MSP430ISelLowering.cpp revision c23197a26f34f559ea9797de51e187087c039c42 
1//===-- MSP430ISelLowering.cpp - MSP430 DAG Lowering Implementation  ------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements the MSP430TargetLowering class.
11//
12//===----------------------------------------------------------------------===//
13
14#define DEBUG_TYPE "msp430-lower"
15
16#include "MSP430ISelLowering.h"
17#include "MSP430.h"
18#include "MSP430TargetMachine.h"
19#include "MSP430Subtarget.h"
20#include "llvm/DerivedTypes.h"
21#include "llvm/Function.h"
22#include "llvm/Intrinsics.h"
23#include "llvm/CallingConv.h"
24#include "llvm/GlobalVariable.h"
25#include "llvm/GlobalAlias.h"
26#include "llvm/CodeGen/CallingConvLower.h"
27#include "llvm/CodeGen/MachineFrameInfo.h"
28#include "llvm/CodeGen/MachineFunction.h"
29#include "llvm/CodeGen/MachineInstrBuilder.h"
30#include "llvm/CodeGen/MachineRegisterInfo.h"
31#include "llvm/CodeGen/PseudoSourceValue.h"
32#include "llvm/CodeGen/SelectionDAGISel.h"
33#include "llvm/CodeGen/ValueTypes.h"
34#include "llvm/Support/Debug.h"
35#include "llvm/Support/ErrorHandling.h"
36#include "llvm/ADT/VectorExtras.h"
37using namespace llvm;
38
39MSP430TargetLowering::MSP430TargetLowering(MSP430TargetMachine &tm) :
40  TargetLowering(tm), Subtarget(*tm.getSubtargetImpl()), TM(tm) {
41
42  // Set up the register classes.
43  addRegisterClass(MVT::i8,  MSP430::GR8RegisterClass);
44  addRegisterClass(MVT::i16, MSP430::GR16RegisterClass);
45
46  // Compute derived properties from the register classes
47  computeRegisterProperties();
48
49  // Provide all sorts of operation actions
50
51  // Division is expensive
52  setIntDivIsCheap(false);
53
54  // Even if we have only 1 bit shift here, we can perform
55  // shifts of the whole bitwidth 1 bit per step.
56  setShiftAmountType(MVT::i8);
57
58  setStackPointerRegisterToSaveRestore(MSP430::SPW);
59  setBooleanContents(ZeroOrOneBooleanContent);
60  setSchedulingPreference(SchedulingForLatency);
61
62  setLoadExtAction(ISD::EXTLOAD,  MVT::i1, Promote);
63  setLoadExtAction(ISD::SEXTLOAD, MVT::i1, Promote);
64  setLoadExtAction(ISD::ZEXTLOAD, MVT::i1, Promote);
65  setLoadExtAction(ISD::SEXTLOAD, MVT::i8, Expand);
66  setLoadExtAction(ISD::SEXTLOAD, MVT::i16, Expand);
67
68  // We don't have any truncstores
69  setTruncStoreAction(MVT::i16, MVT::i8, Expand);
70
71  setOperationAction(ISD::SRA,              MVT::i8,    Custom);
72  setOperationAction(ISD::SHL,              MVT::i8,    Custom);
73  setOperationAction(ISD::SRL,              MVT::i8,    Custom);
74  setOperationAction(ISD::SRA,              MVT::i16,   Custom);
75  setOperationAction(ISD::SHL,              MVT::i16,   Custom);
76  setOperationAction(ISD::SRL,              MVT::i16,   Custom);
77  setOperationAction(ISD::ROTL,             MVT::i8,    Expand);
78  setOperationAction(ISD::ROTR,             MVT::i8,    Expand);
79  setOperationAction(ISD::ROTL,             MVT::i16,   Expand);
80  setOperationAction(ISD::ROTR,             MVT::i16,   Expand);
81  setOperationAction(ISD::RET,              MVT::Other, Custom);
82  setOperationAction(ISD::GlobalAddress,    MVT::i16,   Custom);
83  setOperationAction(ISD::ExternalSymbol,   MVT::i16,   Custom);
84  setOperationAction(ISD::BR_JT,            MVT::Other, Expand);
85  setOperationAction(ISD::BRIND,            MVT::Other, Expand);
86  setOperationAction(ISD::BR_CC,            MVT::i8,    Custom);
87  setOperationAction(ISD::BR_CC,            MVT::i16,   Custom);
88  setOperationAction(ISD::BRCOND,           MVT::Other, Expand);
89  setOperationAction(ISD::SETCC,            MVT::i8,    Expand);
90  setOperationAction(ISD::SETCC,            MVT::i16,   Expand);
91  setOperationAction(ISD::SELECT,           MVT::i8,    Expand);
92  setOperationAction(ISD::SELECT,           MVT::i16,   Expand);
93  setOperationAction(ISD::SELECT_CC,        MVT::i8,    Custom);
94  setOperationAction(ISD::SELECT_CC,        MVT::i16,   Custom);
95  setOperationAction(ISD::SIGN_EXTEND,      MVT::i16,   Custom);
96
97  // FIXME: Implement efficiently multiplication by a constant
98  setOperationAction(ISD::MUL,              MVT::i16,   Expand);
99  setOperationAction(ISD::MULHS,            MVT::i16,   Expand);
100  setOperationAction(ISD::MULHU,            MVT::i16,   Expand);
101  setOperationAction(ISD::SMUL_LOHI,        MVT::i16,   Expand);
102  setOperationAction(ISD::UMUL_LOHI,        MVT::i16,   Expand);
103
104  setOperationAction(ISD::UDIV,             MVT::i16,   Expand);
105  setOperationAction(ISD::UDIVREM,          MVT::i16,   Expand);
106  setOperationAction(ISD::UREM,             MVT::i16,   Expand);
107  setOperationAction(ISD::SDIV,             MVT::i16,   Expand);
108  setOperationAction(ISD::SDIVREM,          MVT::i16,   Expand);
109  setOperationAction(ISD::SREM,             MVT::i16,   Expand);
110}
111
112SDValue MSP430TargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) {
113  switch (Op.getOpcode()) {
114  case ISD::FORMAL_ARGUMENTS: return LowerFORMAL_ARGUMENTS(Op, DAG);
115  case ISD::SHL: // FALLTHROUGH
116  case ISD::SRL:
117  case ISD::SRA:              return LowerShifts(Op, DAG);
118  case ISD::RET:              return LowerRET(Op, DAG);
119  case ISD::CALL:             return LowerCALL(Op, DAG);
120  case ISD::GlobalAddress:    return LowerGlobalAddress(Op, DAG);
121  case ISD::ExternalSymbol:   return LowerExternalSymbol(Op, DAG);
122  case ISD::BR_CC:            return LowerBR_CC(Op, DAG);
123  case ISD::SELECT_CC:        return LowerSELECT_CC(Op, DAG);
124  case ISD::SIGN_EXTEND:      return LowerSIGN_EXTEND(Op, DAG);
125  default:
126    llvm_unreachable("unimplemented operand");
127    return SDValue();
128  }
129}
130
131/// getFunctionAlignment - Return the Log2 alignment of this function.
132unsigned MSP430TargetLowering::getFunctionAlignment(const Function *F) const {
133  return F->hasFnAttr(Attribute::OptimizeForSize) ? 1 : 4;
134}
135
136//===----------------------------------------------------------------------===//
137//                      Calling Convention Implementation
138//===----------------------------------------------------------------------===//
139
140#include "MSP430GenCallingConv.inc"
141
142SDValue MSP430TargetLowering::LowerFORMAL_ARGUMENTS(SDValue Op,
143                                                    SelectionDAG &DAG) {
144  unsigned CC = cast<ConstantSDNode>(Op.getOperand(1))->getZExtValue();
145  switch (CC) {
146  default:
147    llvm_unreachable("Unsupported calling convention");
148  case CallingConv::C:
149  case CallingConv::Fast:
150    return LowerCCCArguments(Op, DAG);
151  }
152}
153
154SDValue MSP430TargetLowering::LowerCALL(SDValue Op, SelectionDAG &DAG) {
155  CallSDNode *TheCall = cast<CallSDNode>(Op.getNode());
156  unsigned CallingConv = TheCall->getCallingConv();
157  switch (CallingConv) {
158  default:
159    llvm_unreachable("Unsupported calling convention");
160  case CallingConv::Fast:
161  case CallingConv::C:
162    return LowerCCCCallTo(Op, DAG, CallingConv);
163  }
164}
165
166/// LowerCCCArguments - transform physical registers into virtual registers and
167/// generate load operations for arguments places on the stack.
168// FIXME: struct return stuff
169// FIXME: varargs
170SDValue MSP430TargetLowering::LowerCCCArguments(SDValue Op,
171                                                SelectionDAG &DAG) {
172  MachineFunction &MF = DAG.getMachineFunction();
173  MachineFrameInfo *MFI = MF.getFrameInfo();
174  MachineRegisterInfo &RegInfo = MF.getRegInfo();
175  SDValue Root = Op.getOperand(0);
176  bool isVarArg = cast<ConstantSDNode>(Op.getOperand(2))->getZExtValue() != 0;
177  unsigned CC = MF.getFunction()->getCallingConv();
178  DebugLoc dl = Op.getDebugLoc();
179
180  // Assign locations to all of the incoming arguments.
181  SmallVector<CCValAssign, 16> ArgLocs;
182  CCState CCInfo(CC, isVarArg, getTargetMachine(), ArgLocs, DAG.getContext());
183  CCInfo.AnalyzeFormalArguments(Op.getNode(), CC_MSP430);
184
185  assert(!isVarArg && "Varargs not supported yet");
186
187  SmallVector<SDValue, 16> ArgValues;
188  for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
189    CCValAssign &VA = ArgLocs[i];
190    if (VA.isRegLoc()) {
191      // Arguments passed in registers
192      MVT RegVT = VA.getLocVT();
193      switch (RegVT.getSimpleVT()) {
194      default:
195        {
196#ifndef NDEBUG
197          cerr << "LowerFORMAL_ARGUMENTS Unhandled argument type: "
198               << RegVT.getSimpleVT() << "\n";
199#endif
200          llvm_unreachable(0);
201        }
202      case MVT::i16:
203        unsigned VReg =
204          RegInfo.createVirtualRegister(MSP430::GR16RegisterClass);
205        RegInfo.addLiveIn(VA.getLocReg(), VReg);
206        SDValue ArgValue = DAG.getCopyFromReg(Root, dl, VReg, RegVT);
207
208        // If this is an 8-bit value, it is really passed promoted to 16
209        // bits. Insert an assert[sz]ext to capture this, then truncate to the
210        // right size.
211        if (VA.getLocInfo() == CCValAssign::SExt)
212          ArgValue = DAG.getNode(ISD::AssertSext, dl, RegVT, ArgValue,
213                                 DAG.getValueType(VA.getValVT()));
214        else if (VA.getLocInfo() == CCValAssign::ZExt)
215          ArgValue = DAG.getNode(ISD::AssertZext, dl, RegVT, ArgValue,
216                                 DAG.getValueType(VA.getValVT()));
217
218        if (VA.getLocInfo() != CCValAssign::Full)
219          ArgValue = DAG.getNode(ISD::TRUNCATE, dl, VA.getValVT(), ArgValue);
220
221        ArgValues.push_back(ArgValue);
222      }
223    } else {
224      // Sanity check
225      assert(VA.isMemLoc());
226      // Load the argument to a virtual register
227      unsigned ObjSize = VA.getLocVT().getSizeInBits()/8;
228      if (ObjSize > 2) {
229        cerr << "LowerFORMAL_ARGUMENTS Unhandled argument type: "
230             << VA.getLocVT().getSimpleVT()
231             << "\n";
232      }
233      // Create the frame index object for this incoming parameter...
234      int FI = MFI->CreateFixedObject(ObjSize, VA.getLocMemOffset());
235
236      // Create the SelectionDAG nodes corresponding to a load
237      //from this parameter
238      SDValue FIN = DAG.getFrameIndex(FI, MVT::i16);
239      ArgValues.push_back(DAG.getLoad(VA.getLocVT(), dl, Root, FIN,
240                                      PseudoSourceValue::getFixedStack(FI), 0));
241    }
242  }
243
244  ArgValues.push_back(Root);
245
246  // Return the new list of results.
247  return DAG.getNode(ISD::MERGE_VALUES, dl, Op.getNode()->getVTList(),
248                     &ArgValues[0], ArgValues.size()).getValue(Op.getResNo());
249}
250
251SDValue MSP430TargetLowering::LowerRET(SDValue Op, SelectionDAG &DAG) {
252  // CCValAssign - represent the assignment of the return value to a location
253  SmallVector<CCValAssign, 16> RVLocs;
254  unsigned CC   = DAG.getMachineFunction().getFunction()->getCallingConv();
255  bool isVarArg = DAG.getMachineFunction().getFunction()->isVarArg();
256  DebugLoc dl = Op.getDebugLoc();
257
258  // CCState - Info about the registers and stack slot.
259  CCState CCInfo(CC, isVarArg, getTargetMachine(), RVLocs, DAG.getContext());
260
261  // Analize return values of ISD::RET
262  CCInfo.AnalyzeReturn(Op.getNode(), RetCC_MSP430);
263
264  // If this is the first return lowered for this function, add the regs to the
265  // liveout set for the function.
266  if (DAG.getMachineFunction().getRegInfo().liveout_empty()) {
267    for (unsigned i = 0; i != RVLocs.size(); ++i)
268      if (RVLocs[i].isRegLoc())
269        DAG.getMachineFunction().getRegInfo().addLiveOut(RVLocs[i].getLocReg());
270  }
271
272  // The chain is always operand #0
273  SDValue Chain = Op.getOperand(0);
274  SDValue Flag;
275
276  // Copy the result values into the output registers.
277  for (unsigned i = 0; i != RVLocs.size(); ++i) {
278    CCValAssign &VA = RVLocs[i];
279    assert(VA.isRegLoc() && "Can only return in registers!");
280
281    // ISD::RET => ret chain, (regnum1,val1), ...
282    // So i*2+1 index only the regnums
283    Chain = DAG.getCopyToReg(Chain, dl, VA.getLocReg(),
284                             Op.getOperand(i*2+1), Flag);
285
286    // Guarantee that all emitted copies are stuck together,
287    // avoiding something bad.
288    Flag = Chain.getValue(1);
289  }
290
291  if (Flag.getNode())
292    return DAG.getNode(MSP430ISD::RET_FLAG, dl, MVT::Other, Chain, Flag);
293
294  // Return Void
295  return DAG.getNode(MSP430ISD::RET_FLAG, dl, MVT::Other, Chain);
296}
297
298/// LowerCCCCallTo - functions arguments are copied from virtual regs to
299/// (physical regs)/(stack frame), CALLSEQ_START and CALLSEQ_END are emitted.
300/// TODO: sret.
301SDValue MSP430TargetLowering::LowerCCCCallTo(SDValue Op, SelectionDAG &DAG,
302                                             unsigned CC) {
303  CallSDNode *TheCall = cast<CallSDNode>(Op.getNode());
304  SDValue Chain  = TheCall->getChain();
305  SDValue Callee = TheCall->getCallee();
306  bool isVarArg  = TheCall->isVarArg();
307  DebugLoc dl = Op.getDebugLoc();
308
309  // Analyze operands of the call, assigning locations to each operand.
310  SmallVector<CCValAssign, 16> ArgLocs;
311  CCState CCInfo(CC, isVarArg, getTargetMachine(), ArgLocs, DAG.getContext());
312
313  CCInfo.AnalyzeCallOperands(TheCall, CC_MSP430);
314
315  // Get a count of how many bytes are to be pushed on the stack.
316  unsigned NumBytes = CCInfo.getNextStackOffset();
317
318  Chain = DAG.getCALLSEQ_START(Chain ,DAG.getConstant(NumBytes,
319                                                      getPointerTy(), true));
320
321  SmallVector<std::pair<unsigned, SDValue>, 4> RegsToPass;
322  SmallVector<SDValue, 12> MemOpChains;
323  SDValue StackPtr;
324
325  // Walk the register/memloc assignments, inserting copies/loads.
326  for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
327    CCValAssign &VA = ArgLocs[i];
328
329    // Arguments start after the 5 first operands of ISD::CALL
330    SDValue Arg = TheCall->getArg(i);
331
332    // Promote the value if needed.
333    switch (VA.getLocInfo()) {
334      default: llvm_unreachable("Unknown loc info!");
335      case CCValAssign::Full: break;
336      case CCValAssign::SExt:
337        Arg = DAG.getNode(ISD::SIGN_EXTEND, dl, VA.getLocVT(), Arg);
338        break;
339      case CCValAssign::ZExt:
340        Arg = DAG.getNode(ISD::ZERO_EXTEND, dl, VA.getLocVT(), Arg);
341        break;
342      case CCValAssign::AExt:
343        Arg = DAG.getNode(ISD::ANY_EXTEND, dl, VA.getLocVT(), Arg);
344        break;
345    }
346
347    // Arguments that can be passed on register must be kept at RegsToPass
348    // vector
349    if (VA.isRegLoc()) {
350      RegsToPass.push_back(std::make_pair(VA.getLocReg(), Arg));
351    } else {
352      assert(VA.isMemLoc());
353
354      if (StackPtr.getNode() == 0)
355        StackPtr = DAG.getCopyFromReg(Chain, dl, MSP430::SPW, getPointerTy());
356
357      SDValue PtrOff = DAG.getNode(ISD::ADD, dl, getPointerTy(),
358                                   StackPtr,
359                                   DAG.getIntPtrConstant(VA.getLocMemOffset()));
360
361
362      MemOpChains.push_back(DAG.getStore(Chain, dl, Arg, PtrOff,
363                                         PseudoSourceValue::getStack(),
364                                         VA.getLocMemOffset()));
365    }
366  }
367
368  // Transform all store nodes into one single node because all store nodes are
369  // independent of each other.
370  if (!MemOpChains.empty())
371    Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
372                        &MemOpChains[0], MemOpChains.size());
373
374  // Build a sequence of copy-to-reg nodes chained together with token chain and
375  // flag operands which copy the outgoing args into registers.  The InFlag in
376  // necessary since all emited instructions must be stuck together.
377  SDValue InFlag;
378  for (unsigned i = 0, e = RegsToPass.size(); i != e; ++i) {
379    Chain = DAG.getCopyToReg(Chain, dl, RegsToPass[i].first,
380                             RegsToPass[i].second, InFlag);
381    InFlag = Chain.getValue(1);
382  }
383
384  // If the callee is a GlobalAddress node (quite common, every direct call is)
385  // turn it into a TargetGlobalAddress node so that legalize doesn't hack it.
386  // Likewise ExternalSymbol -> TargetExternalSymbol.
387  if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee))
388    Callee = DAG.getTargetGlobalAddress(G->getGlobal(), MVT::i16);
389  else if (ExternalSymbolSDNode *E = dyn_cast<ExternalSymbolSDNode>(Callee))
390    Callee = DAG.getTargetExternalSymbol(E->getSymbol(), MVT::i16);
391
392  // Returns a chain & a flag for retval copy to use.
393  SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Flag);
394  SmallVector<SDValue, 8> Ops;
395  Ops.push_back(Chain);
396  Ops.push_back(Callee);
397
398  // Add argument registers to the end of the list so that they are
399  // known live into the call.
400  for (unsigned i = 0, e = RegsToPass.size(); i != e; ++i)
401    Ops.push_back(DAG.getRegister(RegsToPass[i].first,
402                                  RegsToPass[i].second.getValueType()));
403
404  if (InFlag.getNode())
405    Ops.push_back(InFlag);
406
407  Chain = DAG.getNode(MSP430ISD::CALL, dl, NodeTys, &Ops[0], Ops.size());
408  InFlag = Chain.getValue(1);
409
410  // Create the CALLSEQ_END node.
411  Chain = DAG.getCALLSEQ_END(Chain,
412                             DAG.getConstant(NumBytes, getPointerTy(), true),
413                             DAG.getConstant(0, getPointerTy(), true),
414                             InFlag);
415  InFlag = Chain.getValue(1);
416
417  // Handle result values, copying them out of physregs into vregs that we
418  // return.
419  return SDValue(LowerCallResult(Chain, InFlag, TheCall, CC, DAG),
420                 Op.getResNo());
421}
422
423/// LowerCallResult - Lower the result values of an ISD::CALL into the
424/// appropriate copies out of appropriate physical registers.  This assumes that
425/// Chain/InFlag are the input chain/flag to use, and that TheCall is the call
426/// being lowered. Returns a SDNode with the same number of values as the
427/// ISD::CALL.
428SDNode*
429MSP430TargetLowering::LowerCallResult(SDValue Chain, SDValue InFlag,
430                                      CallSDNode *TheCall,
431                                      unsigned CallingConv,
432                                      SelectionDAG &DAG) {
433  bool isVarArg = TheCall->isVarArg();
434  DebugLoc dl = TheCall->getDebugLoc();
435
436  // Assign locations to each value returned by this call.
437  SmallVector<CCValAssign, 16> RVLocs;
438  CCState CCInfo(CallingConv, isVarArg, getTargetMachine(),
439                 RVLocs, DAG.getContext());
440
441  CCInfo.AnalyzeCallResult(TheCall, RetCC_MSP430);
442  SmallVector<SDValue, 8> ResultVals;
443
444  // Copy all of the result registers out of their specified physreg.
445  for (unsigned i = 0; i != RVLocs.size(); ++i) {
446    Chain = DAG.getCopyFromReg(Chain, dl, RVLocs[i].getLocReg(),
447                               RVLocs[i].getValVT(), InFlag).getValue(1);
448    InFlag = Chain.getValue(2);
449    ResultVals.push_back(Chain.getValue(0));
450  }
451
452  ResultVals.push_back(Chain);
453
454  // Merge everything together with a MERGE_VALUES node.
455  return DAG.getNode(ISD::MERGE_VALUES, dl, TheCall->getVTList(),
456                     &ResultVals[0], ResultVals.size()).getNode();
457}
458
459SDValue MSP430TargetLowering::LowerShifts(SDValue Op,
460                                          SelectionDAG &DAG) {
461  unsigned Opc = Op.getOpcode();
462  SDNode* N = Op.getNode();
463  MVT VT = Op.getValueType();
464  DebugLoc dl = N->getDebugLoc();
465
466  // We currently only lower shifts of constant argument.
467  if (!isa<ConstantSDNode>(N->getOperand(1)))
468    return SDValue();
469
470  uint64_t ShiftAmount = cast<ConstantSDNode>(N->getOperand(1))->getZExtValue();
471
472  // Expand the stuff into sequence of shifts.
473  // FIXME: for some shift amounts this might be done better!
474  // E.g.: foo >> (8 + N) => sxt(swpb(foo)) >> N
475  SDValue Victim = N->getOperand(0);
476
477  if (Opc == ISD::SRL && ShiftAmount) {
478    // Emit a special goodness here:
479    // srl A, 1 => clrc; rrc A
480    Victim = DAG.getNode(MSP430ISD::RRC, dl, VT, Victim);
481    ShiftAmount -= 1;
482  }
483
484  while (ShiftAmount--)
485    Victim = DAG.getNode((Opc == ISD::SHL ? MSP430ISD::RLA : MSP430ISD::RRA),
486                         dl, VT, Victim);
487
488  return Victim;
489}
490
491SDValue MSP430TargetLowering::LowerGlobalAddress(SDValue Op, SelectionDAG &DAG) {
492  const GlobalValue *GV = cast<GlobalAddressSDNode>(Op)->getGlobal();
493  int64_t Offset = cast<GlobalAddressSDNode>(Op)->getOffset();
494
495  // Create the TargetGlobalAddress node, folding in the constant offset.
496  SDValue Result = DAG.getTargetGlobalAddress(GV, getPointerTy(), Offset);
497  return DAG.getNode(MSP430ISD::Wrapper, Op.getDebugLoc(),
498                     getPointerTy(), Result);
499}
500
501SDValue MSP430TargetLowering::LowerExternalSymbol(SDValue Op,
502                                                  SelectionDAG &DAG) {
503  DebugLoc dl = Op.getDebugLoc();
504  const char *Sym = cast<ExternalSymbolSDNode>(Op)->getSymbol();
505  SDValue Result = DAG.getTargetExternalSymbol(Sym, getPointerTy());
506
507  return DAG.getNode(MSP430ISD::Wrapper, dl, getPointerTy(), Result);;
508}
509
510static SDValue EmitCMP(SDValue &LHS, SDValue &RHS, unsigned &TargetCC,
511                       ISD::CondCode CC,
512                       DebugLoc dl, SelectionDAG &DAG) {
513  // FIXME: Handle bittests someday
514  assert(!LHS.getValueType().isFloatingPoint() && "We don't handle FP yet");
515
516  // FIXME: Handle jump negative someday
517  TargetCC = MSP430::COND_INVALID;
518  switch (CC) {
519  default: llvm_unreachable("Invalid integer condition!");
520  case ISD::SETEQ:
521    TargetCC = MSP430::COND_E;  // aka COND_Z
522    break;
523  case ISD::SETNE:
524    TargetCC = MSP430::COND_NE; // aka COND_NZ
525    break;
526  case ISD::SETULE:
527    std::swap(LHS, RHS);        // FALLTHROUGH
528  case ISD::SETUGE:
529    TargetCC = MSP430::COND_HS; // aka COND_C
530    break;
531  case ISD::SETUGT:
532    std::swap(LHS, RHS);        // FALLTHROUGH
533  case ISD::SETULT:
534    TargetCC = MSP430::COND_LO; // aka COND_NC
535    break;
536  case ISD::SETLE:
537    std::swap(LHS, RHS);        // FALLTHROUGH
538  case ISD::SETGE:
539    TargetCC = MSP430::COND_GE;
540    break;
541  case ISD::SETGT:
542    std::swap(LHS, RHS);        // FALLTHROUGH
543  case ISD::SETLT:
544    TargetCC = MSP430::COND_L;
545    break;
546  }
547
548  return DAG.getNode(MSP430ISD::CMP, dl, MVT::Flag, LHS, RHS);
549}
550
551
552SDValue MSP430TargetLowering::LowerBR_CC(SDValue Op, SelectionDAG &DAG) {
553  SDValue Chain = Op.getOperand(0);
554  ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(1))->get();
555  SDValue LHS   = Op.getOperand(2);
556  SDValue RHS   = Op.getOperand(3);
557  SDValue Dest  = Op.getOperand(4);
558  DebugLoc dl   = Op.getDebugLoc();
559
560  unsigned TargetCC = MSP430::COND_INVALID;
561  SDValue Flag = EmitCMP(LHS, RHS, TargetCC, CC, dl, DAG);
562
563  return DAG.getNode(MSP430ISD::BR_CC, dl, Op.getValueType(),
564                     Chain,
565                     Dest, DAG.getConstant(TargetCC, MVT::i8),
566                     Flag);
567}
568
569SDValue MSP430TargetLowering::LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) {
570  SDValue LHS    = Op.getOperand(0);
571  SDValue RHS    = Op.getOperand(1);
572  SDValue TrueV  = Op.getOperand(2);
573  SDValue FalseV = Op.getOperand(3);
574  ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(4))->get();
575  DebugLoc dl    = Op.getDebugLoc();
576
577  unsigned TargetCC = MSP430::COND_INVALID;
578  SDValue Flag = EmitCMP(LHS, RHS, TargetCC, CC, dl, DAG);
579
580  SDVTList VTs = DAG.getVTList(Op.getValueType(), MVT::Flag);
581  SmallVector<SDValue, 4> Ops;
582  Ops.push_back(TrueV);
583  Ops.push_back(FalseV);
584  Ops.push_back(DAG.getConstant(TargetCC, MVT::i8));
585  Ops.push_back(Flag);
586
587  return DAG.getNode(MSP430ISD::SELECT_CC, dl, VTs, &Ops[0], Ops.size());
588}
589
590SDValue MSP430TargetLowering::LowerSIGN_EXTEND(SDValue Op,
591                                               SelectionDAG &DAG) {
592  SDValue Val = Op.getOperand(0);
593  MVT VT      = Op.getValueType();
594  DebugLoc dl = Op.getDebugLoc();
595
596  assert(VT == MVT::i16 && "Only support i16 for now!");
597
598  return DAG.getNode(ISD::SIGN_EXTEND_INREG, dl, VT,
599                     DAG.getNode(ISD::ANY_EXTEND, dl, VT, Val),
600                     DAG.getValueType(Val.getValueType()));
601}
602
603const char *MSP430TargetLowering::getTargetNodeName(unsigned Opcode) const {
604  switch (Opcode) {
605  default: return NULL;
606  case MSP430ISD::RET_FLAG:           return "MSP430ISD::RET_FLAG";
607  case MSP430ISD::RRA:                return "MSP430ISD::RRA";
608  case MSP430ISD::RLA:                return "MSP430ISD::RLA";
609  case MSP430ISD::RRC:                return "MSP430ISD::RRC";
610  case MSP430ISD::CALL:               return "MSP430ISD::CALL";
611  case MSP430ISD::Wrapper:            return "MSP430ISD::Wrapper";
612  case MSP430ISD::BR_CC:              return "MSP430ISD::BR_CC";
613  case MSP430ISD::CMP:                return "MSP430ISD::CMP";
614  case MSP430ISD::SELECT_CC:          return "MSP430ISD::SELECT_CC";
615  }
616}
617
618//===----------------------------------------------------------------------===//
619//  Other Lowering Code
620//===----------------------------------------------------------------------===//
621
622MachineBasicBlock*
623MSP430TargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
624                                                  MachineBasicBlock *BB) const {
625  const TargetInstrInfo &TII = *getTargetMachine().getInstrInfo();
626  DebugLoc dl = MI->getDebugLoc();
627  assert((MI->getOpcode() == MSP430::Select16 ||
628          MI->getOpcode() == MSP430::Select8) &&
629         "Unexpected instr type to insert");
630
631  // To "insert" a SELECT instruction, we actually have to insert the diamond
632  // control-flow pattern.  The incoming instruction knows the destination vreg
633  // to set, the condition code register to branch on, the true/false values to
634  // select between, and a branch opcode to use.
635  const BasicBlock *LLVM_BB = BB->getBasicBlock();
636  MachineFunction::iterator I = BB;
637  ++I;
638
639  //  thisMBB:
640  //  ...
641  //   TrueVal = ...
642  //   cmpTY ccX, r1, r2
643  //   jCC copy1MBB
644  //   fallthrough --> copy0MBB
645  MachineBasicBlock *thisMBB = BB;
646  MachineFunction *F = BB->getParent();
647  MachineBasicBlock *copy0MBB = F->CreateMachineBasicBlock(LLVM_BB);
648  MachineBasicBlock *copy1MBB = F->CreateMachineBasicBlock(LLVM_BB);
649  BuildMI(BB, dl, TII.get(MSP430::JCC))
650    .addMBB(copy1MBB)
651    .addImm(MI->getOperand(3).getImm());
652  F->insert(I, copy0MBB);
653  F->insert(I, copy1MBB);
654  // Update machine-CFG edges by transferring all successors of the current
655  // block to the new block which will contain the Phi node for the select.
656  copy1MBB->transferSuccessors(BB);
657  // Next, add the true and fallthrough blocks as its successors.
658  BB->addSuccessor(copy0MBB);
659  BB->addSuccessor(copy1MBB);
660
661  //  copy0MBB:
662  //   %FalseValue = ...
663  //   # fallthrough to copy1MBB
664  BB = copy0MBB;
665
666  // Update machine-CFG edges
667  BB->addSuccessor(copy1MBB);
668
669  //  copy1MBB:
670  //   %Result = phi [ %FalseValue, copy0MBB ], [ %TrueValue, thisMBB ]
671  //  ...
672  BB = copy1MBB;
673  BuildMI(BB, dl, TII.get(MSP430::PHI),
674          MI->getOperand(0).getReg())
675    .addReg(MI->getOperand(2).getReg()).addMBB(copy0MBB)
676    .addReg(MI->getOperand(1).getReg()).addMBB(thisMBB);
677
678  F->DeleteMachineInstr(MI);   // The pseudo instruction is gone now.
679  return BB;
680}
681