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[InstCombine] rename variables in foldICmpAndConstant(); NFC 

llvm-svn: 279831
This commit is contained in:
Sanjay Patel 2016-08-26 16:14:06 +00:00
parent 244ed8b574
commit 311e0fabb1
1 changed files with 55 additions and 54 deletions
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109
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
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@ -1389,48 +1389,49 @@ Instruction *InstCombiner::foldICmpXorConstant(ICmpInst &Cmp,
return nullptr;
}
Instruction *InstCombiner::foldICmpAndConstant(ICmpInst &ICI,
BinaryOperator *LHSI,
const APInt *RHSV) {
/// Fold icmp (and X, Y), C.
Instruction *InstCombiner::foldICmpAndConstant(ICmpInst &Cmp,
BinaryOperator *And,
const APInt *C) {
// FIXME: This check restricts all folds under here to scalar types.
ConstantInt *RHS = dyn_cast<ConstantInt>(ICI.getOperand(1));
ConstantInt *RHS = dyn_cast<ConstantInt>(Cmp.getOperand(1));
if (!RHS)
return nullptr;
if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
LHSI->getOperand(0)->hasOneUse()) {
ConstantInt *AndCst = cast<ConstantInt>(LHSI->getOperand(1));
if (And->hasOneUse() && isa<ConstantInt>(And->getOperand(1)) &&
And->getOperand(0)->hasOneUse()) {
ConstantInt *AndCst = cast<ConstantInt>(And->getOperand(1));
// If the LHS is an AND of a truncating cast, we can widen the
// and/compare to be the input width without changing the value
// produced, eliminating a cast.
if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) {
if (TruncInst *Cast = dyn_cast<TruncInst>(And->getOperand(0))) {
// We can do this transformation if either the AND constant does not
// have its sign bit set or if it is an equality comparison.
// Extending a relational comparison when we're checking the sign
// bit would not work.
if (ICI.isEquality() ||
(!AndCst->isNegative() && RHSV->isNonNegative())) {
if (Cmp.isEquality() ||
(!AndCst->isNegative() && C->isNonNegative())) {
Value *NewAnd =
Builder->CreateAnd(Cast->getOperand(0),
ConstantExpr::getZExt(AndCst, Cast->getSrcTy()));
NewAnd->takeName(LHSI);
return new ICmpInst(ICI.getPredicate(), NewAnd,
NewAnd->takeName(And);
return new ICmpInst(Cmp.getPredicate(), NewAnd,
ConstantExpr::getZExt(RHS, Cast->getSrcTy()));
}
}
// If the LHS is an AND of a zext, and we have an equality compare, we can
// shrink the and/compare to the smaller type, eliminating the cast.
if (ZExtInst *Cast = dyn_cast<ZExtInst>(LHSI->getOperand(0))) {
if (ZExtInst *Cast = dyn_cast<ZExtInst>(And->getOperand(0))) {
IntegerType *Ty = cast<IntegerType>(Cast->getSrcTy());
// Make sure we don't compare the upper bits, SimplifyDemandedBits
// should fold the icmp to true/false in that case.
if (ICI.isEquality() && RHSV->getActiveBits() <= Ty->getBitWidth()) {
if (Cmp.isEquality() && C->getActiveBits() <= Ty->getBitWidth()) {
Value *NewAnd = Builder->CreateAnd(Cast->getOperand(0),
ConstantExpr::getTrunc(AndCst, Ty));
NewAnd->takeName(LHSI);
return new ICmpInst(ICI.getPredicate(), NewAnd,
NewAnd->takeName(And);
return new ICmpInst(Cmp.getPredicate(), NewAnd,
ConstantExpr::getTrunc(RHS, Ty));
}
}
@ -1439,7 +1440,7 @@ Instruction *InstCombiner::foldICmpAndConstant(ICmpInst &ICI,
// could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
// happens a LOT in code produced by the C front-end, for bitfield
// access.
BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0));
BinaryOperator *Shift = dyn_cast<BinaryOperator>(And->getOperand(0));
if (Shift && !Shift->isShift())
Shift = nullptr;
@ -1462,7 +1463,7 @@ Instruction *InstCombiner::foldICmpAndConstant(ICmpInst &ICI,
// comparison value are not negative. These constraints may not be
// obvious, but we can prove that they are correct using an SMT
// solver.
if (!ICI.isSigned() || (!AndCst->isNegative() && !RHS->isNegative()))
if (!Cmp.isSigned() || (!AndCst->isNegative() && !RHS->isNegative()))
CanFold = true;
} else if (ShiftOpcode == Instruction::LShr) {
// For a logical right shift, we can fold if the comparison is not
@ -1470,7 +1471,7 @@ Instruction *InstCombiner::foldICmpAndConstant(ICmpInst &ICI,
// value and the shifted comparison value are not negative.
// These constraints may not be obvious, but we can prove that they
// are correct using an SMT solver.
if (!ICI.isSigned())
if (!Cmp.isSigned())
CanFold = true;
else {
ConstantInt *ShiftedAndCst =
@ -1496,21 +1497,21 @@ Instruction *InstCombiner::foldICmpAndConstant(ICmpInst &ICI,
// If we shifted bits out, the fold is not going to work out.
// As a special case, check to see if this means that the
// result is always true or false now.
if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
return replaceInstUsesWith(ICI, Builder->getFalse());
if (ICI.getPredicate() == ICmpInst::ICMP_NE)
return replaceInstUsesWith(ICI, Builder->getTrue());
if (Cmp.getPredicate() == ICmpInst::ICMP_EQ)
return replaceInstUsesWith(Cmp, Builder->getFalse());
if (Cmp.getPredicate() == ICmpInst::ICMP_NE)
return replaceInstUsesWith(Cmp, Builder->getTrue());
} else {
ICI.setOperand(1, NewCst);
Cmp.setOperand(1, NewCst);
Constant *NewAndCst;
if (ShiftOpcode == Instruction::Shl)
NewAndCst = ConstantExpr::getLShr(AndCst, ShAmt);
else
NewAndCst = ConstantExpr::getShl(AndCst, ShAmt);
LHSI->setOperand(1, NewAndCst);
LHSI->setOperand(0, Shift->getOperand(0));
And->setOperand(1, NewAndCst);
And->setOperand(0, Shift->getOperand(0));
Worklist.Add(Shift); // Shift is dead.
return &ICI;
return &Cmp;
}
}
}
@ -1518,7 +1519,7 @@ Instruction *InstCombiner::foldICmpAndConstant(ICmpInst &ICI,
// Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is
// preferable because it allows the C<<Y expression to be hoisted out
// of a loop if Y is invariant and X is not.
if (Shift && Shift->hasOneUse() && *RHSV == 0 && ICI.isEquality() &&
if (Shift && Shift->hasOneUse() && *C == 0 && Cmp.isEquality() &&
!Shift->isArithmeticShift() && !isa<Constant>(Shift->getOperand(0))) {
// Compute C << Y.
Value *NS;
@ -1531,10 +1532,10 @@ Instruction *InstCombiner::foldICmpAndConstant(ICmpInst &ICI,
// Compute X & (C << Y).
Value *NewAnd =
Builder->CreateAnd(Shift->getOperand(0), NS, LHSI->getName());
Builder->CreateAnd(Shift->getOperand(0), NS, And->getName());
ICI.setOperand(0, NewAnd);
return &ICI;
Cmp.setOperand(0, NewAnd);
return &Cmp;
}
// (icmp pred (and (or (lshr X, Y), X), 1), 0) -->
@ -1543,14 +1544,14 @@ Instruction *InstCombiner::foldICmpAndConstant(ICmpInst &ICI,
// iff pred isn't signed
{
Value *X, *Y, *LShr;
if (!ICI.isSigned() && *RHSV == 0) {
if (match(LHSI->getOperand(1), m_One())) {
Constant *One = cast<Constant>(LHSI->getOperand(1));
Value *Or = LHSI->getOperand(0);
if (!Cmp.isSigned() && *C == 0) {
if (match(And->getOperand(1), m_One())) {
Constant *One = cast<Constant>(And->getOperand(1));
Value *Or = And->getOperand(0);
if (match(Or, m_Or(m_Value(LShr), m_Value(X))) &&
match(LShr, m_LShr(m_Specific(X), m_Value(Y)))) {
unsigned UsesRemoved = 0;
if (LHSI->hasOneUse())
if (And->hasOneUse())
++UsesRemoved;
if (Or->hasOneUse())
++UsesRemoved;
@ -1570,9 +1571,9 @@ Instruction *InstCombiner::foldICmpAndConstant(ICmpInst &ICI,
One, Or->getName());
}
if (NewOr) {
Value *NewAnd = Builder->CreateAnd(X, NewOr, LHSI->getName());
ICI.setOperand(0, NewAnd);
return &ICI;
Value *NewAnd = Builder->CreateAnd(X, NewOr, And->getName());
Cmp.setOperand(0, NewAnd);
return &Cmp;
}
}
}
@ -1581,23 +1582,23 @@ Instruction *InstCombiner::foldICmpAndConstant(ICmpInst &ICI,
// Replace ((X & AndCst) > RHSV) with ((X & AndCst) != 0), if any
// bit set in (X & AndCst) will produce a result greater than RHSV.
if (ICI.getPredicate() == ICmpInst::ICMP_UGT) {
if (Cmp.getPredicate() == ICmpInst::ICMP_UGT) {
unsigned NTZ = AndCst->getValue().countTrailingZeros();
if ((NTZ < AndCst->getBitWidth()) &&
APInt::getOneBitSet(AndCst->getBitWidth(), NTZ).ugt(*RHSV))
return new ICmpInst(ICmpInst::ICMP_NE, LHSI,
APInt::getOneBitSet(AndCst->getBitWidth(), NTZ).ugt(*C))
return new ICmpInst(ICmpInst::ICMP_NE, And,
Constant::getNullValue(RHS->getType()));
}
}
// Try to optimize things like "A[i]&42 == 0" to index computations.
if (LoadInst *LI = dyn_cast<LoadInst>(LHSI->getOperand(0))) {
if (LoadInst *LI = dyn_cast<LoadInst>(And->getOperand(0))) {
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0)))
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
!LI->isVolatile() && isa<ConstantInt>(LHSI->getOperand(1))) {
ConstantInt *C = cast<ConstantInt>(LHSI->getOperand(1));
if (Instruction *Res = foldCmpLoadFromIndexedGlobal(GEP, GV, ICI, C))
!LI->isVolatile() && isa<ConstantInt>(And->getOperand(1))) {
ConstantInt *C = cast<ConstantInt>(And->getOperand(1));
if (Instruction *Res = foldCmpLoadFromIndexedGlobal(GEP, GV, Cmp, C))
return Res;
}
}
@ -1605,22 +1606,22 @@ Instruction *InstCombiner::foldICmpAndConstant(ICmpInst &ICI,
// X & -C == -C -> X > u ~C
// X & -C != -C -> X <= u ~C
// iff C is a power of 2
if (ICI.isEquality() && RHS == LHSI->getOperand(1) && (-(*RHSV)).isPowerOf2())
return new ICmpInst(ICI.getPredicate() == ICmpInst::ICMP_EQ
if (Cmp.isEquality() && RHS == And->getOperand(1) && (-(*C)).isPowerOf2())
return new ICmpInst(Cmp.getPredicate() == ICmpInst::ICMP_EQ
? ICmpInst::ICMP_UGT
: ICmpInst::ICMP_ULE,
LHSI->getOperand(0), SubOne(RHS));
And->getOperand(0), SubOne(RHS));
// (icmp eq (and %A, C), 0) -> (icmp sgt (trunc %A), -1)
// iff C is a power of 2
if (ICI.isEquality() && LHSI->hasOneUse() && match(RHS, m_Zero())) {
if (auto *CI = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
if (Cmp.isEquality() && And->hasOneUse() && match(RHS, m_Zero())) {
if (auto *CI = dyn_cast<ConstantInt>(And->getOperand(1))) {
const APInt &AI = CI->getValue();
int32_t ExactLogBase2 = AI.exactLogBase2();
if (ExactLogBase2 != -1 && DL.isLegalInteger(ExactLogBase2 + 1)) {
Type *NTy = IntegerType::get(ICI.getContext(), ExactLogBase2 + 1);
Value *Trunc = Builder->CreateTrunc(LHSI->getOperand(0), NTy);
return new ICmpInst(ICI.getPredicate() == ICmpInst::ICMP_EQ
Type *NTy = IntegerType::get(Cmp.getContext(), ExactLogBase2 + 1);
Value *Trunc = Builder->CreateTrunc(And->getOperand(0), NTy);
return new ICmpInst(Cmp.getPredicate() == ICmpInst::ICMP_EQ
? ICmpInst::ICMP_SGE
: ICmpInst::ICMP_SLT,
Trunc, Constant::getNullValue(NTy));