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[TargetLowering] fix formatting and comments for ShrinkDemandedConstant; NFC

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llvm-svn: 294325
This commit is contained in:
Sanjay Patel 2017-02-07 18:04:26 +00:00
parent 325b448b53
commit 5128bb8442
1 changed files with 21 additions and 20 deletions
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41
lib/CodeGen/SelectionDAG/TargetLowering.cpp
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@ -334,34 +334,35 @@ TargetLowering::isOffsetFoldingLegal(const GlobalAddressSDNode *GA) const {
// Optimization Methods
//===----------------------------------------------------------------------===//
/// Check to see if the specified operand of the specified instruction is a
/// constant integer. If so, check to see if there are any bits set in the
/// constant that are not demanded. If so, shrink the constant and return true.
bool TargetLowering::TargetLoweringOpt::ShrinkDemandedConstant(SDValue Op,
const APInt &Demanded) {
SDLoc dl(Op);
/// If the specified instruction has a constant integer operand and there are
/// bits set in that constant that are not demanded, then clear those bits and
/// return true.
bool TargetLowering::TargetLoweringOpt::ShrinkDemandedConstant(
SDValue Op, const APInt &Demanded) {
SDLoc DL(Op);
unsigned Opcode = Op.getOpcode();
// FIXME: ISD::SELECT, ISD::SELECT_CC
switch (Op.getOpcode()) {
default: break;
switch (Opcode) {
default:
break;
case ISD::XOR:
case ISD::AND:
case ISD::OR: {
ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op.getOperand(1));
if (!C) return false;
if (Op.getOpcode() == ISD::XOR &&
(C->getAPIntValue() | (~Demanded)).isAllOnesValue())
auto *Op1C = dyn_cast<ConstantSDNode>(Op.getOperand(1));
if (!Op1C)
return false;
// if we can expand it to have all bits set, do it
if (C->getAPIntValue().intersects(~Demanded)) {
// If this is a 'not' op, don't touch it because that's a canonical form.
const APInt &C = Op1C->getAPIntValue();
if (Opcode == ISD::XOR && (C | ~Demanded).isAllOnesValue())
return false;
if (C.intersects(~Demanded)) {
EVT VT = Op.getValueType();
SDValue New = DAG.getNode(Op.getOpcode(), dl, VT, Op.getOperand(0),
DAG.getConstant(Demanded &
C->getAPIntValue(),
dl, VT));
return CombineTo(Op, New);
SDValue NewC = DAG.getConstant(Demanded & C, DL, VT);
SDValue NewOp = DAG.getNode(Opcode, DL, VT, Op.getOperand(0), NewC);
return CombineTo(Op, NewOp);
}
break;