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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169701 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakub Staszak 2012-12-09 15:37:46 +00:00
parent 6297bfa80e
commit 0fb7687b61
1 changed files with 80 additions and 80 deletions
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160
lib/Transforms/InstCombine/InstCombineShifts.cpp
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@ -49,7 +49,7 @@ Instruction *InstCombiner::commonShiftTransforms(BinaryOperator &I) {
I.setOperand(1, Rem); I.setOperand(1, Rem);
return &I; return &I;
} }
return 0; return 0;
} }
@ -70,10 +70,10 @@ static bool CanEvaluateShifted(Value *V, unsigned NumBits, bool isLeftShift,
// We can always evaluate constants shifted. // We can always evaluate constants shifted.
if (isa<Constant>(V)) if (isa<Constant>(V))
return true; return true;
Instruction *I = dyn_cast<Instruction>(V); Instruction *I = dyn_cast<Instruction>(V);
if (!I) return false; if (!I) return false;
// If this is the opposite shift, we can directly reuse the input of the shift // If this is the opposite shift, we can directly reuse the input of the shift
// if the needed bits are already zero in the input. This allows us to reuse // if the needed bits are already zero in the input. This allows us to reuse
// the value which means that we don't care if the shift has multiple uses. // the value which means that we don't care if the shift has multiple uses.
@ -95,14 +95,14 @@ static bool CanEvaluateShifted(Value *V, unsigned NumBits, bool isLeftShift,
return CanEvaluateTruncated(I->getOperand(0), Ty); return CanEvaluateTruncated(I->getOperand(0), Ty);
} }
#endif #endif
} }
} }
// We can't mutate something that has multiple uses: doing so would // We can't mutate something that has multiple uses: doing so would
// require duplicating the instruction in general, which isn't profitable. // require duplicating the instruction in general, which isn't profitable.
if (!I->hasOneUse()) return false; if (!I->hasOneUse()) return false;
switch (I->getOpcode()) { switch (I->getOpcode()) {
default: return false; default: return false;
case Instruction::And: case Instruction::And:
@ -111,7 +111,7 @@ static bool CanEvaluateShifted(Value *V, unsigned NumBits, bool isLeftShift,
// Bitwise operators can all arbitrarily be arbitrarily evaluated shifted. // Bitwise operators can all arbitrarily be arbitrarily evaluated shifted.
return CanEvaluateShifted(I->getOperand(0), NumBits, isLeftShift, IC) && return CanEvaluateShifted(I->getOperand(0), NumBits, isLeftShift, IC) &&
CanEvaluateShifted(I->getOperand(1), NumBits, isLeftShift, IC); CanEvaluateShifted(I->getOperand(1), NumBits, isLeftShift, IC);
case Instruction::Shl: { case Instruction::Shl: {
// We can often fold the shift into shifts-by-a-constant. // We can often fold the shift into shifts-by-a-constant.
CI = dyn_cast<ConstantInt>(I->getOperand(1)); CI = dyn_cast<ConstantInt>(I->getOperand(1));
@ -119,10 +119,10 @@ static bool CanEvaluateShifted(Value *V, unsigned NumBits, bool isLeftShift,
// We can always fold shl(c1)+shl(c2) -> shl(c1+c2). // We can always fold shl(c1)+shl(c2) -> shl(c1+c2).
if (isLeftShift) return true; if (isLeftShift) return true;
// We can always turn shl(c)+shr(c) -> and(c2). // We can always turn shl(c)+shr(c) -> and(c2).
if (CI->getValue() == NumBits) return true; if (CI->getValue() == NumBits) return true;
unsigned TypeWidth = I->getType()->getScalarSizeInBits(); unsigned TypeWidth = I->getType()->getScalarSizeInBits();
// We can turn shl(c1)+shr(c2) -> shl(c3)+and(c4), but it isn't // We can turn shl(c1)+shr(c2) -> shl(c3)+and(c4), but it isn't
@ -133,20 +133,20 @@ static bool CanEvaluateShifted(Value *V, unsigned NumBits, bool isLeftShift,
APInt::getLowBitsSet(TypeWidth, NumBits) << LowBits)) APInt::getLowBitsSet(TypeWidth, NumBits) << LowBits))
return true; return true;
} }
return false; return false;
} }
case Instruction::LShr: { case Instruction::LShr: {
// We can often fold the shift into shifts-by-a-constant. // We can often fold the shift into shifts-by-a-constant.
CI = dyn_cast<ConstantInt>(I->getOperand(1)); CI = dyn_cast<ConstantInt>(I->getOperand(1));
if (CI == 0) return false; if (CI == 0) return false;
// We can always fold lshr(c1)+lshr(c2) -> lshr(c1+c2). // We can always fold lshr(c1)+lshr(c2) -> lshr(c1+c2).
if (!isLeftShift) return true; if (!isLeftShift) return true;
// We can always turn lshr(c)+shl(c) -> and(c2). // We can always turn lshr(c)+shl(c) -> and(c2).
if (CI->getValue() == NumBits) return true; if (CI->getValue() == NumBits) return true;
unsigned TypeWidth = I->getType()->getScalarSizeInBits(); unsigned TypeWidth = I->getType()->getScalarSizeInBits();
// We can always turn lshr(c1)+shl(c2) -> lshr(c3)+and(c4), but it isn't // We can always turn lshr(c1)+shl(c2) -> lshr(c3)+and(c4), but it isn't
@ -157,7 +157,7 @@ static bool CanEvaluateShifted(Value *V, unsigned NumBits, bool isLeftShift,
APInt::getLowBitsSet(TypeWidth, NumBits) << LowBits)) APInt::getLowBitsSet(TypeWidth, NumBits) << LowBits))
return true; return true;
} }
return false; return false;
} }
case Instruction::Select: { case Instruction::Select: {
@ -175,7 +175,7 @@ static bool CanEvaluateShifted(Value *V, unsigned NumBits, bool isLeftShift,
return false; return false;
return true; return true;
} }
} }
} }
/// GetShiftedValue - When CanEvaluateShifted returned true for an expression, /// GetShiftedValue - When CanEvaluateShifted returned true for an expression,
@ -194,7 +194,7 @@ static Value *GetShiftedValue(Value *V, unsigned NumBits, bool isLeftShift,
IC.getTargetLibraryInfo()); IC.getTargetLibraryInfo());
return V; return V;
} }
Instruction *I = cast<Instruction>(V); Instruction *I = cast<Instruction>(V);
IC.Worklist.Add(I); IC.Worklist.Add(I);
@ -207,7 +207,7 @@ static Value *GetShiftedValue(Value *V, unsigned NumBits, bool isLeftShift,
I->setOperand(0, GetShiftedValue(I->getOperand(0), NumBits,isLeftShift,IC)); I->setOperand(0, GetShiftedValue(I->getOperand(0), NumBits,isLeftShift,IC));
I->setOperand(1, GetShiftedValue(I->getOperand(1), NumBits,isLeftShift,IC)); I->setOperand(1, GetShiftedValue(I->getOperand(1), NumBits,isLeftShift,IC));
return I; return I;
case Instruction::Shl: { case Instruction::Shl: {
BinaryOperator *BO = cast<BinaryOperator>(I); BinaryOperator *BO = cast<BinaryOperator>(I);
unsigned TypeWidth = BO->getType()->getScalarSizeInBits(); unsigned TypeWidth = BO->getType()->getScalarSizeInBits();
@ -227,7 +227,7 @@ static Value *GetShiftedValue(Value *V, unsigned NumBits, bool isLeftShift,
BO->setHasNoSignedWrap(false); BO->setHasNoSignedWrap(false);
return I; return I;
} }
// We turn shl(c)+lshr(c) -> and(c2) if the input doesn't already have // We turn shl(c)+lshr(c) -> and(c2) if the input doesn't already have
// zeros. // zeros.
if (CI->getValue() == NumBits) { if (CI->getValue() == NumBits) {
@ -240,7 +240,7 @@ static Value *GetShiftedValue(Value *V, unsigned NumBits, bool isLeftShift,
} }
return V; return V;
} }
// We turn shl(c1)+shr(c2) -> shl(c3)+and(c4), but only when we know that // We turn shl(c1)+shr(c2) -> shl(c3)+and(c4), but only when we know that
// the and won't be needed. // the and won't be needed.
assert(CI->getZExtValue() > NumBits); assert(CI->getZExtValue() > NumBits);
@ -255,19 +255,19 @@ static Value *GetShiftedValue(Value *V, unsigned NumBits, bool isLeftShift,
unsigned TypeWidth = BO->getType()->getScalarSizeInBits(); unsigned TypeWidth = BO->getType()->getScalarSizeInBits();
// We only accept shifts-by-a-constant in CanEvaluateShifted. // We only accept shifts-by-a-constant in CanEvaluateShifted.
ConstantInt *CI = cast<ConstantInt>(BO->getOperand(1)); ConstantInt *CI = cast<ConstantInt>(BO->getOperand(1));
// We can always fold lshr(c1)+lshr(c2) -> lshr(c1+c2). // We can always fold lshr(c1)+lshr(c2) -> lshr(c1+c2).
if (!isLeftShift) { if (!isLeftShift) {
// If this is oversized composite shift, then unsigned shifts get 0. // If this is oversized composite shift, then unsigned shifts get 0.
unsigned NewShAmt = NumBits+CI->getZExtValue(); unsigned NewShAmt = NumBits+CI->getZExtValue();
if (NewShAmt >= TypeWidth) if (NewShAmt >= TypeWidth)
return Constant::getNullValue(BO->getType()); return Constant::getNullValue(BO->getType());
BO->setOperand(1, ConstantInt::get(BO->getType(), NewShAmt)); BO->setOperand(1, ConstantInt::get(BO->getType(), NewShAmt));
BO->setIsExact(false); BO->setIsExact(false);
return I; return I;
} }
// We turn lshr(c)+shl(c) -> and(c2) if the input doesn't already have // We turn lshr(c)+shl(c) -> and(c2) if the input doesn't already have
// zeros. // zeros.
if (CI->getValue() == NumBits) { if (CI->getValue() == NumBits) {
@ -280,7 +280,7 @@ static Value *GetShiftedValue(Value *V, unsigned NumBits, bool isLeftShift,
} }
return V; return V;
} }
// We turn lshr(c1)+shl(c2) -> lshr(c3)+and(c4), but only when we know that // We turn lshr(c1)+shl(c2) -> lshr(c3)+and(c4), but only when we know that
// the and won't be needed. // the and won't be needed.
assert(CI->getZExtValue() > NumBits); assert(CI->getZExtValue() > NumBits);
@ -289,7 +289,7 @@ static Value *GetShiftedValue(Value *V, unsigned NumBits, bool isLeftShift,
BO->setIsExact(false); BO->setIsExact(false);
return BO; return BO;
} }
case Instruction::Select: case Instruction::Select:
I->setOperand(1, GetShiftedValue(I->getOperand(1), NumBits,isLeftShift,IC)); I->setOperand(1, GetShiftedValue(I->getOperand(1), NumBits,isLeftShift,IC));
I->setOperand(2, GetShiftedValue(I->getOperand(2), NumBits,isLeftShift,IC)); I->setOperand(2, GetShiftedValue(I->getOperand(2), NumBits,isLeftShift,IC));
@ -304,7 +304,7 @@ static Value *GetShiftedValue(Value *V, unsigned NumBits, bool isLeftShift,
NumBits, isLeftShift, IC)); NumBits, isLeftShift, IC));
return PN; return PN;
} }
} }
} }
@ -312,24 +312,24 @@ static Value *GetShiftedValue(Value *V, unsigned NumBits, bool isLeftShift,
Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1, Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
BinaryOperator &I) { BinaryOperator &I) {
bool isLeftShift = I.getOpcode() == Instruction::Shl; bool isLeftShift = I.getOpcode() == Instruction::Shl;
// See if we can propagate this shift into the input, this covers the trivial // See if we can propagate this shift into the input, this covers the trivial
// cast of lshr(shl(x,c1),c2) as well as other more complex cases. // cast of lshr(shl(x,c1),c2) as well as other more complex cases.
if (I.getOpcode() != Instruction::AShr && if (I.getOpcode() != Instruction::AShr &&
CanEvaluateShifted(Op0, Op1->getZExtValue(), isLeftShift, *this)) { CanEvaluateShifted(Op0, Op1->getZExtValue(), isLeftShift, *this)) {
DEBUG(dbgs() << "ICE: GetShiftedValue propagating shift through expression" DEBUG(dbgs() << "ICE: GetShiftedValue propagating shift through expression"
" to eliminate shift:\n IN: " << *Op0 << "\n SH: " << I <<"\n"); " to eliminate shift:\n IN: " << *Op0 << "\n SH: " << I <<"\n");
return ReplaceInstUsesWith(I, return ReplaceInstUsesWith(I,
GetShiftedValue(Op0, Op1->getZExtValue(), isLeftShift, *this)); GetShiftedValue(Op0, Op1->getZExtValue(), isLeftShift, *this));
} }
// See if we can simplify any instructions used by the instruction whose sole // See if we can simplify any instructions used by the instruction whose sole
// purpose is to compute bits we don't care about. // purpose is to compute bits we don't care about.
uint32_t TypeBits = Op0->getType()->getScalarSizeInBits(); uint32_t TypeBits = Op0->getType()->getScalarSizeInBits();
// shl i32 X, 32 = 0 and srl i8 Y, 9 = 0, ... just don't eliminate // shl i32 X, 32 = 0 and srl i8 Y, 9 = 0, ... just don't eliminate
// a signed shift. // a signed shift.
// //
@ -340,14 +340,14 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
I.setOperand(1, ConstantInt::get(I.getType(), TypeBits-1)); I.setOperand(1, ConstantInt::get(I.getType(), TypeBits-1));
return &I; return &I;
} }
// ((X*C1) << C2) == (X * (C1 << C2)) // ((X*C1) << C2) == (X * (C1 << C2))
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
if (BO->getOpcode() == Instruction::Mul && isLeftShift) if (BO->getOpcode() == Instruction::Mul && isLeftShift)
if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1))) if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
return BinaryOperator::CreateMul(BO->getOperand(0), return BinaryOperator::CreateMul(BO->getOperand(0),
ConstantExpr::getShl(BOOp, Op1)); ConstantExpr::getShl(BOOp, Op1));
// Try to fold constant and into select arguments. // Try to fold constant and into select arguments.
if (SelectInst *SI = dyn_cast<SelectInst>(Op0)) if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
if (Instruction *R = FoldOpIntoSelect(I, SI)) if (Instruction *R = FoldOpIntoSelect(I, SI))
@ -355,7 +355,7 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
if (isa<PHINode>(Op0)) if (isa<PHINode>(Op0))
if (Instruction *NV = FoldOpIntoPhi(I)) if (Instruction *NV = FoldOpIntoPhi(I))
return NV; return NV;
// Fold shift2(trunc(shift1(x,c1)), c2) -> trunc(shift2(shift1(x,c1),c2)) // Fold shift2(trunc(shift1(x,c1)), c2) -> trunc(shift2(shift1(x,c1),c2))
if (TruncInst *TI = dyn_cast<TruncInst>(Op0)) { if (TruncInst *TI = dyn_cast<TruncInst>(Op0)) {
Instruction *TrOp = dyn_cast<Instruction>(TI->getOperand(0)); Instruction *TrOp = dyn_cast<Instruction>(TI->getOperand(0));
@ -364,7 +364,7 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
// require that the input operand is a shift-by-constant so that we have // require that the input operand is a shift-by-constant so that we have
// confidence that the shifts will get folded together. We could do this // confidence that the shifts will get folded together. We could do this
// xform in more cases, but it is unlikely to be profitable. // xform in more cases, but it is unlikely to be profitable.
if (TrOp && I.isLogicalShift() && TrOp->isShift() && if (TrOp && I.isLogicalShift() && TrOp->isShift() &&
isa<ConstantInt>(TrOp->getOperand(1))) { isa<ConstantInt>(TrOp->getOperand(1))) {
// Okay, we'll do this xform. Make the shift of shift. // Okay, we'll do this xform. Make the shift of shift.
Constant *ShAmt = ConstantExpr::getZExt(Op1, TrOp->getType()); Constant *ShAmt = ConstantExpr::getZExt(Op1, TrOp->getType());
@ -378,7 +378,7 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
unsigned SrcSize = TrOp->getType()->getScalarSizeInBits(); unsigned SrcSize = TrOp->getType()->getScalarSizeInBits();
unsigned DstSize = TI->getType()->getScalarSizeInBits(); unsigned DstSize = TI->getType()->getScalarSizeInBits();
APInt MaskV(APInt::getLowBitsSet(SrcSize, DstSize)); APInt MaskV(APInt::getLowBitsSet(SrcSize, DstSize));
// The mask we constructed says what the trunc would do if occurring // The mask we constructed says what the trunc would do if occurring
// between the shifts. We want to know the effect *after* the second // between the shifts. We want to know the effect *after* the second
// shift. We know that it is a logical shift by a constant, so adjust the // shift. We know that it is a logical shift by a constant, so adjust the
@ -399,7 +399,7 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
return new TruncInst(And, I.getType()); return new TruncInst(And, I.getType());
} }
} }
if (Op0->hasOneUse()) { if (Op0->hasOneUse()) {
if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) { if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
// Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C) // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
@ -425,11 +425,11 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
return BinaryOperator::CreateAnd(X, ConstantInt::get(I.getContext(), return BinaryOperator::CreateAnd(X, ConstantInt::get(I.getContext(),
APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val))); APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
} }
// Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C)) // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
Value *Op0BOOp1 = Op0BO->getOperand(1); Value *Op0BOOp1 = Op0BO->getOperand(1);
if (isLeftShift && Op0BOOp1->hasOneUse() && if (isLeftShift && Op0BOOp1->hasOneUse() &&
match(Op0BOOp1, match(Op0BOOp1,
m_And(m_Shr(m_Value(V1), m_Specific(Op1)), m_And(m_Shr(m_Value(V1), m_Specific(Op1)),
m_ConstantInt(CC))) && m_ConstantInt(CC))) &&
cast<BinaryOperator>(Op0BOOp1)->getOperand(0)->hasOneUse()) { cast<BinaryOperator>(Op0BOOp1)->getOperand(0)->hasOneUse()) {
@ -442,7 +442,7 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
return BinaryOperator::Create(Op0BO->getOpcode(), YS, XM); return BinaryOperator::Create(Op0BO->getOpcode(), YS, XM);
} }
} }
// FALL THROUGH. // FALL THROUGH.
case Instruction::Sub: { case Instruction::Sub: {
// Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C) // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
@ -458,7 +458,7 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
return BinaryOperator::CreateAnd(X, ConstantInt::get(I.getContext(), return BinaryOperator::CreateAnd(X, ConstantInt::get(I.getContext(),
APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val))); APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
} }
// Turn (((X >> C)&CC) + Y) << C -> (X + (Y << C)) & (CC << C) // Turn (((X >> C)&CC) + Y) << C -> (X + (Y << C)) & (CC << C)
if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() && if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
match(Op0BO->getOperand(0), match(Op0BO->getOperand(0),
@ -471,21 +471,21 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
// X & (CC << C) // X & (CC << C)
Value *XM = Builder->CreateAnd(V1, ConstantExpr::getShl(CC, Op1), Value *XM = Builder->CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
V1->getName()+".mask"); V1->getName()+".mask");
return BinaryOperator::Create(Op0BO->getOpcode(), XM, YS); return BinaryOperator::Create(Op0BO->getOpcode(), XM, YS);
} }
break; break;
} }
} }
// If the operand is an bitwise operator with a constant RHS, and the // If the operand is an bitwise operator with a constant RHS, and the
// shift is the only use, we can pull it out of the shift. // shift is the only use, we can pull it out of the shift.
if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) { if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
bool isValid = true; // Valid only for And, Or, Xor bool isValid = true; // Valid only for And, Or, Xor
bool highBitSet = false; // Transform if high bit of constant set? bool highBitSet = false; // Transform if high bit of constant set?
switch (Op0BO->getOpcode()) { switch (Op0BO->getOpcode()) {
default: isValid = false; break; // Do not perform transform! default: isValid = false; break; // Do not perform transform!
case Instruction::Add: case Instruction::Add:
@ -499,7 +499,7 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
highBitSet = true; highBitSet = true;
break; break;
} }
// If this is a signed shift right, and the high bit is modified // If this is a signed shift right, and the high bit is modified
// by the logical operation, do not perform the transformation. // by the logical operation, do not perform the transformation.
// The highBitSet boolean indicates the value of the high bit of // The highBitSet boolean indicates the value of the high bit of
@ -508,26 +508,26 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
// //
if (isValid && I.getOpcode() == Instruction::AShr) if (isValid && I.getOpcode() == Instruction::AShr)
isValid = Op0C->getValue()[TypeBits-1] == highBitSet; isValid = Op0C->getValue()[TypeBits-1] == highBitSet;
if (isValid) { if (isValid) {
Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1); Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1);
Value *NewShift = Value *NewShift =
Builder->CreateBinOp(I.getOpcode(), Op0BO->getOperand(0), Op1); Builder->CreateBinOp(I.getOpcode(), Op0BO->getOperand(0), Op1);
NewShift->takeName(Op0BO); NewShift->takeName(Op0BO);
return BinaryOperator::Create(Op0BO->getOpcode(), NewShift, return BinaryOperator::Create(Op0BO->getOpcode(), NewShift,
NewRHS); NewRHS);
} }
} }
} }
} }
// Find out if this is a shift of a shift by a constant. // Find out if this is a shift of a shift by a constant.
BinaryOperator *ShiftOp = dyn_cast<BinaryOperator>(Op0); BinaryOperator *ShiftOp = dyn_cast<BinaryOperator>(Op0);
if (ShiftOp && !ShiftOp->isShift()) if (ShiftOp && !ShiftOp->isShift())
ShiftOp = 0; ShiftOp = 0;
if (ShiftOp && isa<ConstantInt>(ShiftOp->getOperand(1))) { if (ShiftOp && isa<ConstantInt>(ShiftOp->getOperand(1))) {
// This is a constant shift of a constant shift. Be careful about hiding // This is a constant shift of a constant shift. Be careful about hiding
@ -548,9 +548,9 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
assert(ShiftAmt2 != 0 && "Should have been simplified earlier"); assert(ShiftAmt2 != 0 && "Should have been simplified earlier");
if (ShiftAmt1 == 0) return 0; // Will be simplified in the future. if (ShiftAmt1 == 0) return 0; // Will be simplified in the future.
Value *X = ShiftOp->getOperand(0); Value *X = ShiftOp->getOperand(0);
IntegerType *Ty = cast<IntegerType>(I.getType()); IntegerType *Ty = cast<IntegerType>(I.getType());
// Check for (X << c1) << c2 and (X >> c1) >> c2 // Check for (X << c1) << c2 and (X >> c1) >> c2
if (I.getOpcode() == ShiftOp->getOpcode()) { if (I.getOpcode() == ShiftOp->getOpcode()) {
uint32_t AmtSum = ShiftAmt1+ShiftAmt2; // Fold into one big shift. uint32_t AmtSum = ShiftAmt1+ShiftAmt2; // Fold into one big shift.
@ -561,11 +561,11 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
AmtSum = TypeBits-1; // Saturate to 31 for i32 ashr. AmtSum = TypeBits-1; // Saturate to 31 for i32 ashr.
} }
return BinaryOperator::Create(I.getOpcode(), X, return BinaryOperator::Create(I.getOpcode(), X,
ConstantInt::get(Ty, AmtSum)); ConstantInt::get(Ty, AmtSum));
} }
if (ShiftAmt1 == ShiftAmt2) { if (ShiftAmt1 == ShiftAmt2) {
// If we have ((X << C) >>u C), turn this into X & (-1 >>u C). // If we have ((X << C) >>u C), turn this into X & (-1 >>u C).
if (I.getOpcode() == Instruction::LShr && if (I.getOpcode() == Instruction::LShr &&
@ -605,7 +605,7 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
return NewLShr; return NewLShr;
} }
Value *Shift = Builder->CreateLShr(X, ShiftDiffCst); Value *Shift = Builder->CreateLShr(X, ShiftDiffCst);
APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2)); APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
return BinaryOperator::CreateAnd(Shift, return BinaryOperator::CreateAnd(Shift,
ConstantInt::get(I.getContext(),Mask)); ConstantInt::get(I.getContext(),Mask));
@ -653,12 +653,12 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
return NewShl; return NewShl;
} }
Value *Shift = Builder->CreateShl(X, ShiftDiffCst); Value *Shift = Builder->CreateShl(X, ShiftDiffCst);
APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2)); APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
return BinaryOperator::CreateAnd(Shift, return BinaryOperator::CreateAnd(Shift,
ConstantInt::get(I.getContext(),Mask)); ConstantInt::get(I.getContext(),Mask));
} }
// We can't handle (X << C1) >>s C2, it shifts arbitrary bits in. However, // We can't handle (X << C1) >>s C2, it shifts arbitrary bits in. However,
// we can handle (X <<nsw C1) >>s C2 since it only shifts in sign bits. // we can handle (X <<nsw C1) >>s C2 since it only shifts in sign bits.
if (I.getOpcode() == Instruction::AShr && if (I.getOpcode() == Instruction::AShr &&
@ -682,21 +682,21 @@ Instruction *InstCombiner::visitShl(BinaryOperator &I) {
I.hasNoSignedWrap(), I.hasNoUnsignedWrap(), I.hasNoSignedWrap(), I.hasNoUnsignedWrap(),
TD)) TD))
return ReplaceInstUsesWith(I, V); return ReplaceInstUsesWith(I, V);
if (Instruction *V = commonShiftTransforms(I)) if (Instruction *V = commonShiftTransforms(I))
return V; return V;
if (ConstantInt *Op1C = dyn_cast<ConstantInt>(I.getOperand(1))) { if (ConstantInt *Op1C = dyn_cast<ConstantInt>(I.getOperand(1))) {
unsigned ShAmt = Op1C->getZExtValue(); unsigned ShAmt = Op1C->getZExtValue();
// If the shifted-out value is known-zero, then this is a NUW shift. // If the shifted-out value is known-zero, then this is a NUW shift.
if (!I.hasNoUnsignedWrap() && if (!I.hasNoUnsignedWrap() &&
MaskedValueIsZero(I.getOperand(0), MaskedValueIsZero(I.getOperand(0),
APInt::getHighBitsSet(Op1C->getBitWidth(), ShAmt))) { APInt::getHighBitsSet(Op1C->getBitWidth(), ShAmt))) {
I.setHasNoUnsignedWrap(); I.setHasNoUnsignedWrap();
return &I; return &I;
} }
// If the shifted out value is all signbits, this is a NSW shift. // If the shifted out value is all signbits, this is a NSW shift.
if (!I.hasNoSignedWrap() && if (!I.hasNoSignedWrap() &&
ComputeNumSignBits(I.getOperand(0)) > ShAmt) { ComputeNumSignBits(I.getOperand(0)) > ShAmt) {
@ -712,7 +712,7 @@ Instruction *InstCombiner::visitShl(BinaryOperator &I) {
match(I.getOperand(1), m_Constant(C2))) match(I.getOperand(1), m_Constant(C2)))
return BinaryOperator::CreateShl(ConstantExpr::getShl(C1, C2), A); return BinaryOperator::CreateShl(ConstantExpr::getShl(C1, C2), A);
return 0; return 0;
} }
Instruction *InstCombiner::visitLShr(BinaryOperator &I) { Instruction *InstCombiner::visitLShr(BinaryOperator &I) {
@ -722,9 +722,9 @@ Instruction *InstCombiner::visitLShr(BinaryOperator &I) {
if (Instruction *R = commonShiftTransforms(I)) if (Instruction *R = commonShiftTransforms(I))
return R; return R;
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) { if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
unsigned ShAmt = Op1C->getZExtValue(); unsigned ShAmt = Op1C->getZExtValue();
@ -743,15 +743,15 @@ Instruction *InstCombiner::visitLShr(BinaryOperator &I) {
return new ZExtInst(Cmp, II->getType()); return new ZExtInst(Cmp, II->getType());
} }
} }
// If the shifted-out value is known-zero, then this is an exact shift. // If the shifted-out value is known-zero, then this is an exact shift.
if (!I.isExact() && if (!I.isExact() &&
MaskedValueIsZero(Op0,APInt::getLowBitsSet(Op1C->getBitWidth(),ShAmt))){ MaskedValueIsZero(Op0,APInt::getLowBitsSet(Op1C->getBitWidth(),ShAmt))){
I.setIsExact(); I.setIsExact();
return &I; return &I;
} }
} }
return 0; return 0;
} }
@ -762,12 +762,12 @@ Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
if (Instruction *R = commonShiftTransforms(I)) if (Instruction *R = commonShiftTransforms(I))
return R; return R;
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) { if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
unsigned ShAmt = Op1C->getZExtValue(); unsigned ShAmt = Op1C->getZExtValue();
// If the input is a SHL by the same constant (ashr (shl X, C), C), then we // If the input is a SHL by the same constant (ashr (shl X, C), C), then we
// have a sign-extend idiom. // have a sign-extend idiom.
Value *X; Value *X;
@ -791,23 +791,23 @@ Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
} }
// If the shifted-out value is known-zero, then this is an exact shift. // If the shifted-out value is known-zero, then this is an exact shift.
if (!I.isExact() && if (!I.isExact() &&
MaskedValueIsZero(Op0,APInt::getLowBitsSet(Op1C->getBitWidth(),ShAmt))){ MaskedValueIsZero(Op0,APInt::getLowBitsSet(Op1C->getBitWidth(),ShAmt))){
I.setIsExact(); I.setIsExact();
return &I; return &I;
} }
} }
// See if we can turn a signed shr into an unsigned shr. // See if we can turn a signed shr into an unsigned shr.
if (MaskedValueIsZero(Op0, if (MaskedValueIsZero(Op0,
APInt::getSignBit(I.getType()->getScalarSizeInBits()))) APInt::getSignBit(I.getType()->getScalarSizeInBits())))
return BinaryOperator::CreateLShr(Op0, Op1); return BinaryOperator::CreateLShr(Op0, Op1);
// Arithmetic shifting an all-sign-bit value is a no-op. // Arithmetic shifting an all-sign-bit value is a no-op.
unsigned NumSignBits = ComputeNumSignBits(Op0); unsigned NumSignBits = ComputeNumSignBits(Op0);
if (NumSignBits == Op0->getType()->getScalarSizeInBits()) if (NumSignBits == Op0->getType()->getScalarSizeInBits())
return ReplaceInstUsesWith(I, Op0); return ReplaceInstUsesWith(I, Op0);
return 0; return 0;
} }