lib/Target/PowerPC/PPCCodeEmitter.cpp

   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/MachineCodeEmitter.h"
  21 #include "llvm/CodeGen/MachineFunctionPass.h"
  22 #include "llvm/CodeGen/MachineInstrBuilder.h"
  23 #include "llvm/CodeGen/MachineModuleInfo.h"
  24 #include "llvm/CodeGen/Passes.h"
  25 #include "llvm/Support/Debug.h"
  26 #include "llvm/Support/Compiler.h"
  27 #include "llvm/Target/TargetOptions.h"
  28 using namespace llvm;
  29
  30 namespace {
  31   class VISIBILITY_HIDDEN PPCCodeEmitter : public MachineFunctionPass {
  32     TargetMachine &TM;
  33     MachineCodeEmitter &MCE;
  34
  35     /// MovePCtoLROffset - When/if we see a MovePCtoLR instruction, we record
  36     /// its address in the function into this pointer.
  37     void *MovePCtoLROffset;
  38
  39     /// getMachineOpValue - evaluates the MachineOperand of a given MachineInstr
  40     ///
  41     unsigned getMachineOpValue(const MachineInstr &MI, const MachineOperand &MO);
  42
  43     void getAnalysisUsage(AnalysisUsage &AU) const {
  44       AU.addRequired<MachineModuleInfo>();
  45       MachineFunctionPass::getAnalysisUsage(AU);
  46     }
  47
  48   public:
  49     static char ID;
  50     PPCCodeEmitter(TargetMachine &T, MachineCodeEmitter &M)
  51       : MachineFunctionPass(&ID), TM(T), MCE(M) {}
  52
  53     const char *getPassName() const { return "PowerPC Machine Code Emitter"; }
  54
  55     /// runOnMachineFunction - emits the given MachineFunction to memory
  56     ///
  57     bool runOnMachineFunction(MachineFunction &MF);
  58
  59     /// emitBasicBlock - emits the given MachineBasicBlock to memory
  60     ///
  61     void emitBasicBlock(MachineBasicBlock &MBB);
  62
  63     /// getValueBit - return the particular bit of Val
  64     ///
  65     unsigned getValueBit(int64_t Val, unsigned bit) { return (Val >> bit) & 1; }
  66
  67     /// getBinaryCodeForInstr - This function, generated by the
  68     /// CodeEmitterGenerator using TableGen, produces the binary encoding for
  69     /// machine instructions.
  70     ///
  71     unsigned getBinaryCodeForInstr(const MachineInstr &MI);
  72   };
  73   char PPCCodeEmitter::ID = 0;
  74 }
  75
  76 /// createPPCCodeEmitterPass - Return a pass that emits the collected PPC code
  77 /// to the specified MCE object.
  78 FunctionPass *llvm::createPPCCodeEmitterPass(PPCTargetMachine &TM,
  79                                              MachineCodeEmitter &MCE) {
  80   return new PPCCodeEmitter(TM, MCE);
  81 }
  82
  83 bool PPCCodeEmitter::runOnMachineFunction(MachineFunction &MF) {
  84   assert((MF.getTarget().getRelocationModel() != Reloc::Default ||
  85           MF.getTarget().getRelocationModel() != Reloc::Static) &&
  86          "JIT relocation model must be set to static or default!");
  87
  88   MCE.setModuleInfo(&getAnalysis<MachineModuleInfo>());
  89   do {
  90     MovePCtoLROffset = 0;
  91     MCE.startFunction(MF);
  92     for (MachineFunction::iterator BB = MF.begin(), E = MF.end(); BB != E; ++BB)
  93       emitBasicBlock(*BB);
  94   } while (MCE.finishFunction(MF));
  95
  96   return false;
  97 }
  98
  99 void PPCCodeEmitter::emitBasicBlock(MachineBasicBlock &MBB) {
 100   MCE.StartMachineBasicBlock(&MBB);
 101
 102   for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); I != E; ++I){
 103     const MachineInstr &MI = *I;
 104     switch (MI.getOpcode()) {
 105     default:
 106       MCE.emitWordBE(getBinaryCodeForInstr(MI));
 107       break;
 108     case TargetInstrInfo::DBG_LABEL:
 109     case TargetInstrInfo::EH_LABEL:
 110       MCE.emitLabel(MI.getOperand(0).getImm());
 111       break;
 112     case TargetInstrInfo::IMPLICIT_DEF:
 113       break; // pseudo opcode, no side effects
 114     case PPC::MovePCtoLR:
 115     case PPC::MovePCtoLR8:
 116       assert(TM.getRelocationModel() == Reloc::PIC_);
 117       MovePCtoLROffset = (void*)MCE.getCurrentPCValue();
 118       MCE.emitWordBE(0x48000005);   // bl 1
 119       break;
 120     }
 121   }
 122 }
 123
 124 unsigned PPCCodeEmitter::getMachineOpValue(const MachineInstr &MI,
 125                                            const MachineOperand &MO) {
 126
 127   unsigned rv = 0; // Return value; defaults to 0 for unhandled cases
 128                    // or things that get fixed up later by the JIT.
 129   if (MO.isReg()) {
 130     rv = PPCRegisterInfo::getRegisterNumbering(MO.getReg());
 131
 132     // Special encoding for MTCRF and MFOCRF, which uses a bit mask for the
 133     // register, not the register number directly.
 134     if ((MI.getOpcode() == PPC::MTCRF || MI.getOpcode() == PPC::MFOCRF) &&
 135         (MO.getReg() >= PPC::CR0 && MO.getReg() <= PPC::CR7)) {
 136       rv = 0x80 >> rv;
 137     }
 138   } else if (MO.isImm()) {
 139     rv = MO.getImm();
 140   } else if (MO.isGlobal() || MO.isSymbol() ||
 141              MO.isCPI() || MO.isJTI()) {
 142     unsigned Reloc = 0;
 143     if (MI.getOpcode() == PPC::BL_Macho || MI.getOpcode() == PPC::BL8_Macho ||
 144         MI.getOpcode() == PPC::BL_ELF || MI.getOpcode() == PPC::BL8_ELF ||
 145         MI.getOpcode() == PPC::TAILB || MI.getOpcode() == PPC::TAILB8)
 146       Reloc = PPC::reloc_pcrel_bx;
 147     else {
 148       if (TM.getRelocationModel() == Reloc::PIC_) {
 149         assert(MovePCtoLROffset && "MovePCtoLR not seen yet?");
 150       }
 151       switch (MI.getOpcode()) {
 152       default: MI.dump(); assert(0 && "Unknown instruction for relocation!");
 153       case PPC::LIS:
 154       case PPC::LIS8:
 155       case PPC::ADDIS:
 156       case PPC::ADDIS8:
 157         Reloc = PPC::reloc_absolute_high;       // Pointer to symbol
 158         break;
 159       case PPC::LI:
 160       case PPC::LI8:
 161       case PPC::LA:
 162       // Loads.
 163       case PPC::LBZ:
 164       case PPC::LBZ8:
 165       case PPC::LHA:
 166       case PPC::LHA8:
 167       case PPC::LHZ:
 168       case PPC::LHZ8:
 169       case PPC::LWZ:
 170       case PPC::LWZ8:
 171       case PPC::LFS:
 172       case PPC::LFD:
 173
 174       // Stores.
 175       case PPC::STB:
 176       case PPC::STB8:
 177       case PPC::STH:
 178       case PPC::STH8:
 179       case PPC::STW:
 180       case PPC::STW8:
 181       case PPC::STFS:
 182       case PPC::STFD:
 183         Reloc = PPC::reloc_absolute_low;
 184         break;
 185
 186       case PPC::LWA:
 187       case PPC::LD:
 188       case PPC::STD:
 189       case PPC::STD_32:
 190         Reloc = PPC::reloc_absolute_low_ix;
 191         break;
 192       }
 193     }
 194
 195     MachineRelocation R;
 196     if (MO.isGlobal()) {
 197       R = MachineRelocation::getGV(MCE.getCurrentPCOffset(), Reloc,
 198                                    MO.getGlobal(), 0,
 199                                    isa<Function>(MO.getGlobal()));
 200     } else if (MO.isSymbol()) {
 201       R = MachineRelocation::getExtSym(MCE.getCurrentPCOffset(),
 202                                        Reloc, MO.getSymbolName(), 0);
 203     } else if (MO.isCPI()) {
 204       R = MachineRelocation::getConstPool(MCE.getCurrentPCOffset(),
 205                                           Reloc, MO.getIndex(), 0);
 206     } else {
 207       assert(MO.isJTI());
 208       R = MachineRelocation::getJumpTable(MCE.getCurrentPCOffset(),
 209                                           Reloc, MO.getIndex(), 0);
 210     }
 211
 212     // If in PIC mode, we need to encode the negated address of the
 213     // 'movepctolr' into the unrelocated field.  After relocation, we'll have
 214     // &gv-&movepctolr-4 in the imm field.  Once &movepctolr is added to the imm
 215     // field, we get &gv.  This doesn't happen for branch relocations, which are
 216     // always implicitly pc relative.
 217     if (TM.getRelocationModel() == Reloc::PIC_ && Reloc != PPC::reloc_pcrel_bx){
 218       assert(MovePCtoLROffset && "MovePCtoLR not seen yet?");
 219       R.setConstantVal(-(intptr_t)MovePCtoLROffset - 4);
 220     }
 221     MCE.addRelocation(R);
 222
 223   } else if (MO.isMBB()) {
 224     unsigned Reloc = 0;
 225     unsigned Opcode = MI.getOpcode();
 226     if (Opcode == PPC::B || Opcode == PPC::BL_Macho ||
 227         Opcode == PPC::BLA_Macho || Opcode == PPC::BL_ELF ||
 228         Opcode == PPC::BLA_ELF)
 229       Reloc = PPC::reloc_pcrel_bx;
 230     else // BCC instruction
 231       Reloc = PPC::reloc_pcrel_bcx;
 232     MCE.addRelocation(MachineRelocation::getBB(MCE.getCurrentPCOffset(),
 233                                                Reloc, MO.getMBB()));
 234   } else {
 235     cerr << "ERROR: Unknown type of MachineOperand: " << MO << "\n";
 236     abort();
 237   }
 238
 239   return rv;
 240 }
 241
 242 #include "PPCGenCodeEmitter.inc"
 243