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fix some 176.gcc miscompilation from my previous patch. 

llvm-svn: 25137
This commit is contained in:
Chris Lattner 2006-01-07 01:32:28 +00:00
parent 92e2797ce2
commit 9cbfbc21bb
1 changed files with 33 additions and 7 deletions
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40
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
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@ -3669,7 +3669,7 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantUInt *Op1,
// is a noop cast between the two. // is a noop cast between the two.
bool isShiftOfLeftShift = ShiftOp->getOpcode() == Instruction::Shl; bool isShiftOfLeftShift = ShiftOp->getOpcode() == Instruction::Shl;
bool isShiftOfSignedShift = ShiftOp->getType()->isSigned(); bool isShiftOfSignedShift = ShiftOp->getType()->isSigned();
bool isShiftOfUnsignedShift = !isSignedShift; bool isShiftOfUnsignedShift = !isShiftOfSignedShift;
ConstantUInt *ShiftAmt1C = cast<ConstantUInt>(ShiftOp->getOperand(1)); ConstantUInt *ShiftAmt1C = cast<ConstantUInt>(ShiftOp->getOperand(1));
@ -3704,7 +3704,7 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantUInt *Op1,
if (isLeftShift) if (isLeftShift)
C = ConstantExpr::getShl(C, ShiftAmt1C); C = ConstantExpr::getShl(C, ShiftAmt1C);
else else
C = ConstantExpr::getShr(C, ShiftAmt1C); // must be an unsigned shr. C = ConstantExpr::getUShr(C, ShiftAmt1C);
Value *Op = ShiftOp->getOperand(0); Value *Op = ShiftOp->getOperand(0);
if (isShiftOfSignedShift != isSignedShift) if (isShiftOfSignedShift != isSignedShift)
@ -3715,17 +3715,43 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantUInt *Op1,
InsertNewInstBefore(Mask, I); InsertNewInstBefore(Mask, I);
// Figure out what flavor of shift we should use... // Figure out what flavor of shift we should use...
if (ShiftAmt1 == ShiftAmt2) if (ShiftAmt1 == ShiftAmt2) {
return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
else if (ShiftAmt1 < ShiftAmt2) { } else if (ShiftAmt1 < ShiftAmt2) {
return new ShiftInst(I.getOpcode(), Mask, return new ShiftInst(I.getOpcode(), Mask,
ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1)); ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
} else { } else if (isShiftOfUnsignedShift || isShiftOfLeftShift) {
return new ShiftInst(ShiftOp->getOpcode(), Mask, if (isShiftOfUnsignedShift && !isShiftOfLeftShift && isSignedShift) {
// Make sure to emit an unsigned shift right, not a signed one.
Mask = InsertNewInstBefore(new CastInst(Mask,
Mask->getType()->getUnsignedVersion(),
Op->getName()), I);
Mask = new ShiftInst(Instruction::Shr, Mask,
ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2)); ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
InsertNewInstBefore(Mask, I);
return new CastInst(Mask, I.getType());
} else {
return new ShiftInst(ShiftOp->getOpcode(), Mask,
ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
}
} else {
// (X >>s C1) << C2 where C1 > C2 === (X >>s (C1-C2)) & mask
Op = InsertNewInstBefore(new CastInst(Mask,
I.getType()->getSignedVersion(),
Mask->getName()), I);
Instruction *Shift =
new ShiftInst(ShiftOp->getOpcode(), Op,
ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
InsertNewInstBefore(Shift, I);
C = ConstantIntegral::getAllOnesValue(Shift->getType());
C = ConstantExpr::getShl(C, Op1);
Mask = BinaryOperator::createAnd(Shift, C, Op->getName()+".mask");
InsertNewInstBefore(Mask, I);
return new CastInst(Mask, I.getType());
} }
} else { } else {
// We can handle signed (X << C1) >> C2 if it's a sign extend. In // We can handle signed (X << C1) >>s C2 if it's a sign extend. In
// this case, C1 == C2 and C1 is 8, 16, or 32. // this case, C1 == C2 and C1 is 8, 16, or 32.
if (ShiftAmt1 == ShiftAmt2) { if (ShiftAmt1 == ShiftAmt2) {
const Type *SExtType = 0; const Type *SExtType = 0;