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096aa79276
SimplifyAssociativeOrCommutative) "(A op C1) op C2" -> "A op (C1 op C2)", which previously was only done if C1 and C2 were constants, to occur whenever "C1 op C2" simplifies (a la InstructionSimplify). Since the simplifying operand combination can no longer be assumed to be the right-hand terms, consider all of the possible permutations. When compiling "gcc as one big file", transform 2 (i.e. using right-hand operands) fires about 4000 times but it has to be said that most of the time the simplifying operands are both constants. Transforms 3, 4 and 5 each fired once. Transform 6, which is an existing transform that I didn't change, never fired. With this change, the testcase is now optimized perfectly with one run of instcombine (previously it required instcombine + reassociate + instcombine, and it may just have been luck that this worked). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119002 91177308-0d34-0410-b5e6-96231b3b80d8
696 lines
25 KiB
C++
696 lines
25 KiB
C++
//===- InstCombineMulDivRem.cpp -------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the visit functions for mul, fmul, sdiv, udiv, fdiv,
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// srem, urem, frem.
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//
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//===----------------------------------------------------------------------===//
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#include "InstCombine.h"
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#include "llvm/IntrinsicInst.h"
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#include "llvm/Support/PatternMatch.h"
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using namespace llvm;
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using namespace PatternMatch;
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/// SubOne - Subtract one from a ConstantInt.
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static Constant *SubOne(ConstantInt *C) {
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return ConstantInt::get(C->getContext(), C->getValue()-1);
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}
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/// MultiplyOverflows - True if the multiply can not be expressed in an int
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/// this size.
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static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) {
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uint32_t W = C1->getBitWidth();
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APInt LHSExt = C1->getValue(), RHSExt = C2->getValue();
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if (sign) {
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LHSExt.sext(W * 2);
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RHSExt.sext(W * 2);
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} else {
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LHSExt.zext(W * 2);
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RHSExt.zext(W * 2);
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}
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APInt MulExt = LHSExt * RHSExt;
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if (!sign)
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return MulExt.ugt(APInt::getLowBitsSet(W * 2, W));
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APInt Min = APInt::getSignedMinValue(W).sext(W * 2);
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APInt Max = APInt::getSignedMaxValue(W).sext(W * 2);
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return MulExt.slt(Min) || MulExt.sgt(Max);
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}
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Instruction *InstCombiner::visitMul(BinaryOperator &I) {
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bool Changed = SimplifyAssociativeOrCommutative(I);
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Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
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if (isa<UndefValue>(Op1)) // undef * X -> 0
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return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
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// Simplify mul instructions with a constant RHS.
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if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
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if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1C)) {
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// ((X << C1)*C2) == (X * (C2 << C1))
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if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op0))
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if (SI->getOpcode() == Instruction::Shl)
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if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
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return BinaryOperator::CreateMul(SI->getOperand(0),
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ConstantExpr::getShl(CI, ShOp));
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if (CI->isZero())
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return ReplaceInstUsesWith(I, Op1C); // X * 0 == 0
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if (CI->equalsInt(1)) // X * 1 == X
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return ReplaceInstUsesWith(I, Op0);
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if (CI->isAllOnesValue()) // X * -1 == 0 - X
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return BinaryOperator::CreateNeg(Op0, I.getName());
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const APInt& Val = cast<ConstantInt>(CI)->getValue();
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if (Val.isPowerOf2()) { // Replace X*(2^C) with X << C
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return BinaryOperator::CreateShl(Op0,
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ConstantInt::get(Op0->getType(), Val.logBase2()));
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}
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} else if (Op1C->getType()->isVectorTy()) {
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if (Op1C->isNullValue())
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return ReplaceInstUsesWith(I, Op1C);
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if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1C)) {
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if (Op1V->isAllOnesValue()) // X * -1 == 0 - X
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return BinaryOperator::CreateNeg(Op0, I.getName());
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// As above, vector X*splat(1.0) -> X in all defined cases.
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if (Constant *Splat = Op1V->getSplatValue()) {
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if (ConstantInt *CI = dyn_cast<ConstantInt>(Splat))
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if (CI->equalsInt(1))
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return ReplaceInstUsesWith(I, Op0);
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}
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}
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}
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if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
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if (Op0I->getOpcode() == Instruction::Add && Op0I->hasOneUse() &&
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isa<ConstantInt>(Op0I->getOperand(1)) && isa<ConstantInt>(Op1C)) {
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// Canonicalize (X+C1)*C2 -> X*C2+C1*C2.
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Value *Add = Builder->CreateMul(Op0I->getOperand(0), Op1C, "tmp");
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Value *C1C2 = Builder->CreateMul(Op1C, Op0I->getOperand(1));
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return BinaryOperator::CreateAdd(Add, C1C2);
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}
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// Try to fold constant mul into select arguments.
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if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
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if (Instruction *R = FoldOpIntoSelect(I, SI))
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return R;
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if (isa<PHINode>(Op0))
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if (Instruction *NV = FoldOpIntoPhi(I))
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return NV;
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}
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if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
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if (Value *Op1v = dyn_castNegVal(Op1))
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return BinaryOperator::CreateMul(Op0v, Op1v);
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// (X / Y) * Y = X - (X % Y)
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// (X / Y) * -Y = (X % Y) - X
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{
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Value *Op1C = Op1;
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BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0);
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if (!BO ||
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(BO->getOpcode() != Instruction::UDiv &&
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BO->getOpcode() != Instruction::SDiv)) {
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Op1C = Op0;
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BO = dyn_cast<BinaryOperator>(Op1);
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}
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Value *Neg = dyn_castNegVal(Op1C);
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if (BO && BO->hasOneUse() &&
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(BO->getOperand(1) == Op1C || BO->getOperand(1) == Neg) &&
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(BO->getOpcode() == Instruction::UDiv ||
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BO->getOpcode() == Instruction::SDiv)) {
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Value *Op0BO = BO->getOperand(0), *Op1BO = BO->getOperand(1);
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// If the division is exact, X % Y is zero.
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if (SDivOperator *SDiv = dyn_cast<SDivOperator>(BO))
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if (SDiv->isExact()) {
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if (Op1BO == Op1C)
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return ReplaceInstUsesWith(I, Op0BO);
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return BinaryOperator::CreateNeg(Op0BO);
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}
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Value *Rem;
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if (BO->getOpcode() == Instruction::UDiv)
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Rem = Builder->CreateURem(Op0BO, Op1BO);
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else
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Rem = Builder->CreateSRem(Op0BO, Op1BO);
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Rem->takeName(BO);
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if (Op1BO == Op1C)
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return BinaryOperator::CreateSub(Op0BO, Rem);
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return BinaryOperator::CreateSub(Rem, Op0BO);
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}
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}
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/// i1 mul -> i1 and.
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if (I.getType()->isIntegerTy(1))
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return BinaryOperator::CreateAnd(Op0, Op1);
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// X*(1 << Y) --> X << Y
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// (1 << Y)*X --> X << Y
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{
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Value *Y;
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if (match(Op0, m_Shl(m_One(), m_Value(Y))))
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return BinaryOperator::CreateShl(Op1, Y);
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if (match(Op1, m_Shl(m_One(), m_Value(Y))))
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return BinaryOperator::CreateShl(Op0, Y);
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}
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// If one of the operands of the multiply is a cast from a boolean value, then
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// we know the bool is either zero or one, so this is a 'masking' multiply.
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// X * Y (where Y is 0 or 1) -> X & (0-Y)
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if (!I.getType()->isVectorTy()) {
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// -2 is "-1 << 1" so it is all bits set except the low one.
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APInt Negative2(I.getType()->getPrimitiveSizeInBits(), (uint64_t)-2, true);
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Value *BoolCast = 0, *OtherOp = 0;
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if (MaskedValueIsZero(Op0, Negative2))
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BoolCast = Op0, OtherOp = Op1;
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else if (MaskedValueIsZero(Op1, Negative2))
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BoolCast = Op1, OtherOp = Op0;
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if (BoolCast) {
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Value *V = Builder->CreateSub(Constant::getNullValue(I.getType()),
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BoolCast, "tmp");
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return BinaryOperator::CreateAnd(V, OtherOp);
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}
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}
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return Changed ? &I : 0;
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}
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Instruction *InstCombiner::visitFMul(BinaryOperator &I) {
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bool Changed = SimplifyAssociativeOrCommutative(I);
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Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
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// Simplify mul instructions with a constant RHS...
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if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
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if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1C)) {
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// "In IEEE floating point, x*1 is not equivalent to x for nans. However,
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// ANSI says we can drop signals, so we can do this anyway." (from GCC)
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if (Op1F->isExactlyValue(1.0))
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return ReplaceInstUsesWith(I, Op0); // Eliminate 'fmul double %X, 1.0'
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} else if (Op1C->getType()->isVectorTy()) {
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if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1C)) {
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// As above, vector X*splat(1.0) -> X in all defined cases.
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if (Constant *Splat = Op1V->getSplatValue()) {
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if (ConstantFP *F = dyn_cast<ConstantFP>(Splat))
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if (F->isExactlyValue(1.0))
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return ReplaceInstUsesWith(I, Op0);
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}
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}
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}
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// Try to fold constant mul into select arguments.
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if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
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if (Instruction *R = FoldOpIntoSelect(I, SI))
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return R;
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if (isa<PHINode>(Op0))
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if (Instruction *NV = FoldOpIntoPhi(I))
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return NV;
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}
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if (Value *Op0v = dyn_castFNegVal(Op0)) // -X * -Y = X*Y
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if (Value *Op1v = dyn_castFNegVal(Op1))
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return BinaryOperator::CreateFMul(Op0v, Op1v);
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return Changed ? &I : 0;
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}
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/// SimplifyDivRemOfSelect - Try to fold a divide or remainder of a select
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/// instruction.
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bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) {
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SelectInst *SI = cast<SelectInst>(I.getOperand(1));
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// div/rem X, (Cond ? 0 : Y) -> div/rem X, Y
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int NonNullOperand = -1;
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if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
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if (ST->isNullValue())
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NonNullOperand = 2;
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// div/rem X, (Cond ? Y : 0) -> div/rem X, Y
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if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
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if (ST->isNullValue())
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NonNullOperand = 1;
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if (NonNullOperand == -1)
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return false;
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Value *SelectCond = SI->getOperand(0);
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// Change the div/rem to use 'Y' instead of the select.
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I.setOperand(1, SI->getOperand(NonNullOperand));
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// Okay, we know we replace the operand of the div/rem with 'Y' with no
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// problem. However, the select, or the condition of the select may have
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// multiple uses. Based on our knowledge that the operand must be non-zero,
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// propagate the known value for the select into other uses of it, and
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// propagate a known value of the condition into its other users.
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// If the select and condition only have a single use, don't bother with this,
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// early exit.
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if (SI->use_empty() && SelectCond->hasOneUse())
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return true;
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// Scan the current block backward, looking for other uses of SI.
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BasicBlock::iterator BBI = &I, BBFront = I.getParent()->begin();
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while (BBI != BBFront) {
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--BBI;
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// If we found a call to a function, we can't assume it will return, so
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// information from below it cannot be propagated above it.
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if (isa<CallInst>(BBI) && !isa<IntrinsicInst>(BBI))
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break;
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// Replace uses of the select or its condition with the known values.
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for (Instruction::op_iterator I = BBI->op_begin(), E = BBI->op_end();
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I != E; ++I) {
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if (*I == SI) {
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*I = SI->getOperand(NonNullOperand);
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Worklist.Add(BBI);
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} else if (*I == SelectCond) {
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*I = NonNullOperand == 1 ? ConstantInt::getTrue(BBI->getContext()) :
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ConstantInt::getFalse(BBI->getContext());
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Worklist.Add(BBI);
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}
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}
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// If we past the instruction, quit looking for it.
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if (&*BBI == SI)
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SI = 0;
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if (&*BBI == SelectCond)
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SelectCond = 0;
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// If we ran out of things to eliminate, break out of the loop.
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if (SelectCond == 0 && SI == 0)
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break;
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}
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return true;
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}
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/// This function implements the transforms on div instructions that work
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/// regardless of the kind of div instruction it is (udiv, sdiv, or fdiv). It is
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/// used by the visitors to those instructions.
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/// @brief Transforms common to all three div instructions
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Instruction *InstCombiner::commonDivTransforms(BinaryOperator &I) {
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Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
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// undef / X -> 0 for integer.
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// undef / X -> undef for FP (the undef could be a snan).
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if (isa<UndefValue>(Op0)) {
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if (Op0->getType()->isFPOrFPVectorTy())
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return ReplaceInstUsesWith(I, Op0);
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return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
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}
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// X / undef -> undef
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if (isa<UndefValue>(Op1))
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return ReplaceInstUsesWith(I, Op1);
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return 0;
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}
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/// This function implements the transforms common to both integer division
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/// instructions (udiv and sdiv). It is called by the visitors to those integer
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/// division instructions.
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/// @brief Common integer divide transforms
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Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
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Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
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// (sdiv X, X) --> 1 (udiv X, X) --> 1
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if (Op0 == Op1) {
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if (const VectorType *Ty = dyn_cast<VectorType>(I.getType())) {
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Constant *CI = ConstantInt::get(Ty->getElementType(), 1);
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std::vector<Constant*> Elts(Ty->getNumElements(), CI);
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return ReplaceInstUsesWith(I, ConstantVector::get(Elts));
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}
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Constant *CI = ConstantInt::get(I.getType(), 1);
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return ReplaceInstUsesWith(I, CI);
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}
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if (Instruction *Common = commonDivTransforms(I))
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return Common;
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// Handle cases involving: [su]div X, (select Cond, Y, Z)
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// This does not apply for fdiv.
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if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
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return &I;
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if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
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// div X, 1 == X
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if (RHS->equalsInt(1))
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return ReplaceInstUsesWith(I, Op0);
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// (X / C1) / C2 -> X / (C1*C2)
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if (Instruction *LHS = dyn_cast<Instruction>(Op0))
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if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
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if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
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if (MultiplyOverflows(RHS, LHSRHS,
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I.getOpcode()==Instruction::SDiv))
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return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
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else
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return BinaryOperator::Create(I.getOpcode(), LHS->getOperand(0),
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ConstantExpr::getMul(RHS, LHSRHS));
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}
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if (!RHS->isZero()) { // avoid X udiv 0
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if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
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if (Instruction *R = FoldOpIntoSelect(I, SI))
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return R;
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if (isa<PHINode>(Op0))
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if (Instruction *NV = FoldOpIntoPhi(I))
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return NV;
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}
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}
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// 0 / X == 0, we don't need to preserve faults!
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if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
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if (LHS->equalsInt(0))
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return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
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// It can't be division by zero, hence it must be division by one.
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if (I.getType()->isIntegerTy(1))
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return ReplaceInstUsesWith(I, Op0);
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if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1)) {
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if (ConstantInt *X = cast_or_null<ConstantInt>(Op1V->getSplatValue()))
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// div X, 1 == X
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if (X->isOne())
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return ReplaceInstUsesWith(I, Op0);
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}
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return 0;
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}
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Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
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Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
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// Handle the integer div common cases
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if (Instruction *Common = commonIDivTransforms(I))
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return Common;
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if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
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// X udiv 2^C -> X >> C
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// Check to see if this is an unsigned division with an exact power of 2,
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// if so, convert to a right shift.
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if (C->getValue().isPowerOf2()) // 0 not included in isPowerOf2
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return BinaryOperator::CreateLShr(Op0,
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ConstantInt::get(Op0->getType(), C->getValue().logBase2()));
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// X udiv C, where C >= signbit
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if (C->getValue().isNegative()) {
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Value *IC = Builder->CreateICmpULT( Op0, C);
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return SelectInst::Create(IC, Constant::getNullValue(I.getType()),
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ConstantInt::get(I.getType(), 1));
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}
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}
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// X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2)
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if (BinaryOperator *RHSI = dyn_cast<BinaryOperator>(I.getOperand(1))) {
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if (RHSI->getOpcode() == Instruction::Shl &&
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isa<ConstantInt>(RHSI->getOperand(0))) {
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const APInt& C1 = cast<ConstantInt>(RHSI->getOperand(0))->getValue();
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if (C1.isPowerOf2()) {
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Value *N = RHSI->getOperand(1);
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const Type *NTy = N->getType();
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if (uint32_t C2 = C1.logBase2())
|
|
N = Builder->CreateAdd(N, ConstantInt::get(NTy, C2), "tmp");
|
|
return BinaryOperator::CreateLShr(Op0, N);
|
|
}
|
|
}
|
|
}
|
|
|
|
// udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2)
|
|
// where C1&C2 are powers of two.
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
|
|
if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
|
|
if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
|
|
const APInt &TVA = STO->getValue(), &FVA = SFO->getValue();
|
|
if (TVA.isPowerOf2() && FVA.isPowerOf2()) {
|
|
// Compute the shift amounts
|
|
uint32_t TSA = TVA.logBase2(), FSA = FVA.logBase2();
|
|
// Construct the "on true" case of the select
|
|
Constant *TC = ConstantInt::get(Op0->getType(), TSA);
|
|
Value *TSI = Builder->CreateLShr(Op0, TC, SI->getName()+".t");
|
|
|
|
// Construct the "on false" case of the select
|
|
Constant *FC = ConstantInt::get(Op0->getType(), FSA);
|
|
Value *FSI = Builder->CreateLShr(Op0, FC, SI->getName()+".f");
|
|
|
|
// construct the select instruction and return it.
|
|
return SelectInst::Create(SI->getOperand(0), TSI, FSI, SI->getName());
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
// Handle the integer div common cases
|
|
if (Instruction *Common = commonIDivTransforms(I))
|
|
return Common;
|
|
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
|
|
// sdiv X, -1 == -X
|
|
if (RHS->isAllOnesValue())
|
|
return BinaryOperator::CreateNeg(Op0);
|
|
|
|
// sdiv X, C --> ashr X, log2(C)
|
|
if (cast<SDivOperator>(&I)->isExact() &&
|
|
RHS->getValue().isNonNegative() &&
|
|
RHS->getValue().isPowerOf2()) {
|
|
Value *ShAmt = llvm::ConstantInt::get(RHS->getType(),
|
|
RHS->getValue().exactLogBase2());
|
|
return BinaryOperator::CreateAShr(Op0, ShAmt, I.getName());
|
|
}
|
|
|
|
// -X/C --> X/-C provided the negation doesn't overflow.
|
|
if (SubOperator *Sub = dyn_cast<SubOperator>(Op0))
|
|
if (isa<Constant>(Sub->getOperand(0)) &&
|
|
cast<Constant>(Sub->getOperand(0))->isNullValue() &&
|
|
Sub->hasNoSignedWrap())
|
|
return BinaryOperator::CreateSDiv(Sub->getOperand(1),
|
|
ConstantExpr::getNeg(RHS));
|
|
}
|
|
|
|
// If the sign bits of both operands are zero (i.e. we can prove they are
|
|
// unsigned inputs), turn this into a udiv.
|
|
if (I.getType()->isIntegerTy()) {
|
|
APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
|
|
if (MaskedValueIsZero(Op0, Mask)) {
|
|
if (MaskedValueIsZero(Op1, Mask)) {
|
|
// X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set
|
|
return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
|
|
}
|
|
ConstantInt *ShiftedInt;
|
|
if (match(Op1, m_Shl(m_ConstantInt(ShiftedInt), m_Value())) &&
|
|
ShiftedInt->getValue().isPowerOf2()) {
|
|
// X sdiv (1 << Y) -> X udiv (1 << Y) ( -> X u>> Y)
|
|
// Safe because the only negative value (1 << Y) can take on is
|
|
// INT_MIN, and X sdiv INT_MIN == X udiv INT_MIN == 0 if X doesn't have
|
|
// the sign bit set.
|
|
return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
|
|
return commonDivTransforms(I);
|
|
}
|
|
|
|
/// This function implements the transforms on rem instructions that work
|
|
/// regardless of the kind of rem instruction it is (urem, srem, or frem). It
|
|
/// is used by the visitors to those instructions.
|
|
/// @brief Transforms common to all three rem instructions
|
|
Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (isa<UndefValue>(Op0)) { // undef % X -> 0
|
|
if (I.getType()->isFPOrFPVectorTy())
|
|
return ReplaceInstUsesWith(I, Op0); // X % undef -> undef (could be SNaN)
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
}
|
|
if (isa<UndefValue>(Op1))
|
|
return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
|
|
|
|
// Handle cases involving: rem X, (select Cond, Y, Z)
|
|
if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
|
|
return &I;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/// This function implements the transforms common to both integer remainder
|
|
/// instructions (urem and srem). It is called by the visitors to those integer
|
|
/// remainder instructions.
|
|
/// @brief Common integer remainder transforms
|
|
Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (Instruction *common = commonRemTransforms(I))
|
|
return common;
|
|
|
|
// 0 % X == 0 for integer, we don't need to preserve faults!
|
|
if (Constant *LHS = dyn_cast<Constant>(Op0))
|
|
if (LHS->isNullValue())
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
|
|
// X % 0 == undef, we don't need to preserve faults!
|
|
if (RHS->equalsInt(0))
|
|
return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
|
|
|
|
if (RHS->equalsInt(1)) // X % 1 == 0
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
|
|
if (Instruction *R = FoldOpIntoSelect(I, SI))
|
|
return R;
|
|
} else if (isa<PHINode>(Op0I)) {
|
|
if (Instruction *NV = FoldOpIntoPhi(I))
|
|
return NV;
|
|
}
|
|
|
|
// See if we can fold away this rem instruction.
|
|
if (SimplifyDemandedInstructionBits(I))
|
|
return &I;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitURem(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (Instruction *common = commonIRemTransforms(I))
|
|
return common;
|
|
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
|
|
// X urem C^2 -> X and C
|
|
// Check to see if this is an unsigned remainder with an exact power of 2,
|
|
// if so, convert to a bitwise and.
|
|
if (ConstantInt *C = dyn_cast<ConstantInt>(RHS))
|
|
if (C->getValue().isPowerOf2())
|
|
return BinaryOperator::CreateAnd(Op0, SubOne(C));
|
|
}
|
|
|
|
if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
|
|
// Turn A % (C << N), where C is 2^k, into A & ((C << N)-1)
|
|
if (RHSI->getOpcode() == Instruction::Shl &&
|
|
isa<ConstantInt>(RHSI->getOperand(0))) {
|
|
if (cast<ConstantInt>(RHSI->getOperand(0))->getValue().isPowerOf2()) {
|
|
Constant *N1 = Constant::getAllOnesValue(I.getType());
|
|
Value *Add = Builder->CreateAdd(RHSI, N1, "tmp");
|
|
return BinaryOperator::CreateAnd(Op0, Add);
|
|
}
|
|
}
|
|
}
|
|
|
|
// urem X, (select Cond, 2^C1, 2^C2) --> select Cond, (and X, C1), (and X, C2)
|
|
// where C1&C2 are powers of two.
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
|
|
if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
|
|
if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
|
|
// STO == 0 and SFO == 0 handled above.
|
|
if ((STO->getValue().isPowerOf2()) &&
|
|
(SFO->getValue().isPowerOf2())) {
|
|
Value *TrueAnd = Builder->CreateAnd(Op0, SubOne(STO),
|
|
SI->getName()+".t");
|
|
Value *FalseAnd = Builder->CreateAnd(Op0, SubOne(SFO),
|
|
SI->getName()+".f");
|
|
return SelectInst::Create(SI->getOperand(0), TrueAnd, FalseAnd);
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
// Handle the integer rem common cases
|
|
if (Instruction *Common = commonIRemTransforms(I))
|
|
return Common;
|
|
|
|
if (Value *RHSNeg = dyn_castNegVal(Op1))
|
|
if (!isa<Constant>(RHSNeg) ||
|
|
(isa<ConstantInt>(RHSNeg) &&
|
|
cast<ConstantInt>(RHSNeg)->getValue().isStrictlyPositive())) {
|
|
// X % -Y -> X % Y
|
|
Worklist.AddValue(I.getOperand(1));
|
|
I.setOperand(1, RHSNeg);
|
|
return &I;
|
|
}
|
|
|
|
// If the sign bits of both operands are zero (i.e. we can prove they are
|
|
// unsigned inputs), turn this into a urem.
|
|
if (I.getType()->isIntegerTy()) {
|
|
APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
|
|
if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
|
|
// X srem Y -> X urem Y, iff X and Y don't have sign bit set
|
|
return BinaryOperator::CreateURem(Op0, Op1, I.getName());
|
|
}
|
|
}
|
|
|
|
// If it's a constant vector, flip any negative values positive.
|
|
if (ConstantVector *RHSV = dyn_cast<ConstantVector>(Op1)) {
|
|
unsigned VWidth = RHSV->getNumOperands();
|
|
|
|
bool hasNegative = false;
|
|
for (unsigned i = 0; !hasNegative && i != VWidth; ++i)
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i)))
|
|
if (RHS->getValue().isNegative())
|
|
hasNegative = true;
|
|
|
|
if (hasNegative) {
|
|
std::vector<Constant *> Elts(VWidth);
|
|
for (unsigned i = 0; i != VWidth; ++i) {
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i))) {
|
|
if (RHS->getValue().isNegative())
|
|
Elts[i] = cast<ConstantInt>(ConstantExpr::getNeg(RHS));
|
|
else
|
|
Elts[i] = RHS;
|
|
}
|
|
}
|
|
|
|
Constant *NewRHSV = ConstantVector::get(Elts);
|
|
if (NewRHSV != RHSV) {
|
|
Worklist.AddValue(I.getOperand(1));
|
|
I.setOperand(1, NewRHSV);
|
|
return &I;
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFRem(BinaryOperator &I) {
|
|
return commonRemTransforms(I);
|
|
}
|
|
|