SelectionDAG &DAG = DCI.DAG;
switch (N->getOpcode()) {
default: break;
+ case PPCISD::SHL:
+ if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(N->getOperand(0))) {
+ if (C->getValue() == 0) // 0 << V -> 0.
+ return N->getOperand(0);
+ }
+ break;
+ case PPCISD::SRL:
+ if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(N->getOperand(0))) {
+ if (C->getValue() == 0) // 0 >>u V -> 0.
+ return N->getOperand(0);
+ }
+ break;
+ case PPCISD::SRA:
+ if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(N->getOperand(0))) {
+ if (C->getValue() == 0 || // 0 >>s V -> 0.
+ C->isAllOnesValue()) // -1 >>s V -> -1.
+ return N->getOperand(0);
+ }
+ break;
+
case ISD::SINT_TO_FP:
if (TM.getSubtarget<PPCSubtarget>().has64BitSupport()) {
if (N->getOperand(0).getOpcode() == ISD::FP_TO_SINT) {