PPCCodeEmitter.cpp revision 203954 
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
34    void getAnalysisUsage(AnalysisUsage &AU) const {
35      AU.addRequired<MachineModuleInfo>();
36      MachineFunctionPass::getAnalysisUsage(AU);
37    }
38
39    static char ID;
40
41    /// MovePCtoLROffset - When/if we see a MovePCtoLR instruction, we record
42    /// its address in the function into this pointer.
43    void *MovePCtoLROffset;
44  public:
45
46    PPCCodeEmitter(TargetMachine &tm, JITCodeEmitter &mce)
47      : MachineFunctionPass(&ID), TM(tm), MCE(mce) {}
48
49    /// getBinaryCodeForInstr - This function, generated by the
50    /// CodeEmitterGenerator using TableGen, produces the binary encoding for
51    /// machine instructions.
52
53    unsigned getBinaryCodeForInstr(const MachineInstr &MI);
54
55    /// getMachineOpValue - evaluates the MachineOperand of a given MachineInstr
56
57    unsigned getMachineOpValue(const MachineInstr &MI,
58                               const MachineOperand &MO);
59
60    const char *getPassName() const { return "PowerPC Machine Code Emitter"; }
61
62    /// runOnMachineFunction - emits the given MachineFunction to memory
63    ///
64    bool runOnMachineFunction(MachineFunction &MF);
65
66    /// emitBasicBlock - emits the given MachineBasicBlock to memory
67    ///
68    void emitBasicBlock(MachineBasicBlock &MBB);
69
70    /// getValueBit - return the particular bit of Val
71    ///
72    unsigned getValueBit(int64_t Val, unsigned bit) { return (Val >> bit) & 1; }
73  };
74}
75
76char PPCCodeEmitter::ID = 0;
77
78/// createPPCCodeEmitterPass - Return a pass that emits the collected PPC code
79/// to the specified MCE object.
80FunctionPass *llvm::createPPCJITCodeEmitterPass(PPCTargetMachine &TM,
81                                                JITCodeEmitter &JCE) {
82  return new PPCCodeEmitter(TM, JCE);
83}
84
85bool PPCCodeEmitter::runOnMachineFunction(MachineFunction &MF) {
86  assert((MF.getTarget().getRelocationModel() != Reloc::Default ||
87          MF.getTarget().getRelocationModel() != Reloc::Static) &&
88         "JIT relocation model must be set to static or default!");
89
90  MCE.setModuleInfo(&getAnalysis<MachineModuleInfo>());
91  do {
92    MovePCtoLROffset = 0;
93    MCE.startFunction(MF);
94    for (MachineFunction::iterator BB = MF.begin(), E = MF.end(); BB != E; ++BB)
95      emitBasicBlock(*BB);
96  } while (MCE.finishFunction(MF));
97
98  return false;
99}
100
101void PPCCodeEmitter::emitBasicBlock(MachineBasicBlock &MBB) {
102  MCE.StartMachineBasicBlock(&MBB);
103
104  for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); I != E; ++I){
105    const MachineInstr &MI = *I;
106    MCE.processDebugLoc(MI.getDebugLoc(), true);
107    switch (MI.getOpcode()) {
108    default:
109      MCE.emitWordBE(getBinaryCodeForInstr(MI));
110      break;
111    case TargetOpcode::DBG_LABEL:
112    case TargetOpcode::EH_LABEL:
113      MCE.emitLabel(MI.getOperand(0).getImm());
114      break;
115    case TargetOpcode::IMPLICIT_DEF:
116    case TargetOpcode::KILL:
117      break; // pseudo opcode, no side effects
118    case PPC::MovePCtoLR:
119    case PPC::MovePCtoLR8:
120      assert(TM.getRelocationModel() == Reloc::PIC_);
121      MovePCtoLROffset = (void*)MCE.getCurrentPCValue();
122      MCE.emitWordBE(0x48000005);   // bl 1
123      break;
124    }
125    MCE.processDebugLoc(MI.getDebugLoc(), false);
126  }
127}
128
129unsigned PPCCodeEmitter::getMachineOpValue(const MachineInstr &MI,
130                                           const MachineOperand &MO) {
131
132  unsigned rv = 0; // Return value; defaults to 0 for unhandled cases
133                   // or things that get fixed up later by the JIT.
134  if (MO.isReg()) {
135    rv = PPCRegisterInfo::getRegisterNumbering(MO.getReg());
136
137    // Special encoding for MTCRF and MFOCRF, which uses a bit mask for the
138    // register, not the register number directly.
139    if ((MI.getOpcode() == PPC::MTCRF || MI.getOpcode() == PPC::MFOCRF) &&
140        (MO.getReg() >= PPC::CR0 && MO.getReg() <= PPC::CR7)) {
141      rv = 0x80 >> rv;
142    }
143  } else if (MO.isImm()) {
144    rv = MO.getImm();
145  } else if (MO.isGlobal() || MO.isSymbol() ||
146             MO.isCPI() || MO.isJTI()) {
147    unsigned Reloc = 0;
148    if (MI.getOpcode() == PPC::BL_Darwin || MI.getOpcode() == PPC::BL8_Darwin ||
149        MI.getOpcode() == PPC::BL_SVR4 || MI.getOpcode() == PPC::BL8_ELF ||
150        MI.getOpcode() == PPC::TAILB || MI.getOpcode() == PPC::TAILB8)
151      Reloc = PPC::reloc_pcrel_bx;
152    else {
153      if (TM.getRelocationModel() == Reloc::PIC_) {
154        assert(MovePCtoLROffset && "MovePCtoLR not seen yet?");
155      }
156      switch (MI.getOpcode()) {
157      default: MI.dump(); llvm_unreachable("Unknown instruction for relocation!");
158      case PPC::LIS:
159      case PPC::LIS8:
160      case PPC::ADDIS:
161      case PPC::ADDIS8:
162        Reloc = PPC::reloc_absolute_high;       // Pointer to symbol
163        break;
164      case PPC::LI:
165      case PPC::LI8:
166      case PPC::LA:
167      // Loads.
168      case PPC::LBZ:
169      case PPC::LBZ8:
170      case PPC::LHA:
171      case PPC::LHA8:
172      case PPC::LHZ:
173      case PPC::LHZ8:
174      case PPC::LWZ:
175      case PPC::LWZ8:
176      case PPC::LFS:
177      case PPC::LFD:
178
179      // Stores.
180      case PPC::STB:
181      case PPC::STB8:
182      case PPC::STH:
183      case PPC::STH8:
184      case PPC::STW:
185      case PPC::STW8:
186      case PPC::STFS:
187      case PPC::STFD:
188        Reloc = PPC::reloc_absolute_low;
189        break;
190
191      case PPC::LWA:
192      case PPC::LD:
193      case PPC::STD:
194      case PPC::STD_32:
195        Reloc = PPC::reloc_absolute_low_ix;
196        break;
197      }
198    }
199
200    MachineRelocation R;
201    if (MO.isGlobal()) {
202      R = MachineRelocation::getGV(MCE.getCurrentPCOffset(), Reloc,
203                                   MO.getGlobal(), 0,
204                                   isa<Function>(MO.getGlobal()));
205    } else if (MO.isSymbol()) {
206      R = MachineRelocation::getExtSym(MCE.getCurrentPCOffset(),
207                                       Reloc, MO.getSymbolName(), 0);
208    } else if (MO.isCPI()) {
209      R = MachineRelocation::getConstPool(MCE.getCurrentPCOffset(),
210                                          Reloc, MO.getIndex(), 0);
211    } else {
212      assert(MO.isJTI());
213      R = MachineRelocation::getJumpTable(MCE.getCurrentPCOffset(),
214                                          Reloc, MO.getIndex(), 0);
215    }
216
217    // If in PIC mode, we need to encode the negated address of the
218    // 'movepctolr' into the unrelocated field.  After relocation, we'll have
219    // &gv-&movepctolr-4 in the imm field.  Once &movepctolr is added to the imm
220    // field, we get &gv.  This doesn't happen for branch relocations, which are
221    // always implicitly pc relative.
222    if (TM.getRelocationModel() == Reloc::PIC_ && Reloc != PPC::reloc_pcrel_bx){
223      assert(MovePCtoLROffset && "MovePCtoLR not seen yet?");
224      R.setConstantVal(-(intptr_t)MovePCtoLROffset - 4);
225    }
226    MCE.addRelocation(R);
227
228  } else if (MO.isMBB()) {
229    unsigned Reloc = 0;
230    unsigned Opcode = MI.getOpcode();
231    if (Opcode == PPC::B || Opcode == PPC::BL_Darwin ||
232        Opcode == PPC::BLA_Darwin|| Opcode == PPC::BL_SVR4 ||
233        Opcode == PPC::BLA_SVR4)
234      Reloc = PPC::reloc_pcrel_bx;
235    else // BCC instruction
236      Reloc = PPC::reloc_pcrel_bcx;
237
238    MCE.addRelocation(MachineRelocation::getBB(MCE.getCurrentPCOffset(),
239                                               Reloc, MO.getMBB()));
240  } else {
241#ifndef NDEBUG
242    errs() << "ERROR: Unknown type of MachineOperand: " << MO << "\n";
243#endif
244    llvm_unreachable(0);
245  }
246
247  return rv;
248}
249
250#include "PPCGenCodeEmitter.inc"
251