PPCCodeEmitter.cpp revision 205218 
1//===-- PPCCodeEmitter.cpp - JIT Code Emitter for PowerPC32 -------*- C++ -*-=//
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 defines the PowerPC 32-bit CodeEmitter and associated machinery to
11// JIT-compile bitcode to native PowerPC.
12//
13//===----------------------------------------------------------------------===//
14
15#include "PPCTargetMachine.h"
16#include "PPCRelocations.h"
17#include "PPC.h"
18#include "llvm/Module.h"
19#include "llvm/PassManager.h"
20#include "llvm/CodeGen/JITCodeEmitter.h"
21#include "llvm/CodeGen/MachineFunctionPass.h"
22#include "llvm/CodeGen/MachineInstrBuilder.h"
23#include "llvm/CodeGen/MachineModuleInfo.h"
24#include "llvm/Support/ErrorHandling.h"
25#include "llvm/Support/raw_ostream.h"
26#include "llvm/Target/TargetOptions.h"
27using namespace llvm;
28
29namespace {
30  class PPCCodeEmitter : public MachineFunctionPass {
31    TargetMachine &TM;
32    JITCodeEmitter &MCE;
33    MachineModuleInfo *MMI;
34
35    void getAnalysisUsage(AnalysisUsage &AU) const {
36      AU.addRequired<MachineModuleInfo>();
37      MachineFunctionPass::getAnalysisUsage(AU);
38    }
39
40    static char ID;
41
42    /// MovePCtoLROffset - When/if we see a MovePCtoLR instruction, we record
43    /// its address in the function into this pointer.
44    void *MovePCtoLROffset;
45  public:
46
47    PPCCodeEmitter(TargetMachine &tm, JITCodeEmitter &mce)
48      : MachineFunctionPass(&ID), TM(tm), MCE(mce) {}
49
50    /// getBinaryCodeForInstr - This function, generated by the
51    /// CodeEmitterGenerator using TableGen, produces the binary encoding for
52    /// machine instructions.
53
54    unsigned getBinaryCodeForInstr(const MachineInstr &MI);
55
56    /// getMachineOpValue - evaluates the MachineOperand of a given MachineInstr
57
58    unsigned getMachineOpValue(const MachineInstr &MI,
59                               const MachineOperand &MO);
60
61    const char *getPassName() const { return "PowerPC Machine Code Emitter"; }
62
63    /// runOnMachineFunction - emits the given MachineFunction to memory
64    ///
65    bool runOnMachineFunction(MachineFunction &MF);
66
67    /// emitBasicBlock - emits the given MachineBasicBlock to memory
68    ///
69    void emitBasicBlock(MachineBasicBlock &MBB);
70
71    /// getValueBit - return the particular bit of Val
72    ///
73    unsigned getValueBit(int64_t Val, unsigned bit) { return (Val >> bit) & 1; }
74  };
75}
76
77char PPCCodeEmitter::ID = 0;
78
79/// createPPCCodeEmitterPass - Return a pass that emits the collected PPC code
80/// to the specified MCE object.
81FunctionPass *llvm::createPPCJITCodeEmitterPass(PPCTargetMachine &TM,
82                                                JITCodeEmitter &JCE) {
83  return new PPCCodeEmitter(TM, JCE);
84}
85
86bool PPCCodeEmitter::runOnMachineFunction(MachineFunction &MF) {
87  assert((MF.getTarget().getRelocationModel() != Reloc::Default ||
88          MF.getTarget().getRelocationModel() != Reloc::Static) &&
89         "JIT relocation model must be set to static or default!");
90
91  MMI = &getAnalysis<MachineModuleInfo>();
92  MCE.setModuleInfo(MMI);
93  do {
94    MovePCtoLROffset = 0;
95    MCE.startFunction(MF);
96    for (MachineFunction::iterator BB = MF.begin(), E = MF.end(); BB != E; ++BB)
97      emitBasicBlock(*BB);
98  } while (MCE.finishFunction(MF));
99
100  return false;
101}
102
103void PPCCodeEmitter::emitBasicBlock(MachineBasicBlock &MBB) {
104  MCE.StartMachineBasicBlock(&MBB);
105
106  for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); I != E; ++I){
107    const MachineInstr &MI = *I;
108    MCE.processDebugLoc(MI.getDebugLoc(), true);
109    switch (MI.getOpcode()) {
110    default:
111      MCE.emitWordBE(getBinaryCodeForInstr(MI));
112      break;
113    case TargetOpcode::DBG_LABEL:
114    case TargetOpcode::EH_LABEL:
115      MCE.emitLabel(MI.getOperand(0).getMCSymbol());
116      break;
117    case TargetOpcode::IMPLICIT_DEF:
118    case TargetOpcode::KILL:
119      break; // pseudo opcode, no side effects
120    case PPC::MovePCtoLR:
121    case PPC::MovePCtoLR8:
122      assert(TM.getRelocationModel() == Reloc::PIC_);
123      MovePCtoLROffset = (void*)MCE.getCurrentPCValue();
124      MCE.emitWordBE(0x48000005);   // bl 1
125      break;
126    }
127    MCE.processDebugLoc(MI.getDebugLoc(), false);
128  }
129}
130
131unsigned PPCCodeEmitter::getMachineOpValue(const MachineInstr &MI,
132                                           const MachineOperand &MO) {
133
134  unsigned rv = 0; // Return value; defaults to 0 for unhandled cases
135                   // or things that get fixed up later by the JIT.
136  if (MO.isReg()) {
137    rv = PPCRegisterInfo::getRegisterNumbering(MO.getReg());
138
139    // Special encoding for MTCRF and MFOCRF, which uses a bit mask for the
140    // register, not the register number directly.
141    if ((MI.getOpcode() == PPC::MTCRF || MI.getOpcode() == PPC::MFOCRF) &&
142        (MO.getReg() >= PPC::CR0 && MO.getReg() <= PPC::CR7)) {
143      rv = 0x80 >> rv;
144    }
145  } else if (MO.isImm()) {
146    rv = MO.getImm();
147  } else if (MO.isGlobal() || MO.isSymbol() ||
148             MO.isCPI() || MO.isJTI()) {
149    unsigned Reloc = 0;
150    if (MI.getOpcode() == PPC::BL_Darwin || MI.getOpcode() == PPC::BL8_Darwin ||
151        MI.getOpcode() == PPC::BL_SVR4 || MI.getOpcode() == PPC::BL8_ELF ||
152        MI.getOpcode() == PPC::TAILB || MI.getOpcode() == PPC::TAILB8)
153      Reloc = PPC::reloc_pcrel_bx;
154    else {
155      if (TM.getRelocationModel() == Reloc::PIC_) {
156        assert(MovePCtoLROffset && "MovePCtoLR not seen yet?");
157      }
158      switch (MI.getOpcode()) {
159      default: MI.dump(); llvm_unreachable("Unknown instruction for relocation!");
160      case PPC::LIS:
161      case PPC::LIS8:
162      case PPC::ADDIS:
163      case PPC::ADDIS8:
164        Reloc = PPC::reloc_absolute_high;       // Pointer to symbol
165        break;
166      case PPC::LI:
167      case PPC::LI8:
168      case PPC::LA:
169      // Loads.
170      case PPC::LBZ:
171      case PPC::LBZ8:
172      case PPC::LHA:
173      case PPC::LHA8:
174      case PPC::LHZ:
175      case PPC::LHZ8:
176      case PPC::LWZ:
177      case PPC::LWZ8:
178      case PPC::LFS:
179      case PPC::LFD:
180
181      // Stores.
182      case PPC::STB:
183      case PPC::STB8:
184      case PPC::STH:
185      case PPC::STH8:
186      case PPC::STW:
187      case PPC::STW8:
188      case PPC::STFS:
189      case PPC::STFD:
190        Reloc = PPC::reloc_absolute_low;
191        break;
192
193      case PPC::LWA:
194      case PPC::LD:
195      case PPC::STD:
196      case PPC::STD_32:
197        Reloc = PPC::reloc_absolute_low_ix;
198        break;
199      }
200    }
201
202    MachineRelocation R;
203    if (MO.isGlobal()) {
204      R = MachineRelocation::getGV(MCE.getCurrentPCOffset(), Reloc,
205                                   MO.getGlobal(), 0,
206                                   isa<Function>(MO.getGlobal()));
207    } else if (MO.isSymbol()) {
208      R = MachineRelocation::getExtSym(MCE.getCurrentPCOffset(),
209                                       Reloc, MO.getSymbolName(), 0);
210    } else if (MO.isCPI()) {
211      R = MachineRelocation::getConstPool(MCE.getCurrentPCOffset(),
212                                          Reloc, MO.getIndex(), 0);
213    } else {
214      assert(MO.isJTI());
215      R = MachineRelocation::getJumpTable(MCE.getCurrentPCOffset(),
216                                          Reloc, MO.getIndex(), 0);
217    }
218
219    // If in PIC mode, we need to encode the negated address of the
220    // 'movepctolr' into the unrelocated field.  After relocation, we'll have
221    // &gv-&movepctolr-4 in the imm field.  Once &movepctolr is added to the imm
222    // field, we get &gv.  This doesn't happen for branch relocations, which are
223    // always implicitly pc relative.
224    if (TM.getRelocationModel() == Reloc::PIC_ && Reloc != PPC::reloc_pcrel_bx){
225      assert(MovePCtoLROffset && "MovePCtoLR not seen yet?");
226      R.setConstantVal(-(intptr_t)MovePCtoLROffset - 4);
227    }
228    MCE.addRelocation(R);
229
230  } else if (MO.isMBB()) {
231    unsigned Reloc = 0;
232    unsigned Opcode = MI.getOpcode();
233    if (Opcode == PPC::B || Opcode == PPC::BL_Darwin ||
234        Opcode == PPC::BLA_Darwin|| Opcode == PPC::BL_SVR4 ||
235        Opcode == PPC::BLA_SVR4)
236      Reloc = PPC::reloc_pcrel_bx;
237    else // BCC instruction
238      Reloc = PPC::reloc_pcrel_bcx;
239
240    MCE.addRelocation(MachineRelocation::getBB(MCE.getCurrentPCOffset(),
241                                               Reloc, MO.getMBB()));
242  } else {
243#ifndef NDEBUG
244    errs() << "ERROR: Unknown type of MachineOperand: " << MO << "\n";
245#endif
246    llvm_unreachable(0);
247  }
248
249  return rv;
250}
251
252#include "PPCGenCodeEmitter.inc"
253