From 22e371c74eb6a881f65d677712931297475a69d9 Mon Sep 17 00:00:00 2001 From: Dinesh Dwivedi Date: Fri, 27 Jun 2014 07:47:35 +0000 Subject: Added instruction combine to transform few more negative values addition to subtraction (Part 3) This patch enables transforms for (x + (~(y | c) + 1) --> x - (y | c) if c is odd Differential Revision: http://reviews.llvm.org/D4210 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211881 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/InstCombine/InstCombineAddSub.cpp | 110 +++++++++++++---------- 1 file changed, 62 insertions(+), 48 deletions(-) (limited to 'lib') diff --git a/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/lib/Transforms/InstCombine/InstCombineAddSub.cpp index 6aede84a35..f8d7e0ecf4 100644 --- a/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ b/lib/Transforms/InstCombine/InstCombineAddSub.cpp @@ -954,56 +954,70 @@ bool InstCombiner::WillNotOverflowUnsignedAdd(Value *LHS, Value *RHS) { return true; return false; - } +} // Checks if any operand is negative and we can convert add to sub. - // This function checks for following negative patterns - // ADD(XOR(OR(Z, NOT(C)), C)), 1) == NEG(AND(Z, C)) - // ADD(XOR(AND(Z, C), C), 1) == NEG(OR(Z, ~C)) if C is odd - // TODO: XOR(AND(Z, C), (C + 1)) == NEG(OR(Z, ~C)) if C is even - Value *checkForNegativeOperand(BinaryOperator &I, - InstCombiner::BuilderTy *Builder) { - Value *LHS = I.getOperand(0), *RHS = I.getOperand(1); +// This function checks for following negative patterns +// ADD(XOR(OR(Z, NOT(C)), C)), 1) == NEG(AND(Z, C)) +// ADD(XOR(AND(Z, C), C), 1) == NEG(OR(Z, ~C)) +// XOR(AND(Z, C), (C + 1)) == NEG(OR(Z, ~C)) if C is even +Value *checkForNegativeOperand(BinaryOperator &I, + InstCombiner::BuilderTy *Builder) { + Value *LHS = I.getOperand(0), *RHS = I.getOperand(1); + + // This function creates 2 instructions to replace ADD, we need at least one + // of LHS or RHS to have one use to ensure benefit in transform. + if (!LHS->hasOneUse() && !RHS->hasOneUse()) + return nullptr; - // This function creates 2 instructions to replace ADD, we need at least one - // of LHS or RHS to have one use to ensure benefit in transform. - if (!LHS->hasOneUse() && !RHS->hasOneUse()) - return nullptr; - - Value *X = nullptr, *Y = nullptr, *Z = nullptr; - const APInt *C1 = nullptr, *C2 = nullptr; - - // if ONE is on other side, swap - if (match(RHS, m_Add(m_Value(X), m_One()))) - std::swap(LHS, RHS); - - if (match(LHS, m_Add(m_Value(X), m_One()))) { - // if XOR on other side, swap - if (match(RHS, m_Xor(m_Value(Y), m_APInt(C1)))) - std::swap(X, RHS); - - if (match(X, m_Xor(m_Value(Y), m_APInt(C1)))) { - // X = XOR(Y, C1), Y = OR(Z, C2), C2 = NOT(C1) ==> X == NOT(AND(Z, C1)) - // ADD(ADD(X, 1), RHS) == ADD(X, ADD(RHS, 1)) == SUB(RHS, AND(Z, C1)) - if (match(Y, m_Or(m_Value(Z), m_APInt(C2))) && (*C2 == ~(*C1))) { - Value *NewAnd = Builder->CreateAnd(Z, *C1); - return Builder->CreateSub(RHS, NewAnd, "sub"); - } else if (C1->countTrailingZeros() == 0) { - // if C1 is ODD and - // X = XOR(Y, C1), Y = AND(Z, C2), C2 == C1 ==> X == NOT(OR(Z, ~C1)) - // ADD(ADD(X, 1), RHS) == ADD(X, ADD(RHS, 1)) == SUB(RHS, OR(Z, ~C1)) - if (match(Y, m_And(m_Value(Z), m_APInt(C2))) && (*C1 == *C2)) { - Value *NewOr = Builder->CreateOr(Z, ~(*C1)); - return Builder->CreateSub(RHS, NewOr, "sub"); - } - } - } - } - - return nullptr; - } - - Instruction *InstCombiner::visitAdd(BinaryOperator &I) { + Value *X = nullptr, *Y = nullptr, *Z = nullptr; + const APInt *C1 = nullptr, *C2 = nullptr; + + // if ONE is on other side, swap + if (match(RHS, m_Add(m_Value(X), m_One()))) + std::swap(LHS, RHS); + + if (match(LHS, m_Add(m_Value(X), m_One()))) { + // if XOR on other side, swap + if (match(RHS, m_Xor(m_Value(Y), m_APInt(C1)))) + std::swap(X, RHS); + + if (match(X, m_Xor(m_Value(Y), m_APInt(C1)))) { + // X = XOR(Y, C1), Y = OR(Z, C2), C2 = NOT(C1) ==> X == NOT(AND(Z, C1)) + // ADD(ADD(X, 1), RHS) == ADD(X, ADD(RHS, 1)) == SUB(RHS, AND(Z, C1)) + if (match(Y, m_Or(m_Value(Z), m_APInt(C2))) && (*C2 == ~(*C1))) { + Value *NewAnd = Builder->CreateAnd(Z, *C1); + return Builder->CreateSub(RHS, NewAnd, "sub"); + } else if (match(Y, m_And(m_Value(Z), m_APInt(C2))) && (*C1 == *C2)) { + // X = XOR(Y, C1), Y = AND(Z, C2), C2 == C1 ==> X == NOT(OR(Z, ~C1)) + // ADD(ADD(X, 1), RHS) == ADD(X, ADD(RHS, 1)) == SUB(RHS, OR(Z, ~C1)) + Value *NewOr = Builder->CreateOr(Z, ~(*C1)); + return Builder->CreateSub(RHS, NewOr, "sub"); + } + } + } + + // Restore LHS and RHS + LHS = I.getOperand(0); + RHS = I.getOperand(1); + + // if XOR is on other side, swap + if (match(RHS, m_Xor(m_Value(Y), m_APInt(C1)))) + std::swap(LHS, RHS); + + // C2 is ODD + // LHS = XOR(Y, C1), Y = AND(Z, C2), C1 == (C2 + 1) => LHS == NEG(OR(Z, ~C2)) + // ADD(LHS, RHS) == SUB(RHS, OR(Z, ~C2)) + if (match(LHS, m_Xor(m_Value(Y), m_APInt(C1)))) + if (C1->countTrailingZeros() == 0) + if (match(Y, m_And(m_Value(Z), m_APInt(C2))) && *C1 == (*C2 + 1)) { + Value *NewOr = Builder->CreateOr(Z, ~(*C2)); + return Builder->CreateSub(RHS, NewOr, "sub"); + } + return nullptr; +} + +Instruction *InstCombiner::visitAdd(BinaryOperator &I) { bool Changed = SimplifyAssociativeOrCommutative(I); Value *LHS = I.getOperand(0), *RHS = I.getOperand(1); @@ -1579,7 +1593,7 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) { match(Op1, m_Trunc(m_PtrToInt(m_Value(RHSOp))))) if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType())) return ReplaceInstUsesWith(I, Res); - } + } return nullptr; } -- cgit v1.2.3