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Refactor several ConstantExpr::getXXX calls with ConstantInt arguments

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using the facilities of APInt. While this duplicates a tiny fraction of
the constant folding code, it also makes the code easier to read and
avoids large ConstantExpr overhead for simple, known computations.

llvm-svn: 35335
This commit is contained in:
Reid Spencer 2007-03-25 05:33:51 +00:00
parent ee90a087a6
commit 8449e5fa0e
1 changed files with 40 additions and 27 deletions
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67
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -540,8 +540,9 @@ static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
if (I->getOpcode() == Instruction::Shl)
if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
// The multiplier is really 1 << CST.
Constant *One = ConstantInt::get(V->getType(), 1);
CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST));
APInt Multiplier(V->getType()->getPrimitiveSizeInBits(), 0);
Multiplier.set(CST->getZExtValue()); // set bit is == 1 << CST
CST = ConstantInt::get(Multiplier);
return I->getOperand(0);
}
}
@ -558,14 +559,31 @@ static User *dyn_castGetElementPtr(Value *V) {
return false;
}
// AddOne, SubOne - Add or subtract a constant one from an integer constant...
/// AddOne - Add one to a ConstantInt
static ConstantInt *AddOne(ConstantInt *C) {
return cast<ConstantInt>(ConstantExpr::getAdd(C,
ConstantInt::get(C->getType(), 1)));
APInt One(C->getType()->getPrimitiveSizeInBits(),1);
return ConstantInt::get(C->getValue() + One);
}
/// SubOne - Subtract one from a ConstantInt
static ConstantInt *SubOne(ConstantInt *C) {
return cast<ConstantInt>(ConstantExpr::getSub(C,
ConstantInt::get(C->getType(), 1)));
APInt One(C->getType()->getPrimitiveSizeInBits(),1);
return ConstantInt::get(C->getValue() - One);
}
/// Add - Add two ConstantInts together
static ConstantInt *Add(ConstantInt *C1, ConstantInt *C2) {
return ConstantInt::get(C1->getValue() + C2->getValue());
}
/// And - Bitwise AND two ConstantInts together
static ConstantInt *And(ConstantInt *C1, ConstantInt *C2) {
return ConstantInt::get(C1->getValue() & C2->getValue());
}
/// Subtract - Subtract one ConstantInt from another
static ConstantInt *Subtract(ConstantInt *C1, ConstantInt *C2) {
return ConstantInt::get(C1->getValue() - C2->getValue());
}
/// Multiply - Multiply two ConstantInts together
static ConstantInt *Multiply(ConstantInt *C1, ConstantInt *C2) {
return ConstantInt::get(C1->getValue() * C2->getValue());
}
/// ComputeMaskedBits - Determine which of the bits specified in Mask are
@ -1966,7 +1984,7 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
// X*C1 + X*C2 --> X * (C1+C2)
ConstantInt *C1;
if (X == dyn_castFoldableMul(RHS, C1))
return BinaryOperator::createMul(X, ConstantExpr::getAdd(C1, C2));
return BinaryOperator::createMul(X, Add(C1, C2));
}
// X + X*C --> X * (C+1)
@ -1986,14 +2004,12 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
Value *X = 0;
if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
return BinaryOperator::createSub(C, X);
}
if (match(LHS, m_Not(m_Value(X)))) // ~X + C --> (C-1) - X
return BinaryOperator::createSub(SubOne(CRHS), X);
// (X & FF00) + xx00 -> (X+xx00) & FF00
if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
Constant *Anded = And(CRHS, C2);
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.
@ -2075,8 +2091,8 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
// C - ~X == X + (1+C)
Value *X = 0;
if (match(Op1, m_Not(m_Value(X))))
return BinaryOperator::createAdd(X,
ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
return BinaryOperator::createAdd(X, AddOne(C));
// -(X >>u 31) -> (X >>s 31)
// -(X >>s 31) -> (X >>u 31)
if (C->isNullValue()) {
@ -2125,7 +2141,7 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
// C1-(X+C2) --> (C1-C2)-X
return BinaryOperator::createSub(ConstantExpr::getSub(CI1, CI2),
return BinaryOperator::createSub(Subtract(CI1, CI2),
Op1I->getOperand(0));
}
}
@ -2167,8 +2183,7 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
// X - X*C --> X * (1-C)
ConstantInt *C2 = 0;
if (dyn_castFoldableMul(Op1I, C2) == Op0) {
Constant *CP1 =
ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2);
Constant *CP1 = Subtract(ConstantInt::get(I.getType(), 1), C2);
return BinaryOperator::createMul(Op0, CP1);
}
}
@ -2188,14 +2203,12 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
ConstantInt *C1;
if (Value *X = dyn_castFoldableMul(Op0, C1)) {
if (X == Op1) { // X*C - X --> X * (C-1)
Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1));
return BinaryOperator::createMul(Op1, CP1);
}
if (X == Op1) // X*C - X --> X * (C-1)
return BinaryOperator::createMul(Op1, SubOne(C1));
ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
if (X == dyn_castFoldableMul(Op1, C2))
return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2));
return BinaryOperator::createMul(Op1, Subtract(C1, C2));
}
return 0;
}
@ -2411,7 +2424,7 @@ Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
return BinaryOperator::create(I.getOpcode(), LHS->getOperand(0),
ConstantExpr::getMul(RHS, LHSRHS));
Multiply(RHS, LHSRHS));
}
if (!RHS->isZero()) { // avoid X udiv 0
@ -2906,7 +2919,7 @@ Instruction *InstCombiner::OptAndOp(Instruction *Op,
Value *X = Op->getOperand(0);
Constant *Together = 0;
if (!Op->isShift())
Together = ConstantExpr::getAnd(AndRHS, OpRHS);
Together = And(AndRHS, OpRHS);
switch (Op->getOpcode()) {
case Instruction::Xor:
@ -3112,7 +3125,7 @@ Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
switch (LHSI->getOpcode()) {
default: return 0;
case Instruction::And:
if (ConstantExpr::getAnd(N, Mask) == Mask) {
if (And(N, Mask) == Mask) {
// If the AndRHS is a power of two minus one (0+1+), this is simple.
if ((Mask->getValue().countLeadingZeros() +
Mask->getValue().countPopulation()) ==
@ -3137,7 +3150,7 @@ Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
// If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
if ((Mask->getValue().countLeadingZeros() +
Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth()
&& ConstantExpr::getAnd(N, Mask)->isNullValue())
&& And(N, Mask)->isNullValue())
break;
return 0;
}