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gerrit-public.fairphone.software / toolchain / llvm-project / b4e06328fc260881ba6069ff3012f82aefe9765b / . / llvm / lib / Transforms / InstCombine / InstCombineAndOrXor.cpp
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//===- InstCombineAndOrXor.cpp --------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the visitAnd, visitOr, and visitXor functions.
//
//===----------------------------------------------------------------------===//
#include "InstCombineInternal.h"
#include "llvm/Analysis/CmpInstAnalysis.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/PatternMatch.h"
using namespace llvm;
using namespace PatternMatch;
#define DEBUG_TYPE "instcombine"
/// Similar to getICmpCode but for FCmpInst. This encodes a fcmp predicate into
/// a four bit mask.
static unsigned getFCmpCode(FCmpInst::Predicate CC) {
assert(FCmpInst::FCMP_FALSE <= CC && CC <= FCmpInst::FCMP_TRUE &&
"Unexpected FCmp predicate!");
// Take advantage of the bit pattern of FCmpInst::Predicate here.
// U L G E
static_assert(FCmpInst::FCMP_FALSE == 0, ""); // 0 0 0 0
static_assert(FCmpInst::FCMP_OEQ == 1, ""); // 0 0 0 1
static_assert(FCmpInst::FCMP_OGT == 2, ""); // 0 0 1 0
static_assert(FCmpInst::FCMP_OGE == 3, ""); // 0 0 1 1
static_assert(FCmpInst::FCMP_OLT == 4, ""); // 0 1 0 0
static_assert(FCmpInst::FCMP_OLE == 5, ""); // 0 1 0 1
static_assert(FCmpInst::FCMP_ONE == 6, ""); // 0 1 1 0
static_assert(FCmpInst::FCMP_ORD == 7, ""); // 0 1 1 1
static_assert(FCmpInst::FCMP_UNO == 8, ""); // 1 0 0 0
static_assert(FCmpInst::FCMP_UEQ == 9, ""); // 1 0 0 1
static_assert(FCmpInst::FCMP_UGT == 10, ""); // 1 0 1 0
static_assert(FCmpInst::FCMP_UGE == 11, ""); // 1 0 1 1
static_assert(FCmpInst::FCMP_ULT == 12, ""); // 1 1 0 0
static_assert(FCmpInst::FCMP_ULE == 13, ""); // 1 1 0 1
static_assert(FCmpInst::FCMP_UNE == 14, ""); // 1 1 1 0
static_assert(FCmpInst::FCMP_TRUE == 15, ""); // 1 1 1 1
return CC;
}
/// This is the complement of getICmpCode, which turns an opcode and two
/// operands into either a constant true or false, or a brand new ICmp
/// instruction. The sign is passed in to determine which kind of predicate to
/// use in the new icmp instruction.
static Value *getNewICmpValue(unsigned Code, bool Sign, Value *LHS, Value *RHS,
InstCombiner::BuilderTy &Builder) {
ICmpInst::Predicate NewPred;
if (Constant *TorF = getPredForICmpCode(Code, Sign, LHS->getType(), NewPred))
return TorF;
return Builder.CreateICmp(NewPred, LHS, RHS);
}
/// This is the complement of getFCmpCode, which turns an opcode and two
/// operands into either a FCmp instruction, or a true/false constant.
static Value *getFCmpValue(unsigned Code, Value *LHS, Value *RHS,
InstCombiner::BuilderTy &Builder) {
const auto Pred = static_cast<FCmpInst::Predicate>(Code);
assert(FCmpInst::FCMP_FALSE <= Pred && Pred <= FCmpInst::FCMP_TRUE &&
"Unexpected FCmp predicate!");
if (Pred == FCmpInst::FCMP_FALSE)
return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
if (Pred == FCmpInst::FCMP_TRUE)
return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 1);
return Builder.CreateFCmp(Pred, LHS, RHS);
}
/// Transform BITWISE_OP(BSWAP(A),BSWAP(B)) or
/// BITWISE_OP(BSWAP(A), Constant) to BSWAP(BITWISE_OP(A, B))
/// \param I Binary operator to transform.
/// \return Pointer to node that must replace the original binary operator, or
/// null pointer if no transformation was made.
static Value *SimplifyBSwap(BinaryOperator &I,
InstCombiner::BuilderTy &Builder) {
assert(I.isBitwiseLogicOp() && "Unexpected opcode for bswap simplifying");
Value *OldLHS = I.getOperand(0);
Value *OldRHS = I.getOperand(1);
Value *NewLHS;
if (!match(OldLHS, m_BSwap(m_Value(NewLHS))))
return nullptr;
Value *NewRHS;
const APInt *C;
if (match(OldRHS, m_BSwap(m_Value(NewRHS)))) {
// OP( BSWAP(x), BSWAP(y) ) -> BSWAP( OP(x, y) )
if (!OldLHS->hasOneUse() && !OldRHS->hasOneUse())
return nullptr;
// NewRHS initialized by the matcher.
} else if (match(OldRHS, m_APInt(C))) {
// OP( BSWAP(x), CONSTANT ) -> BSWAP( OP(x, BSWAP(CONSTANT) ) )
if (!OldLHS->hasOneUse())
return nullptr;
NewRHS = ConstantInt::get(I.getType(), C->byteSwap());
} else
return nullptr;
Value *BinOp = Builder.CreateBinOp(I.getOpcode(), NewLHS, NewRHS);
Function *F = Intrinsic::getDeclaration(I.getModule(), Intrinsic::bswap,
I.getType());
return Builder.CreateCall(F, BinOp);
}
/// This handles expressions of the form ((val OP C1) & C2). Where
/// the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'.
Instruction *InstCombiner::OptAndOp(BinaryOperator *Op,
ConstantInt *OpRHS,
ConstantInt *AndRHS,
BinaryOperator &TheAnd) {
Value *X = Op->getOperand(0);
switch (Op->getOpcode()) {
default: break;
case Instruction::Add:
if (Op->hasOneUse()) {
// Adding a one to a single bit bit-field should be turned into an XOR
// of the bit. First thing to check is to see if this AND is with a
// single bit constant.
const APInt &AndRHSV = AndRHS->getValue();
// If there is only one bit set.
if (AndRHSV.isPowerOf2()) {
// Ok, at this point, we know that we are masking the result of the
// ADD down to exactly one bit. If the constant we are adding has
// no bits set below this bit, then we can eliminate the ADD.
const APInt& AddRHS = OpRHS->getValue();
// Check to see if any bits below the one bit set in AndRHSV are set.
if ((AddRHS & (AndRHSV - 1)).isNullValue()) {
// If not, the only thing that can effect the output of the AND is
// the bit specified by AndRHSV. If that bit is set, the effect of
// the XOR is to toggle the bit. If it is clear, then the ADD has
// no effect.
if ((AddRHS & AndRHSV).isNullValue()) { // Bit is not set, noop
TheAnd.setOperand(0, X);
return &TheAnd;
} else {
// Pull the XOR out of the AND.
Value *NewAnd = Builder.CreateAnd(X, AndRHS);
NewAnd->takeName(Op);
return BinaryOperator::CreateXor(NewAnd, AndRHS);
}
}
}
}
break;
}
return nullptr;
}
/// Emit a computation of: (V >= Lo && V < Hi) if Inside is true, otherwise
/// (V < Lo || V >= Hi). This method expects that Lo <= Hi. IsSigned indicates
/// whether to treat V, Lo, and Hi as signed or not.
Value *InstCombiner::insertRangeTest(Value *V, const APInt &Lo, const APInt &Hi,
bool isSigned, bool Inside) {
assert((isSigned ? Lo.sle(Hi) : Lo.ule(Hi)) &&
"Lo is not <= Hi in range emission code!");
Type *Ty = V->getType();
if (Lo == Hi)
return Inside ? ConstantInt::getFalse(Ty) : ConstantInt::getTrue(Ty);
// V >= Min && V < Hi --> V < Hi
// V < Min || V >= Hi --> V >= Hi
ICmpInst::Predicate Pred = Inside ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_UGE;
if (isSigned ? Lo.isMinSignedValue() : Lo.isMinValue()) {
Pred = isSigned ? ICmpInst::getSignedPredicate(Pred) : Pred;
return Builder.CreateICmp(Pred, V, ConstantInt::get(Ty, Hi));
}
// V >= Lo && V < Hi --> V - Lo u< Hi - Lo
// V < Lo || V >= Hi --> V - Lo u>= Hi - Lo
Value *VMinusLo =
Builder.CreateSub(V, ConstantInt::get(Ty, Lo), V->getName() + ".off");
Constant *HiMinusLo = ConstantInt::get(Ty, Hi - Lo);
return Builder.CreateICmp(Pred, VMinusLo, HiMinusLo);
}
/// Classify (icmp eq (A & B), C) and (icmp ne (A & B), C) as matching patterns
/// that can be simplified.
/// One of A and B is considered the mask. The other is the value. This is
/// described as the "AMask" or "BMask" part of the enum. If the enum contains
/// only "Mask", then both A and B can be considered masks. If A is the mask,
/// then it was proven that (A & C) == C. This is trivial if C == A or C == 0.
/// If both A and C are constants, this proof is also easy.
/// For the following explanations, we assume that A is the mask.
///
/// "AllOnes" declares that the comparison is true only if (A & B) == A or all
/// bits of A are set in B.
/// Example: (icmp eq (A & 3), 3) -> AMask_AllOnes
///
/// "AllZeros" declares that the comparison is true only if (A & B) == 0 or all
/// bits of A are cleared in B.
/// Example: (icmp eq (A & 3), 0) -> Mask_AllZeroes
///
/// "Mixed" declares that (A & B) == C and C might or might not contain any
/// number of one bits and zero bits.
/// Example: (icmp eq (A & 3), 1) -> AMask_Mixed
///
/// "Not" means that in above descriptions "==" should be replaced by "!=".
/// Example: (icmp ne (A & 3), 3) -> AMask_NotAllOnes
///
/// If the mask A contains a single bit, then the following is equivalent:
/// (icmp eq (A & B), A) equals (icmp ne (A & B), 0)
/// (icmp ne (A & B), A) equals (icmp eq (A & B), 0)
enum MaskedICmpType {
AMask_AllOnes = 1,
AMask_NotAllOnes = 2,
BMask_AllOnes = 4,
BMask_NotAllOnes = 8,
Mask_AllZeros = 16,
Mask_NotAllZeros = 32,
AMask_Mixed = 64,
AMask_NotMixed = 128,
BMask_Mixed = 256,
BMask_NotMixed = 512
};
/// Return the set of patterns (from MaskedICmpType) that (icmp SCC (A & B), C)
/// satisfies.
static unsigned getMaskedICmpType(Value *A, Value *B, Value *C,
ICmpInst::Predicate Pred) {
ConstantInt *ACst = dyn_cast<ConstantInt>(A);
ConstantInt *BCst = dyn_cast<ConstantInt>(B);
ConstantInt *CCst = dyn_cast<ConstantInt>(C);
bool IsEq = (Pred == ICmpInst::ICMP_EQ);
bool IsAPow2 = (ACst && !ACst->isZero() && ACst->getValue().isPowerOf2());
bool IsBPow2 = (BCst && !BCst->isZero() && BCst->getValue().isPowerOf2());
unsigned MaskVal = 0;
if (CCst && CCst->isZero()) {
// if C is zero, then both A and B qualify as mask
MaskVal |= (IsEq ? (Mask_AllZeros | AMask_Mixed | BMask_Mixed)
: (Mask_NotAllZeros | AMask_NotMixed | BMask_NotMixed));
if (IsAPow2)
MaskVal |= (IsEq ? (AMask_NotAllOnes | AMask_NotMixed)
: (AMask_AllOnes | AMask_Mixed));
if (IsBPow2)
MaskVal |= (IsEq ? (BMask_NotAllOnes | BMask_NotMixed)
: (BMask_AllOnes | BMask_Mixed));
return MaskVal;
}
if (A == C) {
MaskVal |= (IsEq ? (AMask_AllOnes | AMask_Mixed)
: (AMask_NotAllOnes | AMask_NotMixed));
if (IsAPow2)
MaskVal |= (IsEq ? (Mask_NotAllZeros | AMask_NotMixed)
: (Mask_AllZeros | AMask_Mixed));
} else if (ACst && CCst && ConstantExpr::getAnd(ACst, CCst) == CCst) {
MaskVal |= (IsEq ? AMask_Mixed : AMask_NotMixed);
}
if (B == C) {
MaskVal |= (IsEq ? (BMask_AllOnes | BMask_Mixed)
: (BMask_NotAllOnes | BMask_NotMixed));
if (IsBPow2)
MaskVal |= (IsEq ? (Mask_NotAllZeros | BMask_NotMixed)
: (Mask_AllZeros | BMask_Mixed));
} else if (BCst && CCst && ConstantExpr::getAnd(BCst, CCst) == CCst) {
MaskVal |= (IsEq ? BMask_Mixed : BMask_NotMixed);
}
return MaskVal;
}
/// Convert an analysis of a masked ICmp into its equivalent if all boolean
/// operations had the opposite sense. Since each "NotXXX" flag (recording !=)
/// is adjacent to the corresponding normal flag (recording ==), this just
/// involves swapping those bits over.
static unsigned conjugateICmpMask(unsigned Mask) {
unsigned NewMask;
NewMask = (Mask & (AMask_AllOnes | BMask_AllOnes | Mask_AllZeros |
AMask_Mixed | BMask_Mixed))
<< 1;
NewMask |= (Mask & (AMask_NotAllOnes | BMask_NotAllOnes | Mask_NotAllZeros |
AMask_NotMixed | BMask_NotMixed))
>> 1;
return NewMask;
}
// Adapts the external decomposeBitTestICmp for local use.
static bool decomposeBitTestICmp(Value *LHS, Value *RHS, CmpInst::Predicate &Pred,
Value *&X, Value *&Y, Value *&Z) {
APInt Mask;
if (!llvm::decomposeBitTestICmp(LHS, RHS, Pred, X, Mask))
return false;
Y = ConstantInt::get(X->getType(), Mask);
Z = ConstantInt::get(X->getType(), 0);
return true;
}
/// Handle (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E).
/// Return the pattern classes (from MaskedICmpType) for the left hand side and
/// the right hand side as a pair.
/// LHS and RHS are the left hand side and the right hand side ICmps and PredL
/// and PredR are their predicates, respectively.
static
Optional<std::pair<unsigned, unsigned>>
getMaskedTypeForICmpPair(Value *&A, Value *&B, Value *&C,
Value *&D, Value *&E, ICmpInst *LHS,
ICmpInst *RHS,
ICmpInst::Predicate &PredL,
ICmpInst::Predicate &PredR) {
// vectors are not (yet?) supported. Don't support pointers either.
if (!LHS->getOperand(0)->getType()->isIntegerTy() ||
!RHS->getOperand(0)->getType()->isIntegerTy())
return None;
// Here comes the tricky part:
// LHS might be of the form L11 & L12 == X, X == L21 & L22,
// and L11 & L12 == L21 & L22. The same goes for RHS.
// Now we must find those components L** and R**, that are equal, so
// that we can extract the parameters A, B, C, D, and E for the canonical
// above.
Value *L1 = LHS->getOperand(0);
Value *L2 = LHS->getOperand(1);
Value *L11, *L12, *L21, *L22;
// Check whether the icmp can be decomposed into a bit test.
if (decomposeBitTestICmp(L1, L2, PredL, L11, L12, L2)) {
L21 = L22 = L1 = nullptr;
} else {
// Look for ANDs in the LHS icmp.
if (!match(L1, m_And(m_Value(L11), m_Value(L12)))) {
// Any icmp can be viewed as being trivially masked; if it allows us to
// remove one, it's worth it.
L11 = L1;
L12 = Constant::getAllOnesValue(L1->getType());
}
if (!match(L2, m_And(m_Value(L21), m_Value(L22)))) {
L21 = L2;
L22 = Constant::getAllOnesValue(L2->getType());
}
}
// Bail if LHS was a icmp that can't be decomposed into an equality.
if (!ICmpInst::isEquality(PredL))
return None;
Value *R1 = RHS->getOperand(0);
Value *R2 = RHS->getOperand(1);
Value *R11, *R12;
bool Ok = false;
if (decomposeBitTestICmp(R1, R2, PredR, R11, R12, R2)) {
if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) {
A = R11;
D = R12;
} else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) {
A = R12;
D = R11;
} else {
return None;
}
E = R2;
R1 = nullptr;
Ok = true;
} else {
if (!match(R1, m_And(m_Value(R11), m_Value(R12)))) {
// As before, model no mask as a trivial mask if it'll let us do an
// optimization.
R11 = R1;
R12 = Constant::getAllOnesValue(R1->getType());
}
if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) {
A = R11;
D = R12;
E = R2;
Ok = true;
} else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) {
A = R12;
D = R11;
E = R2;
Ok = true;
}
}
// Bail if RHS was a icmp that can't be decomposed into an equality.
if (!ICmpInst::isEquality(PredR))
return None;
// Look for ANDs on the right side of the RHS icmp.
if (!Ok) {
if (!match(R2, m_And(m_Value(R11), m_Value(R12)))) {
R11 = R2;
R12 = Constant::getAllOnesValue(R2->getType());
}
if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) {
A = R11;
D = R12;
E = R1;
Ok = true;
} else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) {
A = R12;
D = R11;
E = R1;
Ok = true;
} else {
return None;
}
}
if (!Ok)
return None;
if (L11 == A) {
B = L12;
C = L2;
} else if (L12 == A) {
B = L11;
C = L2;
} else if (L21 == A) {
B = L22;
C = L1;
} else if (L22 == A) {
B = L21;
C = L1;
}
unsigned LeftType = getMaskedICmpType(A, B, C, PredL);
unsigned RightType = getMaskedICmpType(A, D, E, PredR);
return Optional<std::pair<unsigned, unsigned>>(std::make_pair(LeftType, RightType));
}
/// Try to fold (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E) into a single
/// (icmp(A & X) ==/!= Y), where the left-hand side is of type Mask_NotAllZeros
/// and the right hand side is of type BMask_Mixed. For example,
/// (icmp (A & 12) != 0) & (icmp (A & 15) == 8) -> (icmp (A & 15) == 8).
static Value * foldLogOpOfMaskedICmps_NotAllZeros_BMask_Mixed(
ICmpInst *LHS, ICmpInst *RHS, bool IsAnd,
Value *A, Value *B, Value *C, Value *D, Value *E,
ICmpInst::Predicate PredL, ICmpInst::Predicate PredR,
llvm::InstCombiner::BuilderTy &Builder) {
// We are given the canonical form:
// (icmp ne (A & B), 0) & (icmp eq (A & D), E).
// where D & E == E.
//
// If IsAnd is false, we get it in negated form:
// (icmp eq (A & B), 0) | (icmp ne (A & D), E) ->
// !((icmp ne (A & B), 0) & (icmp eq (A & D), E)).
//
// We currently handle the case of B, C, D, E are constant.
//
ConstantInt *BCst = dyn_cast<ConstantInt>(B);
if (!BCst)
return nullptr;
ConstantInt *CCst = dyn_cast<ConstantInt>(C);
if (!CCst)
return nullptr;
ConstantInt *DCst = dyn_cast<ConstantInt>(D);
if (!DCst)
return nullptr;
ConstantInt *ECst = dyn_cast<ConstantInt>(E);
if (!ECst)
return nullptr;
ICmpInst::Predicate NewCC = IsAnd ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE;
// Update E to the canonical form when D is a power of two and RHS is
// canonicalized as,
// (icmp ne (A & D), 0) -> (icmp eq (A & D), D) or
// (icmp ne (A & D), D) -> (icmp eq (A & D), 0).
if (PredR != NewCC)
ECst = cast<ConstantInt>(ConstantExpr::getXor(DCst, ECst));
// If B or D is zero, skip because if LHS or RHS can be trivially folded by
// other folding rules and this pattern won't apply any more.
if (BCst->getValue() == 0 || DCst->getValue() == 0)
return nullptr;
// If B and D don't intersect, ie. (B & D) == 0, no folding because we can't
// deduce anything from it.
// For example,
// (icmp ne (A & 12), 0) & (icmp eq (A & 3), 1) -> no folding.
if ((BCst->getValue() & DCst->getValue()) == 0)
return nullptr;
// If the following two conditions are met:
//
// 1. mask B covers only a single bit that's not covered by mask D, that is,
// (B & (B ^ D)) is a power of 2 (in other words, B minus the intersection of
// B and D has only one bit set) and,
//
// 2. RHS (and E) indicates that the rest of B's bits are zero (in other
// words, the intersection of B and D is zero), that is, ((B & D) & E) == 0
//
// then that single bit in B must be one and thus the whole expression can be
// folded to
// (A & (B | D)) == (B & (B ^ D)) | E.
//
// For example,
// (icmp ne (A & 12), 0) & (icmp eq (A & 7), 1) -> (icmp eq (A & 15), 9)
// (icmp ne (A & 15), 0) & (icmp eq (A & 7), 0) -> (icmp eq (A & 15), 8)
if ((((BCst->getValue() & DCst->getValue()) & ECst->getValue()) == 0) &&
(BCst->getValue() & (BCst->getValue() ^ DCst->getValue())).isPowerOf2()) {
APInt BorD = BCst->getValue() | DCst->getValue();
APInt BandBxorDorE = (BCst->getValue() & (BCst->getValue() ^ DCst->getValue())) |
ECst->getValue();
Value *NewMask = ConstantInt::get(BCst->getType(), BorD);
Value *NewMaskedValue = ConstantInt::get(BCst->getType(), BandBxorDorE);
Value *NewAnd = Builder.CreateAnd(A, NewMask);
return Builder.CreateICmp(NewCC, NewAnd, NewMaskedValue);
}
auto IsSubSetOrEqual = [](ConstantInt *C1, ConstantInt *C2) {
return (C1->getValue() & C2->getValue()) == C1->getValue();
};
auto IsSuperSetOrEqual = [](ConstantInt *C1, ConstantInt *C2) {
return (C1->getValue() & C2->getValue()) == C2->getValue();
};
// In the following, we consider only the cases where B is a superset of D, B
// is a subset of D, or B == D because otherwise there's at least one bit
// covered by B but not D, in which case we can't deduce much from it, so
// no folding (aside from the single must-be-one bit case right above.)
// For example,
// (icmp ne (A & 14), 0) & (icmp eq (A & 3), 1) -> no folding.
if (!IsSubSetOrEqual(BCst, DCst) && !IsSuperSetOrEqual(BCst, DCst))
return nullptr;
// At this point, either B is a superset of D, B is a subset of D or B == D.
// If E is zero, if B is a subset of (or equal to) D, LHS and RHS contradict
// and the whole expression becomes false (or true if negated), otherwise, no
// folding.
// For example,
// (icmp ne (A & 3), 0) & (icmp eq (A & 7), 0) -> false.
// (icmp ne (A & 15), 0) & (icmp eq (A & 3), 0) -> no folding.
if (ECst->isZero()) {
if (IsSubSetOrEqual(BCst, DCst))
return ConstantInt::get(LHS->getType(), !IsAnd);
return nullptr;
}
// At this point, B, D, E aren't zero and (B & D) == B, (B & D) == D or B ==
// D. If B is a superset of (or equal to) D, since E is not zero, LHS is
// subsumed by RHS (RHS implies LHS.) So the whole expression becomes
// RHS. For example,
// (icmp ne (A & 255), 0) & (icmp eq (A & 15), 8) -> (icmp eq (A & 15), 8).
// (icmp ne (A & 15), 0) & (icmp eq (A & 15), 8) -> (icmp eq (A & 15), 8).
if (IsSuperSetOrEqual(BCst, DCst))
return RHS;
// Otherwise, B is a subset of D. If B and E have a common bit set,
// ie. (B & E) != 0, then LHS is subsumed by RHS. For example.
// (icmp ne (A & 12), 0) & (icmp eq (A & 15), 8) -> (icmp eq (A & 15), 8).
assert(IsSubSetOrEqual(BCst, DCst) && "Precondition due to above code");
if ((BCst->getValue() & ECst->getValue()) != 0)
return RHS;
// Otherwise, LHS and RHS contradict and the whole expression becomes false
// (or true if negated.) For example,
// (icmp ne (A & 7), 0) & (icmp eq (A & 15), 8) -> false.
// (icmp ne (A & 6), 0) & (icmp eq (A & 15), 8) -> false.
return ConstantInt::get(LHS->getType(), !IsAnd);
}
/// Try to fold (icmp(A & B) ==/!= 0) &/| (icmp(A & D) ==/!= E) into a single
/// (icmp(A & X) ==/!= Y), where the left-hand side and the right hand side
/// aren't of the common mask pattern type.
static Value *foldLogOpOfMaskedICmpsAsymmetric(
ICmpInst *LHS, ICmpInst *RHS, bool IsAnd,
Value *A, Value *B, Value *C, Value *D, Value *E,
ICmpInst::Predicate PredL, ICmpInst::Predicate PredR,
unsigned LHSMask, unsigned RHSMask,
llvm::InstCombiner::BuilderTy &Builder) {
assert(ICmpInst::isEquality(PredL) && ICmpInst::isEquality(PredR) &&
"Expected equality predicates for masked type of icmps.");
// Handle Mask_NotAllZeros-BMask_Mixed cases.
// (icmp ne/eq (A & B), C) &/| (icmp eq/ne (A & D), E), or
// (icmp eq/ne (A & B), C) &/| (icmp ne/eq (A & D), E)
// which gets swapped to
// (icmp ne/eq (A & D), E) &/| (icmp eq/ne (A & B), C).
if (!IsAnd) {
LHSMask = conjugateICmpMask(LHSMask);
RHSMask = conjugateICmpMask(RHSMask);
}
if ((LHSMask & Mask_NotAllZeros) && (RHSMask & BMask_Mixed)) {
if (Value *V = foldLogOpOfMaskedICmps_NotAllZeros_BMask_Mixed(
LHS, RHS, IsAnd, A, B, C, D, E,
PredL, PredR, Builder)) {
return V;
}
} else if ((LHSMask & BMask_Mixed) && (RHSMask & Mask_NotAllZeros)) {
if (Value *V = foldLogOpOfMaskedICmps_NotAllZeros_BMask_Mixed(
RHS, LHS, IsAnd, A, D, E, B, C,
PredR, PredL, Builder)) {
return V;
}
}
return nullptr;
}
/// Try to fold (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E)
/// into a single (icmp(A & X) ==/!= Y).
static Value *foldLogOpOfMaskedICmps(ICmpInst *LHS, ICmpInst *RHS, bool IsAnd,
llvm::InstCombiner::BuilderTy &Builder) {
Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr, *E = nullptr;
ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate();
Optional<std::pair<unsigned, unsigned>> MaskPair =
getMaskedTypeForICmpPair(A, B, C, D, E, LHS, RHS, PredL, PredR);
if (!MaskPair)
return nullptr;
assert(ICmpInst::isEquality(PredL) && ICmpInst::isEquality(PredR) &&
"Expected equality predicates for masked type of icmps.");
unsigned LHSMask = MaskPair->first;
unsigned RHSMask = MaskPair->second;
unsigned Mask = LHSMask & RHSMask;
if (Mask == 0) {
// Even if the two sides don't share a common pattern, check if folding can
// still happen.
if (Value *V = foldLogOpOfMaskedICmpsAsymmetric(
LHS, RHS, IsAnd, A, B, C, D, E, PredL, PredR, LHSMask, RHSMask,
Builder))
return V;
return nullptr;
}
// In full generality:
// (icmp (A & B) Op C) | (icmp (A & D) Op E)
// == ![ (icmp (A & B) !Op C) & (icmp (A & D) !Op E) ]
//
// If the latter can be converted into (icmp (A & X) Op Y) then the former is
// equivalent to (icmp (A & X) !Op Y).
//
// Therefore, we can pretend for the rest of this function that we're dealing
// with the conjunction, provided we flip the sense of any comparisons (both
// input and output).
// In most cases we're going to produce an EQ for the "&&" case.
ICmpInst::Predicate NewCC = IsAnd ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE;
if (!IsAnd) {
// Convert the masking analysis into its equivalent with negated
// comparisons.
Mask = conjugateICmpMask(Mask);
}
if (Mask & Mask_AllZeros) {
// (icmp eq (A & B), 0) & (icmp eq (A & D), 0)
// -> (icmp eq (A & (B|D)), 0)
Value *NewOr = Builder.CreateOr(B, D);
Value *NewAnd = Builder.CreateAnd(A, NewOr);
// We can't use C as zero because we might actually handle
// (icmp ne (A & B), B) & (icmp ne (A & D), D)
// with B and D, having a single bit set.
Value *Zero = Constant::getNullValue(A->getType());
return Builder.CreateICmp(NewCC, NewAnd, Zero);
}
if (Mask & BMask_AllOnes) {
// (icmp eq (A & B), B) & (icmp eq (A & D), D)
// -> (icmp eq (A & (B|D)), (B|D))
Value *NewOr = Builder.CreateOr(B, D);
Value *NewAnd = Builder.CreateAnd(A, NewOr);
return Builder.CreateICmp(NewCC, NewAnd, NewOr);
}
if (Mask & AMask_AllOnes) {
// (icmp eq (A & B), A) & (icmp eq (A & D), A)
// -> (icmp eq (A & (B&D)), A)
Value *NewAnd1 = Builder.CreateAnd(B, D);
Value *NewAnd2 = Builder.CreateAnd(A, NewAnd1);
return Builder.CreateICmp(NewCC, NewAnd2, A);
}
// Remaining cases assume at least that B and D are constant, and depend on
// their actual values. This isn't strictly necessary, just a "handle the
// easy cases for now" decision.
ConstantInt *BCst = dyn_cast<ConstantInt>(B);
if (!BCst)
return nullptr;
ConstantInt *DCst = dyn_cast<ConstantInt>(D);
if (!DCst)
return nullptr;
if (Mask & (Mask_NotAllZeros | BMask_NotAllOnes)) {
// (icmp ne (A & B), 0) & (icmp ne (A & D), 0) and
// (icmp ne (A & B), B) & (icmp ne (A & D), D)
// -> (icmp ne (A & B), 0) or (icmp ne (A & D), 0)
// Only valid if one of the masks is a superset of the other (check "B&D" is
// the same as either B or D).
APInt NewMask = BCst->getValue() & DCst->getValue();
if (NewMask == BCst->getValue())
return LHS;
else if (NewMask == DCst->getValue())
return RHS;
}
if (Mask & AMask_NotAllOnes) {
// (icmp ne (A & B), B) & (icmp ne (A & D), D)
// -> (icmp ne (A & B), A) or (icmp ne (A & D), A)
// Only valid if one of the masks is a superset of the other (check "B|D" is
// the same as either B or D).
APInt NewMask = BCst->getValue() | DCst->getValue();
if (NewMask == BCst->getValue())
return LHS;
else if (NewMask == DCst->getValue())
return RHS;
}
if (Mask & BMask_Mixed) {
// (icmp eq (A & B), C) & (icmp eq (A & D), E)
// We already know that B & C == C && D & E == E.
// If we can prove that (B & D) & (C ^ E) == 0, that is, the bits of
// C and E, which are shared by both the mask B and the mask D, don't
// contradict, then we can transform to
// -> (icmp eq (A & (B|D)), (C|E))
// Currently, we only handle the case of B, C, D, and E being constant.
// We can't simply use C and E because we might actually handle
// (icmp ne (A & B), B) & (icmp eq (A & D), D)
// with B and D, having a single bit set.
ConstantInt *CCst = dyn_cast<ConstantInt>(C);
if (!CCst)
return nullptr;
ConstantInt *ECst = dyn_cast<ConstantInt>(E);
if (!ECst)
return nullptr;
if (PredL != NewCC)
CCst = cast<ConstantInt>(ConstantExpr::getXor(BCst, CCst));
if (PredR != NewCC)
ECst = cast<ConstantInt>(ConstantExpr::getXor(DCst, ECst));
// If there is a conflict, we should actually return a false for the
// whole construct.
if (((BCst->getValue() & DCst->getValue()) &
(CCst->getValue() ^ ECst->getValue())).getBoolValue())
return ConstantInt::get(LHS->getType(), !IsAnd);
Value *NewOr1 = Builder.CreateOr(B, D);
Value *NewOr2 = ConstantExpr::getOr(CCst, ECst);
Value *NewAnd = Builder.CreateAnd(A, NewOr1);
return Builder.CreateICmp(NewCC, NewAnd, NewOr2);
}
return nullptr;
}
/// Try to fold a signed range checked with lower bound 0 to an unsigned icmp.
/// Example: (icmp sge x, 0) & (icmp slt x, n) --> icmp ult x, n
/// If \p Inverted is true then the check is for the inverted range, e.g.
/// (icmp slt x, 0) | (icmp sgt x, n) --> icmp ugt x, n
Value *InstCombiner::simplifyRangeCheck(ICmpInst *Cmp0, ICmpInst *Cmp1,
bool Inverted) {
// Check the lower range comparison, e.g. x >= 0
// InstCombine already ensured that if there is a constant it's on the RHS.
ConstantInt *RangeStart = dyn_cast<ConstantInt>(Cmp0->getOperand(1));
if (!RangeStart)
return nullptr;
ICmpInst::Predicate Pred0 = (Inverted ? Cmp0->getInversePredicate() :
Cmp0->getPredicate());
// Accept x > -1 or x >= 0 (after potentially inverting the predicate).
if (!((Pred0 == ICmpInst::ICMP_SGT && RangeStart->isMinusOne()) ||
(Pred0 == ICmpInst::ICMP_SGE && RangeStart->isZero())))
return nullptr;
ICmpInst::Predicate Pred1 = (Inverted ? Cmp1->getInversePredicate() :
Cmp1->getPredicate());
Value *Input = Cmp0->getOperand(0);
Value *RangeEnd;
if (Cmp1->getOperand(0) == Input) {
// For the upper range compare we have: icmp x, n
RangeEnd = Cmp1->getOperand(1);
} else if (Cmp1->getOperand(1) == Input) {
// For the upper range compare we have: icmp n, x
RangeEnd = Cmp1->getOperand(0);
Pred1 = ICmpInst::getSwappedPredicate(Pred1);
} else {
return nullptr;
}
// Check the upper range comparison, e.g. x < n
ICmpInst::Predicate NewPred;
switch (Pred1) {
case ICmpInst::ICMP_SLT: NewPred = ICmpInst::ICMP_ULT; break;
case ICmpInst::ICMP_SLE: NewPred = ICmpInst::ICMP_ULE; break;
default: return nullptr;
}
// This simplification is only valid if the upper range is not negative.
KnownBits Known = computeKnownBits(RangeEnd, /*Depth=*/0, Cmp1);
if (!Known.isNonNegative())
return nullptr;
if (Inverted)
NewPred = ICmpInst::getInversePredicate(NewPred);
return Builder.CreateICmp(NewPred, Input, RangeEnd);
}
static Value *
foldAndOrOfEqualityCmpsWithConstants(ICmpInst *LHS, ICmpInst *RHS,
bool JoinedByAnd,
InstCombiner::BuilderTy &Builder) {
Value *X = LHS->getOperand(0);
if (X != RHS->getOperand(0))
return nullptr;
const APInt *C1, *C2;
if (!match(LHS->getOperand(1), m_APInt(C1)) ||
!match(RHS->getOperand(1), m_APInt(C2)))
return nullptr;
// We only handle (X != C1 && X != C2) and (X == C1 || X == C2).
ICmpInst::Predicate Pred = LHS->getPredicate();
if (Pred != RHS->getPredicate())
return nullptr;
if (JoinedByAnd && Pred != ICmpInst::ICMP_NE)
return nullptr;
if (!JoinedByAnd && Pred != ICmpInst::ICMP_EQ)
return nullptr;
// The larger unsigned constant goes on the right.
if (C1->ugt(*C2))
std::swap(C1, C2);
APInt Xor = *C1 ^ *C2;
if (Xor.isPowerOf2()) {
// If LHSC and RHSC differ by only one bit, then set that bit in X and
// compare against the larger constant:
// (X == C1 || X == C2) --> (X | (C1 ^ C2)) == C2
// (X != C1 && X != C2) --> (X | (C1 ^ C2)) != C2
// We choose an 'or' with a Pow2 constant rather than the inverse mask with
// 'and' because that may lead to smaller codegen from a smaller constant.
Value *Or = Builder.CreateOr(X, ConstantInt::get(X->getType(), Xor));
return Builder.CreateICmp(Pred, Or, ConstantInt::get(X->getType(), *C2));
}
// Special case: get the ordering right when the values wrap around zero.
// Ie, we assumed the constants were unsigned when swapping earlier.
if (C1->isNullValue() && C2->isAllOnesValue())
std::swap(C1, C2);
if (*C1 == *C2 - 1) {
// (X == 13 || X == 14) --> X - 13 <=u 1
// (X != 13 && X != 14) --> X - 13 >u 1
// An 'add' is the canonical IR form, so favor that over a 'sub'.
Value *Add = Builder.CreateAdd(X, ConstantInt::get(X->getType(), -(*C1)));
auto NewPred = JoinedByAnd ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_ULE;
return Builder.CreateICmp(NewPred, Add, ConstantInt::get(X->getType(), 1));
}
return nullptr;
}
// Fold (iszero(A & K1) | iszero(A & K2)) -> (A & (K1 | K2)) != (K1 | K2)
// Fold (!iszero(A & K1) & !iszero(A & K2)) -> (A & (K1 | K2)) == (K1 | K2)
Value *InstCombiner::foldAndOrOfICmpsOfAndWithPow2(ICmpInst *LHS, ICmpInst *RHS,
bool JoinedByAnd,
Instruction &CxtI) {
ICmpInst::Predicate Pred = LHS->getPredicate();
if (Pred != RHS->getPredicate())
return nullptr;
if (JoinedByAnd && Pred != ICmpInst::ICMP_NE)
return nullptr;
if (!JoinedByAnd && Pred != ICmpInst::ICMP_EQ)
return nullptr;
// TODO support vector splats
ConstantInt *LHSC = dyn_cast<ConstantInt>(LHS->getOperand(1));
ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS->getOperand(1));
if (!LHSC || !RHSC || !LHSC->isZero() || !RHSC->isZero())
return nullptr;
Value *A, *B, *C, *D;
if (match(LHS->getOperand(0), m_And(m_Value(A), m_Value(B))) &&
match(RHS->getOperand(0), m_And(m_Value(C), m_Value(D)))) {
if (A == D || B == D)
std::swap(C, D);
if (B == C)
std::swap(A, B);
if (A == C &&
isKnownToBeAPowerOfTwo(B, false, 0, &CxtI) &&
isKnownToBeAPowerOfTwo(D, false, 0, &CxtI)) {
Value *Mask = Builder.CreateOr(B, D);
Value *Masked = Builder.CreateAnd(A, Mask);
auto NewPred = JoinedByAnd ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE;
return Builder.CreateICmp(NewPred, Masked, Mask);
}
}
return nullptr;
}
/// General pattern:
/// X & Y
///
/// Where Y is checking that all the high bits (covered by a mask 4294967168)
/// are uniform, i.e. %arg & 4294967168 can be either 4294967168 or 0
/// Pattern can be one of:
/// %t = add i32 %arg, 128
/// %r = icmp ult i32 %t, 256
/// Or
/// %t0 = shl i32 %arg, 24
/// %t1 = ashr i32 %t0, 24
/// %r = icmp eq i32 %t1, %arg
/// Or
/// %t0 = trunc i32 %arg to i8
/// %t1 = sext i8 %t0 to i32
/// %r = icmp eq i32 %t1, %arg
/// This pattern is a signed truncation check.
///
/// And X is checking that some bit in that same mask is zero.
/// I.e. can be one of:
/// %r = icmp sgt i32 %arg, -1
/// Or
/// %t = and i32 %arg, 2147483648
/// %r = icmp eq i32 %t, 0
///
/// Since we are checking that all the bits in that mask are the same,
/// and a particular bit is zero, what we are really checking is that all the
/// masked bits are zero.
/// So this should be transformed to:
/// %r = icmp ult i32 %arg, 128
static Value *foldSignedTruncationCheck(ICmpInst *ICmp0, ICmpInst *ICmp1,
Instruction &CxtI,
InstCombiner::BuilderTy &Builder) {
assert(CxtI.getOpcode() == Instruction::And);
// Match icmp ult (add %arg, C01), C1 (C1 == C01 << 1; powers of two)
auto tryToMatchSignedTruncationCheck = [](ICmpInst *ICmp, Value *&X,
APInt &SignBitMask) -> bool {
CmpInst::Predicate Pred;
const APInt *I01, *I1; // powers of two; I1 == I01 << 1
if (!(match(ICmp,
m_ICmp(Pred, m_Add(m_Value(X), m_Power2(I01)), m_Power2(I1))) &&
Pred == ICmpInst::ICMP_ULT && I1->ugt(*I01) && I01->shl(1) == *I1))
return false;
// Which bit is the new sign bit as per the 'signed truncation' pattern?
SignBitMask = *I01;
return true;
};
// One icmp needs to be 'signed truncation check'.
// We need to match this first, else we will mismatch commutative cases.
Value *X1;
APInt HighestBit;
ICmpInst *OtherICmp;
if (tryToMatchSignedTruncationCheck(ICmp1, X1, HighestBit))
OtherICmp = ICmp0;
else if (tryToMatchSignedTruncationCheck(ICmp0, X1, HighestBit))
OtherICmp = ICmp1;
else
return nullptr;
assert(HighestBit.isPowerOf2() && "expected to be power of two (non-zero)");
// Try to match/decompose into: icmp eq (X & Mask), 0
auto tryToDecompose = [](ICmpInst *ICmp, Value *&X,
APInt &UnsetBitsMask) -> bool {
CmpInst::Predicate Pred = ICmp->getPredicate();
// Can it be decomposed into icmp eq (X & Mask), 0 ?
if (llvm::decomposeBitTestICmp(ICmp->getOperand(0), ICmp->getOperand(1),
Pred, X, UnsetBitsMask,
/*LookThroughTrunc=*/false) &&
Pred == ICmpInst::ICMP_EQ)
return true;
// Is it icmp eq (X & Mask), 0 already?
const APInt *Mask;
if (match(ICmp, m_ICmp(Pred, m_And(m_Value(X), m_APInt(Mask)), m_Zero())) &&
Pred == ICmpInst::ICMP_EQ) {
UnsetBitsMask = *Mask;
return true;
}
return false;
};
// And the other icmp needs to be decomposable into a bit test.
Value *X0;
APInt UnsetBitsMask;
if (!tryToDecompose(OtherICmp, X0, UnsetBitsMask))
return nullptr;
assert(!UnsetBitsMask.isNullValue() && "empty mask makes no sense.");
// Are they working on the same value?
Value *X;
if (X1 == X0) {
// Ok as is.
X = X1;
} else if (match(X0, m_Trunc(m_Specific(X1)))) {
UnsetBitsMask = UnsetBitsMask.zext(X1->getType()->getScalarSizeInBits());
X = X1;
} else
return nullptr;
// So which bits should be uniform as per the 'signed truncation check'?
// (all the bits starting with (i.e. including) HighestBit)
APInt SignBitsMask = ~(HighestBit - 1U);
// UnsetBitsMask must have some common bits with SignBitsMask,
if (!UnsetBitsMask.intersects(SignBitsMask))
return nullptr;
// Does UnsetBitsMask contain any bits outside of SignBitsMask?
if (!UnsetBitsMask.isSubsetOf(SignBitsMask)) {
APInt OtherHighestBit = (~UnsetBitsMask) + 1U;
if (!OtherHighestBit.isPowerOf2())
return nullptr;
HighestBit = APIntOps::umin(HighestBit, OtherHighestBit);
}
// Else, if it does not, then all is ok as-is.
// %r = icmp ult %X, SignBit
return Builder.CreateICmpULT(X, ConstantInt::get(X->getType(), HighestBit),
CxtI.getName() + ".simplified");
}
/// Reduce a pair of compares that check if a value has exactly 1 bit set.
static Value *foldIsPowerOf2(ICmpInst *Cmp0, ICmpInst *Cmp1, bool JoinedByAnd,
InstCombiner::BuilderTy &Builder) {
// Handle 'and' / 'or' commutation: make the equality check the first operand.
if (JoinedByAnd && Cmp1->getPredicate() == ICmpInst::ICMP_NE)
std::swap(Cmp0, Cmp1);
else if (!JoinedByAnd && Cmp1->getPredicate() == ICmpInst::ICMP_EQ)
std::swap(Cmp0, Cmp1);
// (X != 0) && (ctpop(X) u< 2) --> ctpop(X) == 1
CmpInst::Predicate Pred0, Pred1;
Value *X;
if (JoinedByAnd && match(Cmp0, m_ICmp(Pred0, m_Value(X), m_ZeroInt())) &&
match(Cmp1, m_ICmp(Pred1, m_Intrinsic<Intrinsic::ctpop>(m_Specific(X)),
m_SpecificInt(2))) &&
Pred0 == ICmpInst::ICMP_NE && Pred1 == ICmpInst::ICMP_ULT) {
Value *CtPop = Cmp1->getOperand(0);
return Builder.CreateICmpEQ(CtPop, ConstantInt::get(CtPop->getType(), 1));
}
// (X == 0) || (ctpop(X) u> 1) --> ctpop(X) != 1
if (!JoinedByAnd && match(Cmp0, m_ICmp(Pred0, m_Value(X), m_ZeroInt())) &&
match(Cmp1, m_ICmp(Pred1, m_Intrinsic<Intrinsic::ctpop>(m_Specific(X)),
m_SpecificInt(1))) &&
Pred0 == ICmpInst::ICMP_EQ && Pred1 == ICmpInst::ICMP_UGT) {
Value *CtPop = Cmp1->getOperand(0);
return Builder.CreateICmpNE(CtPop, ConstantInt::get(CtPop->getType(), 1));
}
return nullptr;
}
/// Fold (icmp)&(icmp) if possible.
Value *InstCombiner::foldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS,
Instruction &CxtI) {
// Fold (!iszero(A & K1) & !iszero(A & K2)) -> (A & (K1 | K2)) == (K1 | K2)
// if K1 and K2 are a one-bit mask.
if (Value *V = foldAndOrOfICmpsOfAndWithPow2(LHS, RHS, true, CxtI))
return V;
ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate();
// (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
if (predicatesFoldable(PredL, PredR)) {
if (LHS->getOperand(0) == RHS->getOperand(1) &&
LHS->getOperand(1) == RHS->getOperand(0))
LHS->swapOperands();
if (LHS->getOperand(0) == RHS->getOperand(0) &&
LHS->getOperand(1) == RHS->getOperand(1)) {
Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1);
unsigned Code = getICmpCode(LHS) & getICmpCode(RHS);
bool IsSigned = LHS->isSigned() || RHS->isSigned();
return getNewICmpValue(Code, IsSigned, Op0, Op1, Builder);
}
}
// handle (roughly): (icmp eq (A & B), C) & (icmp eq (A & D), E)
if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, true, Builder))
return V;
// E.g. (icmp sge x, 0) & (icmp slt x, n) --> icmp ult x, n
if (Value *V = simplifyRangeCheck(LHS, RHS, /*Inverted=*/false))
return V;
// E.g. (icmp slt x, n) & (icmp sge x, 0) --> icmp ult x, n
if (Value *V = simplifyRangeCheck(RHS, LHS, /*Inverted=*/false))
return V;
if (Value *V = foldAndOrOfEqualityCmpsWithConstants(LHS, RHS, true, Builder))
return V;
if (Value *V = foldSignedTruncationCheck(LHS, RHS, CxtI, Builder))
return V;
if (Value *V = foldIsPowerOf2(LHS, RHS, true /* JoinedByAnd */, Builder))
return V;
// This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2).
Value *LHS0 = LHS->getOperand(0), *RHS0 = RHS->getOperand(0);
ConstantInt *LHSC = dyn_cast<ConstantInt>(LHS->getOperand(1));
ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS->getOperand(1));
if (!LHSC || !RHSC)
return nullptr;
if (LHSC == RHSC && PredL == PredR) {
// (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (A|B), C)
// where C is a power of 2 or
// (icmp eq A, 0) & (icmp eq B, 0) --> (icmp eq (A|B), 0)
if ((PredL == ICmpInst::ICMP_ULT && LHSC->getValue().isPowerOf2()) ||
(PredL == ICmpInst::ICMP_EQ && LHSC->isZero())) {
Value *NewOr = Builder.CreateOr(LHS0, RHS0);
return Builder.CreateICmp(PredL, NewOr, LHSC);
}
}
// (trunc x) == C1 & (and x, CA) == C2 -> (and x, CA|CMAX) == C1|C2
// where CMAX is the all ones value for the truncated type,
// iff the lower bits of C2 and CA are zero.
if (PredL == ICmpInst::ICMP_EQ && PredL == PredR && LHS->hasOneUse() &&
RHS->hasOneUse()) {
Value *V;
ConstantInt *AndC, *SmallC = nullptr, *BigC = nullptr;
// (trunc x) == C1 & (and x, CA) == C2
// (and x, CA) == C2 & (trunc x) == C1
if (match(RHS0, m_Trunc(m_Value(V))) &&
match(LHS0, m_And(m_Specific(V), m_ConstantInt(AndC)))) {
SmallC = RHSC;
BigC = LHSC;
} else if (match(LHS0, m_Trunc(m_Value(V))) &&
match(RHS0, m_And(m_Specific(V), m_ConstantInt(AndC)))) {
SmallC = LHSC;
BigC = RHSC;
}
if (SmallC && BigC) {
unsigned BigBitSize = BigC->getType()->getBitWidth();
unsigned SmallBitSize = SmallC->getType()->getBitWidth();
// Check that the low bits are zero.
APInt Low = APInt::getLowBitsSet(BigBitSize, SmallBitSize);
if ((Low & AndC->getValue()).isNullValue() &&
(Low & BigC->getValue()).isNullValue()) {
Value *NewAnd = Builder.CreateAnd(V, Low | AndC->getValue());
APInt N = SmallC->getValue().zext(BigBitSize) | BigC->getValue();
Value *NewVal = ConstantInt::get(AndC->getType()->getContext(), N);
return Builder.CreateICmp(PredL, NewAnd, NewVal);
}
}
}
// From here on, we only handle:
// (icmp1 A, C1) & (icmp2 A, C2) --> something simpler.
if (LHS0 != RHS0)
return nullptr;
// ICMP_[US][GL]E X, C is folded to ICMP_[US][GL]T elsewhere.
if (PredL == ICmpInst::ICMP_UGE || PredL == ICmpInst::ICMP_ULE ||
PredR == ICmpInst::ICMP_UGE || PredR == ICmpInst::ICMP_ULE ||
PredL == ICmpInst::ICMP_SGE || PredL == ICmpInst::ICMP_SLE ||
PredR == ICmpInst::ICMP_SGE || PredR == ICmpInst::ICMP_SLE)
return nullptr;
// We can't fold (ugt x, C) & (sgt x, C2).
if (!predicatesFoldable(PredL, PredR))
return nullptr;
// Ensure that the larger constant is on the RHS.
bool ShouldSwap;
if (CmpInst::isSigned(PredL) ||
(ICmpInst::isEquality(PredL) && CmpInst::isSigned(PredR)))
ShouldSwap = LHSC->getValue().sgt(RHSC->getValue());
else
ShouldSwap = LHSC->getValue().ugt(RHSC->getValue());
if (ShouldSwap) {
std::swap(LHS, RHS);
std::swap(LHSC, RHSC);
std::swap(PredL, PredR);
}
// At this point, we know we have two icmp instructions
// comparing a value against two constants and and'ing the result
// together. Because of the above check, we know that we only have
// icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know
// (from the icmp folding check above), that the two constants
// are not equal and that the larger constant is on the RHS
assert(LHSC != RHSC && "Compares not folded above?");
switch (PredL) {
default:
llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_NE:
switch (PredR) {
default:
llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_ULT:
if (LHSC == SubOne(RHSC)) // (X != 13 & X u< 14) -> X < 13
return Builder.CreateICmpULT(LHS0, LHSC);
if (LHSC->isZero()) // (X != 0 & X u< 14) -> X-1 u< 13
return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
false, true);
break; // (X != 13 & X u< 15) -> no change
case ICmpInst::ICMP_SLT:
if (LHSC == SubOne(RHSC)) // (X != 13 & X s< 14) -> X < 13
return Builder.CreateICmpSLT(LHS0, LHSC);
break; // (X != 13 & X s< 15) -> no change
case ICmpInst::ICMP_NE:
// Potential folds for this case should already be handled.
break;
}
break;
case ICmpInst::ICMP_UGT:
switch (PredR) {
default:
llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_NE:
if (RHSC == AddOne(LHSC)) // (X u> 13 & X != 14) -> X u> 14
return Builder.CreateICmp(PredL, LHS0, RHSC);
break; // (X u> 13 & X != 15) -> no change
case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) <u 1
return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
false, true);
}
break;
case ICmpInst::ICMP_SGT:
switch (PredR) {
default:
llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_NE:
if (RHSC == AddOne(LHSC)) // (X s> 13 & X != 14) -> X s> 14
return Builder.CreateICmp(PredL, LHS0, RHSC);
break; // (X s> 13 & X != 15) -> no change
case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) s< 1
return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(), true,
true);
}
break;
}
return nullptr;
}
Value *InstCombiner::foldLogicOfFCmps(FCmpInst *LHS, FCmpInst *RHS, bool IsAnd) {
Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1);
Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1);
FCmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate();
if (LHS0 == RHS1 && RHS0 == LHS1) {
// Swap RHS operands to match LHS.
PredR = FCmpInst::getSwappedPredicate(PredR);
std::swap(RHS0, RHS1);
}
// Simplify (fcmp cc0 x, y) & (fcmp cc1 x, y).
// Suppose the relation between x and y is R, where R is one of
// U(1000), L(0100), G(0010) or E(0001), and CC0 and CC1 are the bitmasks for
// testing the desired relations.
//
// Since (R & CC0) and (R & CC1) are either R or 0, we actually have this:
// bool(R & CC0) && bool(R & CC1)
// = bool((R & CC0) & (R & CC1))
// = bool(R & (CC0 & CC1)) <= by re-association, commutation, and idempotency
//
// Since (R & CC0) and (R & CC1) are either R or 0, we actually have this:
// bool(R & CC0) || bool(R & CC1)
// = bool((R & CC0) | (R & CC1))
// = bool(R & (CC0 | CC1)) <= by reversed distribution (contribution? ;)
if (LHS0 == RHS0 && LHS1 == RHS1) {
unsigned FCmpCodeL = getFCmpCode(PredL);
unsigned FCmpCodeR = getFCmpCode(PredR);
unsigned NewPred = IsAnd ? FCmpCodeL & FCmpCodeR : FCmpCodeL | FCmpCodeR;
return getFCmpValue(NewPred, LHS0, LHS1, Builder);
}
if ((PredL == FCmpInst::FCMP_ORD && PredR == FCmpInst::FCMP_ORD && IsAnd) ||
(PredL == FCmpInst::FCMP_UNO && PredR == FCmpInst::FCMP_UNO && !IsAnd)) {
if (LHS0->getType() != RHS0->getType())
return nullptr;
// FCmp canonicalization ensures that (fcmp ord/uno X, X) and
// (fcmp ord/uno X, C) will be transformed to (fcmp X, +0.0).
if (match(LHS1, m_PosZeroFP()) && match(RHS1, m_PosZeroFP()))
// Ignore the constants because they are obviously not NANs:
// (fcmp ord x, 0.0) & (fcmp ord y, 0.0) -> (fcmp ord x, y)
// (fcmp uno x, 0.0) | (fcmp uno y, 0.0) -> (fcmp uno x, y)
return Builder.CreateFCmp(PredL, LHS0, RHS0);
}
return nullptr;
}
/// This a limited reassociation for a special case (see above) where we are
/// checking if two values are either both NAN (unordered) or not-NAN (ordered).
/// This could be handled more generally in '-reassociation', but it seems like
/// an unlikely pattern for a large number of logic ops and fcmps.
static Instruction *reassociateFCmps(BinaryOperator &BO,
InstCombiner::BuilderTy &Builder) {
Instruction::BinaryOps Opcode = BO.getOpcode();
assert((Opcode == Instruction::And || Opcode == Instruction::Or) &&
"Expecting and/or op for fcmp transform");
// There are 4 commuted variants of the pattern. Canonicalize operands of this
// logic op so an fcmp is operand 0 and a matching logic op is operand 1.
Value *Op0 = BO.getOperand(0), *Op1 = BO.getOperand(1), *X;
FCmpInst::Predicate Pred;
if (match(Op1, m_FCmp(Pred, m_Value(), m_AnyZeroFP())))
std::swap(Op0, Op1);
// Match inner binop and the predicate for combining 2 NAN checks into 1.
BinaryOperator *BO1;
FCmpInst::Predicate NanPred = Opcode == Instruction::And ? FCmpInst::FCMP_ORD
: FCmpInst::FCMP_UNO;
if (!match(Op0, m_FCmp(Pred, m_Value(X), m_AnyZeroFP())) || Pred != NanPred ||
!match(Op1, m_BinOp(BO1)) || BO1->getOpcode() != Opcode)
return nullptr;
// The inner logic op must have a matching fcmp operand.
Value *BO10 = BO1->getOperand(0), *BO11 = BO1->getOperand(1), *Y;
if (!match(BO10, m_FCmp(Pred, m_Value(Y), m_AnyZeroFP())) ||
Pred != NanPred || X->getType() != Y->getType())
std::swap(BO10, BO11);
if (!match(BO10, m_FCmp(Pred, m_Value(Y), m_AnyZeroFP())) ||
Pred != NanPred || X->getType() != Y->getType())
return nullptr;
// and (fcmp ord X, 0), (and (fcmp ord Y, 0), Z) --> and (fcmp ord X, Y), Z
// or (fcmp uno X, 0), (or (fcmp uno Y, 0), Z) --> or (fcmp uno X, Y), Z
Value *NewFCmp = Builder.CreateFCmp(Pred, X, Y);
if (auto *NewFCmpInst = dyn_cast<FCmpInst>(NewFCmp)) {
// Intersect FMF from the 2 source fcmps.
NewFCmpInst->copyIRFlags(Op0);
NewFCmpInst->andIRFlags(BO10);
}
return BinaryOperator::Create(Opcode, NewFCmp, BO11);
}
/// Match De Morgan's Laws:
/// (~A & ~B) == (~(A | B))
/// (~A | ~B) == (~(A & B))
static Instruction *matchDeMorgansLaws(BinaryOperator &I,
InstCombiner::BuilderTy &Builder) {
auto Opcode = I.getOpcode();
assert((Opcode == Instruction::And || Opcode == Instruction::Or) &&
"Trying to match De Morgan's Laws with something other than and/or");
// Flip the logic operation.
Opcode = (Opcode == Instruction::And) ? Instruction::Or : Instruction::And;
Value *A, *B;
if (match(I.getOperand(0), m_OneUse(m_Not(m_Value(A)))) &&
match(I.getOperand(1), m_OneUse(m_Not(m_Value(B)))) &&
!IsFreeToInvert(A, A->hasOneUse()) &&
!IsFreeToInvert(B, B->hasOneUse())) {
Value *AndOr = Builder.CreateBinOp(Opcode, A, B, I.getName() + ".demorgan");
return BinaryOperator::CreateNot(AndOr);
}
return nullptr;
}
bool InstCombiner::shouldOptimizeCast(CastInst *CI) {
Value *CastSrc = CI->getOperand(0);
// Noop casts and casts of constants should be eliminated trivially.
if (CI->getSrcTy() == CI->getDestTy() || isa<Constant>(CastSrc))
return false;
// If this cast is paired with another cast that can be eliminated, we prefer
// to have it eliminated.
if (const auto *PrecedingCI = dyn_cast<CastInst>(CastSrc))
if (isEliminableCastPair(PrecedingCI, CI))
return false;
return true;
}
/// Fold {and,or,xor} (cast X), C.
static Instruction *foldLogicCastConstant(BinaryOperator &Logic, CastInst *Cast,
InstCombiner::BuilderTy &Builder) {
Constant *C = dyn_cast<Constant>(Logic.getOperand(1));
if (!C)
return nullptr;
auto LogicOpc = Logic.getOpcode();
Type *DestTy = Logic.getType();
Type *SrcTy = Cast->getSrcTy();
// Move the logic operation ahead of a zext or sext if the constant is
// unchanged in the smaller source type. Performing the logic in a smaller
// type may provide more information to later folds, and the smaller logic
// instruction may be cheaper (particularly in the case of vectors).
Value *X;
if (match(Cast, m_OneUse(m_ZExt(m_Value(X))))) {
Constant *TruncC = ConstantExpr::getTrunc(C, SrcTy);
Constant *ZextTruncC = ConstantExpr::getZExt(TruncC, DestTy);
if (ZextTruncC == C) {
// LogicOpc (zext X), C --> zext (LogicOpc X, C)
Value *NewOp = Builder.CreateBinOp(LogicOpc, X, TruncC);
return new ZExtInst(NewOp, DestTy);
}
}
if (match(Cast, m_OneUse(m_SExt(m_Value(X))))) {
Constant *TruncC = ConstantExpr::getTrunc(C, SrcTy);
Constant *SextTruncC = ConstantExpr::getSExt(TruncC, DestTy);
if (SextTruncC == C) {
// LogicOpc (sext X), C --> sext (LogicOpc X, C)
Value *NewOp = Builder.CreateBinOp(LogicOpc, X, TruncC);
return new SExtInst(NewOp, DestTy);
}
}
return nullptr;
}
/// Fold {and,or,xor} (cast X), Y.
Instruction *InstCombiner::foldCastedBitwiseLogic(BinaryOperator &I) {
auto LogicOpc = I.getOpcode();
assert(I.isBitwiseLogicOp() && "Unexpected opcode for bitwise logic folding");
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
CastInst *Cast0 = dyn_cast<CastInst>(Op0);
if (!Cast0)
return nullptr;
// This must be a cast from an integer or integer vector source type to allow
// transformation of the logic operation to the source type.
Type *DestTy = I.getType();
Type *SrcTy = Cast0->getSrcTy();
if (!SrcTy->isIntOrIntVectorTy())
return nullptr;
if (Instruction *Ret = foldLogicCastConstant(I, Cast0, Builder))
return Ret;
CastInst *Cast1 = dyn_cast<CastInst>(Op1);
if (!Cast1)
return nullptr;
// Both operands of the logic operation are casts. The casts must be of the
// same type for reduction.
auto CastOpcode = Cast0->getOpcode();
if (CastOpcode != Cast1->getOpcode() || SrcTy != Cast1->getSrcTy())
return nullptr;
Value *Cast0Src = Cast0->getOperand(0);
Value *Cast1Src = Cast1->getOperand(0);
// fold logic(cast(A), cast(B)) -> cast(logic(A, B))
if (shouldOptimizeCast(Cast0) && shouldOptimizeCast(Cast1)) {
Value *NewOp = Builder.CreateBinOp(LogicOpc, Cast0Src, Cast1Src,
I.getName());
return CastInst::Create(CastOpcode, NewOp, DestTy);
}
// For now, only 'and'/'or' have optimizations after this.
if (LogicOpc == Instruction::Xor)
return nullptr;
// If this is logic(cast(icmp), cast(icmp)), try to fold this even if the
// cast is otherwise not optimizable. This happens for vector sexts.
ICmpInst *ICmp0 = dyn_cast<ICmpInst>(Cast0Src);
ICmpInst *ICmp1 = dyn_cast<ICmpInst>(Cast1Src);
if (ICmp0 && ICmp1) {
Value *Res = LogicOpc == Instruction::And ? foldAndOfICmps(ICmp0, ICmp1, I)
: foldOrOfICmps(ICmp0, ICmp1, I);
if (Res)
return CastInst::Create(CastOpcode, Res, DestTy);
return nullptr;
}
// If this is logic(cast(fcmp), cast(fcmp)), try to fold this even if the
// cast is otherwise not optimizable. This happens for vector sexts.
FCmpInst *FCmp0 = dyn_cast<FCmpInst>(Cast0Src);
FCmpInst *FCmp1 = dyn_cast<FCmpInst>(Cast1Src);
if (FCmp0 && FCmp1)
if (Value *R = foldLogicOfFCmps(FCmp0, FCmp1, LogicOpc == Instruction::And))
return CastInst::Create(CastOpcode, R, DestTy);
return nullptr;
}
static Instruction *foldAndToXor(BinaryOperator &I,
InstCombiner::BuilderTy &Builder) {
assert(I.getOpcode() == Instruction::And);
Value *Op0 = I.getOperand(0);
Value *Op1 = I.getOperand(1);
Value *A, *B;
// Operand complexity canonicalization guarantees that the 'or' is Op0.
// (A | B) & ~(A & B) --> A ^ B
// (A | B) & ~(B & A) --> A ^ B
if (match(&I, m_BinOp(m_Or(m_Value(A), m_Value(B)),
m_Not(m_c_And(m_Deferred(A), m_Deferred(B))))))
return BinaryOperator::CreateXor(A, B);
// (A | ~B) & (~A | B) --> ~(A ^ B)
// (A | ~B) & (B | ~A) --> ~(A ^ B)
// (~B | A) & (~A | B) --> ~(A ^ B)
// (~B | A) & (B | ~A) --> ~(A ^ B)
if (Op0->hasOneUse() || Op1->hasOneUse())
if (match(&I, m_BinOp(m_c_Or(m_Value(A), m_Not(m_Value(B))),
m_c_Or(m_Not(m_Deferred(A)), m_Deferred(B)))))
return BinaryOperator::CreateNot(Builder.CreateXor(A, B));
return nullptr;
}
static Instruction *foldOrToXor(BinaryOperator &I,
InstCombiner::BuilderTy &Builder) {
assert(I.getOpcode() == Instruction::Or);
Value *Op0 = I.getOperand(0);
Value *Op1 = I.getOperand(1);
Value *A, *B;
// Operand complexity canonicalization guarantees that the 'and' is Op0.
// (A & B) | ~(A | B) --> ~(A ^ B)
// (A & B) | ~(B | A) --> ~(A ^ B)
if (Op0->hasOneUse() || Op1->hasOneUse())
if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
match(Op1, m_Not(m_c_Or(m_Specific(A), m_Specific(B)))))
return BinaryOperator::CreateNot(Builder.CreateXor(A, B));
// (A & ~B) | (~A & B) --> A ^ B
// (A & ~B) | (B & ~A) --> A ^ B
// (~B & A) | (~A & B) --> A ^ B
// (~B & A) | (B & ~A) --> A ^ B
if (match(Op0, m_c_And(m_Value(A), m_Not(m_Value(B)))) &&
match(Op1, m_c_And(m_Not(m_Specific(A)), m_Specific(B))))
return BinaryOperator::CreateXor(A, B);
return nullptr;
}
/// Return true if a constant shift amount is always less than the specified
/// bit-width. If not, the shift could create poison in the narrower type.
static bool canNarrowShiftAmt(Constant *C, unsigned BitWidth) {
if (auto *ScalarC = dyn_cast<ConstantInt>(C))
return ScalarC->getZExtValue() < BitWidth;
if (C->getType()->isVectorTy()) {
// Check each element of a constant vector.
unsigned NumElts = C->getType()->getVectorNumElements();
for (unsigned i = 0; i != NumElts; ++i) {
Constant *Elt = C->getAggregateElement(i);
if (!Elt)
return false;
if (isa<UndefValue>(Elt))
continue;
auto *CI = dyn_cast<ConstantInt>(Elt);
if (!CI || CI->getZExtValue() >= BitWidth)
return false;
}
return true;
}
// The constant is a constant expression or unknown.
return false;
}
/// Try to use narrower ops (sink zext ops) for an 'and' with binop operand and
/// a common zext operand: and (binop (zext X), C), (zext X).
Instruction *InstCombiner::narrowMaskedBinOp(BinaryOperator &And) {
// This transform could also apply to {or, and, xor}, but there are better
// folds for those cases, so we don't expect those patterns here. AShr is not
// handled because it should always be transformed to LShr in this sequence.
// The subtract transform is different because it has a constant on the left.
// Add/mul commute the constant to RHS; sub with constant RHS becomes add.
Value *Op0 = And.getOperand(0), *Op1 = And.getOperand(1);
Constant *C;
if (!match(Op0, m_OneUse(m_Add(m_Specific(Op1), m_Constant(C)))) &&
!match(Op0, m_OneUse(m_Mul(m_Specific(Op1), m_Constant(C)))) &&
!match(Op0, m_OneUse(m_LShr(m_Specific(Op1), m_Constant(C)))) &&
!match(Op0, m_OneUse(m_Shl(m_Specific(Op1), m_Constant(C)))) &&
!match(Op0, m_OneUse(m_Sub(m_Constant(C), m_Specific(Op1)))))
return nullptr;
Value *X;
if (!match(Op1, m_ZExt(m_Value(X))) || Op1->hasNUsesOrMore(3))
return nullptr;
Type *Ty = And.getType();
if (!isa<VectorType>(Ty) && !shouldChangeType(Ty, X->getType()))
return nullptr;
// If we're narrowing a shift, the shift amount must be safe (less than the
// width) in the narrower type. If the shift amount is greater, instsimplify
// usually handles that case, but we can't guarantee/assert it.
Instruction::BinaryOps Opc = cast<BinaryOperator>(Op0)->getOpcode();
if (Opc == Instruction::LShr || Opc == Instruction::Shl)
if (!canNarrowShiftAmt(C, X->getType()->getScalarSizeInBits()))
return nullptr;
// and (sub C, (zext X)), (zext X) --> zext (and (sub C', X), X)
// and (binop (zext X), C), (zext X) --> zext (and (binop X, C'), X)
Value *NewC = ConstantExpr::getTrunc(C, X->getType());
Value *NewBO = Opc == Instruction::Sub ? Builder.CreateBinOp(Opc, NewC, X)
: Builder.CreateBinOp(Opc, X, NewC);
return new ZExtInst(Builder.CreateAnd(NewBO, X), Ty);
}
// FIXME: We use commutative matchers (m_c_*) for some, but not all, matches
// here. We should standardize that construct where it is needed or choose some
// other way to ensure that commutated variants of patterns are not missed.
Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
if (Value *V = SimplifyAndInst(I.getOperand(0), I.getOperand(1),
SQ.getWithInstruction(&I)))
return replaceInstUsesWith(I, V);
if (SimplifyAssociativeOrCommutative(I))
return &I;
if (Instruction *X = foldVectorBinop(I))
return X;
// See if we can simplify any instructions used by the instruction whose sole
// purpose is to compute bits we don't care about.
if (SimplifyDemandedInstructionBits(I))
return &I;
// Do this before using distributive laws to catch simple and/or/not patterns.
if (Instruction *Xor = foldAndToXor(I, Builder))
return Xor;
// (A|B)&(A|C) -> A|(B&C) etc
if (Value *V = SimplifyUsingDistributiveLaws(I))
return replaceInstUsesWith(I, V);
if (Value *V = SimplifyBSwap(I, Builder))
return replaceInstUsesWith(I, V);
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
const APInt *C;
if (match(Op1, m_APInt(C))) {
Value *X, *Y;
if (match(Op0, m_OneUse(m_LogicalShift(m_One(), m_Value(X)))) &&
C->isOneValue()) {
// (1 << X) & 1 --> zext(X == 0)
// (1 >> X) & 1 --> zext(X == 0)
Value *IsZero = Builder.CreateICmpEQ(X, ConstantInt::get(I.getType(), 0));
return new ZExtInst(IsZero, I.getType());
}
const APInt *XorC;
if (match(Op0, m_OneUse(m_Xor(m_Value(X), m_APInt(XorC))))) {
// (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
Constant *NewC = ConstantInt::get(I.getType(), *C & *XorC);
Value *And = Builder.CreateAnd(X, Op1);
And->takeName(Op0);
return BinaryOperator::CreateXor(And, NewC);
}
const APInt *OrC;
if (match(Op0, m_OneUse(m_Or(m_Value(X), m_APInt(OrC))))) {
// (X | C1) & C2 --> (X & C2^(C1&C2)) | (C1&C2)
// NOTE: This reduces the number of bits set in the & mask, which
// can expose opportunities for store narrowing for scalars.
// NOTE: SimplifyDemandedBits should have already removed bits from C1
// that aren't set in C2. Meaning we can replace (C1&C2) with C1 in
// above, but this feels safer.
APInt Together = *C & *OrC;
Value *And = Builder.CreateAnd(X, ConstantInt::get(I.getType(),
Together ^ *C));
And->takeName(Op0);
return BinaryOperator::CreateOr(And, ConstantInt::get(I.getType(),
Together));
}
// If the mask is only needed on one incoming arm, push the 'and' op up.
if (match(Op0, m_OneUse(m_Xor(m_Value(X), m_Value(Y)))) ||
match(Op0, m_OneUse(m_Or(m_Value(X), m_Value(Y))))) {
APInt NotAndMask(~(*C));
BinaryOperator::BinaryOps BinOp = cast<BinaryOperator>(Op0)->getOpcode();
if (MaskedValueIsZero(X, NotAndMask, 0, &I)) {
// Not masking anything out for the LHS, move mask to RHS.
// and ({x}or X, Y), C --> {x}or X, (and Y, C)
Value *NewRHS = Builder.CreateAnd(Y, Op1, Y->getName() + ".masked");
return BinaryOperator::Create(BinOp, X, NewRHS);
}
if (!isa<Constant>(Y) && MaskedValueIsZero(Y, NotAndMask, 0, &I)) {
// Not masking anything out for the RHS, move mask to LHS.
// and ({x}or X, Y), C --> {x}or (and X, C), Y
Value *NewLHS = Builder.CreateAnd(X, Op1, X->getName() + ".masked");
return BinaryOperator::Create(BinOp, NewLHS, Y);
}
}
}
if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) {
const APInt &AndRHSMask = AndRHS->getValue();
// Optimize a variety of ((val OP C1) & C2) combinations...
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
// ((C1 OP zext(X)) & C2) -> zext((C1-X) & C2) if C2 fits in the bitwidth
// of X and OP behaves well when given trunc(C1) and X.
// TODO: Do this for vectors by using m_APInt isntead of m_ConstantInt.
switch (Op0I->getOpcode()) {
default:
break;
case Instruction::Xor:
case Instruction::Or:
case Instruction::Mul:
case Instruction::Add:
case Instruction::Sub:
Value *X;
ConstantInt *C1;
// TODO: The one use restrictions could be relaxed a little if the AND
// is going to be removed.
if (match(Op0I, m_OneUse(m_c_BinOp(m_OneUse(m_ZExt(m_Value(X))),
m_ConstantInt(C1))))) {
if (AndRHSMask.isIntN(X->getType()->getScalarSizeInBits())) {
auto *TruncC1 = ConstantExpr::getTrunc(C1, X->getType());
Value *BinOp;
Value *Op0LHS = Op0I->getOperand(0);
if (isa<ZExtInst>(Op0LHS))
BinOp = Builder.CreateBinOp(Op0I->getOpcode(), X, TruncC1);
else
BinOp = Builder.CreateBinOp(Op0I->getOpcode(), TruncC1, X);
auto *TruncC2 = ConstantExpr::getTrunc(AndRHS, X->getType());
auto *And = Builder.CreateAnd(BinOp, TruncC2);
return new ZExtInst(And, I.getType());
}
}
}
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
return Res;
}
// If this is an integer truncation, and if the source is an 'and' with
// immediate, transform it. This frequently occurs for bitfield accesses.
{
Value *X = nullptr; ConstantInt *YC = nullptr;
if (match(Op0, m_Trunc(m_And(m_Value(X), m_ConstantInt(YC))))) {
// Change: and (trunc (and X, YC) to T), C2
// into : and (trunc X to T), trunc(YC) & C2
// This will fold the two constants together, which may allow
// other simplifications.
Value *NewCast = Builder.CreateTrunc(X, I.getType(), "and.shrunk");
Constant *C3 = ConstantExpr::getTrunc(YC, I.getType());
C3 = ConstantExpr::getAnd(C3, AndRHS);
return BinaryOperator::CreateAnd(NewCast, C3);
}
}
}
if (Instruction *Z = narrowMaskedBinOp(I))
return Z;
if (Instruction *FoldedLogic = foldBinOpIntoSelectOrPhi(I))
return FoldedLogic;
if (Instruction *DeMorgan = matchDeMorgansLaws(I, Builder))
return DeMorgan;
{
Value *A, *B, *C;
// A & (A ^ B) --> A & ~B
if (match(Op1, m_OneUse(m_c_Xor(m_Specific(Op0), m_Value(B)))))
return BinaryOperator::CreateAnd(Op0, Builder.CreateNot(B));
// (A ^ B) & A --> A & ~B
if (match(Op0, m_OneUse(m_c_Xor(m_Specific(Op1), m_Value(B)))))
return BinaryOperator::CreateAnd(Op1, Builder.CreateNot(B));
// (A ^ B) & ((B ^ C) ^ A) -> (A ^ B) & ~C
if (match(Op0, m_Xor(m_Value(A), m_Value(B))))
if (match(Op1, m_Xor(m_Xor(m_Specific(B), m_Value(C)), m_Specific(A))))
if (Op1->hasOneUse() || IsFreeToInvert(C, C->hasOneUse()))
return BinaryOperator::CreateAnd(Op0, Builder.CreateNot(C));
// ((A ^ C) ^ B) & (B ^ A) -> (B ^ A) & ~C
if (match(Op0, m_Xor(m_Xor(m_Value(A), m_Value(C)), m_Value(B))))
if (match(Op1, m_Xor(m_Specific(B), m_Specific(A))))
if (Op0->hasOneUse() || IsFreeToInvert(C, C->hasOneUse()))
return BinaryOperator::CreateAnd(Op1, Builder.CreateNot(C));
// (A | B) & ((~A) ^ B) -> (A & B)
// (A | B) & (B ^ (~A)) -> (A & B)
// (B | A) & ((~A) ^ B) -> (A & B)
// (B | A) & (B ^ (~A)) -> (A & B)
if (match(Op1, m_c_Xor(m_Not(m_Value(A)), m_Value(B))) &&
match(Op0, m_c_Or(m_Specific(A), m_Specific(B))))
return BinaryOperator::CreateAnd(A, B);
// ((~A) ^ B) & (A | B) -> (A & B)
// ((~A) ^ B) & (B | A) -> (A & B)
// (B ^ (~A)) & (A | B) -> (A & B)
// (B ^ (~A)) & (B | A) -> (A & B)
if (match(Op0, m_c_Xor(m_Not(m_Value(A)), m_Value(B))) &&
match(Op1, m_c_Or(m_Specific(A), m_Specific(B))))
return BinaryOperator::CreateAnd(A, B);
}
{
ICmpInst *LHS = dyn_cast<ICmpInst>(Op0);
ICmpInst *RHS = dyn_cast<ICmpInst>(Op1);
if (LHS && RHS)
if (Value *Res = foldAndOfICmps(LHS, RHS, I))
return replaceInstUsesWith(I, Res);
// TODO: Make this recursive; it's a little tricky because an arbitrary
// number of 'and' instructions might have to be created.
Value *X, *Y;
if (LHS && match(Op1, m_OneUse(m_And(m_Value(X), m_Value(Y))))) {
if (auto *Cmp = dyn_cast<ICmpInst>(X))
if (Value *Res = foldAndOfICmps(LHS, Cmp, I))
return replaceInstUsesWith(I, Builder.CreateAnd(Res, Y));
if (auto *Cmp = dyn_cast<ICmpInst>(Y))
if (Value *Res = foldAndOfICmps(LHS, Cmp, I))
return replaceInstUsesWith(I, Builder.CreateAnd(Res, X));
}
if (RHS && match(Op0, m_OneUse(m_And(m_Value(X), m_Value(Y))))) {
if (auto *Cmp = dyn_cast<ICmpInst>(X))
if (Value *Res = foldAndOfICmps(Cmp, RHS, I))
return replaceInstUsesWith(I, Builder.CreateAnd(Res, Y));
if (auto *Cmp = dyn_cast<ICmpInst>(Y))
if (Value *Res = foldAndOfICmps(Cmp, RHS, I))
return replaceInstUsesWith(I, Builder.CreateAnd(Res, X));
}
}
if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0)))
if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
if (Value *Res = foldLogicOfFCmps(LHS, RHS, true))
return replaceInstUsesWith(I, Res);
if (Instruction *FoldedFCmps = reassociateFCmps(I, Builder))
return FoldedFCmps;
if (Instruction *CastedAnd = foldCastedBitwiseLogic(I))
return CastedAnd;
// and(sext(A), B) / and(B, sext(A)) --> A ? B : 0, where A is i1 or <N x i1>.
Value *A;
if (match(Op0, m_OneUse(m_SExt(m_Value(A)))) &&
A->getType()->isIntOrIntVectorTy(1))
return SelectInst::Create(A, Op1, Constant::getNullValue(I.getType()));
if (match(Op1, m_OneUse(m_SExt(m_Value(A)))) &&
A->getType()->isIntOrIntVectorTy(1))
return SelectInst::Create(A, Op0, Constant::getNullValue(I.getType()));
return nullptr;
}
Instruction *InstCombiner::matchBSwap(BinaryOperator &Or) {
assert(Or.getOpcode() == Instruction::Or && "bswap requires an 'or'");
Value *Op0 = Or.getOperand(0), *Op1 = Or.getOperand(1);
// Look through zero extends.
if (Instruction *Ext = dyn_cast<ZExtInst>(Op0))
Op0 = Ext->getOperand(0);
if (Instruction *Ext = dyn_cast<ZExtInst>(Op1))
Op1 = Ext->getOperand(0);
// (A | B) | C and A | (B | C) -> bswap if possible.
bool OrOfOrs = match(Op0, m_Or(m_Value(), m_Value())) ||
match(Op1, m_Or(m_Value(), m_Value()));
// (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible.
bool OrOfShifts = match(Op0, m_LogicalShift(m_Value(), m_Value())) &&
match(Op1, m_LogicalShift(m_Value(), m_Value()));
// (A & B) | (C & D) -> bswap if possible.
bool OrOfAnds = match(Op0, m_And(m_Value(), m_Value())) &&
match(Op1, m_And(m_Value(), m_Value()));
// (A << B) | (C & D) -> bswap if possible.
// The bigger pattern here is ((A & C1) << C2) | ((B >> C2) & C1), which is a
// part of the bswap idiom for specific values of C1, C2 (e.g. C1 = 16711935,
// C2 = 8 for i32).
// This pattern can occur when the operands of the 'or' are not canonicalized
// for some reason (not having only one use, for example).
bool OrOfAndAndSh = (match(Op0, m_LogicalShift(m_Value(), m_Value())) &&
match(Op1, m_And(m_Value(), m_Value()))) ||
(match(Op0, m_And(m_Value(), m_Value())) &&
match(Op1, m_LogicalShift(m_Value(), m_Value())));
if (!OrOfOrs && !OrOfShifts && !OrOfAnds && !OrOfAndAndSh)
return nullptr;
SmallVector<Instruction*, 4> Insts;
if (!recognizeBSwapOrBitReverseIdiom(&Or, true, false, Insts))
return nullptr;
Instruction *LastInst = Insts.pop_back_val();
LastInst->removeFromParent();
for (auto *Inst : Insts)
Worklist.Add(Inst);
return LastInst;
}
/// Transform UB-safe variants of bitwise rotate to the funnel shift intrinsic.
static Instruction *matchRotate(Instruction &Or) {
// TODO: Can we reduce the code duplication between this and the related
// rotate matching code under visitSelect and visitTrunc?
unsigned Width = Or.getType()->getScalarSizeInBits();
if (!isPowerOf2_32(Width))
return nullptr;
// First, find an or'd pair of opposite shifts with the same shifted operand:
// or (lshr ShVal, ShAmt0), (shl ShVal, ShAmt1)
BinaryOperator *Or0, *Or1;
if (!match(Or.getOperand(0), m_BinOp(Or0)) ||
!match(Or.getOperand(1), m_BinOp(Or1)))
return nullptr;
Value *ShVal, *ShAmt0, *ShAmt1;
if (!match(Or0, m_OneUse(m_LogicalShift(m_Value(ShVal), m_Value(ShAmt0)))) ||
!match(Or1, m_OneUse(m_LogicalShift(m_Specific(ShVal), m_Value(ShAmt1)))))
return nullptr;
BinaryOperator::BinaryOps ShiftOpcode0 = Or0->getOpcode();
BinaryOperator::BinaryOps ShiftOpcode1 = Or1->getOpcode();
if (ShiftOpcode0 == ShiftOpcode1)
return nullptr;
// Match the shift amount operands for a rotate pattern. This always matches
// a subtraction on the R operand.
auto matchShiftAmount = [](Value *L, Value *R, unsigned Width) -> Value * {
// The shift amount may be masked with negation:
// (shl ShVal, (X & (Width - 1))) | (lshr ShVal, ((-X) & (Width - 1)))
Value *X;
unsigned Mask = Width - 1;
if (match(L, m_And(m_Value(X), m_SpecificInt(Mask))) &&
match(R, m_And(m_Neg(m_Specific(X)), m_SpecificInt(Mask))))
return X;
// Similar to above, but the shift amount may be extended after masking,
// so return the extended value as the parameter for the intrinsic.
if (match(L, m_ZExt(m_And(m_Value(X), m_SpecificInt(Mask)))) &&
match(R, m_And(m_Neg(m_ZExt(m_And(m_Specific(X), m_SpecificInt(Mask)))),
m_SpecificInt(Mask))))
return L;
return nullptr;
};
Value *ShAmt = matchShiftAmount(ShAmt0, ShAmt1, Width);
bool SubIsOnLHS = false;
if (!ShAmt) {
ShAmt = matchShiftAmount(ShAmt1, ShAmt0, Width);
SubIsOnLHS = true;
}
if (!ShAmt)
return nullptr;
bool IsFshl = (!SubIsOnLHS && ShiftOpcode0 == BinaryOperator::Shl) ||
(SubIsOnLHS && ShiftOpcode1 == BinaryOperator::Shl);
Intrinsic::ID IID = IsFshl ? Intrinsic::fshl : Intrinsic::fshr;
Function *F = Intrinsic::getDeclaration(Or.getModule(), IID, Or.getType());
return IntrinsicInst::Create(F, { ShVal, ShVal, ShAmt });
}
/// If all elements of two constant vectors are 0/-1 and inverses, return true.
static bool areInverseVectorBitmasks(Constant *C1, Constant *C2) {
unsigned NumElts = C1->getType()->getVectorNumElements();
for (unsigned i = 0; i != NumElts; ++i) {
Constant *EltC1 = C1->getAggregateElement(i);
Constant *EltC2 = C2->getAggregateElement(i);
if (!EltC1 || !EltC2)
return false;
// One element must be all ones, and the other must be all zeros.
if (!((match(EltC1, m_Zero()) && match(EltC2, m_AllOnes())) ||
(match(EltC2, m_Zero()) && match(EltC1, m_AllOnes()))))
return false;
}
return true;
}
/// We have an expression of the form (A & C) | (B & D). If A is a scalar or
/// vector composed of all-zeros or all-ones values and is the bitwise 'not' of
/// B, it can be used as the condition operand of a select instruction.
Value *InstCombiner::getSelectCondition(Value *A, Value *B) {
// Step 1: We may have peeked through bitcasts in the caller.
// Exit immediately if we don't have (vector) integer types.
Type *Ty = A->getType();
if (!Ty->isIntOrIntVectorTy() || !B->getType()->isIntOrIntVectorTy())
return nullptr;
// Step 2: We need 0 or all-1's bitmasks.
if (ComputeNumSignBits(A) != Ty->getScalarSizeInBits())
return nullptr;
// Step 3: If B is the 'not' value of A, we have our answer.
if (match(A, m_Not(m_Specific(B)))) {
// If these are scalars or vectors of i1, A can be used directly.
if (Ty->isIntOrIntVectorTy(1))
return A;
return Builder.CreateTrunc(A, CmpInst::makeCmpResultType(Ty));
}
// If both operands are constants, see if the constants are inverse bitmasks.
Constant *AConst, *BConst;
if (match(A, m_Constant(AConst)) && match(B, m_Constant(BConst)))
if (AConst == ConstantExpr::getNot(BConst))
return Builder.CreateZExtOrTrunc(A, CmpInst::makeCmpResultType(Ty));
// Look for more complex patterns. The 'not' op may be hidden behind various
// casts. Look through sexts and bitcasts to find the booleans.
Value *Cond;
Value *NotB;
if (match(A, m_SExt(m_Value(Cond))) &&
Cond->getType()->isIntOrIntVectorTy(1) &&
match(B, m_OneUse(m_Not(m_Value(NotB))))) {
NotB = peekThroughBitcast(NotB, true);
if (match(NotB, m_SExt(m_Specific(Cond))))
return Cond;
}
// All scalar (and most vector) possibilities should be handled now.
// Try more matches that only apply to non-splat constant vectors.
if (!Ty->isVectorTy())
return nullptr;
// If both operands are xor'd with constants using the same sexted boolean
// operand, see if the constants are inverse bitmasks.
// TODO: Use ConstantExpr::getNot()?
if (match(A, (m_Xor(m_SExt(m_Value(Cond)), m_Constant(AConst)))) &&
match(B, (m_Xor(m_SExt(m_Specific(Cond)), m_Constant(BConst)))) &&
Cond->getType()->isIntOrIntVectorTy(1) &&
areInverseVectorBitmasks(AConst, BConst)) {
AConst = ConstantExpr::getTrunc(AConst, CmpInst::makeCmpResultType(Ty));
return Builder.CreateXor(Cond, AConst);
}
return nullptr;
}
/// We have an expression of the form (A & C) | (B & D). Try to simplify this
/// to "A' ? C : D", where A' is a boolean or vector of booleans.
Value *InstCombiner::matchSelectFromAndOr(Value *A, Value *C, Value *B,
Value *D) {
// The potential condition of the select may be bitcasted. In that case, look
// through its bitcast and the corresponding bitcast of the 'not' condition.
Type *OrigType = A->getType();
A = peekThroughBitcast(A, true);
B = peekThroughBitcast(B, true);
if (Value *Cond = getSelectCondition(A, B)) {
// ((bc Cond) & C) | ((bc ~Cond) & D) --> bc (select Cond, (bc C), (bc D))
// The bitcasts will either all exist or all not exist. The builder will
// not create unnecessary casts if the types already match.
Value *BitcastC = Builder.CreateBitCast(C, A->getType());
Value *BitcastD = Builder.CreateBitCast(D, A->getType());
Value *Select = Builder.CreateSelect(Cond, BitcastC, BitcastD);
return Builder.CreateBitCast(Select, OrigType);
}
return nullptr;
}
/// Fold (icmp)|(icmp) if possible.
Value *InstCombiner::foldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
Instruction &CxtI) {
// Fold (iszero(A & K1) | iszero(A & K2)) -> (A & (K1 | K2)) != (K1 | K2)
// if K1 and K2 are a one-bit mask.
if (Value *V = foldAndOrOfICmpsOfAndWithPow2(LHS, RHS, false, CxtI))
return V;
ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate();
ConstantInt *LHSC = dyn_cast<ConstantInt>(LHS->getOperand(1));
ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS->getOperand(1));
// Fold (icmp ult/ule (A + C1), C3) | (icmp ult/ule (A + C2), C3)
// --> (icmp ult/ule ((A & ~(C1 ^ C2)) + max(C1, C2)), C3)
// The original condition actually refers to the following two ranges:
// [MAX_UINT-C1+1, MAX_UINT-C1+1+C3] and [MAX_UINT-C2+1, MAX_UINT-C2+1+C3]
// We can fold these two ranges if:
// 1) C1 and C2 is unsigned greater than C3.
// 2) The two ranges are separated.
// 3) C1 ^ C2 is one-bit mask.
// 4) LowRange1 ^ LowRange2 and HighRange1 ^ HighRange2 are one-bit mask.
// This implies all values in the two ranges differ by exactly one bit.
if ((PredL == ICmpInst::ICMP_ULT || PredL == ICmpInst::ICMP_ULE) &&
PredL == PredR && LHSC && RHSC && LHS->hasOneUse() && RHS->hasOneUse() &&
LHSC->getType() == RHSC->getType() &&
LHSC->getValue() == (RHSC->getValue())) {
Value *LAdd = LHS->getOperand(0);
Value *RAdd = RHS->getOperand(0);
Value *LAddOpnd, *RAddOpnd;
ConstantInt *LAddC, *RAddC;
if (match(LAdd, m_Add(m_Value(LAddOpnd), m_ConstantInt(LAddC))) &&
match(RAdd, m_Add(m_Value(RAddOpnd), m_ConstantInt(RAddC))) &&
LAddC->getValue().ugt(LHSC->getValue()) &&
RAddC->getValue().ugt(LHSC->getValue())) {
APInt DiffC = LAddC->getValue() ^ RAddC->getValue();
if (LAddOpnd == RAddOpnd && DiffC.isPowerOf2()) {
ConstantInt *MaxAddC = nullptr;
if (LAddC->getValue().ult(RAddC->getValue()))
MaxAddC = RAddC;
else
MaxAddC = LAddC;
APInt RRangeLow = -RAddC->getValue();
APInt RRangeHigh = RRangeLow + LHSC->getValue();
APInt LRangeLow = -LAddC->getValue();
APInt LRangeHigh = LRangeLow + LHSC->getValue();
APInt LowRangeDiff = RRangeLow ^ LRangeLow;
APInt HighRangeDiff = RRangeHigh ^ LRangeHigh;
APInt RangeDiff = LRangeLow.sgt(RRangeLow) ? LRangeLow - RRangeLow
: RRangeLow - LRangeLow;
if (LowRangeDiff.isPowerOf2() && LowRangeDiff == HighRangeDiff &&
RangeDiff.ugt(LHSC->getValue())) {
Value *MaskC = ConstantInt::get(LAddC->getType(), ~DiffC);
Value *NewAnd = Builder.CreateAnd(LAddOpnd, MaskC);
Value *NewAdd = Builder.CreateAdd(NewAnd, MaxAddC);
return Builder.CreateICmp(LHS->getPredicate(), NewAdd, LHSC);
}
}
}
}
// (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
if (predicatesFoldable(PredL, PredR)) {
if (LHS->getOperand(0) == RHS->getOperand(1) &&
LHS->getOperand(1) == RHS->getOperand(0))
LHS->swapOperands();
if (LHS->getOperand(0) == RHS->getOperand(0) &&
LHS->getOperand(1) == RHS->getOperand(1)) {
Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1);
unsigned Code = getICmpCode(LHS) | getICmpCode(RHS);
bool IsSigned = LHS->isSigned() || RHS->isSigned();
return getNewICmpValue(Code, IsSigned, Op0, Op1, Builder);
}
}
// handle (roughly):
// (icmp ne (A & B), C) | (icmp ne (A & D), E)
if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, false, Builder))
return V;
Value *LHS0 = LHS->getOperand(0), *RHS0 = RHS->getOperand(0);
if (LHS->hasOneUse() || RHS->hasOneUse()) {
// (icmp eq B, 0) | (icmp ult A, B) -> (icmp ule A, B-1)
// (icmp eq B, 0) | (icmp ugt B, A) -> (icmp ule A, B-1)
Value *A = nullptr, *B = nullptr;
if (PredL == ICmpInst::ICMP_EQ && LHSC && LHSC->isZero()) {
B = LHS0;
if (PredR == ICmpInst::ICMP_ULT && LHS0 == RHS->getOperand(1))
A = RHS0;
else if (PredR == ICmpInst::ICMP_UGT && LHS0 == RHS0)
A = RHS->getOperand(1);
}
// (icmp ult A, B) | (icmp eq B, 0) -> (icmp ule A, B-1)
// (icmp ugt B, A) | (icmp eq B, 0) -> (icmp ule A, B-1)
else if (PredR == ICmpInst::ICMP_EQ && RHSC && RHSC->isZero()) {
B = RHS0;
if (PredL == ICmpInst::ICMP_ULT && RHS0 == LHS->getOperand(1))
A = LHS0;
else if (PredL == ICmpInst::ICMP_UGT && LHS0 == RHS0)
A = LHS->getOperand(1);
}
if (A && B)
return Builder.CreateICmp(
ICmpInst::ICMP_UGE,
Builder.CreateAdd(B, ConstantInt::getSigned(B->getType(), -1)), A);
}
// E.g. (icmp slt x, 0) | (icmp sgt x, n) --> icmp ugt x, n
if (Value *V = simplifyRangeCheck(LHS, RHS, /*Inverted=*/true))
return V;
// E.g. (icmp sgt x, n) | (icmp slt x, 0) --> icmp ugt x, n
if (Value *V = simplifyRangeCheck(RHS, LHS, /*Inverted=*/true))
return V;
if (Value *V = foldAndOrOfEqualityCmpsWithConstants(LHS, RHS, false, Builder))
return V;
if (Value *V = foldIsPowerOf2(LHS, RHS, false /* JoinedByAnd */, Builder))
return V;
// This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2).
if (!LHSC || !RHSC)
return nullptr;
if (LHSC == RHSC && PredL == PredR) {
// (icmp ne A, 0) | (icmp ne B, 0) --> (icmp ne (A|B), 0)
if (PredL == ICmpInst::ICMP_NE && LHSC->isZero()) {
Value *NewOr = Builder.CreateOr(LHS0, RHS0);
return Builder.CreateICmp(PredL, NewOr, LHSC);
}
}
// (icmp ult (X + CA), C1) | (icmp eq X, C2) -> (icmp ule (X + CA), C1)
// iff C2 + CA == C1.
if (PredL == ICmpInst::ICMP_ULT && PredR == ICmpInst::ICMP_EQ) {
ConstantInt *AddC;
if (match(LHS0, m_Add(m_Specific(RHS0), m_ConstantInt(AddC))))
if (RHSC->getValue() + AddC->getValue() == LHSC->getValue())
return Builder.CreateICmpULE(LHS0, LHSC);
}
// From here on, we only handle:
// (icmp1 A, C1) | (icmp2 A, C2) --> something simpler.
if (LHS0 != RHS0)
return nullptr;
// ICMP_[US][GL]E X, C is folded to ICMP_[US][GL]T elsewhere.
if (PredL == ICmpInst::ICMP_UGE || PredL == ICmpInst::ICMP_ULE ||
PredR == ICmpInst::ICMP_UGE || PredR == ICmpInst::ICMP_ULE ||
PredL == ICmpInst::ICMP_SGE || PredL == ICmpInst::ICMP_SLE ||
PredR == ICmpInst::ICMP_SGE || PredR == ICmpInst::ICMP_SLE)
return nullptr;
// We can't fold (ugt x, C) | (sgt x, C2).
if (!predicatesFoldable(PredL, PredR))
return nullptr;
// Ensure that the larger constant is on the RHS.
bool ShouldSwap;
if (CmpInst::isSigned(PredL) ||
(ICmpInst::isEquality(PredL) && CmpInst::isSigned(PredR)))
ShouldSwap = LHSC->getValue().sgt(RHSC->getValue());
else
ShouldSwap = LHSC->getValue().ugt(RHSC->getValue());
if (ShouldSwap) {
std::swap(LHS, RHS);
std::swap(LHSC, RHSC);
std::swap(PredL, PredR);
}
// At this point, we know we have two icmp instructions
// comparing a value against two constants and or'ing the result
// together. Because of the above check, we know that we only have
// ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
// icmp folding check above), that the two constants are not
// equal.
assert(LHSC != RHSC && "Compares not folded above?");
switch (PredL) {
default:
llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_EQ:
switch (PredR) {
default:
llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_EQ:
// Potential folds for this case should already be handled.
break;
case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change
case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change
break;
}
break;
case ICmpInst::ICMP_ULT:
switch (PredR) {
default:
llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change
break;
case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2
assert(!RHSC->isMaxValue(false) && "Missed icmp simplification");
return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue() + 1,
false, false);
}
break;
case ICmpInst::ICMP_SLT:
switch (PredR) {
default:
llvm_unreachable("Unknown integer condition code!");
case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change
break;
case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) s> 2
assert(!RHSC->isMaxValue(true) && "Missed icmp simplification");
return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue() + 1, true,
false);
}
break;
}
return nullptr;
}
// FIXME: We use commutative matchers (m_c_*) for some, but not all, matches
// here. We should standardize that construct where it is needed or choose some
// other way to ensure that commutated variants of patterns are not missed.
Instruction *InstCombiner::visitOr(BinaryOperator &I) {
if (Value *V = SimplifyOrInst(I.getOperand(0), I.getOperand(1),
SQ.getWithInstruction(&I)))
return replaceInstUsesWith(I, V);
if (SimplifyAssociativeOrCommutative(I))
return &I;
if (Instruction *X = foldVectorBinop(I))
return X;
// See if we can simplify any instructions used by the instruction whose sole
// purpose is to compute bits we don't care about.
if (SimplifyDemandedInstructionBits(I))
return &I;
// Do this before using distributive laws to catch simple and/or/not patterns.
if (Instruction *Xor = foldOrToXor(I, Builder))
return Xor;
// (A&B)|(A&C) -> A&(B|C) etc
if (Value *V = SimplifyUsingDistributiveLaws(I))
return replaceInstUsesWith(I, V);
if (Value *V = SimplifyBSwap(I, Builder))
return replaceInstUsesWith(I, V);
if (Instruction *FoldedLogic = foldBinOpIntoSelectOrPhi(I))
return FoldedLogic;
if (Instruction *BSwap = matchBSwap(I))
return BSwap;
if (Instruction *Rotate = matchRotate(I))
return Rotate;
Value *X, *Y;
const APInt *CV;
if (match(&I, m_c_Or(m_OneUse(m_Xor(m_Value(X), m_APInt(CV))), m_Value(Y))) &&
!CV->isAllOnesValue() && MaskedValueIsZero(Y, *CV, 0, &I)) {
// (X ^ C) | Y -> (X | Y) ^ C iff Y & C == 0
// The check for a 'not' op is for efficiency (if Y is known zero --> ~X).
Value *Or = Builder.CreateOr(X, Y);
return BinaryOperator::CreateXor(Or, ConstantInt::get(I.getType(), *CV));
}
// (A & C)|(B & D)
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
Value *A, *B, *C, *D;
if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
match(Op1, m_And(m_Value(B), m_Value(D)))) {
ConstantInt *C1 = dyn_cast<ConstantInt>(C);
ConstantInt *C2 = dyn_cast<ConstantInt>(D);
if (C1 && C2) { // (A & C1)|(B & C2)
Value *V1 = nullptr, *V2 = nullptr;
if ((C1->getValue() & C2->getValue()).isNullValue()) {
// ((V | N) & C1) | (V & C2) --> (V|N) & (C1|C2)
// iff (C1&C2) == 0 and (N&~C1) == 0
if (match(A, m_Or(m_Value(V1), m_Value(V2))) &&
((V1 == B &&
MaskedValueIsZero(V2, ~C1->getValue(), 0, &I)) || // (V|N)
(V2 == B &&
MaskedValueIsZero(V1, ~C1->getValue(), 0, &I)))) // (N|V)
return BinaryOperator::CreateAnd(A,
Builder.getInt(C1->getValue()|C2->getValue()));
// Or commutes, try both ways.
if (match(B, m_Or(m_Value(V1), m_Value(V2))) &&
((V1 == A &&
MaskedValueIsZero(V2, ~C2->getValue(), 0, &I)) || // (V|N)
(V2 == A &&
MaskedValueIsZero(V1, ~C2->getValue(), 0, &I)))) // (N|V)
return BinaryOperator::CreateAnd(B,
Builder.getInt(C1->getValue()|C2->getValue()));
// ((V|C3)&C1) | ((V|C4)&C2) --> (V|C3|C4)&(C1|C2)
// iff (C1&C2) == 0 and (C3&~C1) == 0 and (C4&~C2) == 0.
ConstantInt *C3 = nullptr, *C4 = nullptr;
if (match(A, m_Or(m_Value(V1), m_ConstantInt(C3))) &&
(C3->getValue() & ~C1->getValue()).isNullValue() &&
match(B, m_Or(m_Specific(V1), m_ConstantInt(C4))) &&
(C4->getValue() & ~C2->getValue()).isNullValue()) {
V2 = Builder.CreateOr(V1, ConstantExpr::getOr(C3, C4), "bitfield");
return BinaryOperator::CreateAnd(V2,
Builder.getInt(C1->getValue()|C2->getValue()));
}
}
if (C1->getValue() == ~C2->getValue()) {
Value *X;
// ((X|B)&C1)|(B&C2) -> (X&C1) | B iff C1 == ~C2
if (match(A, m_c_Or(m_Value(X), m_Specific(B))))
return BinaryOperator::CreateOr(Builder.CreateAnd(X, C1), B);
// (A&C2)|((X|A)&C1) -> (X&C2) | A iff C1 == ~C2
if (match(B, m_c_Or(m_Specific(A), m_Value(X))))
return BinaryOperator::CreateOr(Builder.CreateAnd(X, C2), A);
// ((X^B)&C1)|(B&C2) -> (X&C1) ^ B iff C1 == ~C2
if (match(A, m_c_Xor(m_Value(X), m_Specific(B))))
return BinaryOperator::CreateXor(Builder.CreateAnd(X, C1), B);
// (A&C2)|((X^A)&C1) -> (X&C2) ^ A iff C1 == ~C2
if (match(B, m_c_Xor(m_Specific(A), m_Value(X))))
return BinaryOperator::CreateXor(Builder.CreateAnd(X, C2), A);
}
}
// Don't try to form a select if it's unlikely that we'll get rid of at
// least one of the operands. A select is generally more expensive than the
// 'or' that it is replacing.
if (Op0->hasOneUse() || Op1->hasOneUse()) {
// (Cond & C) | (~Cond & D) -> Cond ? C : D, and commuted variants.
if (Value *V = matchSelectFromAndOr(A, C, B, D))
return replaceInstUsesWith(I, V);
if (Value *V = matchSelectFromAndOr(A, C, D, B))
return replaceInstUsesWith(I, V);
if (Value *V = matchSelectFromAndOr(C, A, B, D))
return replaceInstUsesWith(I, V);
if (Value *V = matchSelectFromAndOr(C, A, D, B))
return replaceInstUsesWith(I, V);
if (Value *V = matchSelectFromAndOr(B, D, A, C))
return replaceInstUsesWith(I, V);
if (Value *V = matchSelectFromAndOr(B, D, C, A))
return replaceInstUsesWith(I, V);
if (Value *V = matchSelectFromAndOr(D, B, A, C))
return replaceInstUsesWith(I, V);
if (Value *V = matchSelectFromAndOr(D, B, C, A))
return replaceInstUsesWith(I, V);
}
}
// (A ^ B) | ((B ^ C) ^ A) -> (A ^ B) | C
if (match(Op0, m_Xor(m_Value(A), m_Value(B))))
if (match(Op1, m_Xor(m_Xor(m_Specific(B), m_Value(C)), m_Specific(A))))
return BinaryOperator::CreateOr(Op0, C);
// ((A ^ C) ^ B) | (B ^ A) -> (B ^ A) | C
if (match(Op0, m_Xor(m_Xor(m_Value(A), m_Value(C)), m_Value(B))))
if (match(Op1, m_Xor(m_Specific(B), m_Specific(A))))
return BinaryOperator::CreateOr(Op1, C);
// ((B | C) & A) | B -> B | (A & C)
if (match(Op0, m_And(m_Or(m_Specific(Op1), m_Value(C)), m_Value(A))))
return BinaryOperator::CreateOr(Op1, Builder.CreateAnd(A, C));
if (Instruction *DeMorgan = matchDeMorgansLaws(I, Builder))
return DeMorgan;
// Canonicalize xor to the RHS.
bool SwappedForXor = false;
if (match(Op0, m_Xor(m_Value(), m_Value()))) {
std::swap(Op0, Op1);
SwappedForXor = true;
}
// A | ( A ^ B) -> A | B
// A | (~A ^ B) -> A | ~B
// (A & B) | (A ^ B)
if (match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
if (Op0 == A || Op0 == B)
return BinaryOperator::CreateOr(A, B);
if (match(Op0, m_And(m_Specific(A), m_Specific(B))) ||
match(Op0, m_And(m_Specific(B), m_Specific(A))))
return BinaryOperator::CreateOr(A, B);
if (Op1->hasOneUse() && match(A, m_Not(m_Specific(Op0)))) {
Value *Not = Builder.CreateNot(B, B->getName() + ".not");
return BinaryOperator::CreateOr(Not, Op0);
}
if (Op1->hasOneUse() && match(B, m_Not(m_Specific(Op0)))) {
Value *Not = Builder.CreateNot(A, A->getName() + ".not");
return BinaryOperator::CreateOr(Not, Op0);
}
}
// A | ~(A | B) -> A | ~B
// A | ~(A ^ B) -> A | ~B
if (match(Op1, m_Not(m_Value(A))))
if (BinaryOperator *B = dyn_cast<BinaryOperator>(A))
if ((Op0 == B->getOperand(0) || Op0 == B->getOperand(1)) &&
Op1->hasOneUse() && (B->getOpcode() == Instruction::Or ||
B->getOpcode() == Instruction::Xor)) {
Value *NotOp = Op0 == B->getOperand(0) ? B->getOperand(1) :
B->getOperand(0);
Value *Not = Builder.CreateNot(NotOp, NotOp->getName() + ".not");
return BinaryOperator::CreateOr(Not, Op0);
}
if (SwappedForXor)
std::swap(Op0, Op1);
{
ICmpInst *LHS = dyn_cast<ICmpInst>(Op0);
ICmpInst *RHS = dyn_cast<ICmpInst>(Op1);
if (LHS && RHS)
if (Value *Res = foldOrOfICmps(LHS, RHS, I))
return replaceInstUsesWith(I, Res);
// TODO: Make this recursive; it's a little tricky because an arbitrary
// number of 'or' instructions might have to be created.
Value *X, *Y;
if (LHS && match(Op1, m_OneUse(m_Or(m_Value(X), m_Value(Y))))) {
if (auto *Cmp = dyn_cast<ICmpInst>(X))
if (Value *Res = foldOrOfICmps(LHS, Cmp, I))
return replaceInstUsesWith(I, Builder.CreateOr(Res, Y));
if (auto *Cmp = dyn_cast<ICmpInst>(Y))
if (Value *Res = foldOrOfICmps(LHS, Cmp, I))
return replaceInstUsesWith(I, Builder.CreateOr(Res, X));
}
if (RHS && match(Op0, m_OneUse(m_Or(m_Value(X), m_Value(Y))))) {
if (auto *Cmp = dyn_cast<ICmpInst>(X))
if (Value *Res = foldOrOfICmps(Cmp, RHS, I))
return replaceInstUsesWith(I, Builder.CreateOr(Res, Y));
if (auto *Cmp = dyn_cast<ICmpInst>(Y))
if (Value *Res = foldOrOfICmps(Cmp, RHS, I))
return replaceInstUsesWith(I, Builder.CreateOr(Res, X));
}
}
if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0)))
if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
if (Value *Res = foldLogicOfFCmps(LHS, RHS, false))
return replaceInstUsesWith(I, Res);
if (Instruction *FoldedFCmps = reassociateFCmps(I, Builder))
return FoldedFCmps;
if (Instruction *CastedOr = foldCastedBitwiseLogic(I))
return CastedOr;
// or(sext(A), B) / or(B, sext(A)) --> A ? -1 : B, where A is i1 or <N x i1>.
if (match(Op0, m_OneUse(m_SExt(m_Value(A)))) &&
A->getType()->isIntOrIntVectorTy(1))
return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op1);
if (match(Op1, m_OneUse(m_SExt(m_Value(A)))) &&
A->getType()->isIntOrIntVectorTy(1))
return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op0);
// Note: If we've gotten to the point of visiting the outer OR, then the
// inner one couldn't be simplified. If it was a constant, then it won't
// be simplified by a later pass either, so we try swapping the inner/outer
// ORs in the hopes that we'll be able to simplify it this way.
// (X|C) | V --> (X|V) | C
ConstantInt *CI;
if (Op0->hasOneUse() && !isa<ConstantInt>(Op1) &&
match(Op0, m_Or(m_Value(A), m_ConstantInt(CI)))) {
Value *Inner = Builder.CreateOr(A, Op1);
Inner->takeName(Op0);
return BinaryOperator::CreateOr(Inner, CI);
}
// Change (or (bool?A:B),(bool?C:D)) --> (bool?(or A,C):(or B,D))
// Since this OR statement hasn't been optimized further yet, we hope
// that this transformation will allow the new ORs to be optimized.
{
Value *X = nullptr, *Y = nullptr;
if (Op0->hasOneUse() && Op1->hasOneUse() &&
match(Op0, m_Select(m_Value(X), m_Value(A), m_Value(B))) &&
match(Op1, m_Select(m_Value(Y), m_Value(C), m_Value(D))) && X == Y) {
Value *orTrue = Builder.CreateOr(A, C);
Value *orFalse = Builder.CreateOr(B, D);
return SelectInst::Create(X, orTrue, orFalse);
}
}
return nullptr;
}
/// A ^ B can be specified using other logic ops in a variety of patterns. We
/// can fold these early and efficiently by morphing an existing instruction.
static Instruction *foldXorToXor(BinaryOperator &I,
InstCombiner::BuilderTy &Builder) {
assert(I.getOpcode() == Instruction::Xor);
Value *Op0 = I.getOperand(0);
Value *Op1 = I.getOperand(1);
Value *A, *B;
// There are 4 commuted variants for each of the basic patterns.
// (A & B) ^ (A | B) -> A ^ B
// (A & B) ^ (B | A) -> A ^ B
// (A | B) ^ (A & B) -> A ^ B
// (A | B) ^ (B & A) -> A ^ B
if (match(&I, m_c_Xor(m_And(m_Value(A), m_Value(B)),
m_c_Or(m_Deferred(A), m_Deferred(B))))) {
I.setOperand(0, A);
I.setOperand(1, B);
return &I;
}
// (A | ~B) ^ (~A | B) -> A ^ B
// (~B | A) ^ (~A | B) -> A ^ B
// (~A | B) ^ (A | ~B) -> A ^ B
// (B | ~A) ^ (A | ~B) -> A ^ B
if (match(&I, m_Xor(m_c_Or(m_Value(A), m_Not(m_Value(B))),
m_c_Or(m_Not(m_Deferred(A)), m_Deferred(B))))) {
I.setOperand(0, A);
I.setOperand(1, B);
return &I;
}
// (A & ~B) ^ (~A & B) -> A ^ B
// (~B & A) ^ (~A & B) -> A ^ B
// (~A & B) ^ (A & ~B) -> A ^ B
// (B & ~A) ^ (A & ~B) -> A ^ B
if (match(&I, m_Xor(m_c_And(m_Value(A), m_Not(m_Value(B))),
m_c_And(m_Not(m_Deferred(A)), m_Deferred(B))))) {
I.setOperand(0, A);
I.setOperand(1, B);
return &I;
}
// For the remaining cases we need to get rid of one of the operands.
if (!Op0->hasOneUse() && !Op1->hasOneUse())
return nullptr;
// (A | B) ^ ~(A & B) -> ~(A ^ B)
// (A | B) ^ ~(B & A) -> ~(A ^ B)
// (A & B) ^ ~(A | B) -> ~(A ^ B)
// (A & B) ^ ~(B | A) -> ~(A ^ B)
// Complexity sorting ensures the not will be on the right side.
if ((match(Op0, m_Or(m_Value(A), m_Value(B))) &&
match(Op1, m_Not(m_c_And(m_Specific(A), m_Specific(B))))) ||
(match(Op0, m_And(m_Value(A), m_Value(B))) &&
match(Op1, m_Not(m_c_Or(m_Specific(A), m_Specific(B))))))
return BinaryOperator::CreateNot(Builder.CreateXor(A, B));
return nullptr;
}
Value *InstCombiner::foldXorOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
if (predicatesFoldable(LHS->getPredicate(), RHS->getPredicate())) {
if (LHS->getOperand(0) == RHS->getOperand(1) &&
LHS->getOperand(1) == RHS->getOperand(0))
LHS->swapOperands();
if (LHS->getOperand(0) == RHS->getOperand(0) &&
LHS->getOperand(1) == RHS->getOperand(1)) {
// (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B)
Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1);
unsigned Code = getICmpCode(LHS) ^ getICmpCode(RHS);
bool IsSigned = LHS->isSigned() || RHS->isSigned();
return getNewICmpValue(Code, IsSigned, Op0, Op1, Builder);
}
}
// TODO: This can be generalized to compares of non-signbits using
// decomposeBitTestICmp(). It could be enhanced more by using (something like)
// foldLogOpOfMaskedICmps().
ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate();
Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1);
Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1);
if ((LHS->hasOneUse() || RHS->hasOneUse()) &&
LHS0->getType() == RHS0->getType() &&
LHS0->getType()->isIntOrIntVectorTy()) {
// (X > -1) ^ (Y > -1) --> (X ^ Y) < 0
// (X < 0) ^ (Y < 0) --> (X ^ Y) < 0
if ((PredL == CmpInst::ICMP_SGT && match(LHS1, m_AllOnes()) &&
PredR == CmpInst::ICMP_SGT && match(RHS1, m_AllOnes())) ||
(PredL == CmpInst::ICMP_SLT && match(LHS1, m_Zero()) &&
PredR == CmpInst::ICMP_SLT && match(RHS1, m_Zero()))) {
Value *Zero = ConstantInt::getNullValue(LHS0->getType());
return Builder.CreateICmpSLT(Builder.CreateXor(LHS0, RHS0), Zero);
}
// (X > -1) ^ (Y < 0) --> (X ^ Y) > -1
// (X < 0) ^ (Y > -1) --> (X ^ Y) > -1
if ((PredL == CmpInst::ICMP_SGT && match(LHS1, m_AllOnes()) &&
PredR == CmpInst::ICMP_SLT && match(RHS1, m_Zero())) ||
(PredL == CmpInst::ICMP_SLT && match(LHS1, m_Zero()) &&
PredR == CmpInst::ICMP_SGT && match(RHS1, m_AllOnes()))) {
Value *MinusOne = ConstantInt::getAllOnesValue(LHS0->getType());
return Builder.CreateICmpSGT(Builder.CreateXor(LHS0, RHS0), MinusOne);
}
}
// Instead of trying to imitate the folds for and/or, decompose this 'xor'
// into those logic ops. That is, try to turn this into an and-of-icmps
// because we have many folds for that pattern.
//
// This is based on a truth table definition of xor:
// X ^ Y --> (X | Y) & !(X & Y)
if (Value *OrICmp = SimplifyBinOp(Instruction::Or, LHS, RHS, SQ)) {
// TODO: If OrICmp is true, then the definition of xor simplifies to !(X&Y).
// TODO: If OrICmp is false, the whole thing is false (InstSimplify?).
if (Value *AndICmp = SimplifyBinOp(Instruction::And, LHS, RHS, SQ)) {
// TODO: Independently handle cases where the 'and' side is a constant.
if (OrICmp == LHS && AndICmp == RHS && RHS->hasOneUse()) {
// (LHS | RHS) & !(LHS & RHS) --> LHS & !RHS
RHS->setPredicate(RHS->getInversePredicate());
return Builder.CreateAnd(LHS, RHS);
}
if (OrICmp == RHS && AndICmp == LHS && LHS->hasOneUse()) {
// !(LHS & RHS) & (LHS | RHS) --> !LHS & RHS
LHS->setPredicate(LHS->getInversePredicate());
return Builder.CreateAnd(LHS, RHS);
}
}
}
return nullptr;
}
/// If we have a masked merge, in the canonical form of:
/// (assuming that A only has one use.)
/// | A | |B|
/// ((x ^ y) & M) ^ y
/// | D |
/// * If M is inverted:
/// | D |
/// ((x ^ y) & ~M) ^ y
/// We can canonicalize by swapping the final xor operand
/// to eliminate the 'not' of the mask.
/// ((x ^ y) & M) ^ x
/// * If M is a constant, and D has one use, we transform to 'and' / 'or' ops
/// because that shortens the dependency chain and improves analysis:
/// (x & M) | (y & ~M)
static Instruction *visitMaskedMerge(BinaryOperator &I,
InstCombiner::BuilderTy &Builder) {
Value *B, *X, *D;
Value *M;
if (!match(&I, m_c_Xor(m_Value(B),
m_OneUse(m_c_And(
m_CombineAnd(m_c_Xor(m_Deferred(B), m_Value(X)),
m_Value(D)),
m_Value(M))))))
return nullptr;
Value *NotM;
if (match(M, m_Not(m_Value(NotM)))) {
// De-invert the mask and swap the value in B part.
Value *NewA = Builder.CreateAnd(D, NotM);
return BinaryOperator::CreateXor(NewA, X);
}
Constant *C;
if (D->hasOneUse() && match(M, m_Constant(C))) {
// Unfold.
Value *LHS = Builder.CreateAnd(X, C);
Value *NotC = Builder.CreateNot(C);
Value *RHS = Builder.CreateAnd(B, NotC);
return BinaryOperator::CreateOr(LHS, RHS);
}
return nullptr;
}
// Transform
// ~(x ^ y)
// into:
// (~x) ^ y
// or into
// x ^ (~y)
static Instruction *sinkNotIntoXor(BinaryOperator &I,
InstCombiner::BuilderTy &Builder) {
Value *X, *Y;
// FIXME: one-use check is not needed in general, but currently we are unable
// to fold 'not' into 'icmp', if that 'icmp' has multiple uses. (D35182)
if (!match(&I, m_Not(m_OneUse(m_Xor(m_Value(X), m_Value(Y))))))
return nullptr;
// We only want to do the transform if it is free to do.
if (IsFreeToInvert(X, X->hasOneUse())) {
// Ok, good.
} else if (IsFreeToInvert(Y, Y->hasOneUse())) {
std::swap(X, Y);
} else
return nullptr;
Value *NotX = Builder.CreateNot(X, X->getName() + ".not");
return BinaryOperator::CreateXor(NotX, Y, I.getName() + ".demorgan");
}
// FIXME: We use commutative matchers (m_c_*) for some, but not all, matches
// here. We should standardize that construct where it is needed or choose some
// other way to ensure that commutated variants of patterns are not missed.
Instruction *InstCombiner::visitXor(BinaryOperator &I) {
if (Value *V = SimplifyXorInst(I.getOperand(0), I.getOperand(1),
SQ.getWithInstruction(&I)))
return replaceInstUsesWith(I, V);
if (SimplifyAssociativeOrCommutative(I))
return &I;
if (Instruction *X = foldVectorBinop(I))
return X;
if (Instruction *NewXor = foldXorToXor(I, Builder))
return NewXor;
// (A&B)^(A&C) -> A&(B^C) etc
if (Value *V = SimplifyUsingDistributiveLaws(I))
return replaceInstUsesWith(I, V);
// See if we can simplify any instructions used by the instruction whose sole
// purpose is to compute bits we don't care about.
if (SimplifyDemandedInstructionBits(I))
return &I;
if (Value *V = SimplifyBSwap(I, Builder))
return replaceInstUsesWith(I, V);
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
// Fold (X & M) ^ (Y & ~M) -> (X & M) | (Y & ~M)
// This it a special case in haveNoCommonBitsSet, but the computeKnownBits
// calls in there are unnecessary as SimplifyDemandedInstructionBits should
// have already taken care of those cases.
Value *M;
if (match(&I, m_c_Xor(m_c_And(m_Not(m_Value(M)), m_Value()),
m_c_And(m_Deferred(M), m_Value()))))
return BinaryOperator::CreateOr(Op0, Op1);
// Apply DeMorgan's Law for 'nand' / 'nor' logic with an inverted operand.
Value *X, *Y;
// We must eliminate the and/or (one-use) for these transforms to not increase
// the instruction count.
// ~(~X & Y) --> (X | ~Y)
// ~(Y & ~X) --> (X | ~Y)
if (match(&I, m_Not(m_OneUse(m_c_And(m_Not(m_Value(X)), m_Value(Y)))))) {
Value *NotY = Builder.CreateNot(Y, Y->getName() + ".not");
return BinaryOperator::CreateOr(X, NotY);
}
// ~(~X | Y) --> (X & ~Y)
// ~(Y | ~X) --> (X & ~Y)
if (match(&I, m_Not(m_OneUse(m_c_Or(m_Not(m_Value(X)), m_Value(Y)))))) {
Value *NotY = Builder.CreateNot(Y, Y->getName() + ".not");
return BinaryOperator::CreateAnd(X, NotY);
}
if (Instruction *Xor = visitMaskedMerge(I, Builder))
return Xor;
// Is this a 'not' (~) fed by a binary operator?
BinaryOperator *NotVal;
if (match(&I, m_Not(m_BinOp(NotVal)))) {
if (NotVal->getOpcode() == Instruction::And ||
NotVal->getOpcode() == Instruction::Or) {
// Apply DeMorgan's Law when inverts are free:
// ~(X & Y) --> (~X | ~Y)
// ~(X | Y) --> (~X & ~Y)
if (IsFreeToInvert(NotVal->getOperand(0),
NotVal->getOperand(0)->hasOneUse()) &&
IsFreeToInvert(NotVal->getOperand(1),
NotVal->getOperand(1)->hasOneUse())) {
Value *NotX = Builder.CreateNot(NotVal->getOperand(0), "notlhs");
Value *NotY = Builder.CreateNot(NotVal->getOperand(1), "notrhs");
if (NotVal->getOpcode() == Instruction::And)
return BinaryOperator::CreateOr(NotX, NotY);
return BinaryOperator::CreateAnd(NotX, NotY);
}
}
// ~(X - Y) --> ~X + Y
if (match(NotVal, m_Sub(m_Value(X), m_Value(Y))))
if (isa<Constant>(X) || NotVal->hasOneUse())
return BinaryOperator::CreateAdd(Builder.CreateNot(X), Y);
// ~(~X >>s Y) --> (X >>s Y)
if (match(NotVal, m_AShr(m_Not(m_Value(X)), m_Value(Y))))
return BinaryOperator::CreateAShr(X, Y);
// If we are inverting a right-shifted constant, we may be able to eliminate
// the 'not' by inverting the constant and using the opposite shift type.
// Canonicalization rules ensure that only a negative constant uses 'ashr',
// but we must check that in case that transform has not fired yet.
// ~(C >>s Y) --> ~C >>u Y (when inverting the replicated sign bits)
Constant *C;
if (match(NotVal, m_AShr(m_Constant(C), m_Value(Y))) &&
match(C, m_Negative()))
return BinaryOperator::CreateLShr(ConstantExpr::getNot(C), Y);
// ~(C >>u Y) --> ~C >>s Y (when inverting the replicated sign bits)
if (match(NotVal, m_LShr(m_Constant(C), m_Value(Y))) &&
match(C, m_NonNegative()))
return BinaryOperator::CreateAShr(ConstantExpr::getNot(C), Y);
// ~(X + C) --> -(C + 1) - X
if (match(Op0, m_Add(m_Value(X), m_Constant(C))))
return BinaryOperator::CreateSub(ConstantExpr::getNeg(AddOne(C)), X);
}
// Use DeMorgan and reassociation to eliminate a 'not' op.
Constant *C1;
if (match(Op1, m_Constant(C1))) {
Constant *C2;
if (match(Op0, m_OneUse(m_Or(m_Not(m_Value(X)), m_Constant(C2))))) {
// (~X | C2) ^ C1 --> ((X & ~C2) ^ -1) ^ C1 --> (X & ~C2) ^ ~C1
Value *And = Builder.CreateAnd(X, ConstantExpr::getNot(C2));
return BinaryOperator::CreateXor(And, ConstantExpr::getNot(C1));
}
if (match(Op0, m_OneUse(m_And(m_Not(m_Value(X)), m_Constant(C2))))) {
// (~X & C2) ^ C1 --> ((X | ~C2) ^ -1) ^ C1 --> (X | ~C2) ^ ~C1
Value *Or = Builder.CreateOr(X, ConstantExpr::getNot(C2));
return BinaryOperator::CreateXor(Or, ConstantExpr::getNot(C1));
}
}
// not (cmp A, B) = !cmp A, B
CmpInst::Predicate Pred;
if (match(&I, m_Not(m_OneUse(m_Cmp(Pred, m_Value(), m_Value()))))) {
cast<CmpInst>(Op0)->setPredicate(CmpInst::getInversePredicate(Pred));
return replaceInstUsesWith(I, Op0);
}
{
const APInt *RHSC;
if (match(Op1, m_APInt(RHSC))) {
Value *X;
const APInt *C;
if (RHSC->isSignMask() && match(Op0, m_Sub(m_APInt(C), m_Value(X)))) {
// (C - X) ^ signmask -> (C + signmask - X)
Constant *NewC = ConstantInt::get(I.getType(), *C + *RHSC);
return BinaryOperator::CreateSub(NewC, X);
}
if (RHSC->isSignMask() && match(Op0, m_Add(m_Value(X), m_APInt(C)))) {
// (X + C) ^ signmask -> (X + C + signmask)
Constant *NewC = ConstantInt::get(I.getType(), *C + *RHSC);
return BinaryOperator::CreateAdd(X, NewC);
}
// (X|C1)^C2 -> X^(C1^C2) iff X&~C1 == 0
if (match(Op0, m_Or(m_Value(X), m_APInt(C))) &&
MaskedValueIsZero(X, *C, 0, &I)) {
Constant *NewC = ConstantInt::get(I.getType(), *C ^ *RHSC);
Worklist.Add(cast<Instruction>(Op0));
I.setOperand(0, X);
I.setOperand(1, NewC);
return &I;
}
}
}
if (ConstantInt *RHSC = dyn_cast<ConstantInt>(Op1)) {
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
if (Op0I->getOpcode() == Instruction::LShr) {
// ((X^C1) >> C2) ^ C3 -> (X>>C2) ^ ((C1>>C2)^C3)
// E1 = "X ^ C1"
BinaryOperator *E1;
ConstantInt *C1;
if (Op0I->hasOneUse() &&
(E1 = dyn_cast<BinaryOperator>(Op0I->getOperand(0))) &&
E1->getOpcode() == Instruction::Xor &&
(C1 = dyn_cast<ConstantInt>(E1->getOperand(1)))) {
// fold (C1 >> C2) ^ C3
ConstantInt *C2 = Op0CI, *C3 = RHSC;
APInt FoldConst = C1->getValue().lshr(C2->getValue());
FoldConst ^= C3->getValue();
// Prepare the two operands.
Value *Opnd0 = Builder.CreateLShr(E1->getOperand(0), C2);
Opnd0->takeName(Op0I);
cast<Instruction>(Opnd0)->setDebugLoc(I.getDebugLoc());
Value *FoldVal = ConstantInt::get(Opnd0->getType(), FoldConst);
return BinaryOperator::CreateXor(Opnd0, FoldVal);
}
}
}
}
}
if (Instruction *FoldedLogic = foldBinOpIntoSelectOrPhi(I))
return FoldedLogic;
// Y ^ (X | Y) --> X & ~Y
// Y ^ (Y | X) --> X & ~Y
if (match(Op1, m_OneUse(m_c_Or(m_Value(X), m_Specific(Op0)))))
return BinaryOperator::CreateAnd(X, Builder.CreateNot(Op0));
// (X | Y) ^ Y --> X & ~Y
// (Y | X) ^ Y --> X & ~Y
if (match(Op0, m_OneUse(m_c_Or(m_Value(X), m_Specific(Op1)))))
return BinaryOperator::CreateAnd(X, Builder.CreateNot(Op1));
// Y ^ (X & Y) --> ~X & Y
// Y ^ (Y & X) --> ~X & Y
if (match(Op1, m_OneUse(m_c_And(m_Value(X), m_Specific(Op0)))))
return BinaryOperator::CreateAnd(Op0, Builder.CreateNot(X));
// (X & Y) ^ Y --> ~X & Y
// (Y & X) ^ Y --> ~X & Y
// Canonical form is (X & C) ^ C; don't touch that.
// TODO: A 'not' op is better for analysis and codegen, but demanded bits must
// be fixed to prefer that (otherwise we get infinite looping).
if (!match(Op1, m_Constant()) &&
match(Op0, m_OneUse(m_c_And(m_Value(X), m_Specific(Op1)))))
return BinaryOperator::CreateAnd(Op1, Builder.CreateNot(X));
Value *A, *B, *C;
// (A ^ B) ^ (A | C) --> (~A & C) ^ B -- There are 4 commuted variants.
if (match(&I, m_c_Xor(m_OneUse(m_Xor(m_Value(A), m_Value(B))),
m_OneUse(m_c_Or(m_Deferred(A), m_Value(C))))))
return BinaryOperator::CreateXor(
Builder.CreateAnd(Builder.CreateNot(A), C), B);
// (A ^ B) ^ (B | C) --> (~B & C) ^ A -- There are 4 commuted variants.
if (match(&I, m_c_Xor(m_OneUse(m_Xor(m_Value(A), m_Value(B))),
m_OneUse(m_c_Or(m_Deferred(B), m_Value(C))))))
return BinaryOperator::CreateXor(
Builder.CreateAnd(Builder.CreateNot(B), C), A);
// (A & B) ^ (A ^ B) -> (A | B)
if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
match(Op1, m_c_Xor(m_Specific(A), m_Specific(B))))
return BinaryOperator::CreateOr(A, B);
// (A ^ B) ^ (A & B) -> (A | B)
if (match(Op0, m_Xor(m_Value(A), m_Value(B))) &&
match(Op1, m_c_And(m_Specific(A), m_Specific(B))))
return BinaryOperator::CreateOr(A, B);
// (A & ~B) ^ ~A -> ~(A & B)
// (~B & A) ^ ~A -> ~(A & B)
if (match(Op0, m_c_And(m_Value(A), m_Not(m_Value(B)))) &&
match(Op1, m_Not(m_Specific(A))))
return BinaryOperator::CreateNot(Builder.CreateAnd(A, B));
if (auto *LHS = dyn_cast<ICmpInst>(I.getOperand(0)))
if (auto *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
if (Value *V = foldXorOfICmps(LHS, RHS))
return replaceInstUsesWith(I, V);
if (Instruction *CastedXor = foldCastedBitwiseLogic(I))
return CastedXor;
// Canonicalize a shifty way to code absolute value to the common pattern.
// There are 4 potential commuted variants. Move the 'ashr' candidate to Op1.
// We're relying on the fact that we only do this transform when the shift has
// exactly 2 uses and the add has exactly 1 use (otherwise, we might increase
// instructions).
if (Op0->hasNUses(2))
std::swap(Op0, Op1);
const APInt *ShAmt;
Type *Ty = I.getType();
if (match(Op1, m_AShr(m_Value(A), m_APInt(ShAmt))) &&
Op1->hasNUses(2) && *ShAmt == Ty->getScalarSizeInBits() - 1 &&
match(Op0, m_OneUse(m_c_Add(m_Specific(A), m_Specific(Op1))))) {
// B = ashr i32 A, 31 ; smear the sign bit
// xor (add A, B), B ; add -1 and flip bits if negative
// --> (A < 0) ? -A : A
Value *Cmp = Builder.CreateICmpSLT(A, ConstantInt::getNullValue(Ty));
// Copy the nuw/nsw flags from the add to the negate.
auto *Add = cast<BinaryOperator>(Op0);
Value *Neg = Builder.CreateNeg(A, "", Add->hasNoUnsignedWrap(),
Add->hasNoSignedWrap());
return SelectInst::Create(Cmp, Neg, A);
}
// Eliminate a bitwise 'not' op of 'not' min/max by inverting the min/max:
//
// %notx = xor i32 %x, -1
// %cmp1 = icmp sgt i32 %notx, %y
// %smax = select i1 %cmp1, i32 %notx, i32 %y
// %res = xor i32 %smax, -1
// =>
// %noty = xor i32 %y, -1
// %cmp2 = icmp slt %x, %noty
// %res = select i1 %cmp2, i32 %x, i32 %noty
//
// Same is applicable for smin/umax/umin.
if (match(Op1, m_AllOnes()) && Op0->hasOneUse()) {
Value *LHS, *RHS;
SelectPatternFlavor SPF = matchSelectPattern(Op0, LHS, RHS).Flavor;
if (SelectPatternResult::isMinOrMax(SPF)) {
// It's possible we get here before the not has been simplified, so make
// sure the input to the not isn't freely invertible.
if (match(LHS, m_Not(m_Value(X))) && !IsFreeToInvert(X, X->hasOneUse())) {
Value *NotY = Builder.CreateNot(RHS);
return SelectInst::Create(
Builder.CreateICmp(getInverseMinMaxPred(SPF), X, NotY), X, NotY);
}
// It's possible we get here before the not has been simplified, so make
// sure the input to the not isn't freely invertible.
if (match(RHS, m_Not(m_Value(Y))) && !IsFreeToInvert(Y, Y->hasOneUse())) {
Value *NotX = Builder.CreateNot(LHS);
return SelectInst::Create(
Builder.CreateICmp(getInverseMinMaxPred(SPF), NotX, Y), NotX, Y);
}
// If both sides are freely invertible, then we can get rid of the xor
// completely.
if (IsFreeToInvert(LHS, !LHS->hasNUsesOrMore(3)) &&
IsFreeToInvert(RHS, !RHS->hasNUsesOrMore(3))) {
Value *NotLHS = Builder.CreateNot(LHS);
Value *NotRHS = Builder.CreateNot(RHS);
return SelectInst::Create(
Builder.CreateICmp(getInverseMinMaxPred(SPF), NotLHS, NotRHS),
NotLHS, NotRHS);
}
}
}
if (Instruction *NewXor = sinkNotIntoXor(I, Builder))
return NewXor;
return nullptr;
}