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      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"
     27 using namespace llvm;
     28 
     29 namespace {
     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     unsigned getBinaryCodeForInstr(const MachineInstr &MI) const;
     54 
     55 
     56     MachineRelocation GetRelocation(const MachineOperand &MO,
     57                                     unsigned RelocID) const;
     58 
     59     /// getMachineOpValue - evaluates the MachineOperand of a given MachineInstr
     60     unsigned getMachineOpValue(const MachineInstr &MI,
     61                                const MachineOperand &MO) const;
     62 
     63     unsigned get_crbitm_encoding(const MachineInstr &MI, unsigned OpNo) const;
     64     unsigned getDirectBrEncoding(const MachineInstr &MI, unsigned OpNo) const;
     65     unsigned getCondBrEncoding(const MachineInstr &MI, unsigned OpNo) const;
     66 
     67     unsigned getHA16Encoding(const MachineInstr &MI, unsigned OpNo) const;
     68     unsigned getLO16Encoding(const MachineInstr &MI, unsigned OpNo) const;
     69     unsigned getMemRIEncoding(const MachineInstr &MI, unsigned OpNo) const;
     70     unsigned getMemRIXEncoding(const MachineInstr &MI, unsigned OpNo) const;
     71 
     72     const char *getPassName() const { return "PowerPC Machine Code Emitter"; }
     73 
     74     /// runOnMachineFunction - emits the given MachineFunction to memory
     75     ///
     76     bool runOnMachineFunction(MachineFunction &MF);
     77 
     78     /// emitBasicBlock - emits the given MachineBasicBlock to memory
     79     ///
     80     void emitBasicBlock(MachineBasicBlock &MBB);
     81   };
     82 }
     83 
     84 char PPCCodeEmitter::ID = 0;
     85 
     86 /// createPPCCodeEmitterPass - Return a pass that emits the collected PPC code
     87 /// to the specified MCE object.
     88 FunctionPass *llvm::createPPCJITCodeEmitterPass(PPCTargetMachine &TM,
     89                                                 JITCodeEmitter &JCE) {
     90   return new PPCCodeEmitter(TM, JCE);
     91 }
     92 
     93 bool PPCCodeEmitter::runOnMachineFunction(MachineFunction &MF) {
     94   assert((MF.getTarget().getRelocationModel() != Reloc::Default ||
     95           MF.getTarget().getRelocationModel() != Reloc::Static) &&
     96          "JIT relocation model must be set to static or default!");
     97 
     98   MMI = &getAnalysis<MachineModuleInfo>();
     99   MCE.setModuleInfo(MMI);
    100   do {
    101     MovePCtoLROffset = 0;
    102     MCE.startFunction(MF);
    103     for (MachineFunction::iterator BB = MF.begin(), E = MF.end(); BB != E; ++BB)
    104       emitBasicBlock(*BB);
    105   } while (MCE.finishFunction(MF));
    106 
    107   return false;
    108 }
    109 
    110 void PPCCodeEmitter::emitBasicBlock(MachineBasicBlock &MBB) {
    111   MCE.StartMachineBasicBlock(&MBB);
    112 
    113   for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); I != E; ++I){
    114     const MachineInstr &MI = *I;
    115     MCE.processDebugLoc(MI.getDebugLoc(), true);
    116     switch (MI.getOpcode()) {
    117     default:
    118       MCE.emitWordBE(getBinaryCodeForInstr(MI));
    119       break;
    120     case TargetOpcode::PROLOG_LABEL:
    121     case TargetOpcode::EH_LABEL:
    122       MCE.emitLabel(MI.getOperand(0).getMCSymbol());
    123       break;
    124     case TargetOpcode::IMPLICIT_DEF:
    125     case TargetOpcode::KILL:
    126       break; // pseudo opcode, no side effects
    127     case PPC::MovePCtoLR:
    128     case PPC::MovePCtoLR8:
    129       assert(TM.getRelocationModel() == Reloc::PIC_);
    130       MovePCtoLROffset = (void*)MCE.getCurrentPCValue();
    131       MCE.emitWordBE(0x48000005);   // bl 1
    132       break;
    133     }
    134     MCE.processDebugLoc(MI.getDebugLoc(), false);
    135   }
    136 }
    137 
    138 unsigned PPCCodeEmitter::get_crbitm_encoding(const MachineInstr &MI,
    139                                              unsigned OpNo) const {
    140   const MachineOperand &MO = MI.getOperand(OpNo);
    141   assert((MI.getOpcode() == PPC::MTCRF || MI.getOpcode() == PPC::MFOCRF) &&
    142          (MO.getReg() >= PPC::CR0 && MO.getReg() <= PPC::CR7));
    143   return 0x80 >> getPPCRegisterNumbering(MO.getReg());
    144 }
    145 
    146 MachineRelocation PPCCodeEmitter::GetRelocation(const MachineOperand &MO,
    147                                                 unsigned RelocID) const {
    148   // If in PIC mode, we need to encode the negated address of the
    149   // 'movepctolr' into the unrelocated field.  After relocation, we'll have
    150   // &gv-&movepctolr-4 in the imm field.  Once &movepctolr is added to the imm
    151   // field, we get &gv.  This doesn't happen for branch relocations, which are
    152   // always implicitly pc relative.
    153   intptr_t Cst = 0;
    154   if (TM.getRelocationModel() == Reloc::PIC_) {
    155     assert(MovePCtoLROffset && "MovePCtoLR not seen yet?");
    156     Cst = -(intptr_t)MovePCtoLROffset - 4;
    157   }
    158 
    159   if (MO.isGlobal())
    160     return MachineRelocation::getGV(MCE.getCurrentPCOffset(), RelocID,
    161                                     const_cast<GlobalValue *>(MO.getGlobal()),
    162                                     Cst, isa<Function>(MO.getGlobal()));
    163   if (MO.isSymbol())
    164     return MachineRelocation::getExtSym(MCE.getCurrentPCOffset(),
    165                                         RelocID, MO.getSymbolName(), Cst);
    166   if (MO.isCPI())
    167     return MachineRelocation::getConstPool(MCE.getCurrentPCOffset(),
    168                                            RelocID, MO.getIndex(), Cst);
    169 
    170   if (MO.isMBB())
    171     return MachineRelocation::getBB(MCE.getCurrentPCOffset(),
    172                                     RelocID, MO.getMBB());
    173 
    174   assert(MO.isJTI());
    175   return MachineRelocation::getJumpTable(MCE.getCurrentPCOffset(),
    176                                          RelocID, MO.getIndex(), Cst);
    177 }
    178 
    179 unsigned PPCCodeEmitter::getDirectBrEncoding(const MachineInstr &MI,
    180                                              unsigned OpNo) const {
    181   const MachineOperand &MO = MI.getOperand(OpNo);
    182   if (MO.isReg() || MO.isImm()) return getMachineOpValue(MI, MO);
    183 
    184   MCE.addRelocation(GetRelocation(MO, PPC::reloc_pcrel_bx));
    185   return 0;
    186 }
    187 
    188 unsigned PPCCodeEmitter::getCondBrEncoding(const MachineInstr &MI,
    189                                            unsigned OpNo) const {
    190   const MachineOperand &MO = MI.getOperand(OpNo);
    191   MCE.addRelocation(GetRelocation(MO, PPC::reloc_pcrel_bcx));
    192   return 0;
    193 }
    194 
    195 unsigned PPCCodeEmitter::getHA16Encoding(const MachineInstr &MI,
    196                                          unsigned OpNo) const {
    197   const MachineOperand &MO = MI.getOperand(OpNo);
    198   if (MO.isReg() || MO.isImm()) return getMachineOpValue(MI, MO);
    199 
    200   MCE.addRelocation(GetRelocation(MO, PPC::reloc_absolute_high));
    201   return 0;
    202 }
    203 
    204 unsigned PPCCodeEmitter::getLO16Encoding(const MachineInstr &MI,
    205                                          unsigned OpNo) const {
    206   const MachineOperand &MO = MI.getOperand(OpNo);
    207   if (MO.isReg() || MO.isImm()) return getMachineOpValue(MI, MO);
    208 
    209   MCE.addRelocation(GetRelocation(MO, PPC::reloc_absolute_low));
    210   return 0;
    211 }
    212 
    213 unsigned PPCCodeEmitter::getMemRIEncoding(const MachineInstr &MI,
    214                                           unsigned OpNo) const {
    215   // Encode (imm, reg) as a memri, which has the low 16-bits as the
    216   // displacement and the next 5 bits as the register #.
    217   assert(MI.getOperand(OpNo+1).isReg());
    218   unsigned RegBits = getMachineOpValue(MI, MI.getOperand(OpNo+1)) << 16;
    219 
    220   const MachineOperand &MO = MI.getOperand(OpNo);
    221   if (MO.isImm())
    222     return (getMachineOpValue(MI, MO) & 0xFFFF) | RegBits;
    223 
    224   // Add a fixup for the displacement field.
    225   MCE.addRelocation(GetRelocation(MO, PPC::reloc_absolute_low));
    226   return RegBits;
    227 }
    228 
    229 unsigned PPCCodeEmitter::getMemRIXEncoding(const MachineInstr &MI,
    230                                            unsigned OpNo) const {
    231   // Encode (imm, reg) as a memrix, which has the low 14-bits as the
    232   // displacement and the next 5 bits as the register #.
    233   assert(MI.getOperand(OpNo+1).isReg());
    234   unsigned RegBits = getMachineOpValue(MI, MI.getOperand(OpNo+1)) << 14;
    235 
    236   const MachineOperand &MO = MI.getOperand(OpNo);
    237   if (MO.isImm())
    238     return (getMachineOpValue(MI, MO) & 0x3FFF) | RegBits;
    239 
    240   MCE.addRelocation(GetRelocation(MO, PPC::reloc_absolute_low_ix));
    241   return RegBits;
    242 }
    243 
    244 
    245 unsigned PPCCodeEmitter::getMachineOpValue(const MachineInstr &MI,
    246                                            const MachineOperand &MO) const {
    247 
    248   if (MO.isReg()) {
    249     // MTCRF/MFOCRF should go through get_crbitm_encoding for the CR operand.
    250     // The GPR operand should come through here though.
    251     assert((MI.getOpcode() != PPC::MTCRF && MI.getOpcode() != PPC::MFOCRF) ||
    252            MO.getReg() < PPC::CR0 || MO.getReg() > PPC::CR7);
    253     return getPPCRegisterNumbering(MO.getReg());
    254   }
    255 
    256   assert(MO.isImm() &&
    257          "Relocation required in an instruction that we cannot encode!");
    258   return MO.getImm();
    259 }
    260 
    261 #include "PPCGenCodeEmitter.inc"
    262