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Some cleanup from review:

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* Don't assume shift amounts are <= 64 bits
* Avoid creating an extra APInt in SubOne and AddOne by using -- and ++
* Add another use of getLowBitsSet
* Convert a series of if statements to a switch


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35339 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Reid Spencer 2007-03-25 19:55:33 +00:00
parent 3a84b9baf6
commit 2149a9dfec
1 changed files with 18 additions and 16 deletions
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34
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -540,9 +540,8 @@ 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.
APInt Multiplier(V->getType()->getPrimitiveSizeInBits(), 0);
Multiplier.set(CST->getZExtValue()); // set bit is == 1 << CST
CST = ConstantInt::get(Multiplier);
Constant *One = ConstantInt::get(V->getType(), 1);
CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST));
return I->getOperand(0);
}
}
@ -561,13 +560,13 @@ static User *dyn_castGetElementPtr(Value *V) {
/// AddOne - Add one to a ConstantInt
static ConstantInt *AddOne(ConstantInt *C) {
APInt One(C->getType()->getPrimitiveSizeInBits(),1);
return ConstantInt::get(C->getValue() + One);
APInt Val(C->getValue());
return ConstantInt::get(++Val);
}
/// SubOne - Subtract one from a ConstantInt
static ConstantInt *SubOne(ConstantInt *C) {
APInt One(C->getType()->getPrimitiveSizeInBits(),1);
return ConstantInt::get(C->getValue() - One);
APInt Val(C->getValue());
return ConstantInt::get(--Val);
}
/// Add - Add two ConstantInts together
static ConstantInt *Add(ConstantInt *C1, ConstantInt *C2) {
@ -752,7 +751,7 @@ static void ComputeMaskedBits(Value *V, const APInt& Mask, APInt& KnownZero,
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
KnownZero <<= ShiftAmt;
KnownOne <<= ShiftAmt;
KnownZero |= APInt(BitWidth, 1ULL).shl(ShiftAmt)-1; // low bits known 0
KnownZero |= APInt::getLowBitsSet(BitWidth, ShiftAmt); // low bits known 0
return;
}
break;
@ -4654,14 +4653,17 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
// appropriate icmp lt or icmp gt instruction. Since the border cases have
// already been handled above, this requires little checking.
//
if (I.getPredicate() == ICmpInst::ICMP_ULE)
return new ICmpInst(ICmpInst::ICMP_ULT, Op0, AddOne(CI));
if (I.getPredicate() == ICmpInst::ICMP_SLE)
return new ICmpInst(ICmpInst::ICMP_SLT, Op0, AddOne(CI));
if (I.getPredicate() == ICmpInst::ICMP_UGE)
return new ICmpInst( ICmpInst::ICMP_UGT, Op0, SubOne(CI));
if (I.getPredicate() == ICmpInst::ICMP_SGE)
return new ICmpInst(ICmpInst::ICMP_SGT, Op0, SubOne(CI));
switch (I.getPredicate()) {
default: break;
case ICmpInst::ICMP_ULE:
return new ICmpInst(ICmpInst::ICMP_ULT, Op0, AddOne(CI));
case ICmpInst::ICMP_SLE:
return new ICmpInst(ICmpInst::ICMP_SLT, Op0, AddOne(CI));
case ICmpInst::ICMP_UGE:
return new ICmpInst( ICmpInst::ICMP_UGT, Op0, SubOne(CI));
case ICmpInst::ICMP_SGE:
return new ICmpInst(ICmpInst::ICMP_SGT, Op0, SubOne(CI));
}
// See if we can fold the comparison based on bits known to be zero or one
// in the input.