Add first draft of MSP430 calling convention stuff and draft of ISD::FORMAL_ARGUMENTS node lowering.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70702 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/MSP430/MSP430.td

@@ -36,6 +36,12 @@ def : Proc<"generic",         []>;
 
 include "MSP430RegisterInfo.td"
 
+//===----------------------------------------------------------------------===//
+// Calling Convention Description
+//===----------------------------------------------------------------------===//
+
+include "MSP430CallingConv.td"
+
 //===----------------------------------------------------------------------===//
 // Instruction Descriptions
 //===----------------------------------------------------------------------===//

lib/Target/MSP430/MSP430CallingConv.td

@@ -0,0 +1,34 @@
+//==- MSP430CallingConv.td - Calling Conventions for MSP430 -*- tablegen -*-==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// This describes the calling conventions for MSP430 architecture.
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+// MSP430 Return Value Calling Convention
+//===----------------------------------------------------------------------===//
+def RetCC_MSP430 : CallingConv<[
+  // i16 are returned in registers R15, R14, R13, R12
+  CCIfType<[i16], CCAssignToReg<[R15, R14, R13, R12]>>
+]>;
+
+//===----------------------------------------------------------------------===//
+// MSP430 Argument Calling Conventions
+//===----------------------------------------------------------------------===//
+def CC_MSP430 : CallingConv<[
+  // Promote i8 arguments to i16.
+  CCIfType<[i8], CCPromoteToType<i16>>,
+
+  // The first 4 integer arguments of non-varargs functions are passed in
+  // integer registers.
+  CCIfNotVarArg<CCIfType<[i16], CCAssignToReg<[R15, R14, R13, R12]>>>,
+
+  // Integer values get stored in stack slots that are 2 bytes in
+  // size and 2-byte aligned.
+  CCIfType<[i16], CCAssignToStack<2, 2>>
+]>;

lib/Target/MSP430/MSP430ISelLowering.cpp

@@ -28,6 +28,7 @@
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/PseudoSourceValue.h"
 #include "llvm/CodeGen/SelectionDAGISel.h"
 #include "llvm/CodeGen/ValueTypes.h"
 #include "llvm/Support/Debug.h"
@@ -47,10 +48,109 @@ MSP430TargetLowering::MSP430TargetLowering(MSP430TargetMachine &tm) :
 SDValue MSP430TargetLowering::
 LowerOperation(SDValue Op, SelectionDAG &DAG) {
   switch (Op.getOpcode()) {
+  case ISD::FORMAL_ARGUMENTS: return LowerFORMAL_ARGUMENTS(Op, DAG);
   default:
     assert(0 && "unimplemented operand");
     return SDValue();
   }
 }
 
+//===----------------------------------------------------------------------===//
+//                      Calling Convention Implementation
+//===----------------------------------------------------------------------===//
+
 #include "MSP430GenCallingConv.inc"
+
+SDValue MSP430TargetLowering::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 MSP430TargetLowering:: 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_MSP430);
+
+  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::i16:
+        unsigned VReg =
+          RegInfo.createVirtualRegister(MSP430::MSP430RegsRegisterClass);
+        RegInfo.addLiveIn(VA.getLocReg(), VReg);
+        SDValue ArgValue = DAG.getCopyFromReg(Root, dl, VReg, RegVT);
+
+        // If this is an 8-bit value, it is really passed promoted to 16
+        // 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 > 2) {
+        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::i16);
+      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());
+}

lib/Target/MSP430/MSP430ISelLowering.h

@@ -30,6 +30,8 @@ namespace llvm {
 
     /// LowerOperation - Provide custom lowering hooks for some operations.
     virtual SDValue LowerOperation(SDValue Op, SelectionDAG &DAG);
+    SDValue LowerFORMAL_ARGUMENTS(SDValue Op, SelectionDAG &DAG);
+    SDValue LowerCCCArguments(SDValue Op, SelectionDAG &DAG);
 
   private:
     const MSP430Subtarget &Subtarget;