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For PR1205:
* APIntify visitAdd and visitSelectInst * Remove unused uint64_t versions of utility functions that have been replaced with APInt versions. This completes most of the changes for APIntification of InstCombine. This passes llvm-test and llvm/test/Transforms/InstCombine/APInt. Patch by Zhou Sheng. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35287 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Reid Spencer
parent
b37b80ce46
commit
2ec619a29a
@ -319,10 +319,8 @@ namespace {
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/// most-complex to least-complex order.
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bool SimplifyCompare(CmpInst &I);
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bool SimplifyDemandedBits(Value *V, uint64_t DemandedMask,
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uint64_t &KnownZero, uint64_t &KnownOne,
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unsigned Depth = 0);
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/// SimplifyDemandedBits - Attempts to replace V with a simpler value based
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/// on the demanded bits.
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bool SimplifyDemandedBits(Value *V, APInt DemandedMask,
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APInt& KnownZero, APInt& KnownOne,
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unsigned Depth = 0);
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@ -784,214 +782,6 @@ static void ComputeMaskedBits(Value *V, APInt Mask, APInt& KnownZero,
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}
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}
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/// ComputeMaskedBits - Determine which of the bits specified in Mask are
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/// known to be either zero or one and return them in the KnownZero/KnownOne
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/// bitsets. This code only analyzes bits in Mask, in order to short-circuit
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/// processing.
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static void ComputeMaskedBits(Value *V, uint64_t Mask, uint64_t &KnownZero,
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uint64_t &KnownOne, unsigned Depth = 0) {
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// Note, we cannot consider 'undef' to be "IsZero" here. The problem is that
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// we cannot optimize based on the assumption that it is zero without changing
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// it to be an explicit zero. If we don't change it to zero, other code could
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// optimized based on the contradictory assumption that it is non-zero.
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// Because instcombine aggressively folds operations with undef args anyway,
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// this won't lose us code quality.
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if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
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// We know all of the bits for a constant!
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KnownOne = CI->getZExtValue() & Mask;
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KnownZero = ~KnownOne & Mask;
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return;
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}
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KnownZero = KnownOne = 0; // Don't know anything.
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if (Depth == 6 || Mask == 0)
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return; // Limit search depth.
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uint64_t KnownZero2, KnownOne2;
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Instruction *I = dyn_cast<Instruction>(V);
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if (!I) return;
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Mask &= cast<IntegerType>(V->getType())->getBitMask();
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switch (I->getOpcode()) {
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case Instruction::And:
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// If either the LHS or the RHS are Zero, the result is zero.
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ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
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Mask &= ~KnownZero;
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ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
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// Output known-1 bits are only known if set in both the LHS & RHS.
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KnownOne &= KnownOne2;
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// Output known-0 are known to be clear if zero in either the LHS | RHS.
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KnownZero |= KnownZero2;
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return;
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case Instruction::Or:
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ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
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Mask &= ~KnownOne;
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ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
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// Output known-0 bits are only known if clear in both the LHS & RHS.
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KnownZero &= KnownZero2;
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// Output known-1 are known to be set if set in either the LHS | RHS.
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KnownOne |= KnownOne2;
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return;
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case Instruction::Xor: {
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ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
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ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
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// Output known-0 bits are known if clear or set in both the LHS & RHS.
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uint64_t KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
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// Output known-1 are known to be set if set in only one of the LHS, RHS.
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KnownOne = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
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KnownZero = KnownZeroOut;
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return;
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}
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case Instruction::Select:
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ComputeMaskedBits(I->getOperand(2), Mask, KnownZero, KnownOne, Depth+1);
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ComputeMaskedBits(I->getOperand(1), Mask, KnownZero2, KnownOne2, Depth+1);
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
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// Only known if known in both the LHS and RHS.
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KnownOne &= KnownOne2;
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KnownZero &= KnownZero2;
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return;
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case Instruction::FPTrunc:
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case Instruction::FPExt:
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case Instruction::FPToUI:
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case Instruction::FPToSI:
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case Instruction::SIToFP:
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case Instruction::PtrToInt:
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case Instruction::UIToFP:
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case Instruction::IntToPtr:
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return; // Can't work with floating point or pointers
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case Instruction::Trunc:
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// All these have integer operands
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ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
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return;
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case Instruction::BitCast: {
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const Type *SrcTy = I->getOperand(0)->getType();
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if (SrcTy->isInteger()) {
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ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
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return;
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}
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break;
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}
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case Instruction::ZExt: {
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// Compute the bits in the result that are not present in the input.
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const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
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uint64_t NotIn = ~SrcTy->getBitMask();
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uint64_t NewBits = cast<IntegerType>(I->getType())->getBitMask() & NotIn;
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Mask &= SrcTy->getBitMask();
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ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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// The top bits are known to be zero.
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KnownZero |= NewBits;
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return;
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}
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case Instruction::SExt: {
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// Compute the bits in the result that are not present in the input.
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const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
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uint64_t NotIn = ~SrcTy->getBitMask();
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uint64_t NewBits = cast<IntegerType>(I->getType())->getBitMask() & NotIn;
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Mask &= SrcTy->getBitMask();
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ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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// If the sign bit of the input is known set or clear, then we know the
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// top bits of the result.
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uint64_t InSignBit = 1ULL << (SrcTy->getPrimitiveSizeInBits()-1);
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if (KnownZero & InSignBit) { // Input sign bit known zero
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KnownZero |= NewBits;
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KnownOne &= ~NewBits;
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} else if (KnownOne & InSignBit) { // Input sign bit known set
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KnownOne |= NewBits;
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KnownZero &= ~NewBits;
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} else { // Input sign bit unknown
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KnownZero &= ~NewBits;
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KnownOne &= ~NewBits;
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}
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return;
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}
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case Instruction::Shl:
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// (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
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if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
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uint64_t ShiftAmt = SA->getZExtValue();
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Mask >>= ShiftAmt;
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ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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KnownZero <<= ShiftAmt;
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KnownOne <<= ShiftAmt;
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KnownZero |= (1ULL << ShiftAmt)-1; // low bits known zero.
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return;
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}
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break;
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case Instruction::LShr:
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// (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
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if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
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// Compute the new bits that are at the top now.
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uint64_t ShiftAmt = SA->getZExtValue();
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uint64_t HighBits = (1ULL << ShiftAmt)-1;
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HighBits <<= I->getType()->getPrimitiveSizeInBits()-ShiftAmt;
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// Unsigned shift right.
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Mask <<= ShiftAmt;
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ComputeMaskedBits(I->getOperand(0), Mask, KnownZero,KnownOne,Depth+1);
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assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
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KnownZero >>= ShiftAmt;
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KnownOne >>= ShiftAmt;
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KnownZero |= HighBits; // high bits known zero.
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return;
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}
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break;
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case Instruction::AShr:
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// (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
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if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
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// Compute the new bits that are at the top now.
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uint64_t ShiftAmt = SA->getZExtValue();
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uint64_t HighBits = (1ULL << ShiftAmt)-1;
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HighBits <<= I->getType()->getPrimitiveSizeInBits()-ShiftAmt;
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// Signed shift right.
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Mask <<= ShiftAmt;
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ComputeMaskedBits(I->getOperand(0), Mask, KnownZero,KnownOne,Depth+1);
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assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
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KnownZero >>= ShiftAmt;
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KnownOne >>= ShiftAmt;
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// Handle the sign bits.
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uint64_t SignBit = 1ULL << (I->getType()->getPrimitiveSizeInBits()-1);
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SignBit >>= ShiftAmt; // Adjust to where it is now in the mask.
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if (KnownZero & SignBit) { // New bits are known zero.
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KnownZero |= HighBits;
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} else if (KnownOne & SignBit) { // New bits are known one.
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KnownOne |= HighBits;
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}
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return;
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}
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break;
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}
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}
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/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
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/// this predicate to simplify operations downstream. Mask is known to be zero
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/// for bits that V cannot have.
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static bool MaskedValueIsZero(Value *V, uint64_t Mask, unsigned Depth = 0) {
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uint64_t KnownZero, KnownOne;
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ComputeMaskedBits(V, Mask, KnownZero, KnownOne, Depth);
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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return (KnownZero & Mask) == Mask;
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}
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/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
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/// this predicate to simplify operations downstream. Mask is known to be zero
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/// for bits that V cannot have.
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@ -1002,25 +792,6 @@ static bool MaskedValueIsZero(Value *V, const APInt& Mask, unsigned Depth = 0) {
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return (KnownZero & Mask) == Mask;
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}
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/// ShrinkDemandedConstant - Check to see if the specified operand of the
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/// specified instruction is a constant integer. If so, check to see if there
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/// are any bits set in the constant that are not demanded. If so, shrink the
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/// constant and return true.
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static bool ShrinkDemandedConstant(Instruction *I, unsigned OpNo,
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uint64_t Demanded) {
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ConstantInt *OpC = dyn_cast<ConstantInt>(I->getOperand(OpNo));
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if (!OpC) return false;
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// If there are no bits set that aren't demanded, nothing to do.
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if ((~Demanded & OpC->getZExtValue()) == 0)
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return false;
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// This is producing any bits that are not needed, shrink the RHS.
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uint64_t Val = Demanded & OpC->getZExtValue();
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I->setOperand(OpNo, ConstantInt::get(OpC->getType(), Val));
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return true;
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}
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/// ShrinkDemandedConstant - Check to see if the specified operand of the
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/// specified instruction is a constant integer. If so, check to see if there
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/// are any bits set in the constant that are not demanded. If so, shrink the
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@ -1097,475 +868,6 @@ static void ComputeUnsignedMinMaxValuesFromKnownBits(const Type *Ty,
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Max = KnownOne|UnknownBits;
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}
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/// SimplifyDemandedBits - Look at V. At this point, we know that only the
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/// DemandedMask bits of the result of V are ever used downstream. If we can
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/// use this information to simplify V, do so and return true. Otherwise,
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/// analyze the expression and return a mask of KnownOne and KnownZero bits for
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/// the expression (used to simplify the caller). The KnownZero/One bits may
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/// only be accurate for those bits in the DemandedMask.
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bool InstCombiner::SimplifyDemandedBits(Value *V, uint64_t DemandedMask,
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uint64_t &KnownZero, uint64_t &KnownOne,
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unsigned Depth) {
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const IntegerType *VTy = cast<IntegerType>(V->getType());
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if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
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// We know all of the bits for a constant!
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KnownOne = CI->getZExtValue() & DemandedMask;
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KnownZero = ~KnownOne & DemandedMask;
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return false;
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}
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KnownZero = KnownOne = 0;
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if (!V->hasOneUse()) { // Other users may use these bits.
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if (Depth != 0) { // Not at the root.
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// Just compute the KnownZero/KnownOne bits to simplify things downstream.
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ComputeMaskedBits(V, DemandedMask, KnownZero, KnownOne, Depth);
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return false;
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}
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// If this is the root being simplified, allow it to have multiple uses,
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// just set the DemandedMask to all bits.
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DemandedMask = VTy->getBitMask();
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} else if (DemandedMask == 0) { // Not demanding any bits from V.
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if (V != UndefValue::get(VTy))
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return UpdateValueUsesWith(V, UndefValue::get(VTy));
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return false;
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} else if (Depth == 6) { // Limit search depth.
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return false;
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}
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Instruction *I = dyn_cast<Instruction>(V);
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if (!I) return false; // Only analyze instructions.
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DemandedMask &= VTy->getBitMask();
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uint64_t KnownZero2 = 0, KnownOne2 = 0;
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switch (I->getOpcode()) {
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default: break;
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case Instruction::And:
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// If either the LHS or the RHS are Zero, the result is zero.
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if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
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KnownZero, KnownOne, Depth+1))
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return true;
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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// If something is known zero on the RHS, the bits aren't demanded on the
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// LHS.
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if (SimplifyDemandedBits(I->getOperand(0), DemandedMask & ~KnownZero,
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KnownZero2, KnownOne2, Depth+1))
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return true;
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assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
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// If all of the demanded bits are known 1 on one side, return the other.
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// These bits cannot contribute to the result of the 'and'.
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if ((DemandedMask & ~KnownZero2 & KnownOne) == (DemandedMask & ~KnownZero2))
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return UpdateValueUsesWith(I, I->getOperand(0));
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if ((DemandedMask & ~KnownZero & KnownOne2) == (DemandedMask & ~KnownZero))
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return UpdateValueUsesWith(I, I->getOperand(1));
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// If all of the demanded bits in the inputs are known zeros, return zero.
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if ((DemandedMask & (KnownZero|KnownZero2)) == DemandedMask)
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return UpdateValueUsesWith(I, Constant::getNullValue(VTy));
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// If the RHS is a constant, see if we can simplify it.
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if (ShrinkDemandedConstant(I, 1, DemandedMask & ~KnownZero2))
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return UpdateValueUsesWith(I, I);
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// Output known-1 bits are only known if set in both the LHS & RHS.
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KnownOne &= KnownOne2;
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// Output known-0 are known to be clear if zero in either the LHS | RHS.
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KnownZero |= KnownZero2;
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break;
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case Instruction::Or:
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if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
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KnownZero, KnownOne, Depth+1))
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return true;
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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if (SimplifyDemandedBits(I->getOperand(0), DemandedMask & ~KnownOne,
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KnownZero2, KnownOne2, Depth+1))
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return true;
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assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
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// If all of the demanded bits are known zero on one side, return the other.
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// These bits cannot contribute to the result of the 'or'.
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if ((DemandedMask & ~KnownOne2 & KnownZero) == (DemandedMask & ~KnownOne2))
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return UpdateValueUsesWith(I, I->getOperand(0));
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if ((DemandedMask & ~KnownOne & KnownZero2) == (DemandedMask & ~KnownOne))
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return UpdateValueUsesWith(I, I->getOperand(1));
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// If all of the potentially set bits on one side are known to be set on
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// the other side, just use the 'other' side.
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if ((DemandedMask & (~KnownZero) & KnownOne2) ==
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(DemandedMask & (~KnownZero)))
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return UpdateValueUsesWith(I, I->getOperand(0));
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if ((DemandedMask & (~KnownZero2) & KnownOne) ==
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(DemandedMask & (~KnownZero2)))
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return UpdateValueUsesWith(I, I->getOperand(1));
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// If the RHS is a constant, see if we can simplify it.
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if (ShrinkDemandedConstant(I, 1, DemandedMask))
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return UpdateValueUsesWith(I, I);
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// Output known-0 bits are only known if clear in both the LHS & RHS.
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KnownZero &= KnownZero2;
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// Output known-1 are known to be set if set in either the LHS | RHS.
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KnownOne |= KnownOne2;
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break;
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case Instruction::Xor: {
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if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
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KnownZero, KnownOne, Depth+1))
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return true;
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
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KnownZero2, KnownOne2, Depth+1))
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return true;
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assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
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// If all of the demanded bits are known zero on one side, return the other.
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// These bits cannot contribute to the result of the 'xor'.
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if ((DemandedMask & KnownZero) == DemandedMask)
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return UpdateValueUsesWith(I, I->getOperand(0));
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if ((DemandedMask & KnownZero2) == DemandedMask)
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return UpdateValueUsesWith(I, I->getOperand(1));
|
||||
|
||||
// Output known-0 bits are known if clear or set in both the LHS & RHS.
|
||||
uint64_t KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
|
||||
// Output known-1 are known to be set if set in only one of the LHS, RHS.
|
||||
uint64_t KnownOneOut = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
|
||||
|
||||
// If all of the demanded bits are known to be zero on one side or the
|
||||
// other, turn this into an *inclusive* or.
|
||||
// e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
|
||||
if ((DemandedMask & ~KnownZero & ~KnownZero2) == 0) {
|
||||
Instruction *Or =
|
||||
BinaryOperator::createOr(I->getOperand(0), I->getOperand(1),
|
||||
I->getName());
|
||||
InsertNewInstBefore(Or, *I);
|
||||
return UpdateValueUsesWith(I, Or);
|
||||
}
|
||||
|
||||
// If all of the demanded bits on one side are known, and all of the set
|
||||
// bits on that side are also known to be set on the other side, turn this
|
||||
// into an AND, as we know the bits will be cleared.
|
||||
// e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
|
||||
if ((DemandedMask & (KnownZero|KnownOne)) == DemandedMask) { // all known
|
||||
if ((KnownOne & KnownOne2) == KnownOne) {
|
||||
Constant *AndC = ConstantInt::get(VTy, ~KnownOne & DemandedMask);
|
||||
Instruction *And =
|
||||
BinaryOperator::createAnd(I->getOperand(0), AndC, "tmp");
|
||||
InsertNewInstBefore(And, *I);
|
||||
return UpdateValueUsesWith(I, And);
|
||||
}
|
||||
}
|
||||
|
||||
// If the RHS is a constant, see if we can simplify it.
|
||||
// FIXME: for XOR, we prefer to force bits to 1 if they will make a -1.
|
||||
if (ShrinkDemandedConstant(I, 1, DemandedMask))
|
||||
return UpdateValueUsesWith(I, I);
|
||||
|
||||
KnownZero = KnownZeroOut;
|
||||
KnownOne = KnownOneOut;
|
||||
break;
|
||||
}
|
||||
case Instruction::Select:
|
||||
if (SimplifyDemandedBits(I->getOperand(2), DemandedMask,
|
||||
KnownZero, KnownOne, Depth+1))
|
||||
return true;
|
||||
if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
|
||||
KnownZero2, KnownOne2, Depth+1))
|
||||
return true;
|
||||
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
||||
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
|
||||
|
||||
// If the operands are constants, see if we can simplify them.
|
||||
if (ShrinkDemandedConstant(I, 1, DemandedMask))
|
||||
return UpdateValueUsesWith(I, I);
|
||||
if (ShrinkDemandedConstant(I, 2, DemandedMask))
|
||||
return UpdateValueUsesWith(I, I);
|
||||
|
||||
// Only known if known in both the LHS and RHS.
|
||||
KnownOne &= KnownOne2;
|
||||
KnownZero &= KnownZero2;
|
||||
break;
|
||||
case Instruction::Trunc:
|
||||
if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
|
||||
KnownZero, KnownOne, Depth+1))
|
||||
return true;
|
||||
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
||||
break;
|
||||
case Instruction::BitCast:
|
||||
if (!I->getOperand(0)->getType()->isInteger())
|
||||
return false;
|
||||
|
||||
if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
|
||||
KnownZero, KnownOne, Depth+1))
|
||||
return true;
|
||||
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
||||
break;
|
||||
case Instruction::ZExt: {
|
||||
// Compute the bits in the result that are not present in the input.
|
||||
const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
|
||||
uint64_t NotIn = ~SrcTy->getBitMask();
|
||||
uint64_t NewBits = VTy->getBitMask() & NotIn;
|
||||
|
||||
DemandedMask &= SrcTy->getBitMask();
|
||||
if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
|
||||
KnownZero, KnownOne, Depth+1))
|
||||
return true;
|
||||
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
||||
// The top bits are known to be zero.
|
||||
KnownZero |= NewBits;
|
||||
break;
|
||||
}
|
||||
case Instruction::SExt: {
|
||||
// Compute the bits in the result that are not present in the input.
|
||||
const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
|
||||
uint64_t NotIn = ~SrcTy->getBitMask();
|
||||
uint64_t NewBits = VTy->getBitMask() & NotIn;
|
||||
|
||||
// Get the sign bit for the source type
|
||||
uint64_t InSignBit = 1ULL << (SrcTy->getPrimitiveSizeInBits()-1);
|
||||
int64_t InputDemandedBits = DemandedMask & SrcTy->getBitMask();
|
||||
|
||||
// If any of the sign extended bits are demanded, we know that the sign
|
||||
// bit is demanded.
|
||||
if (NewBits & DemandedMask)
|
||||
InputDemandedBits |= InSignBit;
|
||||
|
||||
if (SimplifyDemandedBits(I->getOperand(0), InputDemandedBits,
|
||||
KnownZero, KnownOne, Depth+1))
|
||||
return true;
|
||||
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
||||
|
||||
// If the sign bit of the input is known set or clear, then we know the
|
||||
// top bits of the result.
|
||||
|
||||
// If the input sign bit is known zero, or if the NewBits are not demanded
|
||||
// convert this into a zero extension.
|
||||
if ((KnownZero & InSignBit) || (NewBits & ~DemandedMask) == NewBits) {
|
||||
// Convert to ZExt cast
|
||||
CastInst *NewCast = new ZExtInst(I->getOperand(0), VTy, I->getName(), I);
|
||||
return UpdateValueUsesWith(I, NewCast);
|
||||
} else if (KnownOne & InSignBit) { // Input sign bit known set
|
||||
KnownOne |= NewBits;
|
||||
KnownZero &= ~NewBits;
|
||||
} else { // Input sign bit unknown
|
||||
KnownZero &= ~NewBits;
|
||||
KnownOne &= ~NewBits;
|
||||
}
|
||||
break;
|
||||
}
|
||||
case Instruction::Add:
|
||||
// If there is a constant on the RHS, there are a variety of xformations
|
||||
// we can do.
|
||||
if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
|
||||
// If null, this should be simplified elsewhere. Some of the xforms here
|
||||
// won't work if the RHS is zero.
|
||||
if (RHS->isNullValue())
|
||||
break;
|
||||
|
||||
// Figure out what the input bits are. If the top bits of the and result
|
||||
// are not demanded, then the add doesn't demand them from its input
|
||||
// either.
|
||||
|
||||
// Shift the demanded mask up so that it's at the top of the uint64_t.
|
||||
unsigned BitWidth = VTy->getPrimitiveSizeInBits();
|
||||
unsigned NLZ = CountLeadingZeros_64(DemandedMask << (64-BitWidth));
|
||||
|
||||
// If the top bit of the output is demanded, demand everything from the
|
||||
// input. Otherwise, we demand all the input bits except NLZ top bits.
|
||||
uint64_t InDemandedBits = ~0ULL >> (64-BitWidth+NLZ);
|
||||
|
||||
// Find information about known zero/one bits in the input.
|
||||
if (SimplifyDemandedBits(I->getOperand(0), InDemandedBits,
|
||||
KnownZero2, KnownOne2, Depth+1))
|
||||
return true;
|
||||
|
||||
// If the RHS of the add has bits set that can't affect the input, reduce
|
||||
// the constant.
|
||||
if (ShrinkDemandedConstant(I, 1, InDemandedBits))
|
||||
return UpdateValueUsesWith(I, I);
|
||||
|
||||
// Avoid excess work.
|
||||
if (KnownZero2 == 0 && KnownOne2 == 0)
|
||||
break;
|
||||
|
||||
// Turn it into OR if input bits are zero.
|
||||
if ((KnownZero2 & RHS->getZExtValue()) == RHS->getZExtValue()) {
|
||||
Instruction *Or =
|
||||
BinaryOperator::createOr(I->getOperand(0), I->getOperand(1),
|
||||
I->getName());
|
||||
InsertNewInstBefore(Or, *I);
|
||||
return UpdateValueUsesWith(I, Or);
|
||||
}
|
||||
|
||||
// We can say something about the output known-zero and known-one bits,
|
||||
// depending on potential carries from the input constant and the
|
||||
// unknowns. For example if the LHS is known to have at most the 0x0F0F0
|
||||
// bits set and the RHS constant is 0x01001, then we know we have a known
|
||||
// one mask of 0x00001 and a known zero mask of 0xE0F0E.
|
||||
|
||||
// To compute this, we first compute the potential carry bits. These are
|
||||
// the bits which may be modified. I'm not aware of a better way to do
|
||||
// this scan.
|
||||
uint64_t RHSVal = RHS->getZExtValue();
|
||||
|
||||
bool CarryIn = false;
|
||||
uint64_t CarryBits = 0;
|
||||
uint64_t CurBit = 1;
|
||||
for (unsigned i = 0; i != BitWidth; ++i, CurBit <<= 1) {
|
||||
// Record the current carry in.
|
||||
if (CarryIn) CarryBits |= CurBit;
|
||||
|
||||
bool CarryOut;
|
||||
|
||||
// This bit has a carry out unless it is "zero + zero" or
|
||||
// "zero + anything" with no carry in.
|
||||
if ((KnownZero2 & CurBit) && ((RHSVal & CurBit) == 0)) {
|
||||
CarryOut = false; // 0 + 0 has no carry out, even with carry in.
|
||||
} else if (!CarryIn &&
|
||||
((KnownZero2 & CurBit) || ((RHSVal & CurBit) == 0))) {
|
||||
CarryOut = false; // 0 + anything has no carry out if no carry in.
|
||||
} else {
|
||||
// Otherwise, we have to assume we have a carry out.
|
||||
CarryOut = true;
|
||||
}
|
||||
|
||||
// This stage's carry out becomes the next stage's carry-in.
|
||||
CarryIn = CarryOut;
|
||||
}
|
||||
|
||||
// Now that we know which bits have carries, compute the known-1/0 sets.
|
||||
|
||||
// Bits are known one if they are known zero in one operand and one in the
|
||||
// other, and there is no input carry.
|
||||
KnownOne = ((KnownZero2 & RHSVal) | (KnownOne2 & ~RHSVal)) & ~CarryBits;
|
||||
|
||||
// Bits are known zero if they are known zero in both operands and there
|
||||
// is no input carry.
|
||||
KnownZero = KnownZero2 & ~RHSVal & ~CarryBits;
|
||||
} else {
|
||||
// If the high-bits of this ADD are not demanded, then it does not demand
|
||||
// the high bits of its LHS or RHS.
|
||||
if ((DemandedMask & VTy->getSignBit()) == 0) {
|
||||
// Right fill the mask of bits for this ADD to demand the most
|
||||
// significant bit and all those below it.
|
||||
unsigned NLZ = CountLeadingZeros_64(DemandedMask);
|
||||
uint64_t DemandedFromOps = ~0ULL >> NLZ;
|
||||
if (SimplifyDemandedBits(I->getOperand(0), DemandedFromOps,
|
||||
KnownZero2, KnownOne2, Depth+1))
|
||||
return true;
|
||||
if (SimplifyDemandedBits(I->getOperand(1), DemandedFromOps,
|
||||
KnownZero2, KnownOne2, Depth+1))
|
||||
return true;
|
||||
}
|
||||
}
|
||||
break;
|
||||
case Instruction::Sub:
|
||||
// If the high-bits of this SUB are not demanded, then it does not demand
|
||||
// the high bits of its LHS or RHS.
|
||||
if ((DemandedMask & VTy->getSignBit()) == 0) {
|
||||
// Right fill the mask of bits for this SUB to demand the most
|
||||
// significant bit and all those below it.
|
||||
unsigned NLZ = CountLeadingZeros_64(DemandedMask);
|
||||
uint64_t DemandedFromOps = ~0ULL >> NLZ;
|
||||
if (SimplifyDemandedBits(I->getOperand(0), DemandedFromOps,
|
||||
KnownZero2, KnownOne2, Depth+1))
|
||||
return true;
|
||||
if (SimplifyDemandedBits(I->getOperand(1), DemandedFromOps,
|
||||
KnownZero2, KnownOne2, Depth+1))
|
||||
return true;
|
||||
}
|
||||
break;
|
||||
case Instruction::Shl:
|
||||
if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
|
||||
uint64_t ShiftAmt = SA->getZExtValue();
|
||||
if (SimplifyDemandedBits(I->getOperand(0), DemandedMask >> ShiftAmt,
|
||||
KnownZero, KnownOne, Depth+1))
|
||||
return true;
|
||||
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
||||
KnownZero <<= ShiftAmt;
|
||||
KnownOne <<= ShiftAmt;
|
||||
KnownZero |= (1ULL << ShiftAmt) - 1; // low bits known zero.
|
||||
}
|
||||
break;
|
||||
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 <<= VTy->getBitWidth() - ShiftAmt;
|
||||
uint64_t TypeMask = VTy->getBitMask();
|
||||
// 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) {
|
||||
// Perform the logical shift right.
|
||||
Value *NewVal = BinaryOperator::createLShr(
|
||||
I->getOperand(0), I->getOperand(1), I->getName());
|
||||
InsertNewInstBefore(cast<Instruction>(NewVal), *I);
|
||||
return UpdateValueUsesWith(I, NewVal);
|
||||
}
|
||||
|
||||
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 <<= VTy->getBitWidth() - ShiftAmt;
|
||||
uint64_t TypeMask = VTy->getBitMask();
|
||||
// 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 << (VTy->getBitWidth()-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) {
|
||||
// Perform the logical shift right.
|
||||
Value *NewVal = BinaryOperator::createLShr(
|
||||
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;
|
||||
}
|
||||
|
||||
// If the client is only demanding bits that we know, return the known
|
||||
// constant.
|
||||
if ((DemandedMask & (KnownZero|KnownOne)) == DemandedMask)
|
||||
return UpdateValueUsesWith(I, ConstantInt::get(VTy, KnownOne));
|
||||
return false;
|
||||
}
|
||||
|
||||
/// SimplifyDemandedBits - This function attempts to replace V with a simpler
|
||||
/// value based on the demanded bits. When this function is called, it is known
|
||||
/// that only the bits set in DemandedMask of the result of V are ever used
|
||||
@ -2574,17 +1876,19 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
|
||||
|
||||
if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
|
||||
// X + (signbit) --> X ^ signbit
|
||||
uint64_t Val = CI->getZExtValue();
|
||||
if (Val == (1ULL << (CI->getType()->getPrimitiveSizeInBits()-1)))
|
||||
APInt Val(CI->getValue());
|
||||
unsigned BitWidth = Val.getBitWidth();
|
||||
if (Val == APInt::getSignBit(BitWidth))
|
||||
return BinaryOperator::createXor(LHS, RHS);
|
||||
|
||||
// See if SimplifyDemandedBits can simplify this. This handles stuff like
|
||||
// (X & 254)+1 -> (X&254)|1
|
||||
uint64_t KnownZero, KnownOne;
|
||||
if (!isa<VectorType>(I.getType()) &&
|
||||
SimplifyDemandedBits(&I, cast<IntegerType>(I.getType())->getBitMask(),
|
||||
KnownZero, KnownOne))
|
||||
return &I;
|
||||
if (!isa<VectorType>(I.getType())) {
|
||||
APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
|
||||
if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth),
|
||||
KnownZero, KnownOne))
|
||||
return &I;
|
||||
}
|
||||
}
|
||||
|
||||
if (isa<PHINode>(LHS))
|
||||
@ -2596,48 +1900,32 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
|
||||
if (isa<ConstantInt>(RHSC) &&
|
||||
match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
|
||||
unsigned TySizeBits = I.getType()->getPrimitiveSizeInBits();
|
||||
int64_t RHSSExt = cast<ConstantInt>(RHSC)->getSExtValue();
|
||||
uint64_t RHSZExt = cast<ConstantInt>(RHSC)->getZExtValue();
|
||||
APInt RHSVal(cast<ConstantInt>(RHSC)->getValue());
|
||||
|
||||
uint64_t C0080Val = 1ULL << 31;
|
||||
int64_t CFF80Val = -C0080Val;
|
||||
unsigned Size = 32;
|
||||
unsigned Size = TySizeBits / 2;
|
||||
APInt C0080Val(APInt(TySizeBits, 1ULL).shl(Size - 1));
|
||||
APInt CFF80Val(-C0080Val);
|
||||
do {
|
||||
if (TySizeBits > Size) {
|
||||
bool Found = false;
|
||||
// If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
|
||||
// If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
|
||||
if (RHSSExt == CFF80Val) {
|
||||
if (XorRHS->getZExtValue() == C0080Val)
|
||||
Found = true;
|
||||
} else if (RHSZExt == C0080Val) {
|
||||
if (XorRHS->getSExtValue() == CFF80Val)
|
||||
Found = true;
|
||||
}
|
||||
if (Found) {
|
||||
if ((RHSVal == CFF80Val && XorRHS->getValue() == C0080Val) ||
|
||||
(RHSVal == C0080Val && XorRHS->getValue() == CFF80Val)) {
|
||||
// This is a sign extend if the top bits are known zero.
|
||||
uint64_t Mask = ~0ULL;
|
||||
Mask <<= 64-(TySizeBits-Size);
|
||||
Mask &= cast<IntegerType>(XorLHS->getType())->getBitMask();
|
||||
APInt Mask(APInt::getAllOnesValue(TySizeBits));
|
||||
Mask <<= Size;
|
||||
if (!MaskedValueIsZero(XorLHS, Mask))
|
||||
Size = 0; // Not a sign ext, but can't be any others either.
|
||||
goto FoundSExt;
|
||||
break;
|
||||
}
|
||||
}
|
||||
Size >>= 1;
|
||||
C0080Val >>= Size;
|
||||
CFF80Val >>= Size;
|
||||
} while (Size >= 8);
|
||||
C0080Val = APIntOps::lshr(C0080Val, Size);
|
||||
CFF80Val = APIntOps::ashr(CFF80Val, Size);
|
||||
} while (Size >= 1);
|
||||
|
||||
FoundSExt:
|
||||
const Type *MiddleType = 0;
|
||||
switch (Size) {
|
||||
default: break;
|
||||
case 32: MiddleType = Type::Int32Ty; break;
|
||||
case 16: MiddleType = Type::Int16Ty; break;
|
||||
case 8: MiddleType = Type::Int8Ty; break;
|
||||
}
|
||||
if (MiddleType) {
|
||||
if (Size) {
|
||||
const Type *MiddleType = IntegerType::get(Size);
|
||||
Instruction *NewTrunc = new TruncInst(XorLHS, MiddleType, "sext");
|
||||
InsertNewInstBefore(NewTrunc, I);
|
||||
return new SExtInst(NewTrunc, I.getType());
|
||||
@ -2710,14 +1998,14 @@ FoundSExt:
|
||||
if (Anded == CRHS) {
|
||||
// See if all bits from the first bit set in the Add RHS up are included
|
||||
// in the mask. First, get the rightmost bit.
|
||||
uint64_t AddRHSV = CRHS->getZExtValue();
|
||||
APInt AddRHSV(CRHS->getValue());
|
||||
|
||||
// Form a mask of all bits from the lowest bit added through the top.
|
||||
uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
|
||||
AddRHSHighBits &= C2->getType()->getBitMask();
|
||||
APInt AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
|
||||
AddRHSHighBits &= C2->getType()->getMask();
|
||||
|
||||
// See if the and mask includes all of these bits.
|
||||
uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getZExtValue();
|
||||
APInt AddRHSHighBitsAnd = AddRHSHighBits & C2->getValue();
|
||||
|
||||
if (AddRHSHighBits == AddRHSHighBitsAnd) {
|
||||
// Okay, the xform is safe. Insert the new add pronto.
|
||||
@ -3170,7 +2458,7 @@ Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
|
||||
if (C1.isPowerOf2()) {
|
||||
Value *N = RHSI->getOperand(1);
|
||||
const Type *NTy = N->getType();
|
||||
if (uint64_t C2 = C1.logBase2()) {
|
||||
if (uint32_t C2 = C1.logBase2()) {
|
||||
Constant *C2V = ConstantInt::get(NTy, C2);
|
||||
N = InsertNewInstBefore(BinaryOperator::createAdd(N, C2V, "tmp"), I);
|
||||
}
|
||||
@ -3474,19 +2762,6 @@ static bool isOneBitSet(const ConstantInt *CI) {
|
||||
return CI->getValue().isPowerOf2();
|
||||
}
|
||||
|
||||
#if 0 // Currently unused
|
||||
// isLowOnes - Return true if the constant is of the form 0+1+.
|
||||
static bool isLowOnes(const ConstantInt *CI) {
|
||||
uint64_t V = CI->getZExtValue();
|
||||
|
||||
// There won't be bits set in parts that the type doesn't contain.
|
||||
V &= ConstantInt::getAllOnesValue(CI->getType())->getZExtValue();
|
||||
|
||||
uint64_t U = V+1; // If it is low ones, this should be a power of two.
|
||||
return U && V && (U & V) == 0;
|
||||
}
|
||||
#endif
|
||||
|
||||
// isHighOnes - Return true if the constant is of the form 1+0+.
|
||||
// This is the same as lowones(~X).
|
||||
static bool isHighOnes(const ConstantInt *CI) {
|
||||
@ -7558,9 +6833,9 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
|
||||
if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
|
||||
if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
|
||||
// select C, 1, 0 -> cast C to int
|
||||
if (FalseValC->isNullValue() && TrueValC->getZExtValue() == 1) {
|
||||
if (FalseValC->isZero() && TrueValC->getValue() == 1) {
|
||||
return CastInst::create(Instruction::ZExt, CondVal, SI.getType());
|
||||
} else if (TrueValC->isNullValue() && FalseValC->getZExtValue() == 1) {
|
||||
} else if (TrueValC->isZero() && FalseValC->getValue() == 1) {
|
||||
// select C, 0, 1 -> cast !C to int
|
||||
Value *NotCond =
|
||||
InsertNewInstBefore(BinaryOperator::createNot(CondVal,
|
||||
@ -7572,15 +6847,15 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
|
||||
|
||||
// (x <s 0) ? -1 : 0 -> ashr x, 31
|
||||
// (x >u 2147483647) ? -1 : 0 -> ashr x, 31
|
||||
if (TrueValC->isAllOnesValue() && FalseValC->isNullValue())
|
||||
if (TrueValC->isAllOnesValue() && FalseValC->isZero())
|
||||
if (ConstantInt *CmpCst = dyn_cast<ConstantInt>(IC->getOperand(1))) {
|
||||
bool CanXForm = false;
|
||||
if (IC->isSignedPredicate())
|
||||
CanXForm = CmpCst->isNullValue() &&
|
||||
CanXForm = CmpCst->isZero() &&
|
||||
IC->getPredicate() == ICmpInst::ICMP_SLT;
|
||||
else {
|
||||
unsigned Bits = CmpCst->getType()->getPrimitiveSizeInBits();
|
||||
CanXForm = (CmpCst->getZExtValue() == ~0ULL >> (64-Bits+1)) &&
|
||||
CanXForm = CmpCst->getValue() == APInt::getSignedMaxValue(Bits) &&
|
||||
IC->getPredicate() == ICmpInst::ICMP_UGT;
|
||||
}
|
||||
|
||||
@ -7612,7 +6887,7 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
|
||||
// have a fcmp instruction with zero, and we have an 'and' with the
|
||||
// non-constant value, eliminate this whole mess. This corresponds to
|
||||
// cases like this: ((X & 27) ? 27 : 0)
|
||||
if (TrueValC->isNullValue() || FalseValC->isNullValue())
|
||||
if (TrueValC->isZero() || FalseValC->isZero())
|
||||
if (IC->isEquality() && isa<ConstantInt>(IC->getOperand(1)) &&
|
||||
cast<Constant>(IC->getOperand(1))->isNullValue())
|
||||
if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
|
||||
@ -7624,7 +6899,7 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
|
||||
// Okay, now we know that everything is set up, we just don't
|
||||
// know whether we have a icmp_ne or icmp_eq and whether the
|
||||
// true or false val is the zero.
|
||||
bool ShouldNotVal = !TrueValC->isNullValue();
|
||||
bool ShouldNotVal = !TrueValC->isZero();
|
||||
ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
|
||||
Value *V = ICA;
|
||||
if (ShouldNotVal)
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user