MSP430InstrInfo.cpp revision e837dead3c8dc3445ef6a0e2322179c57e264a13 
1//===- MSP430InstrInfo.cpp - MSP430 Instruction Information ---------------===//
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 contains the MSP430 implementation of the TargetInstrInfo class.
11//
12//===----------------------------------------------------------------------===//
13
14#include "MSP430.h"
15#include "MSP430InstrInfo.h"
16#include "MSP430MachineFunctionInfo.h"
17#include "MSP430TargetMachine.h"
18#include "MSP430GenInstrInfo.inc"
19#include "llvm/Function.h"
20#include "llvm/CodeGen/MachineFrameInfo.h"
21#include "llvm/CodeGen/MachineInstrBuilder.h"
22#include "llvm/CodeGen/MachineRegisterInfo.h"
23#include "llvm/CodeGen/PseudoSourceValue.h"
24#include "llvm/Support/ErrorHandling.h"
25
26using namespace llvm;
27
28MSP430InstrInfo::MSP430InstrInfo(MSP430TargetMachine &tm)
29  : TargetInstrInfoImpl(MSP430Insts, array_lengthof(MSP430Insts)),
30    RI(tm, *this), TM(tm) {}
31
32void MSP430InstrInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
33                                          MachineBasicBlock::iterator MI,
34                                    unsigned SrcReg, bool isKill, int FrameIdx,
35                                          const TargetRegisterClass *RC,
36                                          const TargetRegisterInfo *TRI) const {
37  DebugLoc DL;
38  if (MI != MBB.end()) DL = MI->getDebugLoc();
39  MachineFunction &MF = *MBB.getParent();
40  MachineFrameInfo &MFI = *MF.getFrameInfo();
41
42  MachineMemOperand *MMO =
43    MF.getMachineMemOperand(
44              MachinePointerInfo(PseudoSourceValue::getFixedStack(FrameIdx)),
45                            MachineMemOperand::MOStore,
46                            MFI.getObjectSize(FrameIdx),
47                            MFI.getObjectAlignment(FrameIdx));
48
49  if (RC == &MSP430::GR16RegClass)
50    BuildMI(MBB, MI, DL, get(MSP430::MOV16mr))
51      .addFrameIndex(FrameIdx).addImm(0)
52      .addReg(SrcReg, getKillRegState(isKill)).addMemOperand(MMO);
53  else if (RC == &MSP430::GR8RegClass)
54    BuildMI(MBB, MI, DL, get(MSP430::MOV8mr))
55      .addFrameIndex(FrameIdx).addImm(0)
56      .addReg(SrcReg, getKillRegState(isKill)).addMemOperand(MMO);
57  else
58    llvm_unreachable("Cannot store this register to stack slot!");
59}
60
61void MSP430InstrInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
62                                           MachineBasicBlock::iterator MI,
63                                           unsigned DestReg, int FrameIdx,
64                                           const TargetRegisterClass *RC,
65                                           const TargetRegisterInfo *TRI) const{
66  DebugLoc DL;
67  if (MI != MBB.end()) DL = MI->getDebugLoc();
68  MachineFunction &MF = *MBB.getParent();
69  MachineFrameInfo &MFI = *MF.getFrameInfo();
70
71  MachineMemOperand *MMO =
72    MF.getMachineMemOperand(
73              MachinePointerInfo(PseudoSourceValue::getFixedStack(FrameIdx)),
74                            MachineMemOperand::MOLoad,
75                            MFI.getObjectSize(FrameIdx),
76                            MFI.getObjectAlignment(FrameIdx));
77
78  if (RC == &MSP430::GR16RegClass)
79    BuildMI(MBB, MI, DL, get(MSP430::MOV16rm))
80      .addReg(DestReg).addFrameIndex(FrameIdx).addImm(0).addMemOperand(MMO);
81  else if (RC == &MSP430::GR8RegClass)
82    BuildMI(MBB, MI, DL, get(MSP430::MOV8rm))
83      .addReg(DestReg).addFrameIndex(FrameIdx).addImm(0).addMemOperand(MMO);
84  else
85    llvm_unreachable("Cannot store this register to stack slot!");
86}
87
88void MSP430InstrInfo::copyPhysReg(MachineBasicBlock &MBB,
89                                  MachineBasicBlock::iterator I, DebugLoc DL,
90                                  unsigned DestReg, unsigned SrcReg,
91                                  bool KillSrc) const {
92  unsigned Opc;
93  if (MSP430::GR16RegClass.contains(DestReg, SrcReg))
94    Opc = MSP430::MOV16rr;
95  else if (MSP430::GR8RegClass.contains(DestReg, SrcReg))
96    Opc = MSP430::MOV8rr;
97  else
98    llvm_unreachable("Impossible reg-to-reg copy");
99
100  BuildMI(MBB, I, DL, get(Opc), DestReg)
101    .addReg(SrcReg, getKillRegState(KillSrc));
102}
103
104unsigned MSP430InstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
105  MachineBasicBlock::iterator I = MBB.end();
106  unsigned Count = 0;
107
108  while (I != MBB.begin()) {
109    --I;
110    if (I->isDebugValue())
111      continue;
112    if (I->getOpcode() != MSP430::JMP &&
113        I->getOpcode() != MSP430::JCC &&
114        I->getOpcode() != MSP430::Br &&
115        I->getOpcode() != MSP430::Bm)
116      break;
117    // Remove the branch.
118    I->eraseFromParent();
119    I = MBB.end();
120    ++Count;
121  }
122
123  return Count;
124}
125
126bool MSP430InstrInfo::
127ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const {
128  assert(Cond.size() == 1 && "Invalid Xbranch condition!");
129
130  MSP430CC::CondCodes CC = static_cast<MSP430CC::CondCodes>(Cond[0].getImm());
131
132  switch (CC) {
133  default:
134    assert(0 && "Invalid branch condition!");
135    break;
136  case MSP430CC::COND_E:
137    CC = MSP430CC::COND_NE;
138    break;
139  case MSP430CC::COND_NE:
140    CC = MSP430CC::COND_E;
141    break;
142  case MSP430CC::COND_L:
143    CC = MSP430CC::COND_GE;
144    break;
145  case MSP430CC::COND_GE:
146    CC = MSP430CC::COND_L;
147    break;
148  case MSP430CC::COND_HS:
149    CC = MSP430CC::COND_LO;
150    break;
151  case MSP430CC::COND_LO:
152    CC = MSP430CC::COND_HS;
153    break;
154  }
155
156  Cond[0].setImm(CC);
157  return false;
158}
159
160bool MSP430InstrInfo::isUnpredicatedTerminator(const MachineInstr *MI) const {
161  const MCInstrDesc &MCID = MI->getDesc();
162  if (!MCID.isTerminator()) return false;
163
164  // Conditional branch is a special case.
165  if (MCID.isBranch() && !MCID.isBarrier())
166    return true;
167  if (!MCID.isPredicable())
168    return true;
169  return !isPredicated(MI);
170}
171
172bool MSP430InstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
173                                    MachineBasicBlock *&TBB,
174                                    MachineBasicBlock *&FBB,
175                                    SmallVectorImpl<MachineOperand> &Cond,
176                                    bool AllowModify) const {
177  // Start from the bottom of the block and work up, examining the
178  // terminator instructions.
179  MachineBasicBlock::iterator I = MBB.end();
180  while (I != MBB.begin()) {
181    --I;
182    if (I->isDebugValue())
183      continue;
184
185    // Working from the bottom, when we see a non-terminator
186    // instruction, we're done.
187    if (!isUnpredicatedTerminator(I))
188      break;
189
190    // A terminator that isn't a branch can't easily be handled
191    // by this analysis.
192    if (!I->getDesc().isBranch())
193      return true;
194
195    // Cannot handle indirect branches.
196    if (I->getOpcode() == MSP430::Br ||
197        I->getOpcode() == MSP430::Bm)
198      return true;
199
200    // Handle unconditional branches.
201    if (I->getOpcode() == MSP430::JMP) {
202      if (!AllowModify) {
203        TBB = I->getOperand(0).getMBB();
204        continue;
205      }
206
207      // If the block has any instructions after a JMP, delete them.
208      while (llvm::next(I) != MBB.end())
209        llvm::next(I)->eraseFromParent();
210      Cond.clear();
211      FBB = 0;
212
213      // Delete the JMP if it's equivalent to a fall-through.
214      if (MBB.isLayoutSuccessor(I->getOperand(0).getMBB())) {
215        TBB = 0;
216        I->eraseFromParent();
217        I = MBB.end();
218        continue;
219      }
220
221      // TBB is used to indicate the unconditinal destination.
222      TBB = I->getOperand(0).getMBB();
223      continue;
224    }
225
226    // Handle conditional branches.
227    assert(I->getOpcode() == MSP430::JCC && "Invalid conditional branch");
228    MSP430CC::CondCodes BranchCode =
229      static_cast<MSP430CC::CondCodes>(I->getOperand(1).getImm());
230    if (BranchCode == MSP430CC::COND_INVALID)
231      return true;  // Can't handle weird stuff.
232
233    // Working from the bottom, handle the first conditional branch.
234    if (Cond.empty()) {
235      FBB = TBB;
236      TBB = I->getOperand(0).getMBB();
237      Cond.push_back(MachineOperand::CreateImm(BranchCode));
238      continue;
239    }
240
241    // Handle subsequent conditional branches. Only handle the case where all
242    // conditional branches branch to the same destination.
243    assert(Cond.size() == 1);
244    assert(TBB);
245
246    // Only handle the case where all conditional branches branch to
247    // the same destination.
248    if (TBB != I->getOperand(0).getMBB())
249      return true;
250
251    MSP430CC::CondCodes OldBranchCode = (MSP430CC::CondCodes)Cond[0].getImm();
252    // If the conditions are the same, we can leave them alone.
253    if (OldBranchCode == BranchCode)
254      continue;
255
256    return true;
257  }
258
259  return false;
260}
261
262unsigned
263MSP430InstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
264                              MachineBasicBlock *FBB,
265                              const SmallVectorImpl<MachineOperand> &Cond,
266                              DebugLoc DL) const {
267  // Shouldn't be a fall through.
268  assert(TBB && "InsertBranch must not be told to insert a fallthrough");
269  assert((Cond.size() == 1 || Cond.size() == 0) &&
270         "MSP430 branch conditions have one component!");
271
272  if (Cond.empty()) {
273    // Unconditional branch?
274    assert(!FBB && "Unconditional branch with multiple successors!");
275    BuildMI(&MBB, DL, get(MSP430::JMP)).addMBB(TBB);
276    return 1;
277  }
278
279  // Conditional branch.
280  unsigned Count = 0;
281  BuildMI(&MBB, DL, get(MSP430::JCC)).addMBB(TBB).addImm(Cond[0].getImm());
282  ++Count;
283
284  if (FBB) {
285    // Two-way Conditional branch. Insert the second branch.
286    BuildMI(&MBB, DL, get(MSP430::JMP)).addMBB(FBB);
287    ++Count;
288  }
289  return Count;
290}
291
292/// GetInstSize - Return the number of bytes of code the specified
293/// instruction may be.  This returns the maximum number of bytes.
294///
295unsigned MSP430InstrInfo::GetInstSizeInBytes(const MachineInstr *MI) const {
296  const MCInstrDesc &Desc = MI->getDesc();
297
298  switch (Desc.TSFlags & MSP430II::SizeMask) {
299  default:
300    switch (Desc.getOpcode()) {
301    default:
302      assert(0 && "Unknown instruction size!");
303    case TargetOpcode::PROLOG_LABEL:
304    case TargetOpcode::EH_LABEL:
305    case TargetOpcode::IMPLICIT_DEF:
306    case TargetOpcode::KILL:
307    case TargetOpcode::DBG_VALUE:
308      return 0;
309    case TargetOpcode::INLINEASM: {
310      const MachineFunction *MF = MI->getParent()->getParent();
311      const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();
312      return TII.getInlineAsmLength(MI->getOperand(0).getSymbolName(),
313                                    *MF->getTarget().getMCAsmInfo());
314    }
315    }
316  case MSP430II::SizeSpecial:
317    switch (MI->getOpcode()) {
318    default:
319      assert(0 && "Unknown instruction size!");
320    case MSP430::SAR8r1c:
321    case MSP430::SAR16r1c:
322      return 4;
323    }
324  case MSP430II::Size2Bytes:
325    return 2;
326  case MSP430II::Size4Bytes:
327    return 4;
328  case MSP430II::Size6Bytes:
329    return 6;
330  }
331
332  return 6;
333}
334