From e617c9ed5dd374b05c312e411857c74e9b458aa0 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Fri, 5 Jan 2007 02:17:46 +0000 Subject: [PATCH] Compile X + ~X to -1. This implements Instcombine/add.ll:test34 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@32890 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/InstructionCombining.cpp | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 925db6837cf..aba50dca3e7 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -1871,10 +1871,16 @@ FoundSExt: if (dyn_castFoldableMul(RHS, C2) == LHS) return BinaryOperator::createMul(LHS, AddOne(C2)); + // X + ~X --> -1 since ~X = -X-1 + if (dyn_castNotVal(LHS) == RHS || + dyn_castNotVal(RHS) == LHS) + return ReplaceInstUsesWith(I, ConstantInt::getAllOnesValue(I.getType())); + // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2)))) - if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R; + if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) + return R; if (ConstantInt *CRHS = dyn_cast(RHS)) { Value *X = 0; -- 2.34.1