From 7e1716dc9d5cbbadbcdaf8d68948eedb9fbf0c53 Mon Sep 17 00:00:00 2001 From: Eli Friedman Date: Mon, 13 Jul 2009 22:27:52 +0000 Subject: Canonicalize boolean +/- a constant to a select. (I think it's reasonably clear that we want to have a canonical form for constructs like this; if anyone thinks that a select is not the best canonical form, please tell me.) llvm-svn: 75531 --- llvm/lib/Transforms/Scalar/InstructionCombining.cpp | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) (limited to 'llvm/lib/Transforms/Scalar/InstructionCombining.cpp') diff --git a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp index 5b9659e2004..c93994ff56d 100644 --- a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp @@ -2101,13 +2101,10 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) { if (SimplifyDemandedInstructionBits(I)) return &I; - // zext(i1) - 1 -> select i1, 0, -1 + // zext(bool) + C -> bool ? C + 1 : C if (ZExtInst *ZI = dyn_cast(LHS)) - if (CI->isAllOnesValue() && - ZI->getOperand(0)->getType() == Type::Int1Ty) - return SelectInst::Create(ZI->getOperand(0), - Context->getNullValue(I.getType()), - Context->getAllOnesValue(I.getType())); + if (ZI->getSrcTy() == Type::Int1Ty) + return SelectInst::Create(ZI->getOperand(0), AddOne(CI, Context), CI); } if (isa(LHS)) @@ -2525,6 +2522,11 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) { if (SelectInst *SI = dyn_cast(Op1)) if (Instruction *R = FoldOpIntoSelect(I, SI, this)) return R; + + // C - zext(bool) -> bool ? C - 1 : C + if (ZExtInst *ZI = dyn_cast(Op1)) + if (ZI->getSrcTy() == Type::Int1Ty) + return SelectInst::Create(ZI->getOperand(0), SubOne(C, Context), C); } if (I.getType() == Type::Int1Ty) -- cgit v1.2.3