Changes in directory llvm/lib/Transforms/Scalar:
InstructionCombining.cpp updated: 1.536 -> 1.537 ScalarReplAggregates.cpp updated: 1.48 -> 1.49 --- Log message: For PR950: http://llvm.org/PR950 : This patch converts the old SHR instruction into two instructions, AShr (Arithmetic) and LShr (Logical). The Shr instructions now are not dependent on the sign of their operands. --- Diffs of the changes: (+179 -207) InstructionCombining.cpp | 379 +++++++++++++++++++++-------------------------- ScalarReplAggregates.cpp | 7 2 files changed, 179 insertions(+), 207 deletions(-) Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.536 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.537 --- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.536 Fri Nov 3 16:45:50 2006 +++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp Wed Nov 8 00:47:33 2006 @@ -731,7 +731,7 @@ return; } break; - case Instruction::Shr: + case Instruction::LShr: // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { // Compute the new bits that are at the top now. @@ -739,29 +739,39 @@ uint64_t HighBits = (1ULL << ShiftAmt)-1; HighBits <<= I->getType()->getPrimitiveSizeInBits()-ShiftAmt; - if (I->getType()->isUnsigned()) { // Unsigned shift right. - Mask <<= ShiftAmt; - ComputeMaskedBits(I->getOperand(0), Mask, KnownZero,KnownOne,Depth+1); - assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?"); - KnownZero >>= ShiftAmt; - KnownOne >>= ShiftAmt; - KnownZero |= HighBits; // high bits known zero. - } else { - Mask <<= ShiftAmt; - ComputeMaskedBits(I->getOperand(0), Mask, KnownZero,KnownOne,Depth+1); - assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?"); - KnownZero >>= ShiftAmt; - KnownOne >>= ShiftAmt; + // Unsigned shift right. + Mask <<= ShiftAmt; + ComputeMaskedBits(I->getOperand(0), Mask, KnownZero,KnownOne,Depth+1); + assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?"); + KnownZero >>= ShiftAmt; + KnownOne >>= ShiftAmt; + KnownZero |= HighBits; // high bits known zero. + return; + } + break; + case Instruction::AShr: + // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0 + if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { + // Compute the new bits that are at the top now. + uint64_t ShiftAmt = SA->getZExtValue(); + uint64_t HighBits = (1ULL << ShiftAmt)-1; + HighBits <<= I->getType()->getPrimitiveSizeInBits()-ShiftAmt; + + // Signed shift right. + Mask <<= ShiftAmt; + ComputeMaskedBits(I->getOperand(0), Mask, KnownZero,KnownOne,Depth+1); + assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?"); + KnownZero >>= ShiftAmt; + KnownOne >>= ShiftAmt; - // Handle the sign bits. - uint64_t SignBit = 1ULL << (I->getType()->getPrimitiveSizeInBits()-1); - SignBit >>= ShiftAmt; // Adjust to where it is now in the mask. + // Handle the sign bits. + uint64_t SignBit = 1ULL << (I->getType()->getPrimitiveSizeInBits()-1); + SignBit >>= ShiftAmt; // Adjust to where it is now in the mask. - if (KnownZero & SignBit) { // New bits are known zero. - KnownZero |= HighBits; - } else if (KnownOne & SignBit) { // New bits are known one. - KnownOne |= HighBits; - } + if (KnownZero & SignBit) { // New bits are known zero. + KnownZero |= HighBits; + } else if (KnownOne & SignBit) { // New bits are known one. + KnownOne |= HighBits; } return; } @@ -1119,21 +1129,37 @@ KnownZero |= (1ULL << ShiftAmt) - 1; // low bits known zero. } break; - case Instruction::Shr: + case Instruction::LShr: + // For a logical shift right + if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { + unsigned ShiftAmt = SA->getZExtValue(); + + // Compute the new bits that are at the top now. + uint64_t HighBits = (1ULL << ShiftAmt)-1; + HighBits <<= I->getType()->getPrimitiveSizeInBits() - ShiftAmt; + uint64_t TypeMask = I->getType()->getIntegralTypeMask(); + // Unsigned shift right. + if (SimplifyDemandedBits(I->getOperand(0), + (DemandedMask << ShiftAmt) & TypeMask, + KnownZero, KnownOne, Depth+1)) + return true; + assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); + KnownZero &= TypeMask; + KnownOne &= TypeMask; + KnownZero >>= ShiftAmt; + KnownOne >>= ShiftAmt; + KnownZero |= HighBits; // high bits known zero. + } + break; + case Instruction::AShr: // If this is an arithmetic shift right and only the low-bit is set, we can // always convert this into a logical shr, even if the shift amount is // variable. The low bit of the shift cannot be an input sign bit unless // the shift amount is >= the size of the datatype, which is undefined. - if (DemandedMask == 1 && I->getType()->isSigned()) { - // Convert the input to unsigned. - Value *NewVal = InsertCastBefore(I->getOperand(0), - I->getType()->getUnsignedVersion(), *I); - // Perform the unsigned shift right. - NewVal = new ShiftInst(Instruction::Shr, NewVal, I->getOperand(1), - I->getName()); - InsertNewInstBefore(cast<Instruction>(NewVal), *I); - // Then cast that to the destination type. - NewVal = new CastInst(NewVal, I->getType(), I->getName()); + if (DemandedMask == 1) { + // Perform the logical shift right. + Value *NewVal = new ShiftInst(Instruction::LShr, I->getOperand(0), + I->getOperand(1), I->getName()); InsertNewInstBefore(cast<Instruction>(NewVal), *I); return UpdateValueUsesWith(I, NewVal); } @@ -1145,48 +1171,31 @@ uint64_t HighBits = (1ULL << ShiftAmt)-1; HighBits <<= I->getType()->getPrimitiveSizeInBits() - ShiftAmt; uint64_t TypeMask = I->getType()->getIntegralTypeMask(); - if (I->getType()->isUnsigned()) { // Unsigned shift right. - if (SimplifyDemandedBits(I->getOperand(0), - (DemandedMask << ShiftAmt) & TypeMask, - KnownZero, KnownOne, Depth+1)) - return true; - assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); - KnownZero &= TypeMask; - KnownOne &= TypeMask; - KnownZero >>= ShiftAmt; - KnownOne >>= ShiftAmt; - KnownZero |= HighBits; // high bits known zero. - } else { // Signed shift right. - if (SimplifyDemandedBits(I->getOperand(0), - (DemandedMask << ShiftAmt) & TypeMask, - KnownZero, KnownOne, Depth+1)) - return true; - assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); - KnownZero &= TypeMask; - KnownOne &= TypeMask; - KnownZero >>= ShiftAmt; - KnownOne >>= ShiftAmt; + // Signed shift right. + if (SimplifyDemandedBits(I->getOperand(0), + (DemandedMask << ShiftAmt) & TypeMask, + KnownZero, KnownOne, Depth+1)) + return true; + assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); + KnownZero &= TypeMask; + KnownOne &= TypeMask; + KnownZero >>= ShiftAmt; + KnownOne >>= ShiftAmt; - // Handle the sign bits. - uint64_t SignBit = 1ULL << (I->getType()->getPrimitiveSizeInBits()-1); - SignBit >>= ShiftAmt; // Adjust to where it is now in the mask. + // Handle the sign bits. + uint64_t SignBit = 1ULL << (I->getType()->getPrimitiveSizeInBits()-1); + SignBit >>= ShiftAmt; // Adjust to where it is now in the mask. - // If the input sign bit is known to be zero, or if none of the top bits - // are demanded, turn this into an unsigned shift right. - if ((KnownZero & SignBit) || (HighBits & ~DemandedMask) == HighBits) { - // Convert the input to unsigned. - Value *NewVal = InsertCastBefore(I->getOperand(0), - I->getType()->getUnsignedVersion(), *I); - // Perform the unsigned shift right. - NewVal = new ShiftInst(Instruction::Shr, NewVal, SA, I->getName()); - InsertNewInstBefore(cast<Instruction>(NewVal), *I); - // Then cast that to the destination type. - NewVal = new CastInst(NewVal, I->getType(), I->getName()); - InsertNewInstBefore(cast<Instruction>(NewVal), *I); - return UpdateValueUsesWith(I, NewVal); - } else if (KnownOne & SignBit) { // New bits are known one. - KnownOne |= HighBits; - } + // If the input sign bit is known to be zero, or if none of the top bits + // are demanded, turn this into an unsigned shift right. + if ((KnownZero & SignBit) || (HighBits & ~DemandedMask) == HighBits) { + // Perform the logical shift right. + Value *NewVal = new ShiftInst(Instruction::LShr, I->getOperand(0), + SA, I->getName()); + InsertNewInstBefore(cast<Instruction>(NewVal), *I); + return UpdateValueUsesWith(I, NewVal); + } else if (KnownOne & SignBit) { // New bits are known one. + KnownOne |= HighBits; } } break; @@ -1899,29 +1908,28 @@ if (C->isNullValue()) { Value *NoopCastedRHS = RemoveNoopCast(Op1); if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS)) - if (SI->getOpcode() == Instruction::Shr) + if (SI->getOpcode() == Instruction::LShr) { if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) { - const Type *NewTy; - if (SI->getType()->isSigned()) - NewTy = SI->getType()->getUnsignedVersion(); - else - NewTy = SI->getType()->getSignedVersion(); // Check to see if we are shifting out everything but the sign bit. if (CU->getZExtValue() == SI->getType()->getPrimitiveSizeInBits()-1) { - // Ok, the transformation is safe. Insert a cast of the incoming - // value, then the new shift, then the new cast. - Value *InV = InsertCastBefore(SI->getOperand(0), NewTy, I); - Instruction *NewShift = new ShiftInst(Instruction::Shr, InV, - CU, SI->getName()); - if (NewShift->getType() == I.getType()) - return NewShift; - else { - InsertNewInstBefore(NewShift, I); - return new CastInst(NewShift, I.getType()); - } + // Ok, the transformation is safe. Insert AShr. + return new ShiftInst(Instruction::AShr, SI->getOperand(0), + CU, SI->getName()); + } + } + } + else if (SI->getOpcode() == Instruction::AShr) { + if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) { + // Check to see if we are shifting out everything but the sign bit. + if (CU->getZExtValue() == + SI->getType()->getPrimitiveSizeInBits()-1) { + // Ok, the transformation is safe. Insert LShr. + return new ShiftInst(Instruction::LShr, SI->getOperand(0), + CU, SI->getName()); } } + } } // Try to fold constant sub into select arguments. @@ -2138,7 +2146,7 @@ } Value *V = - InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt, + InsertNewInstBefore(new ShiftInst(Instruction::AShr, SCIOp0, Amt, BoolCast->getOperand(0)->getName()+ ".mask"), I); @@ -2262,18 +2270,8 @@ if (uint64_t Val = C->getZExtValue()) // Don't break X / 0 if (isPowerOf2_64(Val)) { uint64_t ShiftAmt = Log2_64(Val); - Value* X = Op0; - const Type* XTy = X->getType(); - bool isSigned = XTy->isSigned(); - if (isSigned) - X = InsertCastBefore(X, XTy->getUnsignedVersion(), I); - Instruction* Result = - new ShiftInst(Instruction::Shr, X, - ConstantInt::get(Type::UByteTy, ShiftAmt)); - if (!isSigned) - return Result; - InsertNewInstBefore(Result, I); - return new CastInst(Result, XTy->getSignedVersion(), I.getName()); + return new ShiftInst(Instruction::LShr, Op0, + ConstantInt::get(Type::UByteTy, ShiftAmt)); } } @@ -2285,20 +2283,11 @@ if (isPowerOf2_64(C1)) { Value *N = RHSI->getOperand(1); const Type* NTy = N->getType(); - bool isSigned = NTy->isSigned(); if (uint64_t C2 = Log2_64(C1)) { - if (isSigned) { - NTy = NTy->getUnsignedVersion(); - N = InsertCastBefore(N, NTy, I); - } Constant *C2V = ConstantInt::get(NTy, C2); N = InsertNewInstBefore(BinaryOperator::createAdd(N, C2V, "tmp"), I); } - Instruction* Result = new ShiftInst(Instruction::Shr, Op0, N); - if (!isSigned) - return Result; - InsertNewInstBefore(Result, I); - return new CastInst(Result, NTy->getSignedVersion(), I.getName()); + return new ShiftInst(Instruction::LShr, Op0, N); } } } @@ -2313,31 +2302,20 @@ if (isPowerOf2_64(TVA) && isPowerOf2_64(FVA)) { // Compute the shift amounts unsigned TSA = Log2_64(TVA), FSA = Log2_64(FVA); - // Make sure we get the unsigned version of X - Value* X = Op0; - const Type* origXTy = X->getType(); - bool isSigned = origXTy->isSigned(); - if (isSigned) - X = InsertCastBefore(X, X->getType()->getUnsignedVersion(), I); // Construct the "on true" case of the select Constant *TC = ConstantInt::get(Type::UByteTy, TSA); Instruction *TSI = - new ShiftInst(Instruction::Shr, X, TC, SI->getName()+".t"); + new ShiftInst(Instruction::LShr, Op0, TC, SI->getName()+".t"); TSI = InsertNewInstBefore(TSI, I); // Construct the "on false" case of the select Constant *FC = ConstantInt::get(Type::UByteTy, FSA); Instruction *FSI = - new ShiftInst(Instruction::Shr, X, FC, SI->getName()+".f"); + new ShiftInst(Instruction::LShr, Op0, FC, SI->getName()+".f"); FSI = InsertNewInstBefore(FSI, I); // construct the select instruction and return it. - SelectInst* NewSI = - new SelectInst(SI->getOperand(0), TSI, FSI, SI->getName()); - if (!isSigned) - return NewSI; - InsertNewInstBefore(NewSI, I); - return new CastInst(NewSI, origXTy, NewSI->getName()); + return new SelectInst(SI->getOperand(0), TSI, FSI, SI->getName()); } } } @@ -2807,44 +2785,40 @@ } break; } - case Instruction::Shr: + case Instruction::LShr: + { // We know that the AND will not produce any of the bits shifted in, so if // the anded constant includes them, clear them now! This only applies to // unsigned shifts, because a signed shr may bring in set bits! // - if (AndRHS->getType()->isUnsigned()) { + Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType()); + Constant *ShrMask = ConstantExpr::getLShr(AllOne, OpRHS); + Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask); + + if (CI == ShrMask) { // Masking out bits that the shift already masks. + return ReplaceInstUsesWith(TheAnd, Op); + } else if (CI != AndRHS) { + TheAnd.setOperand(1, CI); // Reduce bits set in and cst. + return &TheAnd; + } + break; + } + case Instruction::AShr: + // Signed shr. + // See if this is shifting in some sign extension, then masking it out + // with an and. + if (Op->hasOneUse()) { Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType()); - Constant *ShrMask = ConstantExpr::getShr(AllOne, OpRHS); + Constant *ShrMask = ConstantExpr::getLShr(AllOne, OpRHS); Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask); - - if (CI == ShrMask) { // Masking out bits that the shift already masks. - return ReplaceInstUsesWith(TheAnd, Op); - } else if (CI != AndRHS) { - TheAnd.setOperand(1, CI); // Reduce bits set in and cst. - return &TheAnd; - } - } else { // Signed shr. - // See if this is shifting in some sign extension, then masking it out - // with an and. - if (Op->hasOneUse()) { - Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType()); - Constant *ShrMask = ConstantExpr::getUShr(AllOne, OpRHS); - Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask); - if (CI == AndRHS) { // Masking out bits shifted in. - // Make the argument unsigned. - Value *ShVal = Op->getOperand(0); - ShVal = InsertCastBefore(ShVal, - ShVal->getType()->getUnsignedVersion(), - TheAnd); - ShVal = InsertNewInstBefore(new ShiftInst(Instruction::Shr, ShVal, - OpRHS, Op->getName()), - TheAnd); - Value *AndRHS2 = ConstantExpr::getCast(AndRHS, ShVal->getType()); - ShVal = InsertNewInstBefore(BinaryOperator::createAnd(ShVal, AndRHS2, - TheAnd.getName()), - TheAnd); - return new CastInst(ShVal, Op->getType()); - } + if (CI == AndRHS) { // Masking out bits shifted in. + // Make the argument unsigned. + Value *ShVal = Op->getOperand(0); + ShVal = InsertNewInstBefore(new ShiftInst(Instruction::LShr, ShVal, + OpRHS, Op->getName()), + TheAnd); + Value *AndRHS2 = ConstantExpr::getCast(AndRHS, ShVal->getType()); + return BinaryOperator::createAnd(ShVal, AndRHS2, TheAnd.getName()); } } break; @@ -4294,7 +4268,7 @@ if (CanFold) { Constant *NewCst; if (Shift->getOpcode() == Instruction::Shl) - NewCst = ConstantExpr::getUShr(CI, ShAmt); + NewCst = ConstantExpr::getLShr(CI, ShAmt); else NewCst = ConstantExpr::getShl(CI, ShAmt); @@ -4312,7 +4286,7 @@ I.setOperand(1, NewCst); Constant *NewAndCST; if (Shift->getOpcode() == Instruction::Shl) - NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt); + NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt); else NewAndCST = ConstantExpr::getShl(AndCST, ShAmt); LHSI->setOperand(1, NewAndCST); @@ -4338,7 +4312,7 @@ isa<Instruction>(Shift->getOperand(0))) { // Compute C << Y. Value *NS; - if (Shift->getOpcode() == Instruction::Shr) { + if (Shift->getOpcode() == Instruction::LShr) { NS = new ShiftInst(Instruction::Shl, AndCST, Shift->getOperand(1), "tmp"); } else { @@ -4347,7 +4321,7 @@ if (AndCST->getType()->isSigned()) NewAndCST = ConstantExpr::getCast(AndCST, AndCST->getType()->getUnsignedVersion()); - NS = new ShiftInst(Instruction::Shr, NewAndCST, + NS = new ShiftInst(Instruction::LShr, NewAndCST, Shift->getOperand(1), "tmp"); } InsertNewInstBefore(cast<Instruction>(NS), I); @@ -4385,7 +4359,7 @@ // If we are comparing against bits always shifted out, the // comparison cannot succeed. Constant *Comp = - ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt); + ConstantExpr::getShl(ConstantExpr::getLShr(CI, ShAmt), ShAmt); if (Comp != CI) {// Comparing against a bit that we know is zero. bool IsSetNE = I.getOpcode() == Instruction::SetNE; Constant *Cst = ConstantBool::get(IsSetNE); @@ -4411,13 +4385,14 @@ Mask, LHSI->getName()+".mask"); Value *And = InsertNewInstBefore(AndI, I); return new SetCondInst(I.getOpcode(), And, - ConstantExpr::getUShr(CI, ShAmt)); + ConstantExpr::getLShr(CI, ShAmt)); } } } break; - case Instruction::Shr: // (setcc (shr X, ShAmt), CI) + case Instruction::LShr: // (setcc (shr X, ShAmt), CI) + case Instruction::AShr: if (ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1))) { if (I.isEquality()) { // Check that the shift amount is in range. If not, don't perform @@ -4429,8 +4404,13 @@ // If we are comparing against bits always shifted out, the // comparison cannot succeed. - Constant *Comp = - ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt); + Constant *Comp; + if (CI->getType()->isUnsigned()) + Comp = ConstantExpr::getLShr(ConstantExpr::getShl(CI, ShAmt), + ShAmt); + else + Comp = ConstantExpr::getAShr(ConstantExpr::getShl(CI, ShAmt), + ShAmt); if (Comp != CI) {// Comparing against a bit that we know is zero. bool IsSetNE = I.getOpcode() == Instruction::SetNE; @@ -5019,10 +4999,7 @@ if (I.isArithmeticShift()) { if (MaskedValueIsZero(Op0, 1ULL << (I.getType()->getPrimitiveSizeInBits()-1))) { - Value *V = InsertCastBefore(Op0, I.getType()->getUnsignedVersion(), I); - V = InsertNewInstBefore(new ShiftInst(Instruction::Shr, V, Op1, - I.getName()), I); - return new CastInst(V, I.getType()); + return new ShiftInst(Instruction::LShr, Op0, Op1, I.getName()); } } @@ -5036,7 +5013,8 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1, ShiftInst &I) { bool isLeftShift = I.getOpcode() == Instruction::Shl; - bool isSignedShift = Op0->getType()->isSigned(); + bool isSignedShift = isLeftShift ? Op0->getType()->isSigned() : + I.getOpcode() == Instruction::AShr; bool isUnsignedShift = !isSignedShift; // See if we can simplify any instructions used by the instruction whose sole @@ -5229,7 +5207,9 @@ // signedness of the input shift may differ from the current shift if there // is a noop cast between the two. bool isShiftOfLeftShift = ShiftOp->getOpcode() == Instruction::Shl; - bool isShiftOfSignedShift = ShiftOp->getType()->isSigned(); + bool isShiftOfSignedShift = isShiftOfLeftShift ? + ShiftOp->getType()->isSigned() : + ShiftOp->getOpcode() == Instruction::AShr; bool isShiftOfUnsignedShift = !isShiftOfSignedShift; ConstantInt *ShiftAmt1C = cast<ConstantInt>(ShiftOp->getOperand(1)); @@ -5252,8 +5232,12 @@ Value *Op = ShiftOp->getOperand(0); if (isShiftOfSignedShift != isSignedShift) Op = InsertNewInstBefore(new CastInst(Op, I.getType(), "tmp"), I); - return new ShiftInst(I.getOpcode(), Op, + ShiftInst* ShiftResult = new ShiftInst(I.getOpcode(), Op, ConstantInt::get(Type::UByteTy, Amt)); + if (I.getType() == ShiftResult->getType()) + return ShiftResult; + InsertNewInstBefore(ShiftResult, I); + return new CastInst(ShiftResult, I.getType()); } // Check for (A << c1) >> c2 or (A >> c1) << c2. If we are dealing with @@ -5265,10 +5249,10 @@ if (isLeftShift) C = ConstantExpr::getShl(C, ShiftAmt1C); else - C = ConstantExpr::getUShr(C, ShiftAmt1C); + C = ConstantExpr::getLShr(C, ShiftAmt1C); Value *Op = ShiftOp->getOperand(0); - if (isShiftOfSignedShift != isSignedShift) + if (Op->getType() != C->getType()) Op = InsertCastBefore(Op, I.getType(), I); Instruction *Mask = @@ -5283,14 +5267,8 @@ ConstantInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1)); } else if (isShiftOfUnsignedShift || isShiftOfLeftShift) { if (isShiftOfUnsignedShift && !isShiftOfLeftShift && isSignedShift) { - // Make sure to emit an unsigned shift right, not a signed one. - Mask = InsertNewInstBefore(new CastInst(Mask, - Mask->getType()->getUnsignedVersion(), - Op->getName()), I); - Mask = new ShiftInst(Instruction::Shr, Mask, - ConstantInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2)); - InsertNewInstBefore(Mask, I); - return new CastInst(Mask, I.getType()); + return new ShiftInst(Instruction::LShr, Mask, + ConstantInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2)); } else { return new ShiftInst(ShiftOp->getOpcode(), Mask, ConstantInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2)); @@ -5792,7 +5770,7 @@ case Instruction::Shl: // Allow changing the sign of the source operand. Do not allow changing // the size of the shift, UNLESS the shift amount is a constant. We - // mush not change variable sized shifts to a smaller size, because it + // must not change variable sized shifts to a smaller size, because it // is undefined to shift more bits out than exist in the value. if (DestBitSize == SrcBitSize || (DestBitSize < SrcBitSize && isa<Constant>(Op1))) { @@ -5800,21 +5778,16 @@ return new ShiftInst(Instruction::Shl, Op0c, Op1); } break; - case Instruction::Shr: + case Instruction::AShr: // If this is a signed shr, and if all bits shifted in are about to be // truncated off, turn it into an unsigned shr to allow greater // simplifications. - if (DestBitSize < SrcBitSize && Src->getType()->isSigned() && + if (DestBitSize < SrcBitSize && isa<ConstantInt>(Op1)) { unsigned ShiftAmt = cast<ConstantInt>(Op1)->getZExtValue(); if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) { - // Convert to unsigned. - Value *N1 = InsertOperandCastBefore(Op0, - Op0->getType()->getUnsignedVersion(), &CI); - // Insert the new shift, which is now unsigned. - N1 = InsertNewInstBefore(new ShiftInst(Instruction::Shr, N1, - Op1, Src->getName()), CI); - return new CastInst(N1, CI.getType()); + // Insert the new logical shift right. + return new ShiftInst(Instruction::LShr, Op0, Op1); } } break; @@ -5853,13 +5826,9 @@ unsigned ShiftAmt = Log2_64(KnownZero^TypeMask); Value *In = Op0; if (ShiftAmt) { - // Perform an unsigned shr by shiftamt. Convert input to - // unsigned if it is signed. - if (In->getType()->isSigned()) - In = InsertCastBefore( - In, In->getType()->getUnsignedVersion(), CI); + // Perform a logical shr by shiftamt. // Insert the shift to put the result in the low bit. - In = InsertNewInstBefore(new ShiftInst(Instruction::Shr, In, + In = InsertNewInstBefore(new ShiftInst(Instruction::LShr, In, ConstantInt::get(Type::UByteTy, ShiftAmt), In->getName()+".lobit"), CI); } @@ -5934,7 +5903,8 @@ return 3; // Can fold through either operand. case Instruction::Sub: // Can only fold on the amount subtracted. case Instruction::Shl: // Can only fold on the shift amount. - case Instruction::Shr: + case Instruction::LShr: + case Instruction::AShr: return 1; default: return 0; // Cannot fold @@ -5952,7 +5922,8 @@ case Instruction::Xor: return Constant::getNullValue(I->getType()); case Instruction::Shl: - case Instruction::Shr: + case Instruction::LShr: + case Instruction::AShr: return Constant::getNullValue(Type::UByteTy); case Instruction::And: return ConstantInt::getAllOnesValue(I->getType()); @@ -6125,7 +6096,7 @@ // this by inserting a new SRA. unsigned Bits = X->getType()->getPrimitiveSizeInBits(); Constant *ShAmt = ConstantInt::get(Type::UByteTy, Bits-1); - Instruction *SRA = new ShiftInst(Instruction::Shr, X, + Instruction *SRA = new ShiftInst(Instruction::AShr, X, ShAmt, "ones"); InsertNewInstBefore(SRA, SI); Index: llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp diff -u llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp:1.48 llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp:1.49 --- llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp:1.48 Tue Nov 7 16:42:47 2006 +++ llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp Wed Nov 8 00:47:33 2006 @@ -617,10 +617,11 @@ } else { if (Offset) { assert(NV->getType()->isInteger() && "Unknown promotion!"); - if (Offset < TD.getTypeSize(NV->getType())*8) - NV = new ShiftInst(Instruction::Shr, NV, - ConstantInt::get(Type::UByteTy, Offset), + if (Offset < TD.getTypeSize(NV->getType())*8) { + NV = new ShiftInst(Instruction::LShr, NV, + ConstantInt::get(Type::UByteTy, Offset), LI->getName(), LI); + } } else { assert((NV->getType()->isInteger() || isa<PointerType>(NV->getType())) && "Unknown promotion!"); _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
