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Move LHSI->hasOneUse() into the arms of the conditional, reindenting code.

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No functionality changes here.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16505 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-09-23 21:52:49 +00:00
parent b20ba0a83f
commit 648e3bc39c
1 changed files with 72 additions and 71 deletions
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143
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -1451,76 +1451,76 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
// can be folded into the comparison.
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
if (LHSI->hasOneUse())
switch (LHSI->getOpcode()) {
case Instruction::And:
if (isa<ConstantInt>(LHSI->getOperand(1)) &&
LHSI->getOperand(0)->hasOneUse()) {
// If this is: (X >> C1) & C2 != C3 (where any shift and any compare
// could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
// happens a LOT in code produced by the C front-end, for bitfield
// access.
ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
ConstantUInt *ShAmt;
ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
const Type *Ty = LHSI->getType();
// We can fold this as long as we can't shift unknown bits
// into the mask. This can only happen with signed shift
// rights, as they sign-extend.
if (ShAmt) {
bool CanFold = Shift->getOpcode() != Instruction::Shr ||
Shift->getType()->isUnsigned();
if (!CanFold) {
// To test for the bad case of the signed shr, see if any
// of the bits shifted in could be tested after the mask.
Constant *OShAmt = ConstantUInt::get(Type::UByteTy,
switch (LHSI->getOpcode()) {
case Instruction::And:
if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
LHSI->getOperand(0)->hasOneUse()) {
// If this is: (X >> C1) & C2 != C3 (where any shift and any compare
// could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
// happens a LOT in code produced by the C front-end, for bitfield
// access.
ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
ConstantUInt *ShAmt;
ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
const Type *Ty = LHSI->getType();
// We can fold this as long as we can't shift unknown bits
// into the mask. This can only happen with signed shift
// rights, as they sign-extend.
if (ShAmt) {
bool CanFold = Shift->getOpcode() != Instruction::Shr ||
Shift->getType()->isUnsigned();
if (!CanFold) {
// To test for the bad case of the signed shr, see if any
// of the bits shifted in could be tested after the mask.
Constant *OShAmt = ConstantUInt::get(Type::UByteTy,
Ty->getPrimitiveSize()*8-ShAmt->getValue());
Constant *ShVal =
ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
CanFold = true;
}
if (CanFold) {
unsigned ShiftOp = Shift->getOpcode() == Instruction::Shl
? Instruction::Shr : Instruction::Shl;
Constant *NewCst = ConstantExpr::get(ShiftOp, CI, ShAmt);
// Check to see if we are shifting out any of the bits being
// compared.
if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
// If we shifted bits out, the fold is not going to work out.
// As a special case, check to see if this means that the
// result is always true or false now.
if (I.getOpcode() == Instruction::SetEQ)
return ReplaceInstUsesWith(I, ConstantBool::False);
if (I.getOpcode() == Instruction::SetNE)
return ReplaceInstUsesWith(I, ConstantBool::True);
} else {
I.setOperand(1, NewCst);
LHSI->setOperand(1, ConstantExpr::get(ShiftOp, AndCST,ShAmt));
LHSI->setOperand(0, Shift->getOperand(0));
WorkList.push_back(Shift); // Shift is dead.
AddUsesToWorkList(I);
return &I;
}
Constant *ShVal =
ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
CanFold = true;
}
if (CanFold) {
unsigned ShiftOp = Shift->getOpcode() == Instruction::Shl
? Instruction::Shr : Instruction::Shl;
Constant *NewCst = ConstantExpr::get(ShiftOp, CI, ShAmt);
// Check to see if we are shifting out any of the bits being
// compared.
if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
// If we shifted bits out, the fold is not going to work out.
// As a special case, check to see if this means that the
// result is always true or false now.
if (I.getOpcode() == Instruction::SetEQ)
return ReplaceInstUsesWith(I, ConstantBool::False);
if (I.getOpcode() == Instruction::SetNE)
return ReplaceInstUsesWith(I, ConstantBool::True);
} else {
I.setOperand(1, NewCst);
LHSI->setOperand(1, ConstantExpr::get(ShiftOp, AndCST,ShAmt));
LHSI->setOperand(0, Shift->getOperand(0));
WorkList.push_back(Shift); // Shift is dead.
AddUsesToWorkList(I);
return &I;
}
}
}
break;
case Instruction::Div:
if (0 && isa<ConstantInt>(LHSI->getOperand(1))) {
std::cerr << "COULD FOLD: " << *LHSI;
std::cerr << "COULD FOLD: " << I << "\n";
}
break;
case Instruction::Select:
// If either operand of the select is a constant, we can fold the
// comparison into the select arms, which will cause one to be
// constant folded and the select turned into a bitwise or.
Value *Op1 = 0, *Op2 = 0;
}
break;
case Instruction::Div:
if (0 && isa<ConstantInt>(LHSI->getOperand(1))) {
std::cerr << "COULD FOLD: " << *LHSI;
std::cerr << "COULD FOLD: " << I << "\n";
}
break;
case Instruction::Select:
// If either operand of the select is a constant, we can fold the
// comparison into the select arms, which will cause one to be
// constant folded and the select turned into a bitwise or.
Value *Op1 = 0, *Op2 = 0;
if (LHSI->hasOneUse()) {
if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
// Fold the known value into the constant operand.
Op1 = ConstantExpr::get(I.getOpcode(), C, CI);
@ -1536,12 +1536,13 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
LHSI->getOperand(1), CI,
I.getName()), I);
}
if (Op1)
return new SelectInst(LHSI->getOperand(0), Op1, Op2);
break;
}
if (Op1)
return new SelectInst(LHSI->getOperand(0), Op1, Op2);
break;
}
// Simplify seteq and setne instructions...
if (I.getOpcode() == Instruction::SetEQ ||
I.getOpcode() == Instruction::SetNE) {