// could have the specified known zero and known one bits, returning them in
// min/max.
static void ComputeUnsignedMinMaxValuesFromKnownBits(const Type *Ty,
- const APInt& KnownZero,
- const APInt& KnownOne,
- APInt& Min,
- APInt& Max) {
- uint32_t BitWidth = cast<IntegerType>(Ty)->getBitWidth();
+ const APInt &KnownZero,
+ const APInt &KnownOne,
+ APInt &Min, APInt &Max) {
+ uint32_t BitWidth = cast<IntegerType>(Ty)->getBitWidth(); BitWidth = BitWidth;
assert(KnownZero.getBitWidth() == BitWidth &&
KnownOne.getBitWidth() == BitWidth &&
Min.getBitWidth() == BitWidth && Max.getBitWidth() &&
InsertNewInstBefore(cast<Instruction>(NewVal), *I);
return UpdateValueUsesWith(I, NewVal);
}
+
+ // If the sign bit is the only bit demanded by this ashr, then there is no
+ // need to do it, the shift doesn't change the high bit.
+ if (DemandedMask.isSignBit())
+ return UpdateValueUsesWith(I, I->getOperand(0));
if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
uint32_t ShiftAmt = SA->getLimitedValue(BitWidth);
break;
}
case Instruction::BitCast: {
- // Packed->packed casts only.
+ // Vector->vector casts only.
const VectorType *VTy = dyn_cast<VectorType>(I->getOperand(0)->getType());
if (!VTy) break;
unsigned InVWidth = VTy->getNumElements();
unsigned Ratio;
if (VWidth == InVWidth) {
- // If we are converting from <4x i32> -> <4 x f32>, we demand the same
+ // If we are converting from <4 x i32> -> <4 x f32>, we demand the same
// elements as are demanded of us.
Ratio = 1;
InputDemandedElts = DemandedElts;
if (I.getNumOperands() == 2) {
Constant *C = cast<Constant>(I.getOperand(1));
for (unsigned i = 0; i != NumPHIValues; ++i) {
- Value *InV;
+ Value *InV = 0;
if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
if (CmpInst *CI = dyn_cast<CmpInst>(&I))
InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C);
return 0;
}
-/// isSignBitCheck - Given an exploded icmp instruction, return true if it
-/// really just returns true if the most significant (sign) bit is set.
-static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS) {
+/// isSignBitCheck - Given an exploded icmp instruction, return true if the
+/// comparison only checks the sign bit. If it only checks the sign bit, set
+/// TrueIfSigned if the result of the comparison is true when the input value is
+/// signed.
+static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS,
+ bool &TrueIfSigned) {
switch (pred) {
- case ICmpInst::ICMP_SLT:
- // True if LHS s< RHS and RHS == 0
- return RHS->isZero();
- case ICmpInst::ICMP_SLE:
- // True if LHS s<= RHS and RHS == -1
- return RHS->isAllOnesValue();
- case ICmpInst::ICMP_UGE:
- // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
- return RHS->getValue() ==
- APInt::getSignBit(RHS->getType()->getPrimitiveSizeInBits());
- case ICmpInst::ICMP_UGT:
- // True if LHS u> RHS and RHS == high-bit-mask - 1
- return RHS->getValue() ==
- APInt::getSignedMaxValue(RHS->getType()->getPrimitiveSizeInBits());
- default:
- return false;
+ case ICmpInst::ICMP_SLT: // True if LHS s< 0
+ TrueIfSigned = true;
+ return RHS->isZero();
+ case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1
+ TrueIfSigned = true;
+ return RHS->isAllOnesValue();
+ case ICmpInst::ICMP_SGT: // True if LHS s> -1
+ TrueIfSigned = false;
+ return RHS->isAllOnesValue();
+ case ICmpInst::ICMP_UGT:
+ // True if LHS u> RHS and RHS == high-bit-mask - 1
+ TrueIfSigned = true;
+ return RHS->getValue() ==
+ APInt::getSignedMaxValue(RHS->getType()->getPrimitiveSizeInBits());
+ case ICmpInst::ICMP_UGE:
+ // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
+ TrueIfSigned = true;
+ return RHS->getValue() ==
+ APInt::getSignBit(RHS->getType()->getPrimitiveSizeInBits());
+ default:
+ return false;
}
}
if (ICmpInst *SCI = dyn_cast<ICmpInst>(BoolCast->getOperand(0))) {
Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
const Type *SCOpTy = SCIOp0->getType();
-
+ bool TIS = false;
+
// If the icmp is true iff the sign bit of X is set, then convert this
// multiply into a shift/and combination.
if (isa<ConstantInt>(SCIOp1) &&
- isSignBitCheck(SCI->getPredicate(), cast<ConstantInt>(SCIOp1))) {
+ isSignBitCheck(SCI->getPredicate(), cast<ConstantInt>(SCIOp1), TIS) &&
+ TIS) {
// Shift the X value right to turn it into "all signbits".
Constant *Amt = ConstantInt::get(SCIOp0->getType(),
SCOpTy->getPrimitiveSizeInBits()-1);
// isMaxValueMinusOne - return true if this is Max-1
static bool isMaxValueMinusOne(const ConstantInt *C, bool isSigned) {
uint32_t TypeBits = C->getType()->getPrimitiveSizeInBits();
- if (isSigned) {
- // Calculate 0111111111..11111
- APInt Val(APInt::getSignedMaxValue(TypeBits));
- return C->getValue() == Val-1;
- }
- return C->getValue() == APInt::getAllOnesValue(TypeBits) - 1;
+ if (!isSigned)
+ return C->getValue() == APInt::getAllOnesValue(TypeBits) - 1;
+ return C->getValue() == APInt::getSignedMaxValue(TypeBits)-1;
}
// isMinValuePlusOne - return true if this is Min+1
static bool isMinValuePlusOne(const ConstantInt *C, bool isSigned) {
- if (isSigned) {
- // Calculate 1111111111000000000000
- uint32_t TypeBits = C->getType()->getPrimitiveSizeInBits();
- APInt Val(APInt::getSignedMinValue(TypeBits));
- return C->getValue() == Val+1;
- }
- return C->getValue() == 1; // unsigned
+ if (!isSigned)
+ return C->getValue() == 1; // unsigned
+
+ // Calculate 1111111111000000000000
+ uint32_t TypeBits = C->getType()->getPrimitiveSizeInBits();
+ return C->getValue() == APInt::getSignedMinValue(TypeBits)+1;
}
// isOneBitSet - Return true if there is exactly one bit set in the specified
for (unsigned i = 1, e = ByteValues.size(); i != e; ++i)
if (ByteValues[i] != V)
return 0;
- const Type *Tys[] = { ITy, ITy };
+ const Type *Tys[] = { ITy };
Module *M = I.getParent()->getParent()->getParent();
- Function *F = Intrinsic::getDeclaration(M, Intrinsic::bswap, Tys, 2);
+ Function *F = Intrinsic::getDeclaration(M, Intrinsic::bswap, Tys, 1);
return new CallInst(F, V);
}
InsertNewInstBefore(BinaryOperator::createOr(V2, V3, "tmp"), I);
return BinaryOperator::createAnd(V1, Or);
}
-
- // (V1 & V3)|(V2 & ~V3) -> ((V1 ^ V2) & V3) ^ V2
- if (isOnlyUse(Op0) && isOnlyUse(Op1)) {
- // Try all combination of terms to find V3 and ~V3.
- if (A->hasOneUse() && match(A, m_Not(m_Value(V3)))) {
- if (V3 == B)
- V1 = D, V2 = C;
- else if (V3 == D)
- V1 = B, V2 = C;
- }
- if (B->hasOneUse() && match(B, m_Not(m_Value(V3)))) {
- if (V3 == A)
- V1 = C, V2 = D;
- else if (V3 == C)
- V1 = A, V2 = D;
- }
- if (C->hasOneUse() && match(C, m_Not(m_Value(V3)))) {
- if (V3 == B)
- V1 = D, V2 = A;
- else if (V3 == D)
- V1 = B, V2 = A;
- }
- if (D->hasOneUse() && match(D, m_Not(m_Value(V3)))) {
- if (V3 == A)
- V1 = C, V2 = B;
- else if (V3 == C)
- V1 = A, V2 = B;
- }
- if (V1) {
- A = InsertNewInstBefore(BinaryOperator::createXor(V1, V2, "tmp"), I);
- A = InsertNewInstBefore(BinaryOperator::createAnd(A, V3, "tmp"), I);
- return BinaryOperator::createXor(A, V2);
- }
- }
}
}
// xor X, X = 0, even if X is nested in a sequence of Xor's.
if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
- assert(Result == &I && "AssociativeOpt didn't work?");
+ assert(Result == &I && "AssociativeOpt didn't work?"); Result=Result;
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
}
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
- // xor (icmp A, B), true = not (icmp A, B) = !icmp A, B
- if (ICmpInst *ICI = dyn_cast<ICmpInst>(Op0))
- if (RHS == ConstantInt::getTrue() && ICI->hasOneUse())
+ // xor (cmp A, B), true = not (cmp A, B) = !cmp A, B
+ if (RHS == ConstantInt::getTrue() && Op0->hasOneUse()) {
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(Op0))
return new ICmpInst(ICI->getInversePredicate(),
ICI->getOperand(0), ICI->getOperand(1));
+ if (FCmpInst *FCI = dyn_cast<FCmpInst>(Op0))
+ return new FCmpInst(FCI->getInversePredicate(),
+ FCI->getOperand(0), FCI->getOperand(1));
+ }
+
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
// ~(c-X) == X-c-1 == X+(-c-1)
if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
// already been handled above, this requires little checking.
//
switch (I.getPredicate()) {
- default: break;
- case ICmpInst::ICMP_ULE:
- return new ICmpInst(ICmpInst::ICMP_ULT, Op0, AddOne(CI));
- case ICmpInst::ICMP_SLE:
- return new ICmpInst(ICmpInst::ICMP_SLT, Op0, AddOne(CI));
- case ICmpInst::ICMP_UGE:
- return new ICmpInst( ICmpInst::ICMP_UGT, Op0, SubOne(CI));
- case ICmpInst::ICMP_SGE:
- return new ICmpInst(ICmpInst::ICMP_SGT, Op0, SubOne(CI));
+ default: break;
+ case ICmpInst::ICMP_ULE:
+ return new ICmpInst(ICmpInst::ICMP_ULT, Op0, AddOne(CI));
+ case ICmpInst::ICMP_SLE:
+ return new ICmpInst(ICmpInst::ICMP_SLT, Op0, AddOne(CI));
+ case ICmpInst::ICMP_UGE:
+ return new ICmpInst( ICmpInst::ICMP_UGT, Op0, SubOne(CI));
+ case ICmpInst::ICMP_SGE:
+ return new ICmpInst(ICmpInst::ICMP_SGT, Op0, SubOne(CI));
}
// See if we can fold the comparison based on bits known to be zero or one
- // in the input.
+ // in the input. If this comparison is a normal comparison, it demands all
+ // bits, if it is a sign bit comparison, it only demands the sign bit.
+
+ bool UnusedBit;
+ bool isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit);
+
uint32_t BitWidth = cast<IntegerType>(Ty)->getBitWidth();
APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
- if (SimplifyDemandedBits(Op0, APInt::getAllOnesValue(BitWidth),
+ if (SimplifyDemandedBits(Op0,
+ isSignBit ? APInt::getSignBit(BitWidth)
+ : APInt::getAllOnesValue(BitWidth),
KnownZero, KnownOne, 0))
return &I;
}
break;
- case Instruction::Shl: // (icmp pred (shl X, ShAmt), CI)
- if (ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
- if (ICI.isEquality()) {
- uint32_t TypeBits = RHSV.getBitWidth();
-
- // Check that the shift amount is in range. If not, don't perform
- // undefined shifts. When the shift is visited it will be
- // simplified.
- if (ShAmt->uge(TypeBits))
- break;
-
- // If we are comparing against bits always shifted out, the
- // comparison cannot succeed.
- Constant *Comp =
- ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt), ShAmt);
- if (Comp != RHS) {// Comparing against a bit that we know is zero.
- bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
- Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE);
- return ReplaceInstUsesWith(ICI, Cst);
- }
+ case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI)
+ ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
+ if (!ShAmt) break;
+
+ uint32_t TypeBits = RHSV.getBitWidth();
+
+ // Check that the shift amount is in range. If not, don't perform
+ // undefined shifts. When the shift is visited it will be
+ // simplified.
+ if (ShAmt->uge(TypeBits))
+ break;
+
+ if (ICI.isEquality()) {
+ // If we are comparing against bits always shifted out, the
+ // comparison cannot succeed.
+ Constant *Comp =
+ ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt), ShAmt);
+ if (Comp != RHS) {// Comparing against a bit that we know is zero.
+ bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
+ Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE);
+ return ReplaceInstUsesWith(ICI, Cst);
+ }
+
+ if (LHSI->hasOneUse()) {
+ // Otherwise strength reduce the shift into an and.
+ uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
+ Constant *Mask =
+ ConstantInt::get(APInt::getLowBitsSet(TypeBits, TypeBits-ShAmtVal));
- if (LHSI->hasOneUse()) {
- // Otherwise strength reduce the shift into an and.
- uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
- Constant *Mask =
- ConstantInt::get(APInt::getLowBitsSet(TypeBits, TypeBits-ShAmtVal));
-
- Instruction *AndI =
- BinaryOperator::createAnd(LHSI->getOperand(0),
- Mask, LHSI->getName()+".mask");
- Value *And = InsertNewInstBefore(AndI, ICI);
- return new ICmpInst(ICI.getPredicate(), And,
- ConstantInt::get(RHSV.lshr(ShAmtVal)));
- }
+ Instruction *AndI =
+ BinaryOperator::createAnd(LHSI->getOperand(0),
+ Mask, LHSI->getName()+".mask");
+ Value *And = InsertNewInstBefore(AndI, ICI);
+ return new ICmpInst(ICI.getPredicate(), And,
+ ConstantInt::get(RHSV.lshr(ShAmtVal)));
}
}
+
+ // Otherwise, if this is a comparison of the sign bit, simplify to and/test.
+ bool TrueIfSigned = false;
+ if (LHSI->hasOneUse() &&
+ isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) {
+ // (X << 31) <s 0 --> (X&1) != 0
+ Constant *Mask = ConstantInt::get(APInt(TypeBits, 1) <<
+ (TypeBits-ShAmt->getZExtValue()-1));
+ Instruction *AndI =
+ BinaryOperator::createAnd(LHSI->getOperand(0),
+ Mask, LHSI->getName()+".mask");
+ Value *And = InsertNewInstBefore(AndI, ICI);
+
+ return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
+ And, Constant::getNullValue(And->getType()));
+ }
break;
+ }
case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI)
- case Instruction::AShr:
- if (ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
- if (ICI.isEquality()) {
- // Check that the shift amount is in range. If not, don't perform
- // undefined shifts. When the shift is visited it will be
- // simplified.
- uint32_t TypeBits = RHSV.getBitWidth();
- if (ShAmt->uge(TypeBits))
- break;
- uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
-
- // If we are comparing against bits always shifted out, the
- // comparison cannot succeed.
- APInt Comp = RHSV << ShAmtVal;
- if (LHSI->getOpcode() == Instruction::LShr)
- Comp = Comp.lshr(ShAmtVal);
- else
- Comp = Comp.ashr(ShAmtVal);
-
- if (Comp != RHSV) { // Comparing against a bit that we know is zero.
- bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
- Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE);
- return ReplaceInstUsesWith(ICI, Cst);
- }
+ case Instruction::AShr: {
+ ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
+ if (!ShAmt) break;
+
+ if (ICI.isEquality()) {
+ // Check that the shift amount is in range. If not, don't perform
+ // undefined shifts. When the shift is visited it will be
+ // simplified.
+ uint32_t TypeBits = RHSV.getBitWidth();
+ if (ShAmt->uge(TypeBits))
+ break;
+ uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
+
+ // If we are comparing against bits always shifted out, the
+ // comparison cannot succeed.
+ APInt Comp = RHSV << ShAmtVal;
+ if (LHSI->getOpcode() == Instruction::LShr)
+ Comp = Comp.lshr(ShAmtVal);
+ else
+ Comp = Comp.ashr(ShAmtVal);
+
+ if (Comp != RHSV) { // Comparing against a bit that we know is zero.
+ bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
+ Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE);
+ return ReplaceInstUsesWith(ICI, Cst);
+ }
+
+ if (LHSI->hasOneUse() || RHSV == 0) {
+ // Otherwise strength reduce the shift into an and.
+ APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
+ Constant *Mask = ConstantInt::get(Val);
- if (LHSI->hasOneUse() || RHSV == 0) {
- // Otherwise strength reduce the shift into an and.
- APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
- Constant *Mask = ConstantInt::get(Val);
-
- Instruction *AndI =
- BinaryOperator::createAnd(LHSI->getOperand(0),
- Mask, LHSI->getName()+".mask");
- Value *And = InsertNewInstBefore(AndI, ICI);
- return new ICmpInst(ICI.getPredicate(), And,
- ConstantExpr::getShl(RHS, ShAmt));
- }
+ Instruction *AndI =
+ BinaryOperator::createAnd(LHSI->getOperand(0),
+ Mask, LHSI->getName()+".mask");
+ Value *And = InsertNewInstBefore(AndI, ICI);
+ return new ICmpInst(ICI.getPredicate(), And,
+ ConstantExpr::getShl(RHS, ShAmt));
}
}
break;
+ }
case Instruction::SDiv:
case Instruction::UDiv:
/// This is a truncation operation if Ty is smaller than V->getType(), or an
/// extension operation if Ty is larger.
static bool CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
- int &NumCastsRemoved) {
+ unsigned CastOpc, int &NumCastsRemoved) {
// We can always evaluate constants in another type.
if (isa<ConstantInt>(V))
return true;
const IntegerType *OrigTy = cast<IntegerType>(V->getType());
+ // If this is an extension or truncate, we can often eliminate it.
+ if (isa<TruncInst>(I) || isa<ZExtInst>(I) || isa<SExtInst>(I)) {
+ // If this is a cast from the destination type, we can trivially eliminate
+ // it, and this will remove a cast overall.
+ if (I->getOperand(0)->getType() == Ty) {
+ // If the first operand is itself a cast, and is eliminable, do not count
+ // this as an eliminable cast. We would prefer to eliminate those two
+ // casts first.
+ if (!isa<CastInst>(I->getOperand(0)))
+ ++NumCastsRemoved;
+ return true;
+ }
+ }
+
+ // We can't extend or shrink something that has multiple uses: doing so would
+ // require duplicating the instruction in general, which isn't profitable.
+ if (!I->hasOneUse()) return false;
+
switch (I->getOpcode()) {
case Instruction::Add:
case Instruction::Sub:
case Instruction::And:
case Instruction::Or:
case Instruction::Xor:
- if (!I->hasOneUse()) return false;
// These operators can all arbitrarily be extended or truncated.
- return CanEvaluateInDifferentType(I->getOperand(0), Ty, NumCastsRemoved) &&
- CanEvaluateInDifferentType(I->getOperand(1), Ty, NumCastsRemoved);
+ return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
+ NumCastsRemoved) &&
+ CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
+ NumCastsRemoved);
case Instruction::Shl:
- if (!I->hasOneUse()) return false;
// If we are truncating the result of this SHL, and if it's a shift of a
// constant amount, we can always perform a SHL in a smaller type.
if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
uint32_t BitWidth = Ty->getBitWidth();
if (BitWidth < OrigTy->getBitWidth() &&
CI->getLimitedValue(BitWidth) < BitWidth)
- return CanEvaluateInDifferentType(I->getOperand(0), Ty,NumCastsRemoved);
+ return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
+ NumCastsRemoved);
}
break;
case Instruction::LShr:
- if (!I->hasOneUse()) return false;
// If this is a truncate of a logical shr, we can truncate it to a smaller
// lshr iff we know that the bits we would otherwise be shifting in are
// already zeros.
MaskedValueIsZero(I->getOperand(0),
APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
CI->getLimitedValue(BitWidth) < BitWidth) {
- return CanEvaluateInDifferentType(I->getOperand(0), Ty,NumCastsRemoved);
+ return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
+ NumCastsRemoved);
}
}
break;
- case Instruction::Trunc:
case Instruction::ZExt:
case Instruction::SExt:
- // If this is a cast from the destination type, we can trivially eliminate
- // it, and this will remove a cast overall.
- if (I->getOperand(0)->getType() == Ty) {
- // If the first operand is itself a cast, and is eliminable, do not count
- // this as an eliminable cast. We would prefer to eliminate those two
- // casts first.
- if (isa<CastInst>(I->getOperand(0)))
- return true;
-
- ++NumCastsRemoved;
+ case Instruction::Trunc:
+ // If this is the same kind of case as our original (e.g. zext+zext), we
+ // can safely replace it. Note that replacing it does not reduce the number
+ // of casts in the input.
+ if (I->getOpcode() == CastOpc)
return true;
- }
break;
default:
// TODO: Can handle more cases here.
case Instruction::Trunc:
case Instruction::ZExt:
case Instruction::SExt:
- case Instruction::BitCast:
// If the source type of the cast is the type we're trying for then we can
- // just return the source. There's no need to insert it because its not new.
+ // just return the source. There's no need to insert it because it is not
+ // new.
if (I->getOperand(0)->getType() == Ty)
return I->getOperand(0);
- // Some other kind of cast, which shouldn't happen, so just ..
- // FALL THROUGH
+ // Otherwise, must be the same type of case, so just reinsert a new one.
+ Res = CastInst::create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),
+ Ty, I->getName());
+ break;
default:
// TODO: Can handle more cases here.
assert(0 && "Unreachable!");
Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
Value *Src = CI.getOperand(0);
- // Casting undef to anything results in undef so might as just replace it and
- // get rid of the cast.
- if (isa<UndefValue>(Src)) // cast undef -> undef
- return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
-
// Many cases of "cast of a cast" are eliminable. If it's eliminable we just
// eliminate it now.
if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
int NumCastsRemoved = 0;
if (!isa<BitCastInst>(CI) &&
CanEvaluateInDifferentType(SrcI, cast<IntegerType>(DestTy),
- NumCastsRemoved)) {
+ CI.getOpcode(), NumCastsRemoved)) {
// If this cast is a truncate, evaluting in a different type always
- // eliminates the cast, so it is always a win. If this is a noop-cast
- // this just removes a noop cast which isn't pointful, but simplifies
- // the code. If this is a zero-extension, we need to do an AND to
- // maintain the clear top-part of the computation, so we require that
- // the input have eliminated at least one cast. If this is a sign
- // extension, we insert two new casts (to do the extension) so we
+ // eliminates the cast, so it is always a win. If this is a zero-extension,
+ // we need to do an AND to maintain the clear top-part of the computation,
+ // so we require that the input have eliminated at least one cast. If this
+ // is a sign extension, we insert two new casts (to do the extension) so we
// require that two casts have been eliminated.
bool DoXForm;
switch (CI.getOpcode()) {
case Instruction::SExt:
DoXForm = NumCastsRemoved >= 2;
break;
- case Instruction::BitCast:
- DoXForm = false;
- break;
}
if (DoXForm) {
return 0;
}
-/// GetKnownAlignment - If the specified pointer has an alignment that we can
-/// determine, return it, otherwise return 0.
-static unsigned GetKnownAlignment(Value *V, TargetData *TD) {
+/// GetOrEnforceKnownAlignment - If the specified pointer has an alignment that
+/// we can determine, return it, otherwise return 0. If PrefAlign is specified,
+/// and it is more than the alignment of the ultimate object, see if we can
+/// increase the alignment of the ultimate object, making this check succeed.
+static unsigned GetOrEnforceKnownAlignment(Value *V, TargetData *TD,
+ unsigned PrefAlign = 0) {
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
unsigned Align = GV->getAlignment();
if (Align == 0 && TD)
Align = TD->getPrefTypeAlignment(GV->getType()->getElementType());
+
+ // If there is a large requested alignment and we can, bump up the alignment
+ // of the global.
+ if (PrefAlign > Align && GV->hasInitializer()) {
+ GV->setAlignment(PrefAlign);
+ Align = PrefAlign;
+ }
return Align;
} else if (AllocationInst *AI = dyn_cast<AllocationInst>(V)) {
unsigned Align = AI->getAlignment();
(unsigned)TD->getABITypeAlignment(Type::Int64Ty));
}
}
+
+ // If there is a requested alignment and if this is an alloca, round up. We
+ // don't do this for malloc, because some systems can't respect the request.
+ if (PrefAlign > Align && isa<AllocaInst>(AI)) {
+ AI->setAlignment(PrefAlign);
+ Align = PrefAlign;
+ }
return Align;
} else if (isa<BitCastInst>(V) ||
(isa<ConstantExpr>(V) &&
cast<ConstantExpr>(V)->getOpcode() == Instruction::BitCast)) {
- User *CI = cast<User>(V);
- if (isa<PointerType>(CI->getOperand(0)->getType()))
- return GetKnownAlignment(CI->getOperand(0), TD);
- return 0;
+ return GetOrEnforceKnownAlignment(cast<User>(V)->getOperand(0),
+ TD, PrefAlign);
} else if (User *GEPI = dyn_castGetElementPtr(V)) {
- unsigned BaseAlignment = GetKnownAlignment(GEPI->getOperand(0), TD);
- if (BaseAlignment == 0) return 0;
-
// If all indexes are zero, it is just the alignment of the base pointer.
bool AllZeroOperands = true;
for (unsigned i = 1, e = GEPI->getNumOperands(); i != e; ++i)
AllZeroOperands = false;
break;
}
- if (AllZeroOperands)
- return BaseAlignment;
-
+
+ if (AllZeroOperands) {
+ // Treat this like a bitcast.
+ return GetOrEnforceKnownAlignment(GEPI->getOperand(0), TD, PrefAlign);
+ }
+
+ unsigned BaseAlignment = GetOrEnforceKnownAlignment(GEPI->getOperand(0),TD);
+ if (BaseAlignment == 0) return 0;
+
// Otherwise, if the base alignment is >= the alignment we expect for the
// base pointer type, then we know that the resultant pointer is aligned at
// least as much as its type requires.
const Type *BasePtrTy = GEPI->getOperand(0)->getType();
const PointerType *PtrTy = cast<PointerType>(BasePtrTy);
- if (TD->getABITypeAlignment(PtrTy->getElementType())
- <= BaseAlignment) {
+ unsigned Align = TD->getABITypeAlignment(PtrTy->getElementType());
+ if (Align <= BaseAlignment) {
const Type *GEPTy = GEPI->getType();
const PointerType *GEPPtrTy = cast<PointerType>(GEPTy);
- return TD->getABITypeAlignment(GEPPtrTy->getElementType());
+ Align = std::min(Align, (unsigned)
+ TD->getABITypeAlignment(GEPPtrTy->getElementType()));
+ return Align;
}
return 0;
}
// If we can determine a pointer alignment that is bigger than currently
// set, update the alignment.
if (isa<MemCpyInst>(MI) || isa<MemMoveInst>(MI)) {
- unsigned Alignment1 = GetKnownAlignment(MI->getOperand(1), TD);
- unsigned Alignment2 = GetKnownAlignment(MI->getOperand(2), TD);
+ unsigned Alignment1 = GetOrEnforceKnownAlignment(MI->getOperand(1), TD);
+ unsigned Alignment2 = GetOrEnforceKnownAlignment(MI->getOperand(2), TD);
unsigned Align = std::min(Alignment1, Alignment2);
if (MI->getAlignment()->getZExtValue() < Align) {
MI->setAlignment(ConstantInt::get(Type::Int32Ty, Align));
Changed = true;
}
} else if (isa<MemSetInst>(MI)) {
- unsigned Alignment = GetKnownAlignment(MI->getDest(), TD);
+ unsigned Alignment = GetOrEnforceKnownAlignment(MI->getDest(), TD);
if (MI->getAlignment()->getZExtValue() < Alignment) {
MI->setAlignment(ConstantInt::get(Type::Int32Ty, Alignment));
Changed = true;
case Intrinsic::x86_sse2_loadu_dq:
// Turn PPC lvx -> load if the pointer is known aligned.
// Turn X86 loadups -> load if the pointer is known aligned.
- if (GetKnownAlignment(II->getOperand(1), TD) >= 16) {
+ if (GetOrEnforceKnownAlignment(II->getOperand(1), TD, 16) >= 16) {
Value *Ptr = InsertCastBefore(Instruction::BitCast, II->getOperand(1),
PointerType::get(II->getType()), CI);
return new LoadInst(Ptr);
case Intrinsic::ppc_altivec_stvx:
case Intrinsic::ppc_altivec_stvxl:
// Turn stvx -> store if the pointer is known aligned.
- if (GetKnownAlignment(II->getOperand(2), TD) >= 16) {
+ if (GetOrEnforceKnownAlignment(II->getOperand(2), TD, 16) >= 16) {
const Type *OpPtrTy = PointerType::get(II->getOperand(1)->getType());
Value *Ptr = InsertCastBefore(Instruction::BitCast, II->getOperand(2),
OpPtrTy, CI);
case Intrinsic::x86_sse2_storeu_dq:
case Intrinsic::x86_sse2_storel_dq:
// Turn X86 storeu -> store if the pointer is known aligned.
- if (GetKnownAlignment(II->getOperand(1), TD) >= 16) {
+ if (GetOrEnforceKnownAlignment(II->getOperand(1), TD, 16) >= 16) {
const Type *OpPtrTy = PointerType::get(II->getOperand(2)->getType());
Value *Ptr = InsertCastBefore(Instruction::BitCast, II->getOperand(1),
OpPtrTy, CI);
Instruction *NC;
if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
- &Args[0], Args.size(), Caller->getName(), Caller);
- cast<InvokeInst>(II)->setCallingConv(II->getCallingConv());
+ Args.begin(), Args.end(), Caller->getName(), Caller);
+ cast<InvokeInst>(NC)->setCallingConv(II->getCallingConv());
} else {
- NC = new CallInst(Callee, &Args[0], Args.size(), Caller->getName(), Caller);
+ NC = new CallInst(Callee, Args.begin(), Args.end(),
+ Caller->getName(), Caller);
if (cast<CallInst>(Caller)->isTailCall())
cast<CallInst>(NC)->setTailCall();
cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv());
// Remember this node, and if we find the cycle, return.
if (!PotentiallyDeadPHIs.insert(PN))
return true;
+
+ // Don't scan crazily complex things.
+ if (PotentiallyDeadPHIs.size() == 16)
+ return false;
if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
return DeadPHICycle(PU, PotentiallyDeadPHIs);
return false;
}
+/// GetUnderlyingObject - Trace through a series of getelementptrs and bitcasts
+/// until we find the underlying object a pointer is referring to or something
+/// we don't understand. Note that the returned pointer may be offset from the
+/// input, because we ignore GEP indices.
+static Value *GetUnderlyingObject(Value *Ptr) {
+ while (1) {
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr)) {
+ if (CE->getOpcode() == Instruction::BitCast ||
+ CE->getOpcode() == Instruction::GetElementPtr)
+ Ptr = CE->getOperand(0);
+ else
+ return Ptr;
+ } else if (BitCastInst *BCI = dyn_cast<BitCastInst>(Ptr)) {
+ Ptr = BCI->getOperand(0);
+ } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr)) {
+ Ptr = GEP->getOperand(0);
+ } else {
+ return Ptr;
+ }
+ }
+}
+
Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
Value *Op = LI.getOperand(0);
+ // Attempt to improve the alignment.
+ unsigned KnownAlign = GetOrEnforceKnownAlignment(Op, TD);
+ if (KnownAlign > LI.getAlignment())
+ LI.setAlignment(KnownAlign);
+
// load (cast X) --> cast (load X) iff safe
if (isa<CastInst>(Op))
if (Instruction *Res = InstCombineLoadCast(*this, LI))
return Res;
}
}
+
+ // If this load comes from anywhere in a constant global, and if the global
+ // is all undef or zero, we know what it loads.
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GetUnderlyingObject(Op))) {
+ if (GV->isConstant() && GV->hasInitializer()) {
+ if (GV->getInitializer()->isNullValue())
+ return ReplaceInstUsesWith(LI, Constant::getNullValue(LI.getType()));
+ else if (isa<UndefValue>(GV->getInitializer()))
+ return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
+ }
+ }
if (Op->hasOneUse()) {
// Change select and PHI nodes to select values instead of addresses: this
}
}
+ // Attempt to improve the alignment.
+ unsigned KnownAlign = GetOrEnforceKnownAlignment(Ptr, TD);
+ if (KnownAlign > SI.getAlignment())
+ SI.setAlignment(KnownAlign);
+
// Do really simple DSE, to catch cases where there are several consequtive
// stores to the same location, separated by a few arithmetic operations. This
// situation often occurs with bitfield accesses.
Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
- // If packed val is undef, replace extract with scalar undef.
+ // If vector val is undef, replace extract with scalar undef.
if (isa<UndefValue>(EI.getOperand(0)))
return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
- // If packed val is constant 0, replace extract with scalar 0.
+ // If vector val is constant 0, replace extract with scalar 0.
if (isa<ConstantAggregateZero>(EI.getOperand(0)))
return ReplaceInstUsesWith(EI, Constant::getNullValue(EI.getType()));
if (ConstantVector *C = dyn_cast<ConstantVector>(EI.getOperand(0))) {
- // If packed val is constant with uniform operands, replace EI
+ // If vector val is constant with uniform operands, replace EI
// with that operand
Constant *op0 = C->getOperand(0);
for (unsigned i = 1; i < C->getNumOperands(); ++i)
Inst->eraseFromParent();
continue;
}
-
+
IC.AddToWorkList(Inst);
}
}
assert(WorklistMap.empty() && "Worklist empty, but map not?");
+
+ // Do an explicit clear, this shrinks the map if needed.
+ WorklistMap.clear();
return Changed;
}
projects / oota-llvm.git / blobdiff