Minimal lowering for formal_arguments / ret

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75911 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/SystemZ/SystemZISelLowering.cpp

@@ -48,10 +48,15 @@ SystemZTargetLowering::SystemZTargetLowering(SystemZTargetMachine &tm) :
 
   setStackPointerRegisterToSaveRestore(SystemZ::R15);
   setSchedulingPreference(SchedulingForLatency);
+
+  setOperationAction(ISD::RET,              MVT::Other, Custom);
+
 }
 
 SDValue SystemZTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) {
   switch (Op.getOpcode()) {
+  case ISD::FORMAL_ARGUMENTS: return LowerFORMAL_ARGUMENTS(Op, DAG);
+  case ISD::RET:              return LowerRET(Op, DAG);
   default:
     assert(0 && "unimplemented operand");
     return SDValue();
@@ -64,8 +69,150 @@ SDValue SystemZTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) {
 
 #include "SystemZGenCallingConv.inc"
 
+SDValue SystemZTargetLowering::LowerFORMAL_ARGUMENTS(SDValue Op,
+                                                     SelectionDAG &DAG) {
+  unsigned CC = cast<ConstantSDNode>(Op.getOperand(1))->getZExtValue();
+  switch (CC) {
+  default:
+    assert(0 && "Unsupported calling convention");
+  case CallingConv::C:
+  case CallingConv::Fast:
+    return LowerCCCArguments(Op, DAG);
+  }
+}
+
+/// LowerCCCArguments - transform physical registers into virtual registers and
+/// generate load operations for arguments places on the stack.
+// FIXME: struct return stuff
+// FIXME: varargs
+SDValue SystemZTargetLowering::LowerCCCArguments(SDValue Op,
+                                                 SelectionDAG &DAG) {
+  MachineFunction &MF = DAG.getMachineFunction();
+  MachineFrameInfo *MFI = MF.getFrameInfo();
+  MachineRegisterInfo &RegInfo = MF.getRegInfo();
+  SDValue Root = Op.getOperand(0);
+  bool isVarArg = cast<ConstantSDNode>(Op.getOperand(2))->getZExtValue() != 0;
+  unsigned CC = MF.getFunction()->getCallingConv();
+  DebugLoc dl = Op.getDebugLoc();
+
+  // Assign locations to all of the incoming arguments.
+  SmallVector<CCValAssign, 16> ArgLocs;
+  CCState CCInfo(CC, isVarArg, getTargetMachine(), ArgLocs);
+  CCInfo.AnalyzeFormalArguments(Op.getNode(), CC_SystemZ);
+
+  assert(!isVarArg && "Varargs not supported yet");
+
+  SmallVector<SDValue, 16> ArgValues;
+  for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
+    CCValAssign &VA = ArgLocs[i];
+    if (VA.isRegLoc()) {
+      // Arguments passed in registers
+      MVT RegVT = VA.getLocVT();
+      switch (RegVT.getSimpleVT()) {
+      default:
+        cerr << "LowerFORMAL_ARGUMENTS Unhandled argument type: "
+             << RegVT.getSimpleVT()
+             << "\n";
+        abort();
+      case MVT::i64:
+        unsigned VReg =
+          RegInfo.createVirtualRegister(SystemZ::GR64RegisterClass);
+        RegInfo.addLiveIn(VA.getLocReg(), VReg);
+        SDValue ArgValue = DAG.getCopyFromReg(Root, dl, VReg, RegVT);
+
+        // If this is an 8/16/32-bit value, it is really passed promoted to 64
+        // bits. Insert an assert[sz]ext to capture this, then truncate to the
+        // right size.
+        if (VA.getLocInfo() == CCValAssign::SExt)
+          ArgValue = DAG.getNode(ISD::AssertSext, dl, RegVT, ArgValue,
+                                 DAG.getValueType(VA.getValVT()));
+        else if (VA.getLocInfo() == CCValAssign::ZExt)
+          ArgValue = DAG.getNode(ISD::AssertZext, dl, RegVT, ArgValue,
+                                 DAG.getValueType(VA.getValVT()));
+
+        if (VA.getLocInfo() != CCValAssign::Full)
+          ArgValue = DAG.getNode(ISD::TRUNCATE, dl, VA.getValVT(), ArgValue);
+
+        ArgValues.push_back(ArgValue);
+      }
+    } else {
+      // Sanity check
+      assert(VA.isMemLoc());
+      // Load the argument to a virtual register
+      unsigned ObjSize = VA.getLocVT().getSizeInBits()/8;
+      if (ObjSize > 8) {
+        cerr << "LowerFORMAL_ARGUMENTS Unhandled argument type: "
+             << VA.getLocVT().getSimpleVT()
+             << "\n";
+      }
+      // Create the frame index object for this incoming parameter...
+      int FI = MFI->CreateFixedObject(ObjSize, VA.getLocMemOffset());
+
+      // Create the SelectionDAG nodes corresponding to a load
+      //from this parameter
+      SDValue FIN = DAG.getFrameIndex(FI, MVT::i64);
+      ArgValues.push_back(DAG.getLoad(VA.getLocVT(), dl, Root, FIN,
+                                      PseudoSourceValue::getFixedStack(FI), 0));
+    }
+  }
+
+  ArgValues.push_back(Root);
+
+  // Return the new list of results.
+  return DAG.getNode(ISD::MERGE_VALUES, dl, Op.getNode()->getVTList(),
+                     &ArgValues[0], ArgValues.size()).getValue(Op.getResNo());
+}
+
+SDValue SystemZTargetLowering::LowerRET(SDValue Op, SelectionDAG &DAG) {
+  // CCValAssign - represent the assignment of the return value to a location
+  SmallVector<CCValAssign, 16> RVLocs;
+  unsigned CC   = DAG.getMachineFunction().getFunction()->getCallingConv();
+  bool isVarArg = DAG.getMachineFunction().getFunction()->isVarArg();
+  DebugLoc dl = Op.getDebugLoc();
+
+  // CCState - Info about the registers and stack slot.
+  CCState CCInfo(CC, isVarArg, getTargetMachine(), RVLocs);
+
+  // Analize return values of ISD::RET
+  CCInfo.AnalyzeReturn(Op.getNode(), RetCC_SystemZ);
+
+  // If this is the first return lowered for this function, add the regs to the
+  // liveout set for the function.
+  if (DAG.getMachineFunction().getRegInfo().liveout_empty()) {
+    for (unsigned i = 0; i != RVLocs.size(); ++i)
+      if (RVLocs[i].isRegLoc())
+        DAG.getMachineFunction().getRegInfo().addLiveOut(RVLocs[i].getLocReg());
+  }
+
+  // The chain is always operand #0
+  SDValue Chain = Op.getOperand(0);
+  SDValue Flag;
+
+  // Copy the result values into the output registers.
+  for (unsigned i = 0; i != RVLocs.size(); ++i) {
+    CCValAssign &VA = RVLocs[i];
+    assert(VA.isRegLoc() && "Can only return in registers!");
+
+    // ISD::RET => ret chain, (regnum1,val1), ...
+    // So i*2+1 index only the regnums
+    Chain = DAG.getCopyToReg(Chain, dl, VA.getLocReg(),
+                             Op.getOperand(i*2+1), Flag);
+
+    // Guarantee that all emitted copies are stuck together,
+    // avoiding something bad.
+    Flag = Chain.getValue(1);
+  }
+
+  if (Flag.getNode())
+    return DAG.getNode(SystemZISD::RET_FLAG, dl, MVT::Other, Chain, Flag);
+
+  // Return Void
+  return DAG.getNode(SystemZISD::RET_FLAG, dl, MVT::Other, Chain);
+}
+
 const char *SystemZTargetLowering::getTargetNodeName(unsigned Opcode) const {
   switch (Opcode) {
+  case SystemZISD::RET_FLAG:           return "SystemZISD::RET_FLAG";
   default: return NULL;
   }
 }

lib/Target/SystemZ/SystemZISelLowering.h

@@ -22,7 +22,10 @@
 namespace llvm {
   namespace SystemZISD {
     enum {
-      FIRST_NUMBER = ISD::BUILTIN_OP_END
+      FIRST_NUMBER = ISD::BUILTIN_OP_END,
+
+      /// Return with a flag operand. Operand 0 is the chain operand.
+      RET_FLAG
     };
   }
 
@@ -40,6 +43,14 @@ namespace llvm {
     /// DAG node.
     virtual const char *getTargetNodeName(unsigned Opcode) const;
 
+    SDValue LowerFORMAL_ARGUMENTS(SDValue Op, SelectionDAG &DAG);
+    SDValue LowerRET(SDValue Op, SelectionDAG &DAG);
+    SDValue LowerCCCArguments(SDValue Op, SelectionDAG &DAG);
+
+    SDNode* LowerCallResult(SDValue Chain, SDValue InFlag,
+                            CallSDNode *TheCall,
+                            unsigned CallingConv, SelectionDAG &DAG);
+
   private:
     const SystemZSubtarget &Subtarget;
     const SystemZTargetMachine &TM;

lib/Target/SystemZ/SystemZInstrInfo.td

@@ -13,5 +13,20 @@
 
 include "SystemZInstrFormats.td"
 
+//===----------------------------------------------------------------------===//
+// SystemZ Specific Node Definitions.
+//===----------------------------------------------------------------------===//
+def SystemZretflag : SDNode<"SystemZISD::RET_FLAG", SDTNone,
+                     [SDNPHasChain, SDNPOptInFlag]>;
+
 let neverHasSideEffects = 1 in
 def NOP : Pseudo<(outs), (ins), "# no-op", []>;
+
+//===----------------------------------------------------------------------===//
+//  Control Flow Instructions...
+//
+
+// FIXME: Provide proper encoding!
+let isReturn = 1, isTerminator = 1 in {
+  def RET : Pseudo<(outs), (ins), "br\t%r14", [(SystemZretflag)]>;
+}

test/CodeGen/SystemZ/00-RetVoid.ll

@@ -0,0 +1,6 @@
+; RUN: llvm-as < %s | llc -march=systemz
+
+define void @foo() {
+entry:
+    ret void
+}