From 43d84d6b71cc8ed5b08c22e54f5d1fc263919380 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Thu, 7 Apr 2005 16:15:25 +0000 Subject: [PATCH] Transform X-(X+Y) == -Y and X-(Y+X) == -Y git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21134 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/InstructionCombining.cpp | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 40088ba06be..9e40dc3239f 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -792,7 +792,15 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) { return NV; } - if (BinaryOperator *Op1I = dyn_cast(Op1)) + if (BinaryOperator *Op1I = dyn_cast(Op1)) { + if (Op1I->getOpcode() == Instruction::Add && + !Op0->getType()->isFloatingPoint()) { + if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y + return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName()); + else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y + return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName()); + } + if (Op1I->hasOneUse()) { // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression // is not used by anyone else... @@ -822,7 +830,7 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) { // -(X sdiv C) -> (X sdiv -C) if (Op1I->getOpcode() == Instruction::Div) if (ConstantSInt *CSI = dyn_cast(Op0)) - if (CSI->getValue() == 0) + if (CSI->isNullValue()) if (Constant *DivRHS = dyn_cast(Op1I->getOperand(1))) return BinaryOperator::createDiv(Op1I->getOperand(0), ConstantExpr::getNeg(DivRHS)); @@ -835,6 +843,7 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) { return BinaryOperator::createMul(Op0, CP1); } } + } if (BinaryOperator *Op0I = dyn_cast(Op0)) if (Op0I->getOpcode() == Instruction::Add)