C++ codeGen::setRegisterSpace方法代码示例

bool RelDataPatch::apply(codeGen &gen, CodeBuffer *) {
  instruction ugly_insn(orig_insn.ptr(), (gen.width() == 8));
  instPoint *point = gen.point();
  if (!point || (point->type() != instPoint::PreInsn && point->insnAddr() != orig)) {
      point = instPoint::preInsn(func, block, orig, orig_insn, true);
  }
  registerSpace *rs = registerSpace::actualRegSpace(point);
  gen.setRegisterSpace(rs);

  if (!insnCodeGen::modifyData(target_addr, ugly_insn, gen)) {
      relocation_cerr << "RelDataPatch returned false from modifyData (original address: " << std::hex<< orig << ")" <<endl;
      return false;
  }
  return true;
}

bool CFPatch::applyPLT(codeGen &gen, CodeBuffer *) {
   // We should try and keep any prefixes that were on the instruction. 
   // However... yeah, right. I'm not that good with x86. So instead
   // I'm copying the code from emitCallInstruction...
      
   if (target->type() != TargetInt::BlockTarget) {
      return false;
   }
   // And can only handle calls right now. That's a TODO...
   if (type != Call &&
       type != Jump) {
      return false;
   }

   relocation_cerr << "\t\t\t ApplyPLT..." << endl;

   Target<block_instance *> *t = static_cast<Target<block_instance *> *>(target);
   block_instance *tb = t->t();

   // Set caller in codegen structure
   gen.setFunction(const_cast<func_instance *>(func));

   // We can (for now) only jump to functions
   func_instance *callee = tb->entryOfFunc();
   if (!callee) {
      return false;
   }

   // We need a RegisterSpace for this. Amusingly,
   // we want to use the RegisterSpace corresponding to the
   // entry of the callee, as it doesn't matter what's live
   // here. 
   instPoint *calleeEntry = instPoint::funcEntry(callee);
   gen.setRegisterSpace(registerSpace::actualRegSpace(calleeEntry));

   if (type == Call) 
      gen.codeEmitter()->emitPLTCall(callee, gen);
   else if (type == Jump)
      gen.codeEmitter()->emitPLTJump(callee, gen);
   else
      assert(0);

   return true;
}

void insnCodeGen::generateLongBranch(codeGen &gen, 
                                     Address from, 
                                     Address to, 
                                     bool isCall) {
    // First, see if we can cheap out
    long disp = (to - from);
    if (ABS(disp) <= MAX_BRANCH) {
        return generateBranch(gen, disp, isCall);
    }

    // We can use a register branch via the LR or CTR, if either of them
    // is free.
    
    // Let's see if we can grab a free GPregister...
    instPoint *point = gen.point();
    if (!point) {
        // fprintf(stderr, " %s[%d] No point generateBranchViaTrap \n", FILE__, __LINE__);
        return generateBranchViaTrap(gen, from, to, isCall);
    }

    assert(point);
    
    // Could see if the codeGen has it, but right now we have assert
    // code there and we don't want to hit that.
    registerSpace *rs = registerSpace::actualRegSpace(point);
    gen.setRegisterSpace(rs);
    
    Register scratch = rs->getScratchRegister(gen, true);

    bool mustRestore = false;
    
    if (scratch == REG_NULL) { 
        // On Linux we save under the stack and hope it doesn't
        // cause problems.
        fprintf(stderr, " %s[%d] No registers generateBranchViaTrap \n", FILE__, __LINE__);
        return generateBranchViaTrap(gen, from, to, isCall);
    }
    
    // Load the destination into our scratch register
    insnCodeGen::loadImmIntoReg(gen, scratch, to);
    
    // Find out whether the LR or CTR is "dead"...
    bitArray liveRegs = point->liveRegisters();
    unsigned branchRegister = 0;
    if (liveRegs[registerSpace::lr] == false) {
        branchRegister = registerSpace::lr;
    }
    else if (liveRegs[registerSpace::ctr] == false) {
        branchRegister = registerSpace::ctr;
    }

    if (!branchRegister) {
        fprintf(stderr, " %s[%d] No branch register generateBranchViaTrap \n", FILE__, __LINE__);
        return generateBranchViaTrap(gen, from, to, isCall); 
    }
    
    assert(branchRegister);
    
    instruction moveToBr;
    moveToBr.clear();
    XFXFORM_OP_SET(moveToBr, MTSPRop);
    XFXFORM_RT_SET(moveToBr, scratch);
    if (branchRegister == registerSpace::lr) {
        XFORM_RA_SET(moveToBr, SPR_LR & 0x1f);
        XFORM_RB_SET(moveToBr, (SPR_LR >> 5) & 0x1f);
        // The two halves (top 5 bits/bottom 5 bits) are _reversed_ in this encoding. 
    }

bool IPPatch::apply(codeGen &gen, CodeBuffer *) {
  relocation_cerr << "\t\t IPPatch::apply" << endl;

  // We want to generate addr (as modified) into the appropriate location.
  // TODO get rid of the #ifdef here...

#if defined(arch_x86) || defined(arch_x86_64) 
    GET_PTR(newInsn, gen); 
    
    *newInsn = 0xE8;
    newInsn++;
    unsigned int *temp = (uint32_t *) newInsn;
    *temp = 0;
    newInsn += sizeof(uint32_t);
    SET_PTR(newInsn, gen);
    Address offset = addr - gen.currAddr() + insn->size();
    REGET_PTR(newInsn, gen);
    *newInsn = 0x81;
    newInsn++;
    *newInsn = 0x04;
    newInsn++;
    *newInsn = 0x24;
    newInsn++;
    temp =  (uint32_t *) newInsn;
    *temp = offset;
    newInsn += sizeof(uint32_t);	  

    if (type == Reg) {
      assert(reg != (Register) -1);
      // pop...
      *newInsn++ = static_cast<unsigned char>(0x58 + reg); // POP family
    }
    SET_PTR(newInsn, gen);
#else
    // For dynamic we can do this in-line
    assert(gen.addrSpace()->edit());

    // Must be in LR
    if (reg == -1) reg = registerSpace::lr;
    assert(reg == registerSpace::lr);

    instPoint *point = gen.point();
    // If we do not have a point then we have to invent one
    if (!point || 
	(point->type() != instPoint::PreInsn &&
	 point->insnAddr() != addr)) {
      point = instPoint::preInsn(func, block, addr, insn, true);
    }
    assert(point);
    
    registerSpace *rs = registerSpace::actualRegSpace(point);
    gen.setRegisterSpace(rs);
    
    int stackSize = 0;
    pdvector<Register> freeReg;
    pdvector<Register> excludeReg;
    
    Register scratchPCReg = gen.rs()->getScratchRegister(gen, true);
    excludeReg.push_back(scratchPCReg);
    Register scratchReg = gen.rs()->getScratchRegister(gen, excludeReg, true);
    
    if ((scratchPCReg == REG_NULL) && (scratchReg == REG_NULL)) {
      excludeReg.clear();
      stackSize = insnCodeGen::createStackFrame(gen, 2, freeReg, excludeReg);
      assert(stackSize == 2);
      scratchPCReg = freeReg[0];
      scratchReg = freeReg[1];
      
    } else if (scratchReg == REG_NULL && scratchPCReg != REG_NULL) {
      stackSize = insnCodeGen::createStackFrame(gen, 1, freeReg, excludeReg);
      assert(stackSize == 1);
      scratchReg = freeReg[0];
    } 
    
    //scratchPCReg == NULL && scratchReg != NULL - not a valid case 
    //since getScratchRegister works in order
    
    // relocaAddr may have moved if we added instructions to setup a new stack frame
    Address newRelocAddr = gen.currAddr();
    
    insnCodeGen::generateBranch(gen, gen.currAddr(),  gen.currAddr()+4, true); // blrl
    insnCodeGen::generateMoveFromLR(gen, scratchPCReg); // mflr
    
    Address varOffset = addr - newRelocAddr;
    gen.emitter()->emitCallRelative(scratchReg, varOffset, scratchPCReg, gen);
    insnCodeGen::generateMoveToLR(gen, scratchReg);

    if( stackSize > 0) {
      insnCodeGen::removeStackFrame(gen); 
    }
#endif
    return true;
}