lib/Target/Mips/MipsMachineFunction.h

//===-- MipsMachineFunctionInfo.h - Private data used for Mips ----*- C++ -*-=//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares the Mips specific subclass of MachineFunctionInfo.
//
//===----------------------------------------------------------------------===//

#ifndef MIPS_MACHINE_FUNCTION_INFO_H
#define MIPS_MACHINE_FUNCTION_INFO_H

#include <utility>
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/VectorExtras.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFrameInfo.h"

namespace llvm {

/// MipsFunctionInfo - This class is derived from MachineFunction private
/// Mips target-specific information for each MachineFunction.
class MipsFunctionInfo : public MachineFunctionInfo {

private:
  /// At each function entry, two special bitmask directives must be emitted
  /// to help debugging, for CPU and FPU callee saved registers. Both need
  /// the negative offset from the final stack size and its higher registers
  /// location on the stack.
  int CPUTopSavedRegOff;
  int FPUTopSavedRegOff;

  /// MipsFIHolder - Holds a FrameIndex and it's Stack Pointer Offset
  struct MipsFIHolder {

    int FI;
    int SPOffset;

    MipsFIHolder(int FrameIndex, int StackPointerOffset)
      : FI(FrameIndex), SPOffset(StackPointerOffset) {}
  };

  /// When PIC is used the GP must be saved on the stack on the function
  /// prologue and must be reloaded from this stack location after every
  /// call. A reference to its stack location and frame index must be kept
  /// to be used on emitPrologue and processFunctionBeforeFrameFinalized.
  MipsFIHolder GPHolder;

  /// On LowerFormalArguments the stack size is unknown, so the Stack
  /// Pointer Offset calculation of "not in register arguments" must be
  /// postponed to emitPrologue.
  SmallVector<MipsFIHolder, 16> FnLoadArgs;
  bool HasLoadArgs;

  // When VarArgs, we must write registers back to caller stack, preserving
  // on register arguments. Since the stack size is unknown on
  // LowerFormalArguments, the Stack Pointer Offset calculation must be
  // postponed to emitPrologue.
  SmallVector<MipsFIHolder, 4> FnStoreVarArgs;
  bool HasStoreVarArgs;

  /// SRetReturnReg - Some subtargets require that sret lowering includes
  /// returning the value of the returned struct in a register. This field
  /// holds the virtual register into which the sret argument is passed.
  unsigned SRetReturnReg;

  /// GlobalBaseReg - keeps track of the virtual register initialized for
  /// use as the global base register. This is used for PIC in some PIC
  /// relocation models.
  unsigned GlobalBaseReg;

  /// VarArgsFrameIndex - FrameIndex for start of varargs area.
  int VarArgsFrameIndex;

  // Range of frame object indices.
  // InArgFIRange: Range of indices of all frame objects created during call to
  //               LowerFormalArguments.
  // OutArgFIRange: Range of indices of all frame objects created during call to
  //                LowerCall except for the frame object for restoring $gp. 
  std::pair<int, int> InArgFIRange, OutArgFIRange;
  int GPFI; // Index of the frame object for restoring $gp 
  bool HasCall; // True if function has a function call.
public:
  MipsFunctionInfo(MachineFunction& MF)
  : CPUTopSavedRegOff(0),
    FPUTopSavedRegOff(0), GPHolder(-1,-1), HasLoadArgs(false),
    HasStoreVarArgs(false), SRetReturnReg(0), GlobalBaseReg(0),
    VarArgsFrameIndex(0), InArgFIRange(std::make_pair(-1, 0)),
    OutArgFIRange(std::make_pair(-1, 0)), GPFI(0), HasCall(false)
  {}

  int getCPUTopSavedRegOff() const { return CPUTopSavedRegOff; }
  void setCPUTopSavedRegOff(int Off) { CPUTopSavedRegOff = Off; }

  int getFPUTopSavedRegOff() const { return FPUTopSavedRegOff; }
  void setFPUTopSavedRegOff(int Off) { FPUTopSavedRegOff = Off; }

  bool isInArgFI(int FI) const {
    return FI <= InArgFIRange.first && FI >= InArgFIRange.second;
  }
  void setLastInArgFI(int FI) { InArgFIRange.second = FI; }

  bool isOutArgFI(int FI) const { 
    return FI <= OutArgFIRange.first && FI >= OutArgFIRange.second;
  }
  void extendOutArgFIRange(int FirstFI, int LastFI) {
    if (!OutArgFIRange.second)
      // this must be the first time this function was called.
      OutArgFIRange.first = FirstFI;
    OutArgFIRange.second = LastFI;
  }

  int getGPStackOffset() const { return GPHolder.SPOffset; }
  int getGPFI() const { return GPHolder.FI; }
  void setGPStackOffset(int Off) { GPHolder.SPOffset = Off; }
  void setGPFI(int FI) { GPHolder.FI = FI; }
  bool needGPSaveRestore() const { return GPHolder.SPOffset != -1; }
  bool isGPFI(int FI) const { return GPFI && GPFI == FI; }

  bool hasLoadArgs() const { return HasLoadArgs; }
  bool hasStoreVarArgs() const { return HasStoreVarArgs; }

  void recordLoadArgsFI(int FI, int SPOffset) {
    if (!HasLoadArgs) HasLoadArgs=true;
    FnLoadArgs.push_back(MipsFIHolder(FI, SPOffset));
  }
  void recordStoreVarArgsFI(int FI, int SPOffset) {
    if (!HasStoreVarArgs) HasStoreVarArgs=true;
    FnStoreVarArgs.push_back(MipsFIHolder(FI, SPOffset));
  }

  void adjustLoadArgsFI(MachineFrameInfo *MFI) const {
    if (!hasLoadArgs()) return;
    for (unsigned i = 0, e = FnLoadArgs.size(); i != e; ++i)
      MFI->setObjectOffset( FnLoadArgs[i].FI, FnLoadArgs[i].SPOffset );
  }
  void adjustStoreVarArgsFI(MachineFrameInfo *MFI) const {
    if (!hasStoreVarArgs()) return;
    for (unsigned i = 0, e = FnStoreVarArgs.size(); i != e; ++i)
      MFI->setObjectOffset( FnStoreVarArgs[i].FI, FnStoreVarArgs[i].SPOffset );
  }

  unsigned getSRetReturnReg() const { return SRetReturnReg; }
  void setSRetReturnReg(unsigned Reg) { SRetReturnReg = Reg; }

  unsigned getGlobalBaseReg() const { return GlobalBaseReg; }
  void setGlobalBaseReg(unsigned Reg) { GlobalBaseReg = Reg; }

  int getVarArgsFrameIndex() const { return VarArgsFrameIndex; }
  void setVarArgsFrameIndex(int Index) { VarArgsFrameIndex = Index; }

  bool hasCall() const { return HasCall; }
  void setHasCall() { HasCall = true; }
};

} // end of namespace llvm

#endif // MIPS_MACHINE_FUNCTION_INFO_H