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* Factor a bunch of code by using ReplaceInstUsesWith 

* Move isMaxValue, isMinValue, isAllOnesValue to Constants.h

llvm-svn: 3290
This commit is contained in:
Chris Lattner 2002-08-12 21:17:25 +00:00
parent 68fe621771
commit e6794490ec
1 changed files with 51 additions and 163 deletions
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214
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
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@ -1,4 +1,4 @@
//===- InstructionCombining.cpp - Combine multiple instructions -------------=// //===- InstructionCombining.cpp - Combine multiple instructions -----------===//
// //
// InstructionCombining - Combine instructions to form fewer, simple // InstructionCombining - Combine instructions to form fewer, simple
// instructions. This pass does not modify the CFG, and has a tendancy to // instructions. This pass does not modify the CFG, and has a tendancy to
@ -57,7 +57,7 @@ namespace {
// instruction types. The semantics are as follows: // instruction types. The semantics are as follows:
// Return Value: // Return Value:
// null - No change was made // null - No change was made
// I - Change was made, I is still valid // I - Change was made, I is still valid, I may be dead though
// otherwise - Change was made, replace I with returned instruction // otherwise - Change was made, replace I with returned instruction
// //
Instruction *visitNot(UnaryOperator &I); Instruction *visitNot(UnaryOperator &I);
@ -107,11 +107,8 @@ namespace {
Instruction *InstCombiner::visitNot(UnaryOperator &I) { Instruction *InstCombiner::visitNot(UnaryOperator &I) {
// not (not X) = X // not (not X) = X
if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(0))) if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(0)))
if (Op->getOpcode() == Instruction::Not) { if (Op->getOpcode() == Instruction::Not)
AddUsesToWorkList(I); // Add all modified instrs to worklist return ReplaceInstUsesWith(I, Op->getOperand(0));
I.replaceAllUsesWith(Op->getOperand(0));
return &I;
}
return 0; return 0;
} }
@ -142,11 +139,8 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
Value *LHS = I.getOperand(0), *RHS = I.getOperand(1); Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
// Eliminate 'add int %X, 0' // Eliminate 'add int %X, 0'
if (RHS == Constant::getNullValue(I.getType())) { if (RHS == Constant::getNullValue(I.getType()))
AddUsesToWorkList(I); // Add all modified instrs to worklist return ReplaceInstUsesWith(I, LHS);
I.replaceAllUsesWith(LHS);
return &I;
}
// -A + B --> B - A // -A + B --> B - A
if (Value *V = dyn_castNegInst(LHS)) if (Value *V = dyn_castNegInst(LHS))
@ -182,11 +176,8 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
Instruction *InstCombiner::visitSub(BinaryOperator &I) { Instruction *InstCombiner::visitSub(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Op0 == Op1) { // sub X, X -> 0 if (Op0 == Op1) // sub X, X -> 0
AddUsesToWorkList(I); // Add all modified instrs to worklist return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
I.replaceAllUsesWith(Constant::getNullValue(I.getType()));
return &I;
}
// If this is a subtract instruction with a constant RHS, convert it to an add // If this is a subtract instruction with a constant RHS, convert it to an add
// instruction of a negative constant // instruction of a negative constant
@ -195,7 +186,7 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
if (Constant *RHS = *Constant::getNullValue(I.getType()) - *Op2) // 0 - RHS if (Constant *RHS = *Constant::getNullValue(I.getType()) - *Op2) // 0 - RHS
return BinaryOperator::create(Instruction::Add, Op0, RHS, I.getName()); return BinaryOperator::create(Instruction::Add, Op0, RHS, I.getName());
// If this is a 'C = x-B', check to see if 'B = -A', so that C = x+A... // If this is a 'B = x-(-A)', change to B = x+A...
if (Value *V = dyn_castNegInst(Op1)) if (Value *V = dyn_castNegInst(Op1))
return BinaryOperator::create(Instruction::Add, Op0, V); return BinaryOperator::create(Instruction::Add, Op0, V);
@ -219,25 +210,17 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) {
bool Changed = SimplifyBinOp(I); bool Changed = SimplifyBinOp(I);
Value *Op1 = I.getOperand(0); Value *Op1 = I.getOperand(0);
// Simplify add instructions with a constant RHS... // Simplify mul instructions with a constant RHS...
if (Constant *Op2 = dyn_cast<Constant>(I.getOperand(1))) { if (Constant *Op2 = dyn_cast<Constant>(I.getOperand(1))) {
if (I.getType()->isIntegral() && cast<ConstantInt>(Op2)->equalsInt(1)){ if (I.getType()->isIntegral() && cast<ConstantInt>(Op2)->equalsInt(1))
// Eliminate 'mul int %X, 1' return ReplaceInstUsesWith(I, Op1); // Eliminate 'mul int %X, 1'
AddUsesToWorkList(I); // Add all modified instrs to worklist
I.replaceAllUsesWith(Op1);
return &I;
} else if (I.getType()->isIntegral() && if (I.getType()->isIntegral() && cast<ConstantInt>(Op2)->equalsInt(2))
cast<ConstantInt>(Op2)->equalsInt(2)) {
// Convert 'mul int %X, 2' to 'add int %X, %X' // Convert 'mul int %X, 2' to 'add int %X, %X'
return BinaryOperator::create(Instruction::Add, Op1, Op1, I.getName()); return BinaryOperator::create(Instruction::Add, Op1, Op1, I.getName());
} else if (Op2->isNullValue()) { if (Op2->isNullValue())
// Eliminate 'mul int %X, 0' return ReplaceInstUsesWith(I, Op2); // Eliminate 'mul int %X, 0'
AddUsesToWorkList(I); // Add all modified instrs to worklist
I.replaceAllUsesWith(Op2); // Set this value to zero directly
return &I;
}
} }
return Changed ? &I : 0; return Changed ? &I : 0;
@ -247,11 +230,8 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) {
Instruction *InstCombiner::visitDiv(BinaryOperator &I) { Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
// div X, 1 == X // div X, 1 == X
if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1)))
if (RHS->equalsInt(1)) { if (RHS->equalsInt(1))
AddUsesToWorkList(I); // Add all modified instrs to worklist return ReplaceInstUsesWith(I, I.getOperand(0));
I.replaceAllUsesWith(I.getOperand(0));
return &I;
}
return 0; return 0;
} }
@ -259,70 +239,14 @@ Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
Instruction *InstCombiner::visitRem(BinaryOperator &I) { Instruction *InstCombiner::visitRem(BinaryOperator &I) {
// rem X, 1 == 0 // rem X, 1 == 0
if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1)))
if (RHS->equalsInt(1)) { if (RHS->equalsInt(1))
AddUsesToWorkList(I); // Add all modified instrs to worklist return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
I.replaceAllUsesWith(Constant::getNullValue(I.getType()));
return &I;
}
return 0; return 0;
} }
// FIXME: These should be moved to Constants.h
// isAllOnesValue - Return true if integral or boolean value is all ones.
static bool isAllOnesValue(const Constant *C) {
if (const ConstantBool *CB = dyn_cast<ConstantBool>(C))
return CB == ConstantBool::True;
else if (const ConstantSInt *CS = dyn_cast<ConstantSInt>(C))
return CS->getValue() == -1;
else if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
// Calculate -1 casted to the right type...
unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
uint64_t Val = ~0ULL; // All ones
Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
return CU->getValue() == Val;
}
return false;
}
// isMaxValue - Return true if this is the maximum value for this type.
static bool isMaxValue(const Constant *C) {
if (const ConstantBool *CB = dyn_cast<ConstantBool>(C))
return CB == ConstantBool::True;
else if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
return isAllOnesValue(C);
else if (const ConstantSInt *CS = dyn_cast<ConstantSInt>(C)) {
// Calculate 011111111111111...
unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
int64_t Val = INT64_MAX; // All ones
Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
return CS->getValue() == Val;
}
return false;
}
// isMinValue - Return true if this is the minimum value for this type.
static bool isMinValue(const Constant *C) {
if (const ConstantBool *CB = dyn_cast<ConstantBool>(C))
return CB == ConstantBool::False;
else if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
return CU->getValue() == 0;
else if (const ConstantSInt *CS = dyn_cast<ConstantSInt>(C)) {
// Calculate 1111111111000000000000
unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
int64_t Val = -1; // All ones
Val <<= TypeBits-1; // Shift over to the right spot
return CS->getValue() == Val;
}
return false;
}
// isMaxValueMinusOne - return true if this is Max-1 // isMaxValueMinusOne - return true if this is Max-1
static bool isMaxValueMinusOne(const Constant *C) { static bool isMaxValueMinusOne(const ConstantInt *C) {
if (!isa<ConstantInt>(C)) return false;
if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) { if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
// Calculate -1 casted to the right type... // Calculate -1 casted to the right type...
unsigned TypeBits = C->getType()->getPrimitiveSize()*8; unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
@ -341,9 +265,7 @@ static bool isMaxValueMinusOne(const Constant *C) {
} }
// isMinValuePlusOne - return true if this is Min+1 // isMinValuePlusOne - return true if this is Min+1
static bool isMinValuePlusOne(const Constant *C) { static bool isMinValuePlusOne(const ConstantInt *C) {
if (!isa<ConstantInt>(C)) return false;
if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
return CU->getValue() == 1; return CU->getValue() == 1;
@ -357,25 +279,18 @@ static bool isMinValuePlusOne(const Constant *C) {
} }
Instruction *InstCombiner::visitAnd(BinaryOperator &I) { Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
bool Changed = SimplifyBinOp(I); bool Changed = SimplifyBinOp(I);
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
// and X, X = X and X, 0 == 0 // and X, X = X and X, 0 == 0
if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType())) { if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
AddUsesToWorkList(I); // Add all modified instrs to worklist return ReplaceInstUsesWith(I, Op1);
I.replaceAllUsesWith(Op1);
return &I;
}
// and X, -1 == X // and X, -1 == X
if (Constant *RHS = dyn_cast<Constant>(Op1)) if (ConstantGenericIntegral *RHS = dyn_cast<ConstantGenericIntegral>(Op1))
if (isAllOnesValue(RHS)) { if (RHS->isAllOnesValue())
AddUsesToWorkList(I); // Add all modified instrs to worklist return ReplaceInstUsesWith(I, Op0);
I.replaceAllUsesWith(Op0);
return &I;
}
return Changed ? &I : 0; return Changed ? &I : 0;
} }
@ -387,19 +302,13 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
// or X, X = X or X, 0 == X // or X, X = X or X, 0 == X
if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType())) { if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
AddUsesToWorkList(I); // Add all modified instrs to worklist return ReplaceInstUsesWith(I, Op0);
I.replaceAllUsesWith(Op0);
return &I;
}
// or X, -1 == -1 // or X, -1 == -1
if (Constant *RHS = dyn_cast<Constant>(Op1)) if (ConstantGenericIntegral *RHS = dyn_cast<ConstantGenericIntegral>(Op1))
if (isAllOnesValue(RHS)) { if (RHS->isAllOnesValue())
AddUsesToWorkList(I); // Add all modified instrs to worklist return ReplaceInstUsesWith(I, Op1);
I.replaceAllUsesWith(Op1);
return &I;
}
return Changed ? &I : 0; return Changed ? &I : 0;
} }
@ -411,22 +320,16 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
// xor X, X = 0 // xor X, X = 0
if (Op0 == Op1) { if (Op0 == Op1)
AddUsesToWorkList(I); // Add all modified instrs to worklist return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
I.replaceAllUsesWith(Constant::getNullValue(I.getType()));
return &I;
}
if (Constant *Op1C = dyn_cast<Constant>(Op1)) { if (ConstantGenericIntegral *Op1C = dyn_cast<ConstantGenericIntegral>(Op1)) {
// xor X, 0 == X // xor X, 0 == X
if (Op1C->isNullValue()) { if (Op1C->isNullValue())
AddUsesToWorkList(I); // Add all modified instrs to worklist return ReplaceInstUsesWith(I, Op0);
I.replaceAllUsesWith(Op0);
return &I;
}
// xor X, -1 = not X // xor X, -1 = not X
if (isAllOnesValue(Op1C)) if (Op1C->isAllOnesValue())
return UnaryOperator::create(Instruction::Not, Op0, I.getName()); return UnaryOperator::create(Instruction::Not, Op0, I.getName());
} }
@ -506,7 +409,7 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
// //
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
// Check to see if we are comparing against the minimum or maximum value... // Check to see if we are comparing against the minimum or maximum value...
if (isMinValue(CI)) { if (CI->isMinValue()) {
if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
return ReplaceInstUsesWith(I, ConstantBool::False); return ReplaceInstUsesWith(I, ConstantBool::False);
if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
@ -516,7 +419,7 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
return BinaryOperator::create(Instruction::SetNE, Op0,Op1, I.getName()); return BinaryOperator::create(Instruction::SetNE, Op0,Op1, I.getName());
} else if (isMaxValue(CI)) { } else if (CI->isMaxValue()) {
if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
return ReplaceInstUsesWith(I, ConstantBool::False); return ReplaceInstUsesWith(I, ConstantBool::False);
if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
@ -557,23 +460,17 @@ Instruction *InstCombiner::visitShiftInst(Instruction &I) {
// shl X, 0 == X and shr X, 0 == X // shl X, 0 == X and shr X, 0 == X
// shl 0, X == 0 and shr 0, X == 0 // shl 0, X == 0 and shr 0, X == 0
if (Op1 == Constant::getNullValue(Type::UByteTy) || if (Op1 == Constant::getNullValue(Type::UByteTy) ||
Op0 == Constant::getNullValue(Op0->getType())) { Op0 == Constant::getNullValue(Op0->getType()))
AddUsesToWorkList(I); // Add all modified instrs to worklist return ReplaceInstUsesWith(I, Op0);
I.replaceAllUsesWith(Op0);
return &I;
}
// shl int X, 32 = 0 and shr sbyte Y, 9 = 0, ... just don't eliminate shr of // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr of
// a signed value. // a signed value.
// //
if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) { if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
unsigned TypeBits = Op0->getType()->getPrimitiveSize()*8; unsigned TypeBits = Op0->getType()->getPrimitiveSize()*8;
if (CUI->getValue() >= TypeBits && if (CUI->getValue() >= TypeBits &&
!(Op0->getType()->isSigned() && I.getOpcode() == Instruction::Shr)) { !(Op0->getType()->isSigned() && I.getOpcode() == Instruction::Shr))
AddUsesToWorkList(I); // Add all modified instrs to worklist return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
I.replaceAllUsesWith(Constant::getNullValue(Op0->getType()));
return &I;
}
} }
return 0; return 0;
} }
@ -626,11 +523,8 @@ static inline bool isEliminableCastOfCast(const CastInst &CI,
Instruction *InstCombiner::visitCastInst(CastInst &CI) { Instruction *InstCombiner::visitCastInst(CastInst &CI) {
// If the user is casting a value to the same type, eliminate this cast // If the user is casting a value to the same type, eliminate this cast
// instruction... // instruction...
if (CI.getType() == CI.getOperand(0)->getType()) { if (CI.getType() == CI.getOperand(0)->getType())
AddUsesToWorkList(CI); // Add all modified instrs to worklist return ReplaceInstUsesWith(CI, CI.getOperand(0));
CI.replaceAllUsesWith(CI.getOperand(0));
return &CI;
}
// If casting the result of another cast instruction, try to eliminate this // If casting the result of another cast instruction, try to eliminate this
// one! // one!
@ -667,11 +561,8 @@ Instruction *InstCombiner::visitCastInst(CastInst &CI) {
// //
Instruction *InstCombiner::visitPHINode(PHINode &PN) { Instruction *InstCombiner::visitPHINode(PHINode &PN) {
// If the PHI node only has one incoming value, eliminate the PHI node... // If the PHI node only has one incoming value, eliminate the PHI node...
if (PN.getNumIncomingValues() == 1) { if (PN.getNumIncomingValues() == 1)
AddUsesToWorkList(PN); // Add all modified instrs to worklist return ReplaceInstUsesWith(PN, PN.getIncomingValue(0));
PN.replaceAllUsesWith(PN.getIncomingValue(0));
return &PN;
}
return 0; return 0;
} }
@ -682,11 +573,8 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
// If so, eliminate the noop. // If so, eliminate the noop.
if ((GEP.getNumOperands() == 2 && if ((GEP.getNumOperands() == 2 &&
GEP.getOperand(1) == Constant::getNullValue(Type::UIntTy)) || GEP.getOperand(1) == Constant::getNullValue(Type::UIntTy)) ||
GEP.getNumOperands() == 1) { GEP.getNumOperands() == 1)
AddUsesToWorkList(GEP); // Add all modified instrs to worklist return ReplaceInstUsesWith(GEP, GEP.getOperand(0));
GEP.replaceAllUsesWith(GEP.getOperand(0));
return &GEP;
}
// Combine Indices - If the source pointer to this getelementptr instruction // Combine Indices - If the source pointer to this getelementptr instruction
// is a getelementptr instruction, combine the indices of the two // is a getelementptr instruction, combine the indices of the two