+// Check if all users of this node will become isel where the second operand
+// is the constant zero. If this is so, and if we can negate the condition,
+// then we can flip the true and false operands. This will allow the zero to
+// be folded with the isel so that we don't need to materialize a register
+// containing zero.
+bool PPCDAGToDAGISel::AllUsersSelectZero(SDNode *N) {
+ // If we're not using isel, then this does not matter.
+ if (!PPCSubTarget.hasISEL())
+ return false;
+
+ for (SDNode::use_iterator UI = N->use_begin(), UE = N->use_end();
+ UI != UE; ++UI) {
+ SDNode *User = *UI;
+ if (!User->isMachineOpcode())
+ return false;
+ if (User->getMachineOpcode() != PPC::SELECT_I4 &&
+ User->getMachineOpcode() != PPC::SELECT_I8)
+ return false;
+
+ SDNode *Op2 = User->getOperand(2).getNode();
+ if (!Op2->isMachineOpcode())
+ return false;
+
+ if (Op2->getMachineOpcode() != PPC::LI &&
+ Op2->getMachineOpcode() != PPC::LI8)
+ return false;
+
+ ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op2->getOperand(0));
+ if (!C)
+ return false;
+
+ if (!C->isNullValue())
+ return false;
+ }
+
+ return true;
+}
+
+void PPCDAGToDAGISel::SwapAllSelectUsers(SDNode *N) {
+ SmallVector<SDNode *, 4> ToReplace;
+ for (SDNode::use_iterator UI = N->use_begin(), UE = N->use_end();
+ UI != UE; ++UI) {
+ SDNode *User = *UI;
+ assert((User->getMachineOpcode() == PPC::SELECT_I4 ||
+ User->getMachineOpcode() == PPC::SELECT_I8) &&
+ "Must have all select users");
+ ToReplace.push_back(User);
+ }
+
+ for (SmallVector<SDNode *, 4>::iterator UI = ToReplace.begin(),
+ UE = ToReplace.end(); UI != UE; ++UI) {
+ SDNode *User = *UI;
+ SDNode *ResNode =
+ CurDAG->getMachineNode(User->getMachineOpcode(), SDLoc(User),
+ User->getValueType(0), User->getOperand(0),
+ User->getOperand(2),
+ User->getOperand(1));
+
+ DEBUG(dbgs() << "CR Peephole replacing:\nOld: ");
+ DEBUG(User->dump(CurDAG));
+ DEBUG(dbgs() << "\nNew: ");
+ DEBUG(ResNode->dump(CurDAG));
+ DEBUG(dbgs() << "\n");
+
+ ReplaceUses(User, ResNode);
+ }
+}
+