SELECT_CC lowering
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75948 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/SystemZ/SystemZISelLowering.cpp b/lib/Target/SystemZ/SystemZISelLowering.cpp
index 448f521..6860420 100644
--- a/lib/Target/SystemZ/SystemZISelLowering.cpp
+++ b/lib/Target/SystemZ/SystemZISelLowering.cpp
@@ -61,6 +61,14 @@
setOperationAction(ISD::BRCOND, MVT::Other, Expand);
setOperationAction(ISD::BR_CC, MVT::i32, Custom);
setOperationAction(ISD::BR_CC, MVT::i64, Custom);
+
+ // FIXME: Can we lower these 2 efficiently?
+ setOperationAction(ISD::SETCC, MVT::i32, Expand);
+ setOperationAction(ISD::SETCC, MVT::i64, Expand);
+ setOperationAction(ISD::SELECT, MVT::i32, Expand);
+ setOperationAction(ISD::SELECT, MVT::i64, Expand);
+ setOperationAction(ISD::SELECT_CC, MVT::i32, Custom);
+ setOperationAction(ISD::SELECT_CC, MVT::i64, Custom);
}
SDValue SystemZTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) {
@@ -69,6 +77,7 @@
case ISD::RET: return LowerRET(Op, DAG);
case ISD::CALL: return LowerCALL(Op, DAG);
case ISD::BR_CC: return LowerBR_CC(Op, DAG);
+ case ISD::SELECT_CC: return LowerSELECT_CC(Op, DAG);
default:
assert(0 && "unimplemented operand");
return SDValue();
@@ -472,6 +481,27 @@
Chain, Dest, SystemZCC, Flag);
}
+SDValue SystemZTargetLowering::LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) {
+ SDValue LHS = Op.getOperand(0);
+ SDValue RHS = Op.getOperand(1);
+ SDValue TrueV = Op.getOperand(2);
+ SDValue FalseV = Op.getOperand(3);
+ ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(4))->get();
+ DebugLoc dl = Op.getDebugLoc();
+
+ SDValue SystemZCC;
+ SDValue Flag = EmitCmp(LHS, RHS, CC, SystemZCC, DAG);
+
+ SDVTList VTs = DAG.getVTList(Op.getValueType(), MVT::Flag);
+ SmallVector<SDValue, 4> Ops;
+ Ops.push_back(TrueV);
+ Ops.push_back(FalseV);
+ Ops.push_back(SystemZCC);
+ Ops.push_back(Flag);
+
+ return DAG.getNode(SystemZISD::SELECT, dl, VTs, &Ops[0], Ops.size());
+}
+
const char *SystemZTargetLowering::getTargetNodeName(unsigned Opcode) const {
switch (Opcode) {
@@ -480,7 +510,70 @@
case SystemZISD::BRCOND: return "SystemZISD::BRCOND";
case SystemZISD::CMP: return "SystemZISD::CMP";
case SystemZISD::UCMP: return "SystemZISD::UCMP";
+ case SystemZISD::SELECT: return "SystemZISD::SELECT";
default: return NULL;
}
}
+//===----------------------------------------------------------------------===//
+// Other Lowering Code
+//===----------------------------------------------------------------------===//
+
+MachineBasicBlock*
+SystemZTargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
+ MachineBasicBlock *BB) const {
+ const SystemZInstrInfo &TII = *TM.getInstrInfo();
+ DebugLoc dl = MI->getDebugLoc();
+ assert((MI->getOpcode() == SystemZ::Select32 ||
+ MI->getOpcode() == SystemZ::Select64) &&
+ "Unexpected instr type to insert");
+
+ // To "insert" a SELECT instruction, we actually have to insert the diamond
+ // control-flow pattern. The incoming instruction knows the destination vreg
+ // to set, the condition code register to branch on, the true/false values to
+ // select between, and a branch opcode to use.
+ const BasicBlock *LLVM_BB = BB->getBasicBlock();
+ MachineFunction::iterator I = BB;
+ ++I;
+
+ // thisMBB:
+ // ...
+ // TrueVal = ...
+ // cmpTY ccX, r1, r2
+ // jCC copy1MBB
+ // fallthrough --> copy0MBB
+ MachineBasicBlock *thisMBB = BB;
+ MachineFunction *F = BB->getParent();
+ MachineBasicBlock *copy0MBB = F->CreateMachineBasicBlock(LLVM_BB);
+ MachineBasicBlock *copy1MBB = F->CreateMachineBasicBlock(LLVM_BB);
+ SystemZCC::CondCodes CC = (SystemZCC::CondCodes)MI->getOperand(3).getImm();
+ BuildMI(BB, dl, TII.getBrCond(CC)).addMBB(copy1MBB);
+ F->insert(I, copy0MBB);
+ F->insert(I, copy1MBB);
+ // Update machine-CFG edges by transferring all successors of the current
+ // block to the new block which will contain the Phi node for the select.
+ copy1MBB->transferSuccessors(BB);
+ // Next, add the true and fallthrough blocks as its successors.
+ BB->addSuccessor(copy0MBB);
+ BB->addSuccessor(copy1MBB);
+
+ // copy0MBB:
+ // %FalseValue = ...
+ // # fallthrough to copy1MBB
+ BB = copy0MBB;
+
+ // Update machine-CFG edges
+ BB->addSuccessor(copy1MBB);
+
+ // copy1MBB:
+ // %Result = phi [ %FalseValue, copy0MBB ], [ %TrueValue, thisMBB ]
+ // ...
+ BB = copy1MBB;
+ BuildMI(BB, dl, TII.get(SystemZ::PHI),
+ MI->getOperand(0).getReg())
+ .addReg(MI->getOperand(2).getReg()).addMBB(copy0MBB)
+ .addReg(MI->getOperand(1).getReg()).addMBB(thisMBB);
+
+ F->DeleteMachineInstr(MI); // The pseudo instruction is gone now.
+ return BB;
+}