llvm-6502/lib/Target/ARM/ARMBaseRegisterInfo.h
Jim Grosbach b58f498f75 Add register-reuse to frame-index register scavenging. When a target uses
a virtual register to eliminate a frame index, it can return that register
and the constant stored there to PEI to track. When scavenging to allocate
for those registers, PEI then tracks the last-used register and value, and
if it is still available and matches the value for the next index, reuses
the existing value rather and removes the re-materialization instructions.
Fancier tracking and adjustment of scavenger allocations to keep more
values live for longer is possible, but not yet implemented and would likely
be better done via a different, less special-purpose, approach to the
problem.

eliminateFrameIndex() is modified so the target implementations can return
the registers they wish to be tracked for reuse.

ARM Thumb1 implements and utilizes the new mechanism. All other targets are
simply modified to adjust for the changed eliminateFrameIndex() prototype.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83467 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-07 17:12:56 +00:00

149 lines
4.9 KiB
C++

//===- ARMBaseRegisterInfo.h - ARM Register Information Impl ----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the base ARM implementation of TargetRegisterInfo class.
//
//===----------------------------------------------------------------------===//
#ifndef ARMBASEREGISTERINFO_H
#define ARMBASEREGISTERINFO_H
#include "ARM.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "ARMGenRegisterInfo.h.inc"
namespace llvm {
class ARMSubtarget;
class ARMBaseInstrInfo;
class Type;
/// Register allocation hints.
namespace ARMRI {
enum {
RegPairOdd = 1,
RegPairEven = 2
};
}
/// isARMLowRegister - Returns true if the register is low register r0-r7.
///
static inline bool isARMLowRegister(unsigned Reg) {
using namespace ARM;
switch (Reg) {
case R0: case R1: case R2: case R3:
case R4: case R5: case R6: case R7:
return true;
default:
return false;
}
}
struct ARMBaseRegisterInfo : public ARMGenRegisterInfo {
protected:
const ARMBaseInstrInfo &TII;
const ARMSubtarget &STI;
/// FramePtr - ARM physical register used as frame ptr.
unsigned FramePtr;
// Can be only subclassed.
explicit ARMBaseRegisterInfo(const ARMBaseInstrInfo &tii,
const ARMSubtarget &STI);
// Return the opcode that implements 'Op', or 0 if no opcode
unsigned getOpcode(int Op) const;
public:
/// getRegisterNumbering - Given the enum value for some register, e.g.
/// ARM::LR, return the number that it corresponds to (e.g. 14). It
/// also returns true in isSPVFP if the register is a single precision
/// VFP register.
static unsigned getRegisterNumbering(unsigned RegEnum, bool *isSPVFP = 0);
/// Code Generation virtual methods...
const unsigned *getCalleeSavedRegs(const MachineFunction *MF = 0) const;
const TargetRegisterClass* const*
getCalleeSavedRegClasses(const MachineFunction *MF = 0) const;
BitVector getReservedRegs(const MachineFunction &MF) const;
const TargetRegisterClass *getPointerRegClass(unsigned Kind = 0) const;
std::pair<TargetRegisterClass::iterator,TargetRegisterClass::iterator>
getAllocationOrder(const TargetRegisterClass *RC,
unsigned HintType, unsigned HintReg,
const MachineFunction &MF) const;
unsigned ResolveRegAllocHint(unsigned Type, unsigned Reg,
const MachineFunction &MF) const;
void UpdateRegAllocHint(unsigned Reg, unsigned NewReg,
MachineFunction &MF) const;
bool hasFP(const MachineFunction &MF) const;
bool cannotEliminateFrame(const MachineFunction &MF) const;
void processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
RegScavenger *RS = NULL) const;
// Debug information queries.
unsigned getRARegister() const;
unsigned getFrameRegister(MachineFunction &MF) const;
// Exception handling queries.
unsigned getEHExceptionRegister() const;
unsigned getEHHandlerRegister() const;
int getDwarfRegNum(unsigned RegNum, bool isEH) const;
bool isLowRegister(unsigned Reg) const;
/// emitLoadConstPool - Emits a load from constpool to materialize the
/// specified immediate.
virtual void emitLoadConstPool(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI,
DebugLoc dl,
unsigned DestReg, unsigned SubIdx,
int Val,
ARMCC::CondCodes Pred = ARMCC::AL,
unsigned PredReg = 0) const;
/// Code Generation virtual methods...
virtual bool isReservedReg(const MachineFunction &MF, unsigned Reg) const;
virtual bool requiresRegisterScavenging(const MachineFunction &MF) const;
virtual bool hasReservedCallFrame(MachineFunction &MF) const;
virtual void eliminateCallFramePseudoInstr(MachineFunction &MF,
MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) const;
virtual unsigned eliminateFrameIndex(MachineBasicBlock::iterator II,
int SPAdj, int *Value = NULL,
RegScavenger *RS = NULL) const;
virtual void emitPrologue(MachineFunction &MF) const;
virtual void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const;
private:
unsigned estimateRSStackSizeLimit(MachineFunction &MF) const;
unsigned getRegisterPairEven(unsigned Reg, const MachineFunction &MF) const;
unsigned getRegisterPairOdd(unsigned Reg, const MachineFunction &MF) const;
};
} // end namespace llvm
#endif