forked from OSchip/llvm-project
1600 lines
60 KiB
C++
1600 lines
60 KiB
C++
//===- InstCombineMulDivRem.cpp -------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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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 "InstCombineInternal.h"
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#include "llvm/ADT/APFloat.h"
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#include "llvm/ADT/APInt.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/Analysis/InstructionSimplify.h"
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#include "llvm/IR/BasicBlock.h"
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#include "llvm/IR/Constant.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/InstrTypes.h"
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#include "llvm/IR/Instruction.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include "llvm/IR/Intrinsics.h"
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#include "llvm/IR/Operator.h"
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#include "llvm/IR/PatternMatch.h"
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#include "llvm/IR/Type.h"
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#include "llvm/IR/Value.h"
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#include "llvm/Support/Casting.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/KnownBits.h"
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#include "llvm/Transforms/InstCombine/InstCombineWorklist.h"
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#include "llvm/Transforms/InstCombine/InstCombiner.h"
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#include "llvm/Transforms/Utils/BuildLibCalls.h"
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#include <cassert>
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#include <cstddef>
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#include <cstdint>
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#include <utility>
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using namespace llvm;
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using namespace PatternMatch;
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#define DEBUG_TYPE "instcombine"
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/// The specific integer value is used in a context where it is known to be
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/// non-zero. If this allows us to simplify the computation, do so and return
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/// the new operand, otherwise return null.
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static Value *simplifyValueKnownNonZero(Value *V, InstCombinerImpl &IC,
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Instruction &CxtI) {
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// If V has multiple uses, then we would have to do more analysis to determine
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// if this is safe. For example, the use could be in dynamically unreached
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// code.
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if (!V->hasOneUse()) return nullptr;
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bool MadeChange = false;
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// ((1 << A) >>u B) --> (1 << (A-B))
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// Because V cannot be zero, we know that B is less than A.
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Value *A = nullptr, *B = nullptr, *One = nullptr;
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if (match(V, m_LShr(m_OneUse(m_Shl(m_Value(One), m_Value(A))), m_Value(B))) &&
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match(One, m_One())) {
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A = IC.Builder.CreateSub(A, B);
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return IC.Builder.CreateShl(One, A);
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}
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// (PowerOfTwo >>u B) --> isExact since shifting out the result would make it
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// inexact. Similarly for <<.
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BinaryOperator *I = dyn_cast<BinaryOperator>(V);
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if (I && I->isLogicalShift() &&
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IC.isKnownToBeAPowerOfTwo(I->getOperand(0), false, 0, &CxtI)) {
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// We know that this is an exact/nuw shift and that the input is a
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// non-zero context as well.
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if (Value *V2 = simplifyValueKnownNonZero(I->getOperand(0), IC, CxtI)) {
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IC.replaceOperand(*I, 0, V2);
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MadeChange = true;
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}
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if (I->getOpcode() == Instruction::LShr && !I->isExact()) {
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I->setIsExact();
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MadeChange = true;
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}
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if (I->getOpcode() == Instruction::Shl && !I->hasNoUnsignedWrap()) {
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I->setHasNoUnsignedWrap();
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MadeChange = true;
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}
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}
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// TODO: Lots more we could do here:
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// If V is a phi node, we can call this on each of its operands.
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// "select cond, X, 0" can simplify to "X".
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return MadeChange ? V : nullptr;
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}
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// TODO: This is a specific form of a much more general pattern.
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// We could detect a select with any binop identity constant, or we
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// could use SimplifyBinOp to see if either arm of the select reduces.
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// But that needs to be done carefully and/or while removing potential
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// reverse canonicalizations as in InstCombiner::foldSelectIntoOp().
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static Value *foldMulSelectToNegate(BinaryOperator &I,
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InstCombiner::BuilderTy &Builder) {
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Value *Cond, *OtherOp;
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// mul (select Cond, 1, -1), OtherOp --> select Cond, OtherOp, -OtherOp
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// mul OtherOp, (select Cond, 1, -1) --> select Cond, OtherOp, -OtherOp
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if (match(&I, m_c_Mul(m_OneUse(m_Select(m_Value(Cond), m_One(), m_AllOnes())),
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m_Value(OtherOp))))
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return Builder.CreateSelect(Cond, OtherOp, Builder.CreateNeg(OtherOp));
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// mul (select Cond, -1, 1), OtherOp --> select Cond, -OtherOp, OtherOp
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// mul OtherOp, (select Cond, -1, 1) --> select Cond, -OtherOp, OtherOp
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if (match(&I, m_c_Mul(m_OneUse(m_Select(m_Value(Cond), m_AllOnes(), m_One())),
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m_Value(OtherOp))))
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return Builder.CreateSelect(Cond, Builder.CreateNeg(OtherOp), OtherOp);
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// fmul (select Cond, 1.0, -1.0), OtherOp --> select Cond, OtherOp, -OtherOp
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// fmul OtherOp, (select Cond, 1.0, -1.0) --> select Cond, OtherOp, -OtherOp
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if (match(&I, m_c_FMul(m_OneUse(m_Select(m_Value(Cond), m_SpecificFP(1.0),
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m_SpecificFP(-1.0))),
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m_Value(OtherOp)))) {
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IRBuilder<>::FastMathFlagGuard FMFGuard(Builder);
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Builder.setFastMathFlags(I.getFastMathFlags());
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return Builder.CreateSelect(Cond, OtherOp, Builder.CreateFNeg(OtherOp));
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}
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// fmul (select Cond, -1.0, 1.0), OtherOp --> select Cond, -OtherOp, OtherOp
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// fmul OtherOp, (select Cond, -1.0, 1.0) --> select Cond, -OtherOp, OtherOp
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if (match(&I, m_c_FMul(m_OneUse(m_Select(m_Value(Cond), m_SpecificFP(-1.0),
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m_SpecificFP(1.0))),
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m_Value(OtherOp)))) {
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IRBuilder<>::FastMathFlagGuard FMFGuard(Builder);
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Builder.setFastMathFlags(I.getFastMathFlags());
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return Builder.CreateSelect(Cond, Builder.CreateFNeg(OtherOp), OtherOp);
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}
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return nullptr;
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}
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Instruction *InstCombinerImpl::visitMul(BinaryOperator &I) {
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if (Value *V = SimplifyMulInst(I.getOperand(0), I.getOperand(1),
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SQ.getWithInstruction(&I)))
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return replaceInstUsesWith(I, V);
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if (SimplifyAssociativeOrCommutative(I))
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return &I;
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if (Instruction *X = foldVectorBinop(I))
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return X;
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if (Value *V = SimplifyUsingDistributiveLaws(I))
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return replaceInstUsesWith(I, V);
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Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
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unsigned BitWidth = I.getType()->getScalarSizeInBits();
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// X * -1 == 0 - X
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if (match(Op1, m_AllOnes())) {
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BinaryOperator *BO = BinaryOperator::CreateNeg(Op0, I.getName());
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if (I.hasNoSignedWrap())
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BO->setHasNoSignedWrap();
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return BO;
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}
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// Also allow combining multiply instructions on vectors.
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{
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Value *NewOp;
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Constant *C1, *C2;
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const APInt *IVal;
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if (match(&I, m_Mul(m_Shl(m_Value(NewOp), m_Constant(C2)),
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m_Constant(C1))) &&
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match(C1, m_APInt(IVal))) {
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// ((X << C2)*C1) == (X * (C1 << C2))
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Constant *Shl = ConstantExpr::getShl(C1, C2);
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BinaryOperator *Mul = cast<BinaryOperator>(I.getOperand(0));
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BinaryOperator *BO = BinaryOperator::CreateMul(NewOp, Shl);
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if (I.hasNoUnsignedWrap() && Mul->hasNoUnsignedWrap())
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BO->setHasNoUnsignedWrap();
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if (I.hasNoSignedWrap() && Mul->hasNoSignedWrap() &&
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Shl->isNotMinSignedValue())
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BO->setHasNoSignedWrap();
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return BO;
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}
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if (match(&I, m_Mul(m_Value(NewOp), m_Constant(C1)))) {
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// Replace X*(2^C) with X << C, where C is either a scalar or a vector.
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if (Constant *NewCst = ConstantExpr::getExactLogBase2(C1)) {
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BinaryOperator *Shl = BinaryOperator::CreateShl(NewOp, NewCst);
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if (I.hasNoUnsignedWrap())
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Shl->setHasNoUnsignedWrap();
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if (I.hasNoSignedWrap()) {
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const APInt *V;
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if (match(NewCst, m_APInt(V)) && *V != V->getBitWidth() - 1)
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Shl->setHasNoSignedWrap();
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}
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return Shl;
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}
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}
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}
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if (Op0->hasOneUse() && match(Op1, m_NegatedPower2())) {
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// Interpret X * (-1<<C) as (-X) * (1<<C) and try to sink the negation.
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// The "* (1<<C)" thus becomes a potential shifting opportunity.
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if (Value *NegOp0 = Negator::Negate(/*IsNegation*/ true, Op0, *this))
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return BinaryOperator::CreateMul(
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NegOp0, ConstantExpr::getNeg(cast<Constant>(Op1)), I.getName());
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}
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if (Instruction *FoldedMul = foldBinOpIntoSelectOrPhi(I))
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return FoldedMul;
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if (Value *FoldedMul = foldMulSelectToNegate(I, Builder))
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return replaceInstUsesWith(I, FoldedMul);
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// Simplify mul instructions with a constant RHS.
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if (isa<Constant>(Op1)) {
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// Canonicalize (X+C1)*CI -> X*CI+C1*CI.
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Value *X;
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Constant *C1;
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if (match(Op0, m_OneUse(m_Add(m_Value(X), m_Constant(C1))))) {
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Value *Mul = Builder.CreateMul(C1, Op1);
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// Only go forward with the transform if C1*CI simplifies to a tidier
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// constant.
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if (!match(Mul, m_Mul(m_Value(), m_Value())))
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return BinaryOperator::CreateAdd(Builder.CreateMul(X, Op1), Mul);
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}
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}
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// abs(X) * abs(X) -> X * X
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// nabs(X) * nabs(X) -> X * X
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if (Op0 == Op1) {
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Value *X, *Y;
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SelectPatternFlavor SPF = matchSelectPattern(Op0, X, Y).Flavor;
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if (SPF == SPF_ABS || SPF == SPF_NABS)
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return BinaryOperator::CreateMul(X, X);
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if (match(Op0, m_Intrinsic<Intrinsic::abs>(m_Value(X))))
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return BinaryOperator::CreateMul(X, X);
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}
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// -X * C --> X * -C
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Value *X, *Y;
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Constant *Op1C;
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if (match(Op0, m_Neg(m_Value(X))) && match(Op1, m_Constant(Op1C)))
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return BinaryOperator::CreateMul(X, ConstantExpr::getNeg(Op1C));
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// -X * -Y --> X * Y
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if (match(Op0, m_Neg(m_Value(X))) && match(Op1, m_Neg(m_Value(Y)))) {
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auto *NewMul = BinaryOperator::CreateMul(X, Y);
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if (I.hasNoSignedWrap() &&
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cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap() &&
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cast<OverflowingBinaryOperator>(Op1)->hasNoSignedWrap())
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NewMul->setHasNoSignedWrap();
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return NewMul;
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}
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// -X * Y --> -(X * Y)
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// X * -Y --> -(X * Y)
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if (match(&I, m_c_Mul(m_OneUse(m_Neg(m_Value(X))), m_Value(Y))))
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return BinaryOperator::CreateNeg(Builder.CreateMul(X, Y));
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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 *Y = Op1;
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BinaryOperator *Div = dyn_cast<BinaryOperator>(Op0);
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if (!Div || (Div->getOpcode() != Instruction::UDiv &&
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Div->getOpcode() != Instruction::SDiv)) {
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Y = Op0;
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Div = dyn_cast<BinaryOperator>(Op1);
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}
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Value *Neg = dyn_castNegVal(Y);
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if (Div && Div->hasOneUse() &&
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(Div->getOperand(1) == Y || Div->getOperand(1) == Neg) &&
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(Div->getOpcode() == Instruction::UDiv ||
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Div->getOpcode() == Instruction::SDiv)) {
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Value *X = Div->getOperand(0), *DivOp1 = Div->getOperand(1);
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// If the division is exact, X % Y is zero, so we end up with X or -X.
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if (Div->isExact()) {
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if (DivOp1 == Y)
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return replaceInstUsesWith(I, X);
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return BinaryOperator::CreateNeg(X);
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}
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auto RemOpc = Div->getOpcode() == Instruction::UDiv ? Instruction::URem
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: Instruction::SRem;
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Value *Rem = Builder.CreateBinOp(RemOpc, X, DivOp1);
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if (DivOp1 == Y)
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return BinaryOperator::CreateSub(X, Rem);
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return BinaryOperator::CreateSub(Rem, X);
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}
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}
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/// i1 mul -> i1 and.
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if (I.getType()->isIntOrIntVectorTy(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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BinaryOperator *BO = nullptr;
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bool ShlNSW = false;
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if (match(Op0, m_Shl(m_One(), m_Value(Y)))) {
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BO = BinaryOperator::CreateShl(Op1, Y);
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ShlNSW = cast<ShlOperator>(Op0)->hasNoSignedWrap();
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} else if (match(Op1, m_Shl(m_One(), m_Value(Y)))) {
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BO = BinaryOperator::CreateShl(Op0, Y);
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ShlNSW = cast<ShlOperator>(Op1)->hasNoSignedWrap();
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}
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if (BO) {
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if (I.hasNoUnsignedWrap())
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BO->setHasNoUnsignedWrap();
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if (I.hasNoSignedWrap() && ShlNSW)
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BO->setHasNoSignedWrap();
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return BO;
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}
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}
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// (zext bool X) * (zext bool Y) --> zext (and X, Y)
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// (sext bool X) * (sext bool Y) --> zext (and X, Y)
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// Note: -1 * -1 == 1 * 1 == 1 (if the extends match, the result is the same)
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if (((match(Op0, m_ZExt(m_Value(X))) && match(Op1, m_ZExt(m_Value(Y)))) ||
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(match(Op0, m_SExt(m_Value(X))) && match(Op1, m_SExt(m_Value(Y))))) &&
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X->getType()->isIntOrIntVectorTy(1) && X->getType() == Y->getType() &&
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(Op0->hasOneUse() || Op1->hasOneUse())) {
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Value *And = Builder.CreateAnd(X, Y, "mulbool");
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return CastInst::Create(Instruction::ZExt, And, I.getType());
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}
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// (sext bool X) * (zext bool Y) --> sext (and X, Y)
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// (zext bool X) * (sext bool Y) --> sext (and X, Y)
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// Note: -1 * 1 == 1 * -1 == -1
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if (((match(Op0, m_SExt(m_Value(X))) && match(Op1, m_ZExt(m_Value(Y)))) ||
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(match(Op0, m_ZExt(m_Value(X))) && match(Op1, m_SExt(m_Value(Y))))) &&
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X->getType()->isIntOrIntVectorTy(1) && X->getType() == Y->getType() &&
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(Op0->hasOneUse() || Op1->hasOneUse())) {
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Value *And = Builder.CreateAnd(X, Y, "mulbool");
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return CastInst::Create(Instruction::SExt, And, I.getType());
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}
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// (bool X) * Y --> X ? Y : 0
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// Y * (bool X) --> X ? Y : 0
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if (match(Op0, m_ZExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1))
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return SelectInst::Create(X, Op1, ConstantInt::get(I.getType(), 0));
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if (match(Op1, m_ZExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1))
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return SelectInst::Create(X, Op0, ConstantInt::get(I.getType(), 0));
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// (lshr X, 31) * Y --> (ashr X, 31) & Y
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// Y * (lshr X, 31) --> (ashr X, 31) & Y
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// TODO: We are not checking one-use because the elimination of the multiply
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// is better for analysis?
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// TODO: Should we canonicalize to '(X < 0) ? Y : 0' instead? That would be
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// more similar to what we're doing above.
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const APInt *C;
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if (match(Op0, m_LShr(m_Value(X), m_APInt(C))) && *C == C->getBitWidth() - 1)
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return BinaryOperator::CreateAnd(Builder.CreateAShr(X, *C), Op1);
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if (match(Op1, m_LShr(m_Value(X), m_APInt(C))) && *C == C->getBitWidth() - 1)
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return BinaryOperator::CreateAnd(Builder.CreateAShr(X, *C), Op0);
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// ((ashr X, 31) | 1) * X --> abs(X)
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// X * ((ashr X, 31) | 1) --> abs(X)
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if (match(&I, m_c_BinOp(m_Or(m_AShr(m_Value(X),
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m_SpecificIntAllowUndef(BitWidth - 1)),
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m_One()),
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m_Deferred(X)))) {
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Value *Abs = Builder.CreateBinaryIntrinsic(
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Intrinsic::abs, X,
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ConstantInt::getBool(I.getContext(), I.hasNoSignedWrap()));
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Abs->takeName(&I);
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return replaceInstUsesWith(I, Abs);
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}
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if (Instruction *Ext = narrowMathIfNoOverflow(I))
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return Ext;
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bool Changed = false;
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if (!I.hasNoSignedWrap() && willNotOverflowSignedMul(Op0, Op1, I)) {
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Changed = true;
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I.setHasNoSignedWrap(true);
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}
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if (!I.hasNoUnsignedWrap() && willNotOverflowUnsignedMul(Op0, Op1, I)) {
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Changed = true;
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I.setHasNoUnsignedWrap(true);
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}
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return Changed ? &I : nullptr;
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}
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Instruction *InstCombinerImpl::foldFPSignBitOps(BinaryOperator &I) {
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BinaryOperator::BinaryOps Opcode = I.getOpcode();
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assert((Opcode == Instruction::FMul || Opcode == Instruction::FDiv) &&
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"Expected fmul or fdiv");
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Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
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Value *X, *Y;
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// -X * -Y --> X * Y
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// -X / -Y --> X / Y
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if (match(Op0, m_FNeg(m_Value(X))) && match(Op1, m_FNeg(m_Value(Y))))
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return BinaryOperator::CreateWithCopiedFlags(Opcode, X, Y, &I);
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// fabs(X) * fabs(X) -> X * X
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// fabs(X) / fabs(X) -> X / X
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if (Op0 == Op1 && match(Op0, m_FAbs(m_Value(X))))
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return BinaryOperator::CreateWithCopiedFlags(Opcode, X, X, &I);
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// fabs(X) * fabs(Y) --> fabs(X * Y)
|
|
// fabs(X) / fabs(Y) --> fabs(X / Y)
|
|
if (match(Op0, m_FAbs(m_Value(X))) && match(Op1, m_FAbs(m_Value(Y))) &&
|
|
(Op0->hasOneUse() || Op1->hasOneUse())) {
|
|
IRBuilder<>::FastMathFlagGuard FMFGuard(Builder);
|
|
Builder.setFastMathFlags(I.getFastMathFlags());
|
|
Value *XY = Builder.CreateBinOp(Opcode, X, Y);
|
|
Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, XY);
|
|
Fabs->takeName(&I);
|
|
return replaceInstUsesWith(I, Fabs);
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
Instruction *InstCombinerImpl::visitFMul(BinaryOperator &I) {
|
|
if (Value *V = SimplifyFMulInst(I.getOperand(0), I.getOperand(1),
|
|
I.getFastMathFlags(),
|
|
SQ.getWithInstruction(&I)))
|
|
return replaceInstUsesWith(I, V);
|
|
|
|
if (SimplifyAssociativeOrCommutative(I))
|
|
return &I;
|
|
|
|
if (Instruction *X = foldVectorBinop(I))
|
|
return X;
|
|
|
|
if (Instruction *FoldedMul = foldBinOpIntoSelectOrPhi(I))
|
|
return FoldedMul;
|
|
|
|
if (Value *FoldedMul = foldMulSelectToNegate(I, Builder))
|
|
return replaceInstUsesWith(I, FoldedMul);
|
|
|
|
if (Instruction *R = foldFPSignBitOps(I))
|
|
return R;
|
|
|
|
// X * -1.0 --> -X
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
if (match(Op1, m_SpecificFP(-1.0)))
|
|
return UnaryOperator::CreateFNegFMF(Op0, &I);
|
|
|
|
// -X * C --> X * -C
|
|
Value *X, *Y;
|
|
Constant *C;
|
|
if (match(Op0, m_FNeg(m_Value(X))) && match(Op1, m_Constant(C)))
|
|
return BinaryOperator::CreateFMulFMF(X, ConstantExpr::getFNeg(C), &I);
|
|
|
|
// (select A, B, C) * (select A, D, E) --> select A, (B*D), (C*E)
|
|
if (Value *V = SimplifySelectsFeedingBinaryOp(I, Op0, Op1))
|
|
return replaceInstUsesWith(I, V);
|
|
|
|
if (I.hasAllowReassoc()) {
|
|
// Reassociate constant RHS with another constant to form constant
|
|
// expression.
|
|
if (match(Op1, m_Constant(C)) && C->isFiniteNonZeroFP()) {
|
|
Constant *C1;
|
|
if (match(Op0, m_OneUse(m_FDiv(m_Constant(C1), m_Value(X))))) {
|
|
// (C1 / X) * C --> (C * C1) / X
|
|
Constant *CC1 = ConstantExpr::getFMul(C, C1);
|
|
if (CC1->isNormalFP())
|
|
return BinaryOperator::CreateFDivFMF(CC1, X, &I);
|
|
}
|
|
if (match(Op0, m_FDiv(m_Value(X), m_Constant(C1)))) {
|
|
// (X / C1) * C --> X * (C / C1)
|
|
Constant *CDivC1 = ConstantExpr::getFDiv(C, C1);
|
|
if (CDivC1->isNormalFP())
|
|
return BinaryOperator::CreateFMulFMF(X, CDivC1, &I);
|
|
|
|
// If the constant was a denormal, try reassociating differently.
|
|
// (X / C1) * C --> X / (C1 / C)
|
|
Constant *C1DivC = ConstantExpr::getFDiv(C1, C);
|
|
if (Op0->hasOneUse() && C1DivC->isNormalFP())
|
|
return BinaryOperator::CreateFDivFMF(X, C1DivC, &I);
|
|
}
|
|
|
|
// We do not need to match 'fadd C, X' and 'fsub X, C' because they are
|
|
// canonicalized to 'fadd X, C'. Distributing the multiply may allow
|
|
// further folds and (X * C) + C2 is 'fma'.
|
|
if (match(Op0, m_OneUse(m_FAdd(m_Value(X), m_Constant(C1))))) {
|
|
// (X + C1) * C --> (X * C) + (C * C1)
|
|
Constant *CC1 = ConstantExpr::getFMul(C, C1);
|
|
Value *XC = Builder.CreateFMulFMF(X, C, &I);
|
|
return BinaryOperator::CreateFAddFMF(XC, CC1, &I);
|
|
}
|
|
if (match(Op0, m_OneUse(m_FSub(m_Constant(C1), m_Value(X))))) {
|
|
// (C1 - X) * C --> (C * C1) - (X * C)
|
|
Constant *CC1 = ConstantExpr::getFMul(C, C1);
|
|
Value *XC = Builder.CreateFMulFMF(X, C, &I);
|
|
return BinaryOperator::CreateFSubFMF(CC1, XC, &I);
|
|
}
|
|
}
|
|
|
|
Value *Z;
|
|
if (match(&I, m_c_FMul(m_OneUse(m_FDiv(m_Value(X), m_Value(Y))),
|
|
m_Value(Z)))) {
|
|
// Sink division: (X / Y) * Z --> (X * Z) / Y
|
|
Value *NewFMul = Builder.CreateFMulFMF(X, Z, &I);
|
|
return BinaryOperator::CreateFDivFMF(NewFMul, Y, &I);
|
|
}
|
|
|
|
// sqrt(X) * sqrt(Y) -> sqrt(X * Y)
|
|
// nnan disallows the possibility of returning a number if both operands are
|
|
// negative (in that case, we should return NaN).
|
|
if (I.hasNoNaNs() &&
|
|
match(Op0, m_OneUse(m_Intrinsic<Intrinsic::sqrt>(m_Value(X)))) &&
|
|
match(Op1, m_OneUse(m_Intrinsic<Intrinsic::sqrt>(m_Value(Y))))) {
|
|
Value *XY = Builder.CreateFMulFMF(X, Y, &I);
|
|
Value *Sqrt = Builder.CreateUnaryIntrinsic(Intrinsic::sqrt, XY, &I);
|
|
return replaceInstUsesWith(I, Sqrt);
|
|
}
|
|
|
|
// The following transforms are done irrespective of the number of uses
|
|
// for the expression "1.0/sqrt(X)".
|
|
// 1) 1.0/sqrt(X) * X -> X/sqrt(X)
|
|
// 2) X * 1.0/sqrt(X) -> X/sqrt(X)
|
|
// We always expect the backend to reduce X/sqrt(X) to sqrt(X), if it
|
|
// has the necessary (reassoc) fast-math-flags.
|
|
if (I.hasNoSignedZeros() &&
|
|
match(Op0, (m_FDiv(m_SpecificFP(1.0), m_Value(Y)))) &&
|
|
match(Y, m_Intrinsic<Intrinsic::sqrt>(m_Value(X))) && Op1 == X)
|
|
return BinaryOperator::CreateFDivFMF(X, Y, &I);
|
|
if (I.hasNoSignedZeros() &&
|
|
match(Op1, (m_FDiv(m_SpecificFP(1.0), m_Value(Y)))) &&
|
|
match(Y, m_Intrinsic<Intrinsic::sqrt>(m_Value(X))) && Op0 == X)
|
|
return BinaryOperator::CreateFDivFMF(X, Y, &I);
|
|
|
|
// Like the similar transform in instsimplify, this requires 'nsz' because
|
|
// sqrt(-0.0) = -0.0, and -0.0 * -0.0 does not simplify to -0.0.
|
|
if (I.hasNoNaNs() && I.hasNoSignedZeros() && Op0 == Op1 &&
|
|
Op0->hasNUses(2)) {
|
|
// Peek through fdiv to find squaring of square root:
|
|
// (X / sqrt(Y)) * (X / sqrt(Y)) --> (X * X) / Y
|
|
if (match(Op0, m_FDiv(m_Value(X),
|
|
m_Intrinsic<Intrinsic::sqrt>(m_Value(Y))))) {
|
|
Value *XX = Builder.CreateFMulFMF(X, X, &I);
|
|
return BinaryOperator::CreateFDivFMF(XX, Y, &I);
|
|
}
|
|
// (sqrt(Y) / X) * (sqrt(Y) / X) --> Y / (X * X)
|
|
if (match(Op0, m_FDiv(m_Intrinsic<Intrinsic::sqrt>(m_Value(Y)),
|
|
m_Value(X)))) {
|
|
Value *XX = Builder.CreateFMulFMF(X, X, &I);
|
|
return BinaryOperator::CreateFDivFMF(Y, XX, &I);
|
|
}
|
|
}
|
|
|
|
// exp(X) * exp(Y) -> exp(X + Y)
|
|
// Match as long as at least one of exp has only one use.
|
|
if (match(Op0, m_Intrinsic<Intrinsic::exp>(m_Value(X))) &&
|
|
match(Op1, m_Intrinsic<Intrinsic::exp>(m_Value(Y))) &&
|
|
(Op0->hasOneUse() || Op1->hasOneUse())) {
|
|
Value *XY = Builder.CreateFAddFMF(X, Y, &I);
|
|
Value *Exp = Builder.CreateUnaryIntrinsic(Intrinsic::exp, XY, &I);
|
|
return replaceInstUsesWith(I, Exp);
|
|
}
|
|
|
|
// exp2(X) * exp2(Y) -> exp2(X + Y)
|
|
// Match as long as at least one of exp2 has only one use.
|
|
if (match(Op0, m_Intrinsic<Intrinsic::exp2>(m_Value(X))) &&
|
|
match(Op1, m_Intrinsic<Intrinsic::exp2>(m_Value(Y))) &&
|
|
(Op0->hasOneUse() || Op1->hasOneUse())) {
|
|
Value *XY = Builder.CreateFAddFMF(X, Y, &I);
|
|
Value *Exp2 = Builder.CreateUnaryIntrinsic(Intrinsic::exp2, XY, &I);
|
|
return replaceInstUsesWith(I, Exp2);
|
|
}
|
|
|
|
// (X*Y) * X => (X*X) * Y where Y != X
|
|
// The purpose is two-fold:
|
|
// 1) to form a power expression (of X).
|
|
// 2) potentially shorten the critical path: After transformation, the
|
|
// latency of the instruction Y is amortized by the expression of X*X,
|
|
// and therefore Y is in a "less critical" position compared to what it
|
|
// was before the transformation.
|
|
if (match(Op0, m_OneUse(m_c_FMul(m_Specific(Op1), m_Value(Y)))) &&
|
|
Op1 != Y) {
|
|
Value *XX = Builder.CreateFMulFMF(Op1, Op1, &I);
|
|
return BinaryOperator::CreateFMulFMF(XX, Y, &I);
|
|
}
|
|
if (match(Op1, m_OneUse(m_c_FMul(m_Specific(Op0), m_Value(Y)))) &&
|
|
Op0 != Y) {
|
|
Value *XX = Builder.CreateFMulFMF(Op0, Op0, &I);
|
|
return BinaryOperator::CreateFMulFMF(XX, Y, &I);
|
|
}
|
|
}
|
|
|
|
// log2(X * 0.5) * Y = log2(X) * Y - Y
|
|
if (I.isFast()) {
|
|
IntrinsicInst *Log2 = nullptr;
|
|
if (match(Op0, m_OneUse(m_Intrinsic<Intrinsic::log2>(
|
|
m_OneUse(m_FMul(m_Value(X), m_SpecificFP(0.5))))))) {
|
|
Log2 = cast<IntrinsicInst>(Op0);
|
|
Y = Op1;
|
|
}
|
|
if (match(Op1, m_OneUse(m_Intrinsic<Intrinsic::log2>(
|
|
m_OneUse(m_FMul(m_Value(X), m_SpecificFP(0.5))))))) {
|
|
Log2 = cast<IntrinsicInst>(Op1);
|
|
Y = Op0;
|
|
}
|
|
if (Log2) {
|
|
Value *Log2 = Builder.CreateUnaryIntrinsic(Intrinsic::log2, X, &I);
|
|
Value *LogXTimesY = Builder.CreateFMulFMF(Log2, Y, &I);
|
|
return BinaryOperator::CreateFSubFMF(LogXTimesY, Y, &I);
|
|
}
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
/// Fold a divide or remainder with a select instruction divisor when one of the
|
|
/// select operands is zero. In that case, we can use the other select operand
|
|
/// because div/rem by zero is undefined.
|
|
bool InstCombinerImpl::simplifyDivRemOfSelectWithZeroOp(BinaryOperator &I) {
|
|
SelectInst *SI = dyn_cast<SelectInst>(I.getOperand(1));
|
|
if (!SI)
|
|
return false;
|
|
|
|
int NonNullOperand;
|
|
if (match(SI->getTrueValue(), m_Zero()))
|
|
// div/rem X, (Cond ? 0 : Y) -> div/rem X, Y
|
|
NonNullOperand = 2;
|
|
else if (match(SI->getFalseValue(), m_Zero()))
|
|
// div/rem X, (Cond ? Y : 0) -> div/rem X, Y
|
|
NonNullOperand = 1;
|
|
else
|
|
return false;
|
|
|
|
// Change the div/rem to use 'Y' instead of the select.
|
|
replaceOperand(I, 1, SI->getOperand(NonNullOperand));
|
|
|
|
// Okay, we know we replace the operand of the div/rem with 'Y' with no
|
|
// problem. However, the select, or the condition of the select may have
|
|
// multiple uses. Based on our knowledge that the operand must be non-zero,
|
|
// propagate the known value for the select into other uses of it, and
|
|
// propagate a known value of the condition into its other users.
|
|
|
|
// If the select and condition only have a single use, don't bother with this,
|
|
// early exit.
|
|
Value *SelectCond = SI->getCondition();
|
|
if (SI->use_empty() && SelectCond->hasOneUse())
|
|
return true;
|
|
|
|
// Scan the current block backward, looking for other uses of SI.
|
|
BasicBlock::iterator BBI = I.getIterator(), BBFront = I.getParent()->begin();
|
|
Type *CondTy = SelectCond->getType();
|
|
while (BBI != BBFront) {
|
|
--BBI;
|
|
// If we found an instruction that we can't assume will return, so
|
|
// information from below it cannot be propagated above it.
|
|
if (!isGuaranteedToTransferExecutionToSuccessor(&*BBI))
|
|
break;
|
|
|
|
// Replace uses of the select or its condition with the known values.
|
|
for (Use &Op : BBI->operands()) {
|
|
if (Op == SI) {
|
|
replaceUse(Op, SI->getOperand(NonNullOperand));
|
|
Worklist.push(&*BBI);
|
|
} else if (Op == SelectCond) {
|
|
replaceUse(Op, NonNullOperand == 1 ? ConstantInt::getTrue(CondTy)
|
|
: ConstantInt::getFalse(CondTy));
|
|
Worklist.push(&*BBI);
|
|
}
|
|
}
|
|
|
|
// If we past the instruction, quit looking for it.
|
|
if (&*BBI == SI)
|
|
SI = nullptr;
|
|
if (&*BBI == SelectCond)
|
|
SelectCond = nullptr;
|
|
|
|
// If we ran out of things to eliminate, break out of the loop.
|
|
if (!SelectCond && !SI)
|
|
break;
|
|
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// True if the multiply can not be expressed in an int this size.
|
|
static bool multiplyOverflows(const APInt &C1, const APInt &C2, APInt &Product,
|
|
bool IsSigned) {
|
|
bool Overflow;
|
|
Product = IsSigned ? C1.smul_ov(C2, Overflow) : C1.umul_ov(C2, Overflow);
|
|
return Overflow;
|
|
}
|
|
|
|
/// True if C1 is a multiple of C2. Quotient contains C1/C2.
|
|
static bool isMultiple(const APInt &C1, const APInt &C2, APInt &Quotient,
|
|
bool IsSigned) {
|
|
assert(C1.getBitWidth() == C2.getBitWidth() && "Constant widths not equal");
|
|
|
|
// Bail if we will divide by zero.
|
|
if (C2.isNullValue())
|
|
return false;
|
|
|
|
// Bail if we would divide INT_MIN by -1.
|
|
if (IsSigned && C1.isMinSignedValue() && C2.isAllOnesValue())
|
|
return false;
|
|
|
|
APInt Remainder(C1.getBitWidth(), /*val=*/0ULL, IsSigned);
|
|
if (IsSigned)
|
|
APInt::sdivrem(C1, C2, Quotient, Remainder);
|
|
else
|
|
APInt::udivrem(C1, C2, Quotient, Remainder);
|
|
|
|
return Remainder.isMinValue();
|
|
}
|
|
|
|
/// This function implements the transforms common to both integer division
|
|
/// instructions (udiv and sdiv). It is called by the visitors to those integer
|
|
/// division instructions.
|
|
/// Common integer divide transforms
|
|
Instruction *InstCombinerImpl::commonIDivTransforms(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
bool IsSigned = I.getOpcode() == Instruction::SDiv;
|
|
Type *Ty = I.getType();
|
|
|
|
// The RHS is known non-zero.
|
|
if (Value *V = simplifyValueKnownNonZero(I.getOperand(1), *this, I))
|
|
return replaceOperand(I, 1, V);
|
|
|
|
// Handle cases involving: [su]div X, (select Cond, Y, Z)
|
|
// This does not apply for fdiv.
|
|
if (simplifyDivRemOfSelectWithZeroOp(I))
|
|
return &I;
|
|
|
|
const APInt *C2;
|
|
if (match(Op1, m_APInt(C2))) {
|
|
Value *X;
|
|
const APInt *C1;
|
|
|
|
// (X / C1) / C2 -> X / (C1*C2)
|
|
if ((IsSigned && match(Op0, m_SDiv(m_Value(X), m_APInt(C1)))) ||
|
|
(!IsSigned && match(Op0, m_UDiv(m_Value(X), m_APInt(C1))))) {
|
|
APInt Product(C1->getBitWidth(), /*val=*/0ULL, IsSigned);
|
|
if (!multiplyOverflows(*C1, *C2, Product, IsSigned))
|
|
return BinaryOperator::Create(I.getOpcode(), X,
|
|
ConstantInt::get(Ty, Product));
|
|
}
|
|
|
|
if ((IsSigned && match(Op0, m_NSWMul(m_Value(X), m_APInt(C1)))) ||
|
|
(!IsSigned && match(Op0, m_NUWMul(m_Value(X), m_APInt(C1))))) {
|
|
APInt Quotient(C1->getBitWidth(), /*val=*/0ULL, IsSigned);
|
|
|
|
// (X * C1) / C2 -> X / (C2 / C1) if C2 is a multiple of C1.
|
|
if (isMultiple(*C2, *C1, Quotient, IsSigned)) {
|
|
auto *NewDiv = BinaryOperator::Create(I.getOpcode(), X,
|
|
ConstantInt::get(Ty, Quotient));
|
|
NewDiv->setIsExact(I.isExact());
|
|
return NewDiv;
|
|
}
|
|
|
|
// (X * C1) / C2 -> X * (C1 / C2) if C1 is a multiple of C2.
|
|
if (isMultiple(*C1, *C2, Quotient, IsSigned)) {
|
|
auto *Mul = BinaryOperator::Create(Instruction::Mul, X,
|
|
ConstantInt::get(Ty, Quotient));
|
|
auto *OBO = cast<OverflowingBinaryOperator>(Op0);
|
|
Mul->setHasNoUnsignedWrap(!IsSigned && OBO->hasNoUnsignedWrap());
|
|
Mul->setHasNoSignedWrap(OBO->hasNoSignedWrap());
|
|
return Mul;
|
|
}
|
|
}
|
|
|
|
if ((IsSigned && match(Op0, m_NSWShl(m_Value(X), m_APInt(C1))) &&
|
|
*C1 != C1->getBitWidth() - 1) ||
|
|
(!IsSigned && match(Op0, m_NUWShl(m_Value(X), m_APInt(C1))))) {
|
|
APInt Quotient(C1->getBitWidth(), /*val=*/0ULL, IsSigned);
|
|
APInt C1Shifted = APInt::getOneBitSet(
|
|
C1->getBitWidth(), static_cast<unsigned>(C1->getLimitedValue()));
|
|
|
|
// (X << C1) / C2 -> X / (C2 >> C1) if C2 is a multiple of 1 << C1.
|
|
if (isMultiple(*C2, C1Shifted, Quotient, IsSigned)) {
|
|
auto *BO = BinaryOperator::Create(I.getOpcode(), X,
|
|
ConstantInt::get(Ty, Quotient));
|
|
BO->setIsExact(I.isExact());
|
|
return BO;
|
|
}
|
|
|
|
// (X << C1) / C2 -> X * ((1 << C1) / C2) if 1 << C1 is a multiple of C2.
|
|
if (isMultiple(C1Shifted, *C2, Quotient, IsSigned)) {
|
|
auto *Mul = BinaryOperator::Create(Instruction::Mul, X,
|
|
ConstantInt::get(Ty, Quotient));
|
|
auto *OBO = cast<OverflowingBinaryOperator>(Op0);
|
|
Mul->setHasNoUnsignedWrap(!IsSigned && OBO->hasNoUnsignedWrap());
|
|
Mul->setHasNoSignedWrap(OBO->hasNoSignedWrap());
|
|
return Mul;
|
|
}
|
|
}
|
|
|
|
if (!C2->isNullValue()) // avoid X udiv 0
|
|
if (Instruction *FoldedDiv = foldBinOpIntoSelectOrPhi(I))
|
|
return FoldedDiv;
|
|
}
|
|
|
|
if (match(Op0, m_One())) {
|
|
assert(!Ty->isIntOrIntVectorTy(1) && "i1 divide not removed?");
|
|
if (IsSigned) {
|
|
// If Op1 is 0 then it's undefined behaviour, if Op1 is 1 then the
|
|
// result is one, if Op1 is -1 then the result is minus one, otherwise
|
|
// it's zero.
|
|
Value *Inc = Builder.CreateAdd(Op1, Op0);
|
|
Value *Cmp = Builder.CreateICmpULT(Inc, ConstantInt::get(Ty, 3));
|
|
return SelectInst::Create(Cmp, Op1, ConstantInt::get(Ty, 0));
|
|
} else {
|
|
// If Op1 is 0 then it's undefined behaviour. If Op1 is 1 then the
|
|
// result is one, otherwise it's zero.
|
|
return new ZExtInst(Builder.CreateICmpEQ(Op1, Op0), Ty);
|
|
}
|
|
}
|
|
|
|
// See if we can fold away this div instruction.
|
|
if (SimplifyDemandedInstructionBits(I))
|
|
return &I;
|
|
|
|
// (X - (X rem Y)) / Y -> X / Y; usually originates as ((X / Y) * Y) / Y
|
|
Value *X, *Z;
|
|
if (match(Op0, m_Sub(m_Value(X), m_Value(Z)))) // (X - Z) / Y; Y = Op1
|
|
if ((IsSigned && match(Z, m_SRem(m_Specific(X), m_Specific(Op1)))) ||
|
|
(!IsSigned && match(Z, m_URem(m_Specific(X), m_Specific(Op1)))))
|
|
return BinaryOperator::Create(I.getOpcode(), X, Op1);
|
|
|
|
// (X << Y) / X -> 1 << Y
|
|
Value *Y;
|
|
if (IsSigned && match(Op0, m_NSWShl(m_Specific(Op1), m_Value(Y))))
|
|
return BinaryOperator::CreateNSWShl(ConstantInt::get(Ty, 1), Y);
|
|
if (!IsSigned && match(Op0, m_NUWShl(m_Specific(Op1), m_Value(Y))))
|
|
return BinaryOperator::CreateNUWShl(ConstantInt::get(Ty, 1), Y);
|
|
|
|
// X / (X * Y) -> 1 / Y if the multiplication does not overflow.
|
|
if (match(Op1, m_c_Mul(m_Specific(Op0), m_Value(Y)))) {
|
|
bool HasNSW = cast<OverflowingBinaryOperator>(Op1)->hasNoSignedWrap();
|
|
bool HasNUW = cast<OverflowingBinaryOperator>(Op1)->hasNoUnsignedWrap();
|
|
if ((IsSigned && HasNSW) || (!IsSigned && HasNUW)) {
|
|
replaceOperand(I, 0, ConstantInt::get(Ty, 1));
|
|
replaceOperand(I, 1, Y);
|
|
return &I;
|
|
}
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
static const unsigned MaxDepth = 6;
|
|
|
|
namespace {
|
|
|
|
using FoldUDivOperandCb = Instruction *(*)(Value *Op0, Value *Op1,
|
|
const BinaryOperator &I,
|
|
InstCombinerImpl &IC);
|
|
|
|
/// Used to maintain state for visitUDivOperand().
|
|
struct UDivFoldAction {
|
|
/// Informs visitUDiv() how to fold this operand. This can be zero if this
|
|
/// action joins two actions together.
|
|
FoldUDivOperandCb FoldAction;
|
|
|
|
/// Which operand to fold.
|
|
Value *OperandToFold;
|
|
|
|
union {
|
|
/// The instruction returned when FoldAction is invoked.
|
|
Instruction *FoldResult;
|
|
|
|
/// Stores the LHS action index if this action joins two actions together.
|
|
size_t SelectLHSIdx;
|
|
};
|
|
|
|
UDivFoldAction(FoldUDivOperandCb FA, Value *InputOperand)
|
|
: FoldAction(FA), OperandToFold(InputOperand), FoldResult(nullptr) {}
|
|
UDivFoldAction(FoldUDivOperandCb FA, Value *InputOperand, size_t SLHS)
|
|
: FoldAction(FA), OperandToFold(InputOperand), SelectLHSIdx(SLHS) {}
|
|
};
|
|
|
|
} // end anonymous namespace
|
|
|
|
// X udiv 2^C -> X >> C
|
|
static Instruction *foldUDivPow2Cst(Value *Op0, Value *Op1,
|
|
const BinaryOperator &I,
|
|
InstCombinerImpl &IC) {
|
|
Constant *C1 = ConstantExpr::getExactLogBase2(cast<Constant>(Op1));
|
|
if (!C1)
|
|
llvm_unreachable("Failed to constant fold udiv -> logbase2");
|
|
BinaryOperator *LShr = BinaryOperator::CreateLShr(Op0, C1);
|
|
if (I.isExact())
|
|
LShr->setIsExact();
|
|
return LShr;
|
|
}
|
|
|
|
// X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2)
|
|
// X udiv (zext (C1 << N)), where C1 is "1<<C2" --> X >> (N+C2)
|
|
static Instruction *foldUDivShl(Value *Op0, Value *Op1, const BinaryOperator &I,
|
|
InstCombinerImpl &IC) {
|
|
Value *ShiftLeft;
|
|
if (!match(Op1, m_ZExt(m_Value(ShiftLeft))))
|
|
ShiftLeft = Op1;
|
|
|
|
Constant *CI;
|
|
Value *N;
|
|
if (!match(ShiftLeft, m_Shl(m_Constant(CI), m_Value(N))))
|
|
llvm_unreachable("match should never fail here!");
|
|
Constant *Log2Base = ConstantExpr::getExactLogBase2(CI);
|
|
if (!Log2Base)
|
|
llvm_unreachable("getLogBase2 should never fail here!");
|
|
N = IC.Builder.CreateAdd(N, Log2Base);
|
|
if (Op1 != ShiftLeft)
|
|
N = IC.Builder.CreateZExt(N, Op1->getType());
|
|
BinaryOperator *LShr = BinaryOperator::CreateLShr(Op0, N);
|
|
if (I.isExact())
|
|
LShr->setIsExact();
|
|
return LShr;
|
|
}
|
|
|
|
// Recursively visits the possible right hand operands of a udiv
|
|
// instruction, seeing through select instructions, to determine if we can
|
|
// replace the udiv with something simpler. If we find that an operand is not
|
|
// able to simplify the udiv, we abort the entire transformation.
|
|
static size_t visitUDivOperand(Value *Op0, Value *Op1, const BinaryOperator &I,
|
|
SmallVectorImpl<UDivFoldAction> &Actions,
|
|
unsigned Depth = 0) {
|
|
// FIXME: assert that Op1 isn't/doesn't contain undef.
|
|
|
|
// Check to see if this is an unsigned division with an exact power of 2,
|
|
// if so, convert to a right shift.
|
|
if (match(Op1, m_Power2())) {
|
|
Actions.push_back(UDivFoldAction(foldUDivPow2Cst, Op1));
|
|
return Actions.size();
|
|
}
|
|
|
|
// X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2)
|
|
if (match(Op1, m_Shl(m_Power2(), m_Value())) ||
|
|
match(Op1, m_ZExt(m_Shl(m_Power2(), m_Value())))) {
|
|
Actions.push_back(UDivFoldAction(foldUDivShl, Op1));
|
|
return Actions.size();
|
|
}
|
|
|
|
// The remaining tests are all recursive, so bail out if we hit the limit.
|
|
if (Depth++ == MaxDepth)
|
|
return 0;
|
|
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
|
|
// FIXME: missed optimization: if one of the hands of select is/contains
|
|
// undef, just directly pick the other one.
|
|
// FIXME: can both hands contain undef?
|
|
if (size_t LHSIdx =
|
|
visitUDivOperand(Op0, SI->getOperand(1), I, Actions, Depth))
|
|
if (visitUDivOperand(Op0, SI->getOperand(2), I, Actions, Depth)) {
|
|
Actions.push_back(UDivFoldAction(nullptr, Op1, LHSIdx - 1));
|
|
return Actions.size();
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/// If we have zero-extended operands of an unsigned div or rem, we may be able
|
|
/// to narrow the operation (sink the zext below the math).
|
|
static Instruction *narrowUDivURem(BinaryOperator &I,
|
|
InstCombiner::BuilderTy &Builder) {
|
|
Instruction::BinaryOps Opcode = I.getOpcode();
|
|
Value *N = I.getOperand(0);
|
|
Value *D = I.getOperand(1);
|
|
Type *Ty = I.getType();
|
|
Value *X, *Y;
|
|
if (match(N, m_ZExt(m_Value(X))) && match(D, m_ZExt(m_Value(Y))) &&
|
|
X->getType() == Y->getType() && (N->hasOneUse() || D->hasOneUse())) {
|
|
// udiv (zext X), (zext Y) --> zext (udiv X, Y)
|
|
// urem (zext X), (zext Y) --> zext (urem X, Y)
|
|
Value *NarrowOp = Builder.CreateBinOp(Opcode, X, Y);
|
|
return new ZExtInst(NarrowOp, Ty);
|
|
}
|
|
|
|
Constant *C;
|
|
if ((match(N, m_OneUse(m_ZExt(m_Value(X)))) && match(D, m_Constant(C))) ||
|
|
(match(D, m_OneUse(m_ZExt(m_Value(X)))) && match(N, m_Constant(C)))) {
|
|
// If the constant is the same in the smaller type, use the narrow version.
|
|
Constant *TruncC = ConstantExpr::getTrunc(C, X->getType());
|
|
if (ConstantExpr::getZExt(TruncC, Ty) != C)
|
|
return nullptr;
|
|
|
|
// udiv (zext X), C --> zext (udiv X, C')
|
|
// urem (zext X), C --> zext (urem X, C')
|
|
// udiv C, (zext X) --> zext (udiv C', X)
|
|
// urem C, (zext X) --> zext (urem C', X)
|
|
Value *NarrowOp = isa<Constant>(D) ? Builder.CreateBinOp(Opcode, X, TruncC)
|
|
: Builder.CreateBinOp(Opcode, TruncC, X);
|
|
return new ZExtInst(NarrowOp, Ty);
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
Instruction *InstCombinerImpl::visitUDiv(BinaryOperator &I) {
|
|
if (Value *V = SimplifyUDivInst(I.getOperand(0), I.getOperand(1),
|
|
SQ.getWithInstruction(&I)))
|
|
return replaceInstUsesWith(I, V);
|
|
|
|
if (Instruction *X = foldVectorBinop(I))
|
|
return X;
|
|
|
|
// Handle the integer div common cases
|
|
if (Instruction *Common = commonIDivTransforms(I))
|
|
return Common;
|
|
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
Value *X;
|
|
const APInt *C1, *C2;
|
|
if (match(Op0, m_LShr(m_Value(X), m_APInt(C1))) && match(Op1, m_APInt(C2))) {
|
|
// (X lshr C1) udiv C2 --> X udiv (C2 << C1)
|
|
bool Overflow;
|
|
APInt C2ShlC1 = C2->ushl_ov(*C1, Overflow);
|
|
if (!Overflow) {
|
|
bool IsExact = I.isExact() && match(Op0, m_Exact(m_Value()));
|
|
BinaryOperator *BO = BinaryOperator::CreateUDiv(
|
|
X, ConstantInt::get(X->getType(), C2ShlC1));
|
|
if (IsExact)
|
|
BO->setIsExact();
|
|
return BO;
|
|
}
|
|
}
|
|
|
|
// Op0 / C where C is large (negative) --> zext (Op0 >= C)
|
|
// TODO: Could use isKnownNegative() to handle non-constant values.
|
|
Type *Ty = I.getType();
|
|
if (match(Op1, m_Negative())) {
|
|
Value *Cmp = Builder.CreateICmpUGE(Op0, Op1);
|
|
return CastInst::CreateZExtOrBitCast(Cmp, Ty);
|
|
}
|
|
// Op0 / (sext i1 X) --> zext (Op0 == -1) (if X is 0, the div is undefined)
|
|
if (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) {
|
|
Value *Cmp = Builder.CreateICmpEQ(Op0, ConstantInt::getAllOnesValue(Ty));
|
|
return CastInst::CreateZExtOrBitCast(Cmp, Ty);
|
|
}
|
|
|
|
if (Instruction *NarrowDiv = narrowUDivURem(I, Builder))
|
|
return NarrowDiv;
|
|
|
|
// If the udiv operands are non-overflowing multiplies with a common operand,
|
|
// then eliminate the common factor:
|
|
// (A * B) / (A * X) --> B / X (and commuted variants)
|
|
// TODO: The code would be reduced if we had m_c_NUWMul pattern matching.
|
|
// TODO: If -reassociation handled this generally, we could remove this.
|
|
Value *A, *B;
|
|
if (match(Op0, m_NUWMul(m_Value(A), m_Value(B)))) {
|
|
if (match(Op1, m_NUWMul(m_Specific(A), m_Value(X))) ||
|
|
match(Op1, m_NUWMul(m_Value(X), m_Specific(A))))
|
|
return BinaryOperator::CreateUDiv(B, X);
|
|
if (match(Op1, m_NUWMul(m_Specific(B), m_Value(X))) ||
|
|
match(Op1, m_NUWMul(m_Value(X), m_Specific(B))))
|
|
return BinaryOperator::CreateUDiv(A, X);
|
|
}
|
|
|
|
// (LHS udiv (select (select (...)))) -> (LHS >> (select (select (...))))
|
|
SmallVector<UDivFoldAction, 6> UDivActions;
|
|
if (visitUDivOperand(Op0, Op1, I, UDivActions))
|
|
for (unsigned i = 0, e = UDivActions.size(); i != e; ++i) {
|
|
FoldUDivOperandCb Action = UDivActions[i].FoldAction;
|
|
Value *ActionOp1 = UDivActions[i].OperandToFold;
|
|
Instruction *Inst;
|
|
if (Action)
|
|
Inst = Action(Op0, ActionOp1, I, *this);
|
|
else {
|
|
// This action joins two actions together. The RHS of this action is
|
|
// simply the last action we processed, we saved the LHS action index in
|
|
// the joining action.
|
|
size_t SelectRHSIdx = i - 1;
|
|
Value *SelectRHS = UDivActions[SelectRHSIdx].FoldResult;
|
|
size_t SelectLHSIdx = UDivActions[i].SelectLHSIdx;
|
|
Value *SelectLHS = UDivActions[SelectLHSIdx].FoldResult;
|
|
Inst = SelectInst::Create(cast<SelectInst>(ActionOp1)->getCondition(),
|
|
SelectLHS, SelectRHS);
|
|
}
|
|
|
|
// If this is the last action to process, return it to the InstCombiner.
|
|
// Otherwise, we insert it before the UDiv and record it so that we may
|
|
// use it as part of a joining action (i.e., a SelectInst).
|
|
if (e - i != 1) {
|
|
Inst->insertBefore(&I);
|
|
UDivActions[i].FoldResult = Inst;
|
|
} else
|
|
return Inst;
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
Instruction *InstCombinerImpl::visitSDiv(BinaryOperator &I) {
|
|
if (Value *V = SimplifySDivInst(I.getOperand(0), I.getOperand(1),
|
|
SQ.getWithInstruction(&I)))
|
|
return replaceInstUsesWith(I, V);
|
|
|
|
if (Instruction *X = foldVectorBinop(I))
|
|
return X;
|
|
|
|
// Handle the integer div common cases
|
|
if (Instruction *Common = commonIDivTransforms(I))
|
|
return Common;
|
|
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
Type *Ty = I.getType();
|
|
Value *X;
|
|
// sdiv Op0, -1 --> -Op0
|
|
// sdiv Op0, (sext i1 X) --> -Op0 (because if X is 0, the op is undefined)
|
|
if (match(Op1, m_AllOnes()) ||
|
|
(match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)))
|
|
return BinaryOperator::CreateNeg(Op0);
|
|
|
|
// X / INT_MIN --> X == INT_MIN
|
|
if (match(Op1, m_SignMask()))
|
|
return new ZExtInst(Builder.CreateICmpEQ(Op0, Op1), Ty);
|
|
|
|
// sdiv exact X, 1<<C --> ashr exact X, C iff 1<<C is non-negative
|
|
// sdiv exact X, -1<<C --> -(ashr exact X, C)
|
|
if (I.isExact() && ((match(Op1, m_Power2()) && match(Op1, m_NonNegative())) ||
|
|
match(Op1, m_NegatedPower2()))) {
|
|
bool DivisorWasNegative = match(Op1, m_NegatedPower2());
|
|
if (DivisorWasNegative)
|
|
Op1 = ConstantExpr::getNeg(cast<Constant>(Op1));
|
|
auto *AShr = BinaryOperator::CreateExactAShr(
|
|
Op0, ConstantExpr::getExactLogBase2(cast<Constant>(Op1)), I.getName());
|
|
if (!DivisorWasNegative)
|
|
return AShr;
|
|
Builder.Insert(AShr);
|
|
AShr->setName(I.getName() + ".neg");
|
|
return BinaryOperator::CreateNeg(AShr, I.getName());
|
|
}
|
|
|
|
const APInt *Op1C;
|
|
if (match(Op1, m_APInt(Op1C))) {
|
|
// If the dividend is sign-extended and the constant divisor is small enough
|
|
// to fit in the source type, shrink the division to the narrower type:
|
|
// (sext X) sdiv C --> sext (X sdiv C)
|
|
Value *Op0Src;
|
|
if (match(Op0, m_OneUse(m_SExt(m_Value(Op0Src)))) &&
|
|
Op0Src->getType()->getScalarSizeInBits() >= Op1C->getMinSignedBits()) {
|
|
|
|
// In the general case, we need to make sure that the dividend is not the
|
|
// minimum signed value because dividing that by -1 is UB. But here, we
|
|
// know that the -1 divisor case is already handled above.
|
|
|
|
Constant *NarrowDivisor =
|
|
ConstantExpr::getTrunc(cast<Constant>(Op1), Op0Src->getType());
|
|
Value *NarrowOp = Builder.CreateSDiv(Op0Src, NarrowDivisor);
|
|
return new SExtInst(NarrowOp, Ty);
|
|
}
|
|
|
|
// -X / C --> X / -C (if the negation doesn't overflow).
|
|
// TODO: This could be enhanced to handle arbitrary vector constants by
|
|
// checking if all elements are not the min-signed-val.
|
|
if (!Op1C->isMinSignedValue() &&
|
|
match(Op0, m_NSWSub(m_Zero(), m_Value(X)))) {
|
|
Constant *NegC = ConstantInt::get(Ty, -(*Op1C));
|
|
Instruction *BO = BinaryOperator::CreateSDiv(X, NegC);
|
|
BO->setIsExact(I.isExact());
|
|
return BO;
|
|
}
|
|
}
|
|
|
|
// -X / Y --> -(X / Y)
|
|
Value *Y;
|
|
if (match(&I, m_SDiv(m_OneUse(m_NSWSub(m_Zero(), m_Value(X))), m_Value(Y))))
|
|
return BinaryOperator::CreateNSWNeg(
|
|
Builder.CreateSDiv(X, Y, I.getName(), I.isExact()));
|
|
|
|
// abs(X) / X --> X > -1 ? 1 : -1
|
|
// X / abs(X) --> X > -1 ? 1 : -1
|
|
if (match(&I, m_c_BinOp(
|
|
m_OneUse(m_Intrinsic<Intrinsic::abs>(m_Value(X), m_One())),
|
|
m_Deferred(X)))) {
|
|
Constant *NegOne = ConstantInt::getAllOnesValue(Ty);
|
|
Value *Cond = Builder.CreateICmpSGT(X, NegOne);
|
|
return SelectInst::Create(Cond, ConstantInt::get(Ty, 1), NegOne);
|
|
}
|
|
|
|
// If the sign bits of both operands are zero (i.e. we can prove they are
|
|
// unsigned inputs), turn this into a udiv.
|
|
APInt Mask(APInt::getSignMask(Ty->getScalarSizeInBits()));
|
|
if (MaskedValueIsZero(Op0, Mask, 0, &I)) {
|
|
if (MaskedValueIsZero(Op1, Mask, 0, &I)) {
|
|
// X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set
|
|
auto *BO = BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
|
|
BO->setIsExact(I.isExact());
|
|
return BO;
|
|
}
|
|
|
|
if (match(Op1, m_NegatedPower2())) {
|
|
// X sdiv (-(1 << C)) -> -(X sdiv (1 << C)) ->
|
|
// -> -(X udiv (1 << C)) -> -(X u>> C)
|
|
return BinaryOperator::CreateNeg(Builder.Insert(foldUDivPow2Cst(
|
|
Op0, ConstantExpr::getNeg(cast<Constant>(Op1)), I, *this)));
|
|
}
|
|
|
|
if (isKnownToBeAPowerOfTwo(Op1, /*OrZero*/ true, 0, &I)) {
|
|
// 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.
|
|
auto *BO = BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
|
|
BO->setIsExact(I.isExact());
|
|
return BO;
|
|
}
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
/// Remove negation and try to convert division into multiplication.
|
|
static Instruction *foldFDivConstantDivisor(BinaryOperator &I) {
|
|
Constant *C;
|
|
if (!match(I.getOperand(1), m_Constant(C)))
|
|
return nullptr;
|
|
|
|
// -X / C --> X / -C
|
|
Value *X;
|
|
if (match(I.getOperand(0), m_FNeg(m_Value(X))))
|
|
return BinaryOperator::CreateFDivFMF(X, ConstantExpr::getFNeg(C), &I);
|
|
|
|
// If the constant divisor has an exact inverse, this is always safe. If not,
|
|
// then we can still create a reciprocal if fast-math-flags allow it and the
|
|
// constant is a regular number (not zero, infinite, or denormal).
|
|
if (!(C->hasExactInverseFP() || (I.hasAllowReciprocal() && C->isNormalFP())))
|
|
return nullptr;
|
|
|
|
// Disallow denormal constants because we don't know what would happen
|
|
// on all targets.
|
|
// TODO: Use Intrinsic::canonicalize or let function attributes tell us that
|
|
// denorms are flushed?
|
|
auto *RecipC = ConstantExpr::getFDiv(ConstantFP::get(I.getType(), 1.0), C);
|
|
if (!RecipC->isNormalFP())
|
|
return nullptr;
|
|
|
|
// X / C --> X * (1 / C)
|
|
return BinaryOperator::CreateFMulFMF(I.getOperand(0), RecipC, &I);
|
|
}
|
|
|
|
/// Remove negation and try to reassociate constant math.
|
|
static Instruction *foldFDivConstantDividend(BinaryOperator &I) {
|
|
Constant *C;
|
|
if (!match(I.getOperand(0), m_Constant(C)))
|
|
return nullptr;
|
|
|
|
// C / -X --> -C / X
|
|
Value *X;
|
|
if (match(I.getOperand(1), m_FNeg(m_Value(X))))
|
|
return BinaryOperator::CreateFDivFMF(ConstantExpr::getFNeg(C), X, &I);
|
|
|
|
if (!I.hasAllowReassoc() || !I.hasAllowReciprocal())
|
|
return nullptr;
|
|
|
|
// Try to reassociate C / X expressions where X includes another constant.
|
|
Constant *C2, *NewC = nullptr;
|
|
if (match(I.getOperand(1), m_FMul(m_Value(X), m_Constant(C2)))) {
|
|
// C / (X * C2) --> (C / C2) / X
|
|
NewC = ConstantExpr::getFDiv(C, C2);
|
|
} else if (match(I.getOperand(1), m_FDiv(m_Value(X), m_Constant(C2)))) {
|
|
// C / (X / C2) --> (C * C2) / X
|
|
NewC = ConstantExpr::getFMul(C, C2);
|
|
}
|
|
// Disallow denormal constants because we don't know what would happen
|
|
// on all targets.
|
|
// TODO: Use Intrinsic::canonicalize or let function attributes tell us that
|
|
// denorms are flushed?
|
|
if (!NewC || !NewC->isNormalFP())
|
|
return nullptr;
|
|
|
|
return BinaryOperator::CreateFDivFMF(NewC, X, &I);
|
|
}
|
|
|
|
/// Negate the exponent of pow/exp to fold division-by-pow() into multiply.
|
|
static Instruction *foldFDivPowDivisor(BinaryOperator &I,
|
|
InstCombiner::BuilderTy &Builder) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
auto *II = dyn_cast<IntrinsicInst>(Op1);
|
|
if (!II || !II->hasOneUse() || !I.hasAllowReassoc() ||
|
|
!I.hasAllowReciprocal())
|
|
return nullptr;
|
|
|
|
// Z / pow(X, Y) --> Z * pow(X, -Y)
|
|
// Z / exp{2}(Y) --> Z * exp{2}(-Y)
|
|
// In the general case, this creates an extra instruction, but fmul allows
|
|
// for better canonicalization and optimization than fdiv.
|
|
Intrinsic::ID IID = II->getIntrinsicID();
|
|
SmallVector<Value *> Args;
|
|
switch (IID) {
|
|
case Intrinsic::pow:
|
|
Args.push_back(II->getArgOperand(0));
|
|
Args.push_back(Builder.CreateFNegFMF(II->getArgOperand(1), &I));
|
|
break;
|
|
case Intrinsic::powi:
|
|
// Require 'ninf' assuming that makes powi(X, -INT_MIN) acceptable.
|
|
// That is, X ** (huge negative number) is 0.0, ~1.0, or INF and so
|
|
// dividing by that is INF, ~1.0, or 0.0. Code that uses powi allows
|
|
// non-standard results, so this corner case should be acceptable if the
|
|
// code rules out INF values.
|
|
if (!I.hasNoInfs())
|
|
return nullptr;
|
|
Args.push_back(II->getArgOperand(0));
|
|
Args.push_back(Builder.CreateNeg(II->getArgOperand(1)));
|
|
break;
|
|
case Intrinsic::exp:
|
|
case Intrinsic::exp2:
|
|
Args.push_back(Builder.CreateFNegFMF(II->getArgOperand(0), &I));
|
|
break;
|
|
default:
|
|
return nullptr;
|
|
}
|
|
Value *Pow = Builder.CreateIntrinsic(IID, I.getType(), Args, &I);
|
|
return BinaryOperator::CreateFMulFMF(Op0, Pow, &I);
|
|
}
|
|
|
|
Instruction *InstCombinerImpl::visitFDiv(BinaryOperator &I) {
|
|
if (Value *V = SimplifyFDivInst(I.getOperand(0), I.getOperand(1),
|
|
I.getFastMathFlags(),
|
|
SQ.getWithInstruction(&I)))
|
|
return replaceInstUsesWith(I, V);
|
|
|
|
if (Instruction *X = foldVectorBinop(I))
|
|
return X;
|
|
|
|
if (Instruction *R = foldFDivConstantDivisor(I))
|
|
return R;
|
|
|
|
if (Instruction *R = foldFDivConstantDividend(I))
|
|
return R;
|
|
|
|
if (Instruction *R = foldFPSignBitOps(I))
|
|
return R;
|
|
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
if (isa<Constant>(Op0))
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
|
|
if (Instruction *R = FoldOpIntoSelect(I, SI))
|
|
return R;
|
|
|
|
if (isa<Constant>(Op1))
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
|
|
if (Instruction *R = FoldOpIntoSelect(I, SI))
|
|
return R;
|
|
|
|
if (I.hasAllowReassoc() && I.hasAllowReciprocal()) {
|
|
Value *X, *Y;
|
|
if (match(Op0, m_OneUse(m_FDiv(m_Value(X), m_Value(Y)))) &&
|
|
(!isa<Constant>(Y) || !isa<Constant>(Op1))) {
|
|
// (X / Y) / Z => X / (Y * Z)
|
|
Value *YZ = Builder.CreateFMulFMF(Y, Op1, &I);
|
|
return BinaryOperator::CreateFDivFMF(X, YZ, &I);
|
|
}
|
|
if (match(Op1, m_OneUse(m_FDiv(m_Value(X), m_Value(Y)))) &&
|
|
(!isa<Constant>(Y) || !isa<Constant>(Op0))) {
|
|
// Z / (X / Y) => (Y * Z) / X
|
|
Value *YZ = Builder.CreateFMulFMF(Y, Op0, &I);
|
|
return BinaryOperator::CreateFDivFMF(YZ, X, &I);
|
|
}
|
|
// Z / (1.0 / Y) => (Y * Z)
|
|
//
|
|
// This is a special case of Z / (X / Y) => (Y * Z) / X, with X = 1.0. The
|
|
// m_OneUse check is avoided because even in the case of the multiple uses
|
|
// for 1.0/Y, the number of instructions remain the same and a division is
|
|
// replaced by a multiplication.
|
|
if (match(Op1, m_FDiv(m_SpecificFP(1.0), m_Value(Y))))
|
|
return BinaryOperator::CreateFMulFMF(Y, Op0, &I);
|
|
}
|
|
|
|
if (I.hasAllowReassoc() && Op0->hasOneUse() && Op1->hasOneUse()) {
|
|
// sin(X) / cos(X) -> tan(X)
|
|
// cos(X) / sin(X) -> 1/tan(X) (cotangent)
|
|
Value *X;
|
|
bool IsTan = match(Op0, m_Intrinsic<Intrinsic::sin>(m_Value(X))) &&
|
|
match(Op1, m_Intrinsic<Intrinsic::cos>(m_Specific(X)));
|
|
bool IsCot =
|
|
!IsTan && match(Op0, m_Intrinsic<Intrinsic::cos>(m_Value(X))) &&
|
|
match(Op1, m_Intrinsic<Intrinsic::sin>(m_Specific(X)));
|
|
|
|
if ((IsTan || IsCot) &&
|
|
hasFloatFn(&TLI, I.getType(), LibFunc_tan, LibFunc_tanf, LibFunc_tanl)) {
|
|
IRBuilder<> B(&I);
|
|
IRBuilder<>::FastMathFlagGuard FMFGuard(B);
|
|
B.setFastMathFlags(I.getFastMathFlags());
|
|
AttributeList Attrs =
|
|
cast<CallBase>(Op0)->getCalledFunction()->getAttributes();
|
|
Value *Res = emitUnaryFloatFnCall(X, &TLI, LibFunc_tan, LibFunc_tanf,
|
|
LibFunc_tanl, B, Attrs);
|
|
if (IsCot)
|
|
Res = B.CreateFDiv(ConstantFP::get(I.getType(), 1.0), Res);
|
|
return replaceInstUsesWith(I, Res);
|
|
}
|
|
}
|
|
|
|
// X / (X * Y) --> 1.0 / Y
|
|
// Reassociate to (X / X -> 1.0) is legal when NaNs are not allowed.
|
|
// We can ignore the possibility that X is infinity because INF/INF is NaN.
|
|
Value *X, *Y;
|
|
if (I.hasNoNaNs() && I.hasAllowReassoc() &&
|
|
match(Op1, m_c_FMul(m_Specific(Op0), m_Value(Y)))) {
|
|
replaceOperand(I, 0, ConstantFP::get(I.getType(), 1.0));
|
|
replaceOperand(I, 1, Y);
|
|
return &I;
|
|
}
|
|
|
|
// X / fabs(X) -> copysign(1.0, X)
|
|
// fabs(X) / X -> copysign(1.0, X)
|
|
if (I.hasNoNaNs() && I.hasNoInfs() &&
|
|
(match(&I, m_FDiv(m_Value(X), m_FAbs(m_Deferred(X)))) ||
|
|
match(&I, m_FDiv(m_FAbs(m_Value(X)), m_Deferred(X))))) {
|
|
Value *V = Builder.CreateBinaryIntrinsic(
|
|
Intrinsic::copysign, ConstantFP::get(I.getType(), 1.0), X, &I);
|
|
return replaceInstUsesWith(I, V);
|
|
}
|
|
|
|
if (Instruction *Mul = foldFDivPowDivisor(I, Builder))
|
|
return Mul;
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
/// 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.
|
|
/// Common integer remainder transforms
|
|
Instruction *InstCombinerImpl::commonIRemTransforms(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
// The RHS is known non-zero.
|
|
if (Value *V = simplifyValueKnownNonZero(I.getOperand(1), *this, I))
|
|
return replaceOperand(I, 1, V);
|
|
|
|
// Handle cases involving: rem X, (select Cond, Y, Z)
|
|
if (simplifyDivRemOfSelectWithZeroOp(I))
|
|
return &I;
|
|
|
|
if (isa<Constant>(Op1)) {
|
|
if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
|
|
if (Instruction *R = FoldOpIntoSelect(I, SI))
|
|
return R;
|
|
} else if (auto *PN = dyn_cast<PHINode>(Op0I)) {
|
|
const APInt *Op1Int;
|
|
if (match(Op1, m_APInt(Op1Int)) && !Op1Int->isMinValue() &&
|
|
(I.getOpcode() == Instruction::URem ||
|
|
!Op1Int->isMinSignedValue())) {
|
|
// foldOpIntoPhi will speculate instructions to the end of the PHI's
|
|
// predecessor blocks, so do this only if we know the srem or urem
|
|
// will not fault.
|
|
if (Instruction *NV = foldOpIntoPhi(I, PN))
|
|
return NV;
|
|
}
|
|
}
|
|
|
|
// See if we can fold away this rem instruction.
|
|
if (SimplifyDemandedInstructionBits(I))
|
|
return &I;
|
|
}
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
Instruction *InstCombinerImpl::visitURem(BinaryOperator &I) {
|
|
if (Value *V = SimplifyURemInst(I.getOperand(0), I.getOperand(1),
|
|
SQ.getWithInstruction(&I)))
|
|
return replaceInstUsesWith(I, V);
|
|
|
|
if (Instruction *X = foldVectorBinop(I))
|
|
return X;
|
|
|
|
if (Instruction *common = commonIRemTransforms(I))
|
|
return common;
|
|
|
|
if (Instruction *NarrowRem = narrowUDivURem(I, Builder))
|
|
return NarrowRem;
|
|
|
|
// X urem Y -> X and Y-1, where Y is a power of 2,
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
Type *Ty = I.getType();
|
|
if (isKnownToBeAPowerOfTwo(Op1, /*OrZero*/ true, 0, &I)) {
|
|
// This may increase instruction count, we don't enforce that Y is a
|
|
// constant.
|
|
Constant *N1 = Constant::getAllOnesValue(Ty);
|
|
Value *Add = Builder.CreateAdd(Op1, N1);
|
|
return BinaryOperator::CreateAnd(Op0, Add);
|
|
}
|
|
|
|
// 1 urem X -> zext(X != 1)
|
|
if (match(Op0, m_One())) {
|
|
Value *Cmp = Builder.CreateICmpNE(Op1, ConstantInt::get(Ty, 1));
|
|
return CastInst::CreateZExtOrBitCast(Cmp, Ty);
|
|
}
|
|
|
|
// X urem C -> X < C ? X : X - C, where C >= signbit.
|
|
if (match(Op1, m_Negative())) {
|
|
Value *Cmp = Builder.CreateICmpULT(Op0, Op1);
|
|
Value *Sub = Builder.CreateSub(Op0, Op1);
|
|
return SelectInst::Create(Cmp, Op0, Sub);
|
|
}
|
|
|
|
// If the divisor is a sext of a boolean, then the divisor must be max
|
|
// unsigned value (-1). Therefore, the remainder is Op0 unless Op0 is also
|
|
// max unsigned value. In that case, the remainder is 0:
|
|
// urem Op0, (sext i1 X) --> (Op0 == -1) ? 0 : Op0
|
|
Value *X;
|
|
if (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) {
|
|
Value *Cmp = Builder.CreateICmpEQ(Op0, ConstantInt::getAllOnesValue(Ty));
|
|
return SelectInst::Create(Cmp, ConstantInt::getNullValue(Ty), Op0);
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
Instruction *InstCombinerImpl::visitSRem(BinaryOperator &I) {
|
|
if (Value *V = SimplifySRemInst(I.getOperand(0), I.getOperand(1),
|
|
SQ.getWithInstruction(&I)))
|
|
return replaceInstUsesWith(I, V);
|
|
|
|
if (Instruction *X = foldVectorBinop(I))
|
|
return X;
|
|
|
|
// Handle the integer rem common cases
|
|
if (Instruction *Common = commonIRemTransforms(I))
|
|
return Common;
|
|
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
{
|
|
const APInt *Y;
|
|
// X % -Y -> X % Y
|
|
if (match(Op1, m_Negative(Y)) && !Y->isMinSignedValue())
|
|
return replaceOperand(I, 1, ConstantInt::get(I.getType(), -*Y));
|
|
}
|
|
|
|
// -X srem Y --> -(X srem Y)
|
|
Value *X, *Y;
|
|
if (match(&I, m_SRem(m_OneUse(m_NSWSub(m_Zero(), m_Value(X))), m_Value(Y))))
|
|
return BinaryOperator::CreateNSWNeg(Builder.CreateSRem(X, Y));
|
|
|
|
// If the sign bits of both operands are zero (i.e. we can prove they are
|
|
// unsigned inputs), turn this into a urem.
|
|
APInt Mask(APInt::getSignMask(I.getType()->getScalarSizeInBits()));
|
|
if (MaskedValueIsZero(Op1, Mask, 0, &I) &&
|
|
MaskedValueIsZero(Op0, Mask, 0, &I)) {
|
|
// 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 (isa<ConstantVector>(Op1) || isa<ConstantDataVector>(Op1)) {
|
|
Constant *C = cast<Constant>(Op1);
|
|
unsigned VWidth = cast<FixedVectorType>(C->getType())->getNumElements();
|
|
|
|
bool hasNegative = false;
|
|
bool hasMissing = false;
|
|
for (unsigned i = 0; i != VWidth; ++i) {
|
|
Constant *Elt = C->getAggregateElement(i);
|
|
if (!Elt) {
|
|
hasMissing = true;
|
|
break;
|
|
}
|
|
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Elt))
|
|
if (RHS->isNegative())
|
|
hasNegative = true;
|
|
}
|
|
|
|
if (hasNegative && !hasMissing) {
|
|
SmallVector<Constant *, 16> Elts(VWidth);
|
|
for (unsigned i = 0; i != VWidth; ++i) {
|
|
Elts[i] = C->getAggregateElement(i); // Handle undef, etc.
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Elts[i])) {
|
|
if (RHS->isNegative())
|
|
Elts[i] = cast<ConstantInt>(ConstantExpr::getNeg(RHS));
|
|
}
|
|
}
|
|
|
|
Constant *NewRHSV = ConstantVector::get(Elts);
|
|
if (NewRHSV != C) // Don't loop on -MININT
|
|
return replaceOperand(I, 1, NewRHSV);
|
|
}
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
Instruction *InstCombinerImpl::visitFRem(BinaryOperator &I) {
|
|
if (Value *V = SimplifyFRemInst(I.getOperand(0), I.getOperand(1),
|
|
I.getFastMathFlags(),
|
|
SQ.getWithInstruction(&I)))
|
|
return replaceInstUsesWith(I, V);
|
|
|
|
if (Instruction *X = foldVectorBinop(I))
|
|
return X;
|
|
|
|
return nullptr;
|
|
}
|