vhdl.cpp

一种将c高级语言转化给VHDL的编译器

    BasicBlock *Succ = cast<BasicBlock>(SI.getOperand(i+1));
    printBranchToBlock(SI.getParent(), Succ, 2);
    if (Succ == SI.getParent()->getNext())
      Out << "    break;\n";
  }
  Out << "  }\n";
}


bool VWriter::isGotoCodeNecessary(BasicBlock *From, BasicBlock *To) {
  // If PHI nodes need copies, we need the copy code...
  if (isa<PHINode>(To->front()) ||
      From->getNext() != To)      // Not directly successor, need goto
    return true;

  // Otherwise we don't need the code.
  return false;
}

void VWriter::printBranchToBlock(BasicBlock *CurBB, BasicBlock *Succ,
                                 unsigned Indent) {
  for (BasicBlock::iterator I = Succ->begin();
       PHINode *PN = dyn_cast<PHINode>(I); ++I) {
    //  now we have to do the printing
    Out << std::string(Indent, ' ');
    Out << "  " << Mang->getValueName(I) << "__PHI_TEMPORARY = ";
    writeOperand(PN->getIncomingValue(PN->getBasicBlockIndex(CurBB)));
    Out << ";   /* for PHI node */\n";
  }

  if (CurBB->getNext() != Succ ||
      isa<InvokeInst>(CurBB->getTerminator()) ||
      isa<SwitchInst>(CurBB->getTerminator())) {
    Out << std::string(Indent, ' ') << "  goto ";
    writeOperand(Succ);
    Out << ";\n";
  }
}

// Branch instruction printing - Avoid printing out a branch to a basic block
// that immediately succeeds the current one.
//
void VWriter::visitBranchInst(BranchInst &I) {
  if (I.isConditional()) {
    if (isGotoCodeNecessary(I.getParent(), I.getSuccessor(0))) {
      Out << "  if (";
      writeOperand(I.getCondition());
      Out << ") {\n";
      
      printBranchToBlock(I.getParent(), I.getSuccessor(0), 2);
      
      if (isGotoCodeNecessary(I.getParent(), I.getSuccessor(1))) {
        Out << "  } else {\n";
        printBranchToBlock(I.getParent(), I.getSuccessor(1), 2);
      }
    } else {
      // First goto not necessary, assume second one is...
      Out << "  if (!";
      writeOperand(I.getCondition());
      Out << ") {\n";

      printBranchToBlock(I.getParent(), I.getSuccessor(1), 2);
    }

    Out << "  }\n";
  } else {
    printBranchToBlock(I.getParent(), I.getSuccessor(0), 0);
  }
  Out << "\n";
}

// PHI nodes get copied into temporary values at the end of predecessor basic
// blocks.  We now need to copy these temporary values into the REAL value for
// the PHI.
void VWriter::visitPHINode(PHINode &I) {
  writeOperand(&I);
  Out << "__PHI_TEMPORARY";
}


void VWriter::visitBinaryOperator(Instruction &I) {
  // binary instructions, shift instructions, setCond instructions.
  assert(!isa<PointerType>(I.getType()));

  // We must cast the results of binary operations which might be promoted.
  bool needsCast = false;
  if ((I.getType() == Type::UByteTy) || (I.getType() == Type::SByteTy)
      || (I.getType() == Type::UShortTy) || (I.getType() == Type::ShortTy)
      || (I.getType() == Type::FloatTy)) {
    needsCast = true;
    Out << "((";
    printType(Out, I.getType());
    Out << ")(";
  }
      
  writeOperand(I.getOperand(0));

  switch (I.getOpcode()) {
  case Instruction::Add: Out << " + "; break;
  case Instruction::Sub: Out << " - "; break;
  case Instruction::Mul: Out << "*"; break;
  case Instruction::Div: Out << "/"; break;
  case Instruction::Rem: Out << "%"; break;
  case Instruction::And: Out << " & "; break;
  case Instruction::Or: Out << " | "; break;
  case Instruction::Xor: Out << " ^ "; break;
  case Instruction::SetEQ: Out << " == "; break;
  case Instruction::SetNE: Out << " != "; break;
  case Instruction::SetLE: Out << " <= "; break;
  case Instruction::SetGE: Out << " >= "; break;
  case Instruction::SetLT: Out << " < "; break;
  case Instruction::SetGT: Out << " > "; break;
  case Instruction::Shl : Out << " << "; break;
  case Instruction::Shr : Out << " >> "; break;
  default: std::cerr << "Invalid operator type!" << I; abort();
  }

  writeOperand(I.getOperand(1));

  if (needsCast) {
    Out << "))";
  }
}

void VWriter::visitCastInst(CastInst &I) {
  if (I.getType() == Type::BoolTy) {
    Out << "(";
    writeOperand(I.getOperand(0));
    Out << " != 0)";
    return;
  }
  Out << "(";
  printType(Out, I.getType());
  Out << ")";
  if (isa<PointerType>(I.getType())&&I.getOperand(0)->getType()->isIntegral() ||
      isa<PointerType>(I.getOperand(0)->getType())&&I.getType()->isIntegral()) {
    // Avoid "cast to pointer from integer of different size" warnings
    Out << "(long)";  
  }
  
  writeOperand(I.getOperand(0));
}

void VWriter::visitSelectInst(SelectInst &I) {
  Out << "((";
  writeOperand(I.getCondition());
  Out << ") ? (";
  writeOperand(I.getTrueValue());
  Out << ") : (";
  writeOperand(I.getFalseValue());
  Out << "))";    
}


void VWriter::lowerIntrinsics(Function &F) {
  for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
    for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; )
      if (CallInst *CI = dyn_cast<CallInst>(I++))
	if (Function *F = CI->getCalledFunction())
	  switch (F->getIntrinsicID()) {
	  case Intrinsic::not_intrinsic:
	  case Intrinsic::vastart:
	  case Intrinsic::vacopy:
	  case Intrinsic::vaend:
	  case Intrinsic::returnaddress:
	  case Intrinsic::frameaddress:
	  case Intrinsic::setjmp:
	  case Intrinsic::longjmp:
	    // We directly implement these intrinsics
	    break;
	  default:
	    // All other intrinsic calls we must lower.
	    Instruction *Before = CI->getPrev();
	    IL.LowerIntrinsicCall(CI);
	    if (Before) {        // Move iterator to instruction after call
	      I = Before; ++I;
	    } else {
	      I = BB->begin();
	    }
	  }
}



void VWriter::visitCallInst(CallInst &I) {
  // Handle intrinsic function calls first...
  if (Function *F = I.getCalledFunction())
    if (Intrinsic::ID ID = (Intrinsic::ID)F->getIntrinsicID()) {
      switch (ID) {
      default: assert(0 && "Unknown LLVM intrinsic!");
      case Intrinsic::vastart: 
        Out << "0; ";
        
        Out << "va_start(*(va_list*)&" << Mang->getValueName(&I) << ", ";
        // Output the last argument to the enclosing function...
        if (I.getParent()->getParent()->arg_empty()) {
          std::cerr << "The C backend does not currently support zero "
                    << "argument varargs functions, such as '"
                    << I.getParent()->getParent()->getName() << "'!\n";
          abort();
        }
	writeOperand(--I.getParent()->getParent()->arg_end());
        Out << ")";
        return;
      case Intrinsic::vaend:
        Out << "va_end(*(va_list*)&";
        writeOperand(I.getOperand(1));
        Out << ")";
        return;
      case Intrinsic::vacopy:
        Out << "0;";
        Out << "va_copy(*(va_list*)&" << Mang->getValueName(&I) << ", ";
        Out << "*(va_list*)&";
        writeOperand(I.getOperand(1));
        Out << ")";
        return;
      case Intrinsic::returnaddress:
        Out << "__builtin_return_address(";
        writeOperand(I.getOperand(1));
        Out << ")";
        return;
      case Intrinsic::frameaddress:
        Out << "__builtin_frame_address(";
        writeOperand(I.getOperand(1));
        Out << ")";
        return;
      case Intrinsic::setjmp:
        Out << "setjmp(*(jmp_buf*)";
        writeOperand(I.getOperand(1));
        Out << ")";
        return;
      case Intrinsic::longjmp:
        Out << "longjmp(*(jmp_buf*)";
        writeOperand(I.getOperand(1));
        Out << ", ";
        writeOperand(I.getOperand(2));
        Out << ")";
        return;
      }
    }
  visitCallSite(&I);
}

void VWriter::visitCallSite(CallSite CS) {
  const PointerType  *PTy   = cast<PointerType>(CS.getCalledValue()->getType());
  const FunctionType *FTy   = cast<FunctionType>(PTy->getElementType());
  const Type         *RetTy = FTy->getReturnType();
  
  writeOperand(CS.getCalledValue());
  Out << "(";

  if (CS.arg_begin() != CS.arg_end()) {
    CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
    writeOperand(*AI);

    for (++AI; AI != AE; ++AI) {
      Out << ", ";
      writeOperand(*AI);
    }
  }
  Out << ")";
}  

void VWriter::visitMallocInst(MallocInst &I) {
  assert(0 && "lowerallocations pass didn't work!");
}

void VWriter::visitAllocaInst(AllocaInst &I) {
  Out << "(";
  printType(Out, I.getType());
  Out << ") alloca(sizeof(";
  printType(Out, I.getType()->getElementType());
  Out << ")";
  if (I.isArrayAllocation()) {
    Out << " * " ;
    writeOperand(I.getOperand(0));
  }
  Out << ")";
}

void VWriter::visitFreeInst(FreeInst &I) {
  assert(0 && "lowerallocations pass didn't work!");
}

void VWriter::printIndexingExpression(Value *Ptr, gep_type_iterator I,
                                      gep_type_iterator E) {
  bool HasImplicitAddress = false;
  // If accessing a global value with no indexing, avoid *(&GV) syndrome
  if (GlobalValue *V = dyn_cast<GlobalValue>(Ptr)) {
    HasImplicitAddress = true;
  } else if (isDirectAlloca(Ptr)) {
    HasImplicitAddress = true;
  }

  if (I == E) {
    if (!HasImplicitAddress)
      Out << "*";  // Implicit zero first argument: '*x' is equivalent to 'x[0]'

    writeOperandInternal(Ptr);
    return;
  }

  const Constant *CI = dyn_cast<Constant>(I.getOperand());
  if (HasImplicitAddress && (!CI || !CI->isNullValue()))
    Out << "(&";

  writeOperandInternal(Ptr);

  if (HasImplicitAddress && (!CI || !CI->isNullValue())) {
    Out << ")";
    HasImplicitAddress = false;  // HIA is only true if we haven't addressed yet
  }

  assert(!HasImplicitAddress || (CI && CI->isNullValue()) &&
         "Can only have implicit address with direct accessing");

  if (HasImplicitAddress) {
    ++I;
  } else if (CI && CI->isNullValue()) {
    gep_type_iterator TmpI = I; ++TmpI;

    // Print out the -> operator if possible...
    if (TmpI != E && isa<StructType>(*TmpI)) {
      Out << (HasImplicitAddress ? "." : "->");
      Out << "field" << cast<ConstantUInt>(TmpI.getOperand())->getValue();
      I = ++TmpI;
    }
  }

  for (; I != E; ++I)
    if (isa<StructType>(*I)) {
      Out << ".field" << cast<ConstantUInt>(I.getOperand())->getValue();
    } else {
      Out << "[";
      writeOperand(I.getOperand());
      Out << "]";
    }
}

void VWriter::visitLoadInst(LoadInst &I) {
  Out << "*";
  writeOperand(I.getOperand(0));
}

void VWriter::visitStoreInst(StoreInst &I) {
  Out << "*";
  writeOperand(I.getPointerOperand());
  Out << " = ";
  writeOperand(I.getOperand(0));
}

void VWriter::visitGetElementPtrInst(GetElementPtrInst &I) {
  Out << "&";
  printIndexingExpression(I.getPointerOperand(), gep_type_begin(I),
                          gep_type_end(I));
}

void VWriter::visitVANextInst(VANextInst &I) {
  Out << Mang->getValueName(I.getOperand(0));
  Out << ";  va_arg(*(va_list*)&" << Mang->getValueName(&I) << ", ";
  printType(Out, I.getArgType());
  Out << ")";  
}

void VWriter::visitVAArgInst(VAArgInst &I) {
  Out << "0;\n";
  Out << "{ va_list Tmp; va_copy(Tmp, *(va_list*)&";
  writeOperand(I.getOperand(0));
  Out << ");\n  " << Mang->getValueName(&I) << " = va_arg(Tmp, ";
  printType(Out, I.getType());
  Out << ");\n  va_end(Tmp); }";
}

//===----------------------------------------------------------------------===//
//                       External Interface declaration
//===----------------------------------------------------------------------===//

bool VTargetMachine::addPassesToEmitAssembly(PassManager &PM, std::ostream &o) {
  PM.add(createLowerGCPass());
  PM.add(createLowerAllocationsPass());
  PM.add(createLowerInvokePass());
  PM.add(new VBackendNameAllUsedStructs());
  PM.add(new VWriter(o, getIntrinsicLowering()));
  return false;
}