llvm-mirror/lib/Target/TargetMachine.cpp

//===-- TargetMachine.cpp - General Target Information ---------------------==//
//
// This file describes the general parts of a Target machine.
// This file also implements the InstInfo interface as well...
//
//===----------------------------------------------------------------------===//

#include "llvm/Target/MachineInstrInfo.h"
#include "llvm/DerivedTypes.h"

//---------------------------------------------------------------------------
// class TargetMachine
// 
// Purpose:
//   Machine description.
// 
//---------------------------------------------------------------------------


// function TargetMachine::findOptimalStorageSize 
// 
// Purpose:
//   This default implementation assumes that all sub-word data items use
//   space equal to optSizeForSubWordData, and all other primitive data
//   items use space according to the type.
//   
unsigned int
TargetMachine::findOptimalStorageSize(const Type* ty) const
{
  switch(ty->getPrimitiveID())
    {
    case Type::BoolTyID:
    case Type::UByteTyID:
    case Type::SByteTyID:     
    case Type::UShortTyID:
    case Type::ShortTyID:     
      return optSizeForSubWordData;
    
    default:
      return DataLayout.getTypeSize(ty);
    }
}


//---------------------------------------------------------------------------
// class MachineInstructionInfo
//	Interface to description of machine instructions
//---------------------------------------------------------------------------


/*ctor*/
MachineInstrInfo::MachineInstrInfo(const MachineInstrDescriptor* _desc,
				   unsigned int _descSize,
				   unsigned int _numRealOpCodes)
  : desc(_desc), descSize(_descSize), numRealOpCodes(_numRealOpCodes)
{
  // FIXME: TargetInstrDescriptors should not be global
  assert(TargetInstrDescriptors == NULL && desc != NULL);
  TargetInstrDescriptors = desc;	// initialize global variable
}  


MachineInstrInfo::~MachineInstrInfo()
{
  TargetInstrDescriptors = NULL;	// reset global variable
}


bool
MachineInstrInfo::constantFitsInImmedField(MachineOpCode opCode,
					   int64_t intValue) const
{
  // First, check if opCode has an immed field.
  bool isSignExtended;
  uint64_t maxImmedValue = maxImmedConstant(opCode, isSignExtended);
  if (maxImmedValue != 0)
    {
      // Now check if the constant fits
      if (intValue <= (int64_t) maxImmedValue &&
	  intValue >= -((int64_t) maxImmedValue+1))
	return true;
    }
  
  return false;
}