/

https://reviews.llvm.org/D130680