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llvm / llvm-project / 9e3e1aad3161f4ce5301c3a59c7313ad83240a6d / . / 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/IR/ConstantRange.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Transforms/InstCombine/InstCombiner.h"
#include "llvm/Transforms/Utils/Local.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);
}
/// 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 *InstCombinerImpl::insertRangeTest(Value *V, const APInt &Lo,
const APInt &Hi, bool isSigned,
bool Inside) {
assert((isSigned ? Lo.slt(Hi) : Lo.ult(Hi)) &&
"Lo is not < Hi in range emission code!");
Type *Ty = V->getType();
// 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) {
const APInt *ConstA = nullptr, *ConstB = nullptr, *ConstC = nullptr;
match(A, m_APInt(ConstA));
match(B, m_APInt(ConstB));
match(C, m_APInt(ConstC));
bool IsEq = (Pred == ICmpInst::ICMP_EQ);
bool IsAPow2 = ConstA && ConstA->isPowerOf2();
bool IsBPow2 = ConstB && ConstB->isPowerOf2();
unsigned MaskVal = 0;
if (ConstC && ConstC->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 (ConstA && ConstC && ConstC->isSubsetOf(*ConstA)) {
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 (ConstB && ConstC && ConstC->isSubsetOf(*ConstB)) {
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) {
// Don't allow pointers. Splat vectors are fine.
if (!LHS->getOperand(0)->getType()->isIntOrIntVectorTy() ||
!RHS->getOperand(0)->getType()->isIntOrIntVectorTy())
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;
}
assert(Ok && "Failed to find AND on the right side of the RHS icmp.");
}
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,
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, *CCst, *DCst, *ECst;
if (!match(B, m_ConstantInt(BCst)) || !match(C, m_ConstantInt(CCst)) ||
!match(D, m_ConstantInt(DCst)) || !match(E, m_ConstantInt(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, 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,
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.
const APInt *ConstB, *ConstD;
if (!match(B, m_APInt(ConstB)) || !match(D, m_APInt(ConstD)))
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 = *ConstB & *ConstD;
if (NewMask == *ConstB)
return LHS;
else if (NewMask == *ConstD)
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 = *ConstB | *ConstD;
if (NewMask == *ConstB)
return LHS;
else if (NewMask == *ConstD)
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.
const APInt *OldConstC, *OldConstE;
if (!match(C, m_APInt(OldConstC)) || !match(E, m_APInt(OldConstE)))
return nullptr;
const APInt ConstC = PredL != NewCC ? *ConstB ^ *OldConstC : *OldConstC;
const APInt ConstE = PredR != NewCC ? *ConstD ^ *OldConstE : *OldConstE;
// If there is a conflict, we should actually return a false for the
// whole construct.
if (((*ConstB & *ConstD) & (ConstC ^ ConstE)).getBoolValue())
return ConstantInt::get(LHS->getType(), !IsAnd);
Value *NewOr1 = Builder.CreateOr(B, D);
Value *NewAnd = Builder.CreateAnd(A, NewOr1);
Constant *NewOr2 = ConstantInt::get(A->getType(), ConstC | ConstE);
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 *InstCombinerImpl::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));
}
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 *InstCombinerImpl::foldAndOrOfICmpsOfAndWithPow2(ICmpInst *LHS,
ICmpInst *RHS,
Instruction *CxtI,
bool IsAnd,
bool IsLogical) {
CmpInst::Predicate Pred = IsAnd ? CmpInst::ICMP_NE : CmpInst::ICMP_EQ;
if (LHS->getPredicate() != Pred || RHS->getPredicate() != Pred)
return nullptr;
if (!match(LHS->getOperand(1), m_Zero()) ||
!match(RHS->getOperand(1), m_Zero()))
return nullptr;
Value *L1, *L2, *R1, *R2;
if (match(LHS->getOperand(0), m_And(m_Value(L1), m_Value(L2))) &&
match(RHS->getOperand(0), m_And(m_Value(R1), m_Value(R2)))) {
if (L1 == R2 || L2 == R2)
std::swap(R1, R2);
if (L2 == R1)
std::swap(L1, L2);
if (L1 == R1 &&
isKnownToBeAPowerOfTwo(L2, false, 0, CxtI) &&
isKnownToBeAPowerOfTwo(R2, false, 0, CxtI)) {
// If this is a logical and/or, then we must prevent propagation of a
// poison value from the RHS by inserting freeze.
if (IsLogical)
R2 = Builder.CreateFreeze(R2);
Value *Mask = Builder.CreateOr(L2, R2);
Value *Masked = Builder.CreateAnd(L1, Mask);
auto NewPred = IsAnd ? CmpInst::ICMP_EQ : CmpInst::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.isZero() && "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;
}
/// Commuted variants are assumed to be handled by calling this function again
/// with the parameters swapped.
static Value *foldUnsignedUnderflowCheck(ICmpInst *ZeroICmp,
ICmpInst *UnsignedICmp, bool IsAnd,
const SimplifyQuery &Q,
InstCombiner::BuilderTy &Builder) {
Value *ZeroCmpOp;
ICmpInst::Predicate EqPred;
if (!match(ZeroICmp, m_ICmp(EqPred, m_Value(ZeroCmpOp), m_Zero())) ||
!ICmpInst::isEquality(EqPred))
return nullptr;
auto IsKnownNonZero = [&](Value *V) {
return isKnownNonZero(V, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT);
};
ICmpInst::Predicate UnsignedPred;
Value *A, *B;
if (match(UnsignedICmp,
m_c_ICmp(UnsignedPred, m_Specific(ZeroCmpOp), m_Value(A))) &&
match(ZeroCmpOp, m_c_Add(m_Specific(A), m_Value(B))) &&
(ZeroICmp->hasOneUse() || UnsignedICmp->hasOneUse())) {
auto GetKnownNonZeroAndOther = [&](Value *&NonZero, Value *&Other) {
if (!IsKnownNonZero(NonZero))
std::swap(NonZero, Other);
return IsKnownNonZero(NonZero);
};
// Given ZeroCmpOp = (A + B)
// ZeroCmpOp <= A && ZeroCmpOp != 0 --> (0-B) < A
// ZeroCmpOp > A || ZeroCmpOp == 0 --> (0-B) >= A
//
// ZeroCmpOp < A && ZeroCmpOp != 0 --> (0-X) < Y iff
// ZeroCmpOp >= A || ZeroCmpOp == 0 --> (0-X) >= Y iff
// with X being the value (A/B) that is known to be non-zero,
// and Y being remaining value.
if (UnsignedPred == ICmpInst::ICMP_ULE && EqPred == ICmpInst::ICMP_NE &&
IsAnd)
return Builder.CreateICmpULT(Builder.CreateNeg(B), A);
if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_NE &&
IsAnd && GetKnownNonZeroAndOther(B, A))
return Builder.CreateICmpULT(Builder.CreateNeg(B), A);
if (UnsignedPred == ICmpInst::ICMP_UGT && EqPred == ICmpInst::ICMP_EQ &&
!IsAnd)
return Builder.CreateICmpUGE(Builder.CreateNeg(B), A);
if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_EQ &&
!IsAnd && GetKnownNonZeroAndOther(B, A))
return Builder.CreateICmpUGE(Builder.CreateNeg(B), A);
}
Value *Base, *Offset;
if (!match(ZeroCmpOp, m_Sub(m_Value(Base), m_Value(Offset))))
return nullptr;
if (!match(UnsignedICmp,
m_c_ICmp(UnsignedPred, m_Specific(Base), m_Specific(Offset))) ||
!ICmpInst::isUnsigned(UnsignedPred))
return nullptr;
// Base >=/> Offset && (Base - Offset) != 0 <--> Base > Offset
// (no overflow and not null)
if ((UnsignedPred == ICmpInst::ICMP_UGE ||
UnsignedPred == ICmpInst::ICMP_UGT) &&
EqPred == ICmpInst::ICMP_NE && IsAnd)
return Builder.CreateICmpUGT(Base, Offset);
// Base <=/< Offset || (Base - Offset) == 0 <--> Base <= Offset
// (overflow or null)
if ((UnsignedPred == ICmpInst::ICMP_ULE ||
UnsignedPred == ICmpInst::ICMP_ULT) &&
EqPred == ICmpInst::ICMP_EQ && !IsAnd)
return Builder.CreateICmpULE(Base, Offset);
// Base <= Offset && (Base - Offset) != 0 --> Base < Offset
if (UnsignedPred == ICmpInst::ICMP_ULE && EqPred == ICmpInst::ICMP_NE &&
IsAnd)
return Builder.CreateICmpULT(Base, Offset);
// Base > Offset || (Base - Offset) == 0 --> Base >= Offset
if (UnsignedPred == ICmpInst::ICMP_UGT && EqPred == ICmpInst::ICMP_EQ &&
!IsAnd)
return Builder.CreateICmpUGE(Base, Offset);
return nullptr;
}
struct IntPart {
Value *From;
unsigned StartBit;
unsigned NumBits;
};
/// Match an extraction of bits from an integer.
static Optional<IntPart> matchIntPart(Value *V) {
Value *X;
if (!match(V, m_OneUse(m_Trunc(m_Value(X)))))
return None;
unsigned NumOriginalBits = X->getType()->getScalarSizeInBits();
unsigned NumExtractedBits = V->getType()->getScalarSizeInBits();
Value *Y;
const APInt *Shift;
// For a trunc(lshr Y, Shift) pattern, make sure we're only extracting bits
// from Y, not any shifted-in zeroes.
if (match(X, m_OneUse(m_LShr(m_Value(Y), m_APInt(Shift)))) &&
Shift->ule(NumOriginalBits - NumExtractedBits))
return {{Y, (unsigned)Shift->getZExtValue(), NumExtractedBits}};
return {{X, 0, NumExtractedBits}};
}
/// Materialize an extraction of bits from an integer in IR.
static Value *extractIntPart(const IntPart &P, IRBuilderBase &Builder) {
Value *V = P.From;
if (P.StartBit)
V = Builder.CreateLShr(V, P.StartBit);
Type *TruncTy = V->getType()->getWithNewBitWidth(P.NumBits);
if (TruncTy != V->getType())
V = Builder.CreateTrunc(V, TruncTy);
return V;
}
/// (icmp eq X0, Y0) & (icmp eq X1, Y1) -> icmp eq X01, Y01
/// (icmp ne X0, Y0) | (icmp ne X1, Y1) -> icmp ne X01, Y01
/// where X0, X1 and Y0, Y1 are adjacent parts extracted from an integer.
Value *InstCombinerImpl::foldEqOfParts(ICmpInst *Cmp0, ICmpInst *Cmp1,
bool IsAnd) {
if (!Cmp0->hasOneUse() || !Cmp1->hasOneUse())
return nullptr;
CmpInst::Predicate Pred = IsAnd ? CmpInst::ICMP_EQ : CmpInst::ICMP_NE;
if (Cmp0->getPredicate() != Pred || Cmp1->getPredicate() != Pred)
return nullptr;
Optional<IntPart> L0 = matchIntPart(Cmp0->getOperand(0));
Optional<IntPart> R0 = matchIntPart(Cmp0->getOperand(1));
Optional<IntPart> L1 = matchIntPart(Cmp1->getOperand(0));
Optional<IntPart> R1 = matchIntPart(Cmp1->getOperand(1));
if (!L0 || !R0 || !L1 || !R1)
return nullptr;
// Make sure the LHS/RHS compare a part of the same value, possibly after
// an operand swap.
if (L0->From != L1->From || R0->From != R1->From) {
if (L0->From != R1->From || R0->From != L1->From)
return nullptr;
std::swap(L1, R1);
}
// Make sure the extracted parts are adjacent, canonicalizing to L0/R0 being
// the low part and L1/R1 being the high part.
if (L0->StartBit + L0->NumBits != L1->StartBit ||
R0->StartBit + R0->NumBits != R1->StartBit) {
if (L1->StartBit + L1->NumBits != L0->StartBit ||
R1->StartBit + R1->NumBits != R0->StartBit)
return nullptr;
std::swap(L0, L1);
std::swap(R0, R1);
}
// We can simplify to a comparison of these larger parts of the integers.
IntPart L = {L0->From, L0->StartBit, L0->NumBits + L1->NumBits};
IntPart R = {R0->From, R0->StartBit, R0->NumBits + R1->NumBits};
Value *LValue = extractIntPart(L, Builder);
Value *RValue = extractIntPart(R, Builder);
return Builder.CreateICmp(Pred, LValue, RValue);
}
/// Reduce logic-of-compares with equality to a constant by substituting a
/// common operand with the constant. Callers are expected to call this with
/// Cmp0/Cmp1 switched to handle logic op commutativity.
static Value *foldAndOrOfICmpsWithConstEq(ICmpInst *Cmp0, ICmpInst *Cmp1,
BinaryOperator &Logic,
InstCombiner::BuilderTy &Builder,
const SimplifyQuery &Q) {
bool IsAnd = Logic.getOpcode() == Instruction::And;
assert((IsAnd || Logic.getOpcode() == Instruction::Or) && "Wrong logic op");
// Match an equality compare with a non-poison constant as Cmp0.
// Also, give up if the compare can be constant-folded to avoid looping.
ICmpInst::Predicate Pred0;
Value *X;
Constant *C;
if (!match(Cmp0, m_ICmp(Pred0, m_Value(X), m_Constant(C))) ||
!isGuaranteedNotToBeUndefOrPoison(C) || isa<Constant>(X))
return nullptr;
if ((IsAnd && Pred0 != ICmpInst::ICMP_EQ) ||
(!IsAnd && Pred0 != ICmpInst::ICMP_NE))
return nullptr;
// The other compare must include a common operand (X). Canonicalize the
// common operand as operand 1 (Pred1 is swapped if the common operand was
// operand 0).
Value *Y;
ICmpInst::Predicate Pred1;
if (!match(Cmp1, m_c_ICmp(Pred1, m_Value(Y), m_Deferred(X))))
return nullptr;
// Replace variable with constant value equivalence to remove a variable use:
// (X == C) && (Y Pred1 X) --> (X == C) && (Y Pred1 C)
// (X != C) || (Y Pred1 X) --> (X != C) || (Y Pred1 C)
// Can think of the 'or' substitution with the 'and' bool equivalent:
// A || B --> A || (!A && B)
Value *SubstituteCmp = SimplifyICmpInst(Pred1, Y, C, Q);
if (!SubstituteCmp) {
// If we need to create a new instruction, require that the old compare can
// be removed.
if (!Cmp1->hasOneUse())
return nullptr;
SubstituteCmp = Builder.CreateICmp(Pred1, Y, C);
}
return Builder.CreateBinOp(Logic.getOpcode(), Cmp0, SubstituteCmp);
}
/// Fold (icmp Pred1 V1, C1) & (icmp Pred2 V2, C2)
/// or (icmp Pred1 V1, C1) | (icmp Pred2 V2, C2)
/// into a single comparison using range-based reasoning.
static Value *foldAndOrOfICmpsUsingRanges(
ICmpInst::Predicate Pred1, Value *V1, const APInt &C1,
ICmpInst::Predicate Pred2, Value *V2, const APInt &C2,
IRBuilderBase &Builder, bool IsAnd) {
// Look through add of a constant offset on V1, V2, or both operands. This
// allows us to interpret the V + C' < C'' range idiom into a proper range.
const APInt *Offset1 = nullptr, *Offset2 = nullptr;
if (V1 != V2) {
Value *X;
if (match(V1, m_Add(m_Value(X), m_APInt(Offset1))))
V1 = X;
if (match(V2, m_Add(m_Value(X), m_APInt(Offset2))))
V2 = X;
}
if (V1 != V2)
return nullptr;
ConstantRange CR1 = ConstantRange::makeExactICmpRegion(Pred1, C1);
if (Offset1)
CR1 = CR1.subtract(*Offset1);
ConstantRange CR2 = ConstantRange::makeExactICmpRegion(Pred2, C2);
if (Offset2)
CR2 = CR2.subtract(*Offset2);
Optional<ConstantRange> CR =
IsAnd ? CR1.exactIntersectWith(CR2) : CR1.exactUnionWith(CR2);
if (!CR)
return nullptr;
CmpInst::Predicate NewPred;
APInt NewC, Offset;
CR->getEquivalentICmp(NewPred, NewC, Offset);
Type *Ty = V1->getType();
Value *NewV = V1;
if (Offset != 0)
NewV = Builder.CreateAdd(NewV, ConstantInt::get(Ty, Offset));
return Builder.CreateICmp(NewPred, NewV, ConstantInt::get(Ty, NewC));
}
/// Fold (icmp)&(icmp) if possible.
Value *InstCombinerImpl::foldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS,
BinaryOperator &And) {
const SimplifyQuery Q = SQ.getWithInstruction(&And);
// 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, &And,
/* IsAnd */ true))
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;
if (Value *V = foldAndOrOfICmpsWithConstEq(LHS, RHS, And, Builder, Q))
return V;
if (Value *V = foldAndOrOfICmpsWithConstEq(RHS, LHS, And, Builder, Q))
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, And, Builder))
return V;
if (Value *V = foldIsPowerOf2(LHS, RHS, true /* JoinedByAnd */, Builder))
return V;
if (Value *X =
foldUnsignedUnderflowCheck(LHS, RHS, /*IsAnd=*/true, Q, Builder))
return X;
if (Value *X =
foldUnsignedUnderflowCheck(RHS, LHS, /*IsAnd=*/true, Q, Builder))
return X;
if (Value *X = foldEqOfParts(LHS, RHS, /*IsAnd=*/true))
return X;
// This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2).
Value *LHS0 = LHS->getOperand(0), *RHS0 = RHS->getOperand(0);
// (icmp eq A, 0) & (icmp eq B, 0) --> (icmp eq (A|B), 0)
// TODO: Remove this when foldLogOpOfMaskedICmps can handle undefs.
if (PredL == ICmpInst::ICMP_EQ && match(LHS->getOperand(1), m_ZeroInt()) &&
PredR == ICmpInst::ICMP_EQ && match(RHS->getOperand(1), m_ZeroInt()) &&
LHS0->getType() == RHS0->getType()) {
Value *NewOr = Builder.CreateOr(LHS0, RHS0);
return Builder.CreateICmp(PredL, NewOr,
Constant::getNullValue(NewOr->getType()));
}
const APInt *LHSC, *RHSC;
if (!match(LHS->getOperand(1), m_APInt(LHSC)) ||
!match(RHS->getOperand(1), m_APInt(RHSC)))
return nullptr;
// (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;
const APInt *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_APInt(AndC)))) {
SmallC = RHSC;
BigC = LHSC;
} else if (match(LHS0, m_Trunc(m_Value(V))) &&
match(RHS0, m_And(m_Specific(V), m_APInt(AndC)))) {
SmallC = LHSC;
BigC = RHSC;
}
if (SmallC && BigC) {
unsigned BigBitSize = BigC->getBitWidth();
unsigned SmallBitSize = SmallC->getBitWidth();
// Check that the low bits are zero.
APInt Low = APInt::getLowBitsSet(BigBitSize, SmallBitSize);
if ((Low & *AndC).isZero() && (Low & *BigC).isZero()) {
Value *NewAnd = Builder.CreateAnd(V, Low | *AndC);
APInt N = SmallC->zext(BigBitSize) | *BigC;
Value *NewVal = ConstantInt::get(NewAnd->getType(), N);
return Builder.CreateICmp(PredL, NewAnd, NewVal);
}
}
}
return foldAndOrOfICmpsUsingRanges(PredL, LHS0, *LHSC, PredR, RHS0, *RHSC,
Builder, /* IsAnd */ true);
}
Value *InstCombinerImpl::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.
Value *BO10, *BO11;
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(Opcode, m_Value(BO10), m_Value(BO11))))
return nullptr;
// The inner logic op must have a matching fcmp operand.
Value *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 variations of De Morgan's Laws:
/// (~A & ~B) == (~(A | B))
/// (~A | ~B) == (~(A & B))
static Instruction *matchDeMorgansLaws(BinaryOperator &I,
InstCombiner::BuilderTy &Builder) {
const Instruction::BinaryOps 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.
const Instruction::BinaryOps FlippedOpcode =
(Opcode == Instruction::And) ? Instruction::Or : Instruction::And;
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
Value *A, *B;
if (match(Op0, m_OneUse(m_Not(m_Value(A)))) &&
match(Op1, m_OneUse(m_Not(m_Value(B)))) &&
!InstCombiner::isFreeToInvert(A, A->hasOneUse()) &&
!InstCombiner::isFreeToInvert(B, B->hasOneUse())) {
Value *AndOr =
Builder.CreateBinOp(FlippedOpcode, A, B, I.getName() + ".demorgan");
return BinaryOperator::CreateNot(AndOr);
}
// The 'not' ops may require reassociation.
// (A & ~B) & ~C --> A & ~(B | C)
// (~B & A) & ~C --> A & ~(B | C)
// (A | ~B) | ~C --> A | ~(B & C)
// (~B | A) | ~C --> A | ~(B & C)
Value *C;
if (match(Op0, m_OneUse(m_c_BinOp(Opcode, m_Value(A), m_Not(m_Value(B))))) &&
match(Op1, m_Not(m_Value(C)))) {
Value *FlippedBO = Builder.CreateBinOp(FlippedOpcode, B, C);
return BinaryOperator::Create(Opcode, A, Builder.CreateNot(FlippedBO));
}
return nullptr;
}
bool InstCombinerImpl::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 *InstCombinerImpl::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));
// Operand complexity canonicalization guarantees that the 'xor' is Op0.
// (A ^ B) | ~(A | B) --> ~(A & B)
// (A ^ B) | ~(B | A) --> ~(A & B)
if (Op0->hasOneUse() || Op1->hasOneUse())
if (match(Op0, m_Xor(m_Value(A), m_Value(B))) &&
match(Op1, m_Not(m_c_Or(m_Specific(A), m_Specific(B)))))
return BinaryOperator::CreateNot(Builder.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_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) {
APInt Threshold(C->getType()->getScalarSizeInBits(), BitWidth);
return match(C, m_SpecificInt_ICMP(ICmpInst::ICMP_ULT, Threshold));
}
/// 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 *InstCombinerImpl::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);
}
/// Try folding relatively complex patterns for both And and Or operations
/// with all And and Or swapped.
static Instruction *foldComplexAndOrPatterns(BinaryOperator &I,
InstCombiner::BuilderTy &Builder) {
const Instruction::BinaryOps Opcode = I.getOpcode();
assert(Opcode == Instruction::And || Opcode == Instruction::Or);
// Flip the logic operation.
const Instruction::BinaryOps FlippedOpcode =
(Opcode == Instruction::And) ? Instruction::Or : Instruction::And;
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
Value *A, *B, *C, *X, *Y;
// (~(A | B) & C) | ... --> ...
// (~(A & B) | C) & ... --> ...
// TODO: One use checks are conservative. We just need to check that a total
// number of multiple used values does not exceed reduction
// in operations.
if (match(Op0,
m_c_BinOp(FlippedOpcode,
m_CombineAnd(m_Value(X), m_Not(m_BinOp(Opcode, m_Value(A),
m_Value(B)))),
m_Value(C)))) {
// (~(A | B) & C) | (~(A | C) & B) --> (B ^ C) & ~A
// (~(A & B) | C) & (~(A & C) | B) --> ~((B ^ C) & A)
if (match(Op1,
m_OneUse(m_c_BinOp(FlippedOpcode,
m_OneUse(m_Not(m_c_BinOp(Opcode, m_Specific(A),
m_Specific(C)))),
m_Specific(B))))) {
Value *Xor = Builder.CreateXor(B, C);
return (Opcode == Instruction::Or)
? BinaryOperator::CreateAnd(Xor, Builder.CreateNot(A))
: BinaryOperator::CreateNot(Builder.CreateAnd(Xor, A));
}
// (~(A | B) & C) | (~(B | C) & A) --> (A ^ C) & ~B
// (~(A & B) | C) & (~(B & C) | A) --> ~((A ^ C) & B)
if (match(Op1,
m_OneUse(m_c_BinOp(FlippedOpcode,
m_OneUse(m_Not(m_c_BinOp(Opcode, m_Specific(B),
m_Specific(C)))),
m_Specific(A))))) {
Value *Xor = Builder.CreateXor(A, C);
return (Opcode == Instruction::Or)
? BinaryOperator::CreateAnd(Xor, Builder.CreateNot(B))
: BinaryOperator::CreateNot(Builder.CreateAnd(Xor, B));
}
// (~(A | B) & C) | ~(A | C) --> ~((B & C) | A)
// (~(A & B) | C) & ~(A & C) --> ~((B | C) & A)
if (match(Op1, m_OneUse(m_Not(m_OneUse(
m_c_BinOp(Opcode, m_Specific(A), m_Specific(C)))))))
return BinaryOperator::CreateNot(Builder.CreateBinOp(
Opcode, Builder.CreateBinOp(FlippedOpcode, B, C), A));
// (~(A | B) & C) | ~(B | C) --> ~((A & C) | B)
// (~(A & B) | C) & ~(B & C) --> ~((A | C) & B)
if (match(Op1, m_OneUse(m_Not(m_OneUse(
m_c_BinOp(Opcode, m_Specific(B), m_Specific(C)))))))
return BinaryOperator::CreateNot(Builder.CreateBinOp(
Opcode, Builder.CreateBinOp(FlippedOpcode, A, C), B));
// (~(A | B) & C) | ~(C | (A ^ B)) --> ~((A | B) & (C | (A ^ B)))
// Note, the pattern with swapped and/or is not handled because the
// result is more undefined than a source:
// (~(A & B) | C) & ~(C & (A ^ B)) --> (A ^ B ^ C) | ~(A | C) is invalid.
if (Opcode == Instruction::Or && Op0->hasOneUse() &&
match(Op1, m_OneUse(m_Not(m_CombineAnd(
m_Value(Y),
m_c_BinOp(Opcode, m_Specific(C),
m_c_Xor(m_Specific(A), m_Specific(B)))))))) {
// X = ~(A | B)
// Y = (C | (A ^ B)
Value *Or = cast<BinaryOperator>(X)->getOperand(0);
return BinaryOperator::CreateNot(Builder.CreateAnd(Or, Y));
}
}
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 *InstCombinerImpl::visitAnd(BinaryOperator &I) {
Type *Ty = I.getType();
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;
if (Instruction *X = foldComplexAndOrPatterns(I, Builder))
return X;
// (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);
Value *X, *Y;
if (match(Op0, m_OneUse(m_LogicalShift(m_One(), m_Value(X)))) &&
match(Op1, m_One())) {
// (1 << X) & 1 --> zext(X == 0)
// (1 >> X) & 1 --> zext(X == 0)
Value *IsZero = Builder.CreateICmpEQ(X, ConstantInt::get(Ty, 0));
return new ZExtInst(IsZero, Ty);
}
const APInt *C;
if (match(Op1, m_APInt(C))) {
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(Ty, *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(Ty, Together ^ *C));
And->takeName(Op0);
return BinaryOperator::CreateOr(And, ConstantInt::get(Ty, 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);
}
}
unsigned Width = Ty->getScalarSizeInBits();
const APInt *ShiftC;
if (match(Op0, m_OneUse(m_SExt(m_AShr(m_Value(X), m_APInt(ShiftC)))))) {
if (*C == APInt::getLowBitsSet(Width, Width - ShiftC->getZExtValue())) {
// We are clearing high bits that were potentially set by sext+ashr:
// and (sext (ashr X, ShiftC)), C --> lshr (sext X), ShiftC
Value *Sext = Builder.CreateSExt(X, Ty);
Constant *ShAmtC = ConstantInt::get(Ty, ShiftC->zext(Width));
return BinaryOperator::CreateLShr(Sext, ShAmtC);
}
}
const APInt *AddC;
if (match(Op0, m_Add(m_Value(X), m_APInt(AddC)))) {
// If we add zeros to every bit below a mask, the add has no effect:
// (X + AddC) & LowMaskC --> X & LowMaskC
unsigned Ctlz = C->countLeadingZeros();
APInt LowMask(APInt::getLowBitsSet(Width, Width - Ctlz));
if ((*AddC & LowMask).isZero())
return BinaryOperator::CreateAnd(X, Op1);
// If we are masking the result of the add down to exactly one bit and
// the constant we are adding has no bits set below that bit, then the
// add is flipping a single bit. Example:
// (X + 4) & 4 --> (X & 4) ^ 4
if (Op0->hasOneUse() && C->isPowerOf2() && (*AddC & (*C - 1)) == 0) {
assert((*C & *AddC) != 0 && "Expected common bit");
Value *NewAnd = Builder.CreateAnd(X, Op1);
return BinaryOperator::CreateXor(NewAnd, Op1);
}
}
// ((C1 OP zext(X)) & C2) -> zext((C1 OP X) & C2) if C2 fits in the
// bitwidth of X and OP behaves well when given trunc(C1) and X.
auto isSuitableBinOpcode = [](BinaryOperator *B) {
switch (B->getOpcode()) {
case Instruction::Xor:
case Instruction::Or:
case Instruction::Mul:
case Instruction::Add:
case Instruction::Sub:
return true;
default:
return false;
}
};
BinaryOperator *BO;
if (match(Op0, m_OneUse(m_BinOp(BO))) && isSuitableBinOpcode(BO)) {
Value *X;
const APInt *C1;
// TODO: The one-use restrictions could be relaxed a little if the AND
// is going to be removed.
if (match(BO, m_c_BinOp(m_OneUse(m_ZExt(m_Value(X))), m_APInt(C1))) &&
C->isIntN(X->getType()->getScalarSizeInBits())) {
unsigned XWidth = X->getType()->getScalarSizeInBits();
Constant *TruncC1 = ConstantInt::get(X->getType(), C1->trunc(XWidth));
Value *BinOp = isa<ZExtInst>(BO->getOperand(0))
? Builder.CreateBinOp(BO->getOpcode(), X, TruncC1)
: Builder.CreateBinOp(BO->getOpcode(), TruncC1, X);
Constant *TruncC = ConstantInt::get(X->getType(), C->trunc(XWidth));
Value *And = Builder.CreateAnd(BinOp, TruncC);
return new ZExtInst(And, Ty);
}
}
}
if (match(&I, m_And(m_OneUse(m_Shl(m_ZExt(m_Value(X)), m_Value(Y))),
m_SignMask())) &&
match(Y, m_SpecificInt_ICMP(
ICmpInst::Predicate::ICMP_EQ,
APInt(Ty->getScalarSizeInBits(),
Ty->getScalarSizeInBits() -
X->getType()->getScalarSizeInBits())))) {
auto *SExt = Builder.CreateSExt(X, Ty, X->getName() + ".signext");
auto *SanitizedSignMask = cast<Constant>(Op1);
// We must be careful with the undef elements of the sign bit mask, however:
// the mask elt can be undef iff the shift amount for that lane was undef,
// otherwise we need to sanitize undef masks to zero.
SanitizedSignMask = Constant::replaceUndefsWith(
SanitizedSignMask, ConstantInt::getNullValue(Ty->getScalarType()));
SanitizedSignMask =
Constant::mergeUndefsWith(SanitizedSignMask, cast<Constant>(Y));
return BinaryOperator::CreateAnd(SExt, SanitizedSignMask);
}
if (Instruction *Z = narrowMaskedBinOp(I))
return Z;
if (I.getType()->isIntOrIntVectorTy(1)) {
if (auto *SI0 = dyn_cast<SelectInst>(Op0)) {
if (auto *I =
foldAndOrOfSelectUsingImpliedCond(Op1, *SI0, /* IsAnd */ true))
return I;
}
if (auto *SI1 = dyn_cast<SelectInst>(Op1)) {
if (auto *I =
foldAndOrOfSelectUsingImpliedCond(Op0, *SI1, /* IsAnd */ true))
return I;
}
}
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 & ~(A ^ B) --> A & B
if (match(Op1, m_Not(m_c_Xor(m_Specific(Op0), m_Value(B)))))
return BinaryOperator::CreateAnd(Op0, B);
// ~(A ^ B) & A --> A & B
if (match(Op0, m_Not(m_c_Xor(m_Specific(Op1), m_Value(B)))))
return BinaryOperator::CreateAnd(Op1, 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.
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;
if (Instruction *Sel = foldBinopOfSextBoolToSelect(I))
return Sel;
// and(sext(A), B) / and(B, sext(A)) --> A ? B : 0, where A is i1 or <N x i1>.
// TODO: Move this into foldBinopOfSextBoolToSelect as a more generalized fold
// with binop identity constant. But creating a select with non-constant
// arm may not be reversible due to poison semantics. Is that a good
// canonicalization?
Value *A;
if (match(Op0, m_OneUse(m_SExt(m_Value(A)))) &&
A->getType()->isIntOrIntVectorTy(1))
return SelectInst::Create(A, Op1, Constant::getNullValue(Ty));
if (match(Op1, m_OneUse(m_SExt(m_Value(A)))) &&
A->getType()->isIntOrIntVectorTy(1))
return SelectInst::Create(A, Op0, Constant::getNullValue(Ty));
// (iN X s>> (N-1)) & Y --> (X s< 0) ? Y : 0
unsigned FullShift = Ty->getScalarSizeInBits() - 1;
if (match(&I, m_c_And(m_OneUse(m_AShr(m_Value(X), m_SpecificInt(FullShift))),
m_Value(Y)))) {
Constant *Zero = ConstantInt::getNullValue(Ty);
Value *Cmp = Builder.CreateICmpSLT(X, Zero, "isneg");
return SelectInst::Create(Cmp, Y, Zero);
}
// (~x) & y --> ~(x | (~y)) iff that gets rid of inversions
if (sinkNotIntoOtherHandOfAndOrOr(I))
return &I;
// An and recurrence w/loop invariant step is equivelent to (and start, step)
PHINode *PN = nullptr;
Value *Start = nullptr, *Step = nullptr;
if (matchSimpleRecurrence(&I, PN, Start, Step) && DT.dominates(Step, PN))
return replaceInstUsesWith(I, Builder.CreateAnd(Start, Step));
return nullptr;
}
Instruction *InstCombinerImpl::matchBSwapOrBitReverse(Instruction &I,
bool MatchBSwaps,
bool MatchBitReversals) {
SmallVector<Instruction *, 4> Insts;
if (!recognizeBSwapOrBitReverseIdiom(&I, MatchBSwaps, MatchBitReversals,
Insts))
return nullptr;
Instruction *LastInst = Insts.pop_back_val();
LastInst->removeFromParent();
for (auto *Inst : Insts)
Worklist.push(Inst);
return LastInst;
}
/// Match UB-safe variants of the funnel shift intrinsic.
static Instruction *matchFunnelShift(Instruction &Or, InstCombinerImpl &IC) {
// TODO: Can we reduce the code duplication between this and the related
// rotate matching code under visitSelect and visitTrunc?
unsigned Width = Or.getType()->getScalarSizeInBits();
// First, find an or'd pair of opposite shifts:
// or (lshr ShVal0, ShAmt0), (shl ShVal1, ShAmt1)
BinaryOperator *Or0, *Or1;
if (!match(Or.getOperand(0), m_BinOp(Or0)) ||
!match(Or.getOperand(1), m_BinOp(Or1)))
return nullptr;
Value *ShVal0, *ShVal1, *ShAmt0, *ShAmt1;
if (!match(Or0, m_OneUse(m_LogicalShift(m_Value(ShVal0), m_Value(ShAmt0)))) ||
!match(Or1, m_OneUse(m_LogicalShift(m_Value(ShVal1), m_Value(ShAmt1)))) ||
Or0->getOpcode() == Or1->getOpcode())
return nullptr;
// Canonicalize to or(shl(ShVal0, ShAmt0), lshr(ShVal1, ShAmt1)).
if (Or0->getOpcode() == BinaryOperator::LShr) {
std::swap(Or0, Or1);
std::swap(ShVal0, ShVal1);
std::swap(ShAmt0, ShAmt1);
}
assert(Or0->getOpcode() == BinaryOperator::Shl &&
Or1->getOpcode() == BinaryOperator::LShr &&
"Illegal or(shift,shift) pair");
// Match the shift amount operands for a funnel shift pattern. This always
// matches a subtraction on the R operand.
auto matchShiftAmount = [&](Value *L, Value *R, unsigned Width) -> Value * {
// Check for constant shift amounts that sum to the bitwidth.
const APInt *LI, *RI;
if (match(L, m_APIntAllowUndef(LI)) && match(R, m_APIntAllowUndef(RI)))
if (LI->ult(Width) && RI->ult(Width) && (*LI + *RI) == Width)
return ConstantInt::get(L->getType(), *LI);
Constant *LC, *RC;
if (match(L, m_Constant(LC)) && match(R, m_Constant(RC)) &&
match(L, m_SpecificInt_ICMP(ICmpInst::ICMP_ULT, APInt(Width, Width))) &&
match(R, m_SpecificInt_ICMP(ICmpInst::ICMP_ULT, APInt(Width, Width))) &&
match(ConstantExpr::getAdd(LC, RC), m_SpecificIntAllowUndef(Width)))
return ConstantExpr::mergeUndefsWith(LC, RC);
// (shl ShVal, X) | (lshr ShVal, (Width - x)) iff X < Width.
// We limit this to X < Width in case the backend re-expands the intrinsic,
// and has to reintroduce a shift modulo operation (InstCombine might remove
// it after this fold). This still doesn't guarantee that the final codegen
// will match this original pattern.
if (match(R, m_OneUse(m_Sub(m_SpecificInt(Width), m_Specific(L))))) {
KnownBits KnownL = IC.computeKnownBits(L, /*Depth*/ 0, &Or);
return KnownL.getMaxValue().ult(Width) ? L : nullptr;
}
// For non-constant cases, the following patterns currently only work for
// rotation patterns.
// TODO: Add general funnel-shift compatible patterns.
if (ShVal0 != ShVal1)
return nullptr;
// For non-constant cases we don't support non-pow2 shift masks.
// TODO: Is it worth matching urem as well?
if (!isPowerOf2_32(Width))
return nullptr;
// 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;
if (match(L, m_ZExt(m_And(m_Value(X), m_SpecificInt(Mask)))) &&
match(R, m_ZExt(m_And(m_Neg(m_Specific(X)), m_SpecificInt(Mask)))))
return L;
return nullptr;
};
Value *ShAmt = matchShiftAmount(ShAmt0, ShAmt1, Width);
bool IsFshl = true; // Sub on LSHR.
if (!ShAmt) {
ShAmt = matchShiftAmount(ShAmt1, ShAmt0, Width);
IsFshl = false; // Sub on SHL.
}
if (!ShAmt)
return nullptr;
Intrinsic::ID IID = IsFshl ? Intrinsic::fshl : Intrinsic::fshr;
Function *F = Intrinsic::getDeclaration(Or.getModule(), IID, Or.getType());
return CallInst::Create(F, {ShVal0, ShVal1, ShAmt});
}
/// Attempt to combine or(zext(x),shl(zext(y),bw/2) concat packing patterns.
static Instruction *matchOrConcat(Instruction &Or,
InstCombiner::BuilderTy &Builder) {
assert(Or.getOpcode() == Instruction::Or && "bswap requires an 'or'");
Value *Op0 = Or.getOperand(0), *Op1 = Or.getOperand(1);
Type *Ty = Or.getType();
unsigned Width = Ty->getScalarSizeInBits();
if ((Width & 1) != 0)
return nullptr;
unsigned HalfWidth = Width / 2;
// Canonicalize zext (lower half) to LHS.
if (!isa<ZExtInst>(Op0))
std::swap(Op0, Op1);
// Find lower/upper half.
Value *LowerSrc, *ShlVal, *UpperSrc;
const APInt *C;
if (!match(Op0, m_OneUse(m_ZExt(m_Value(LowerSrc)))) ||
!match(Op1, m_OneUse(m_Shl(m_Value(ShlVal), m_APInt(C)))) ||
!match(ShlVal, m_OneUse(m_ZExt(m_Value(UpperSrc)))))
return nullptr;
if (*C != HalfWidth || LowerSrc->getType() != UpperSrc->getType() ||
LowerSrc->getType()->getScalarSizeInBits() != HalfWidth)
return nullptr;
auto ConcatIntrinsicCalls = [&](Intrinsic::ID id, Value *Lo, Value *Hi) {
Value *NewLower = Builder.CreateZExt(Lo, Ty);
Value *NewUpper = Builder.CreateZExt(Hi, Ty);
NewUpper = Builder.CreateShl(NewUpper, HalfWidth);
Value *BinOp = Builder.CreateOr(NewLower, NewUpper);
Function *F = Intrinsic::getDeclaration(Or.getModule(), id, Ty);
return Builder.CreateCall(F, BinOp);
};
// BSWAP: Push the concat down, swapping the lower/upper sources.
// concat(bswap(x),bswap(y)) -> bswap(concat(x,y))
Value *LowerBSwap, *UpperBSwap;
if (match(LowerSrc, m_BSwap(m_Value(LowerBSwap))) &&
match(UpperSrc, m_BSwap(m_Value(UpperBSwap))))
return ConcatIntrinsicCalls(Intrinsic::bswap, UpperBSwap, LowerBSwap);
// BITREVERSE: Push the concat down, swapping the lower/upper sources.
// concat(bitreverse(x),bitreverse(y)) -> bitreverse(concat(x,y))
Value *LowerBRev, *UpperBRev;
if (match(LowerSrc, m_BitReverse(m_Value(LowerBRev))) &&
match(UpperSrc, m_BitReverse(m_Value(UpperBRev))))
return ConcatIntrinsicCalls(Intrinsic::bitreverse, UpperBRev, LowerBRev);
return nullptr;
}
/// If all elements of two constant vectors are 0/-1 and inverses, return true.
static bool areInverseVectorBitmasks(Constant *C1, Constant *C2) {
unsigned NumElts = cast<FixedVectorType>(C1->getType())->getNumElements();
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 *InstCombinerImpl::getSelectCondition(Value *A, Value *B) {
// 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;
// If A is the 'not' operand of B and has enough signbits, we have our answer.
if (match(B, m_Not(m_Specific(A)))) {
// If these are scalars or vectors of i1, A can be used directly.
if (Ty->isIntOrIntVectorTy(1))
return A;
// If we look through a vector bitcast, the caller will bitcast the operands
// to match the condition's number of bits (N x i1).
// To make this poison-safe, disallow bitcast from wide element to narrow
// element. That could allow poison in lanes where it was not present in the
// original code.
A = peekThroughBitcast(A);
if (A->getType()->isIntOrIntVectorTy()) {
unsigned NumSignBits = ComputeNumSignBits(A);
if (NumSignBits == A->getType()->getScalarSizeInBits() &&
NumSignBits <= Ty->getScalarSizeInBits())
return Builder.CreateTrunc(A, CmpInst::makeCmpResultType(A->getType()));
}
return nullptr;
}
// 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) &&
ComputeNumSignBits(A) == Ty->getScalarSizeInBits())
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)) {
// A = sext i1 Cond; B = sext (not (i1 Cond))
if (match(B, m_SExt(m_Not(m_Specific(Cond)))))
return Cond;
// A = sext i1 Cond; B = not ({bitcast} (sext (i1 Cond)))
// TODO: The one-use checks are unnecessary or misplaced. If the caller
// checked for uses on logic ops/casts, that should be enough to
// make this transform worthwhile.
if (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 *InstCombinerImpl::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))
// If this is a vector, we may need to cast to match the condition's length.
// The bitcasts will either all exist or all not exist. The builder will
// not create unnecessary casts if the types already match.
Type *SelTy = A->getType();
if (auto *VecTy = dyn_cast<VectorType>(Cond->getType())) {
unsigned Elts = VecTy->getElementCount().getKnownMinValue();
Type *EltTy = Builder.getIntNTy(SelTy->getPrimitiveSizeInBits() / Elts);
SelTy = VectorType::get(EltTy, VecTy->getElementCount());
}
Value *BitcastC = Builder.CreateBitCast(C, SelTy);
Value *BitcastD = Builder.CreateBitCast(D, SelTy);
Value *Select = Builder.CreateSelect(Cond, BitcastC, BitcastD);
return Builder.CreateBitCast(Select, OrigType);
}
return nullptr;
}
/// Fold (icmp)|(icmp) if possible.
Value *InstCombinerImpl::foldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
BinaryOperator &Or) {
const SimplifyQuery Q = SQ.getWithInstruction(&Or);
// 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, &Or,
/* IsAnd */ false))
return V;
ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate();
Value *LHS0 = LHS->getOperand(0), *RHS0 = RHS->getOperand(0);
Value *LHS1 = LHS->getOperand(1), *RHS1 = RHS->getOperand(1);
const APInt *LHSC = nullptr, *RHSC = nullptr;
match(LHS1, m_APInt(LHSC));
match(RHS1, m_APInt(RHSC));
// 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->getBitWidth() == RHSC->getBitWidth() && *LHSC == *RHSC) {
Value *AddOpnd;
const APInt *LAddC, *RAddC;
if (match(LHS0, m_Add(m_Value(AddOpnd), m_APInt(LAddC))) &&
match(RHS0, m_Add(m_Specific(AddOpnd), m_APInt(RAddC))) &&
LAddC->ugt(*LHSC) && RAddC->ugt(*LHSC)) {
APInt DiffC = *LAddC ^ *RAddC;
if (DiffC.isPowerOf2()) {
const APInt *MaxAddC = nullptr;
if (LAddC->ult(*RAddC))
MaxAddC = RAddC;
else
MaxAddC = LAddC;