llvm-6502/lib/CodeGen/SimpleRegisterCoalescing.h
2009-01-05 17:59:02 +00:00

286 lines
12 KiB
C++

//===-- SimpleRegisterCoalescing.h - Register Coalescing --------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements a simple register copy coalescing phase.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_SIMPLE_REGISTER_COALESCING_H
#define LLVM_CODEGEN_SIMPLE_REGISTER_COALESCING_H
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/RegisterCoalescer.h"
#include "llvm/ADT/BitVector.h"
#include <queue>
namespace llvm {
class SimpleRegisterCoalescing;
class LiveVariables;
class TargetRegisterInfo;
class TargetInstrInfo;
class VirtRegMap;
class MachineLoopInfo;
/// CopyRec - Representation for copy instructions in coalescer queue.
///
struct CopyRec {
MachineInstr *MI;
unsigned LoopDepth;
bool isBackEdge;
CopyRec(MachineInstr *mi, unsigned depth, bool be)
: MI(mi), LoopDepth(depth), isBackEdge(be) {};
};
template<class SF> class JoinPriorityQueue;
/// CopyRecSort - Sorting function for coalescer queue.
///
struct CopyRecSort : public std::binary_function<CopyRec,CopyRec,bool> {
JoinPriorityQueue<CopyRecSort> *JPQ;
explicit CopyRecSort(JoinPriorityQueue<CopyRecSort> *jpq) : JPQ(jpq) {}
CopyRecSort(const CopyRecSort &RHS) : JPQ(RHS.JPQ) {}
bool operator()(CopyRec left, CopyRec right) const;
};
/// JoinQueue - A priority queue of copy instructions the coalescer is
/// going to process.
template<class SF>
class JoinPriorityQueue {
SimpleRegisterCoalescing *Rc;
std::priority_queue<CopyRec, std::vector<CopyRec>, SF> Queue;
public:
explicit JoinPriorityQueue(SimpleRegisterCoalescing *rc)
: Rc(rc), Queue(SF(this)) {}
bool empty() const { return Queue.empty(); }
void push(CopyRec R) { Queue.push(R); }
CopyRec pop() {
if (empty()) return CopyRec(0, 0, false);
CopyRec R = Queue.top();
Queue.pop();
return R;
}
// Callbacks to SimpleRegisterCoalescing.
unsigned getRepIntervalSize(unsigned Reg);
};
class SimpleRegisterCoalescing : public MachineFunctionPass,
public RegisterCoalescer {
MachineFunction* mf_;
MachineRegisterInfo* mri_;
const TargetMachine* tm_;
const TargetRegisterInfo* tri_;
const TargetInstrInfo* tii_;
LiveIntervals *li_;
const MachineLoopInfo* loopInfo;
BitVector allocatableRegs_;
DenseMap<const TargetRegisterClass*, BitVector> allocatableRCRegs_;
/// JoinQueue - A priority queue of copy instructions the coalescer is
/// going to process.
JoinPriorityQueue<CopyRecSort> *JoinQueue;
/// JoinedCopies - Keep track of copies eliminated due to coalescing.
///
SmallPtrSet<MachineInstr*, 32> JoinedCopies;
/// ReMatCopies - Keep track of copies eliminated due to remat.
///
SmallPtrSet<MachineInstr*, 32> ReMatCopies;
/// ReMatDefs - Keep track of definition instructions which have
/// been remat'ed.
SmallPtrSet<MachineInstr*, 8> ReMatDefs;
public:
static char ID; // Pass identifcation, replacement for typeid
SimpleRegisterCoalescing() : MachineFunctionPass(&ID) {}
struct InstrSlots {
enum {
LOAD = 0,
USE = 1,
DEF = 2,
STORE = 3,
NUM = 4
};
};
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
virtual void releaseMemory();
/// runOnMachineFunction - pass entry point
virtual bool runOnMachineFunction(MachineFunction&);
bool coalesceFunction(MachineFunction &mf, RegallocQuery &) {
// This runs as an independent pass, so don't do anything.
return false;
};
/// getRepIntervalSize - Called from join priority queue sorting function.
/// It returns the size of the interval that represent the given register.
unsigned getRepIntervalSize(unsigned Reg) {
if (!li_->hasInterval(Reg))
return 0;
return li_->getApproximateInstructionCount(li_->getInterval(Reg)) *
LiveIntervals::InstrSlots::NUM;
}
/// print - Implement the dump method.
virtual void print(std::ostream &O, const Module* = 0) const;
void print(std::ostream *O, const Module* M = 0) const {
if (O) print(*O, M);
}
private:
/// joinIntervals - join compatible live intervals
void joinIntervals();
/// CopyCoalesceInMBB - Coalesce copies in the specified MBB, putting
/// copies that cannot yet be coalesced into the "TryAgain" list.
void CopyCoalesceInMBB(MachineBasicBlock *MBB,
std::vector<CopyRec> &TryAgain);
/// JoinCopy - Attempt to join intervals corresponding to SrcReg/DstReg,
/// which are the src/dst of the copy instruction CopyMI. This returns true
/// if the copy was successfully coalesced away. If it is not currently
/// possible to coalesce this interval, but it may be possible if other
/// things get coalesced, then it returns true by reference in 'Again'.
bool JoinCopy(CopyRec &TheCopy, bool &Again);
/// JoinIntervals - Attempt to join these two intervals. On failure, this
/// returns false. Otherwise, if one of the intervals being joined is a
/// physreg, this method always canonicalizes DestInt to be it. The output
/// "SrcInt" will not have been modified, so we can use this information
/// below to update aliases.
bool JoinIntervals(LiveInterval &LHS, LiveInterval &RHS, bool &Swapped);
/// SimpleJoin - Attempt to join the specified interval into this one. The
/// caller of this method must guarantee that the RHS only contains a single
/// value number and that the RHS is not defined by a copy from this
/// interval. This returns false if the intervals are not joinable, or it
/// joins them and returns true.
bool SimpleJoin(LiveInterval &LHS, LiveInterval &RHS);
/// Return true if the two specified registers belong to different register
/// classes. The registers may be either phys or virt regs. In the
/// case where both registers are virtual registers, it would also returns
/// true by reference the RegB register class in SubRC if it is a subset of
/// RegA's register class.
bool differingRegisterClasses(unsigned RegA, unsigned RegB,
const TargetRegisterClass *&SubRC) const;
/// AdjustCopiesBackFrom - We found a non-trivially-coalescable copy. If
/// the source value number is defined by a copy from the destination reg
/// see if we can merge these two destination reg valno# into a single
/// value number, eliminating a copy.
bool AdjustCopiesBackFrom(LiveInterval &IntA, LiveInterval &IntB,
MachineInstr *CopyMI);
/// HasOtherReachingDefs - Return true if there are definitions of IntB
/// other than BValNo val# that can reach uses of AValno val# of IntA.
bool HasOtherReachingDefs(LiveInterval &IntA, LiveInterval &IntB,
VNInfo *AValNo, VNInfo *BValNo);
/// RemoveCopyByCommutingDef - We found a non-trivially-coalescable copy.
/// If the source value number is defined by a commutable instruction and
/// its other operand is coalesced to the copy dest register, see if we
/// can transform the copy into a noop by commuting the definition.
bool RemoveCopyByCommutingDef(LiveInterval &IntA, LiveInterval &IntB,
MachineInstr *CopyMI);
bool ReMaterializeTrivialDef(LiveInterval &SrcInt, unsigned DstReg,
MachineInstr *CopyMI);
/// TurnCopyIntoImpDef - If source of the specified copy is an implicit def,
/// turn the copy into an implicit def.
bool TurnCopyIntoImpDef(MachineBasicBlock::iterator &I,
MachineBasicBlock *MBB,
unsigned DstReg, unsigned SrcReg);
/// CanCoalesceWithImpDef - Returns true if the specified copy instruction
/// from an implicit def to another register can be coalesced away.
bool CanCoalesceWithImpDef(MachineInstr *CopyMI,
LiveInterval &li, LiveInterval &ImpLi) const;
/// RemoveCopiesFromValNo - The specified value# is defined by an implicit
/// def and it is being removed. Turn all copies from this value# into
/// identity copies so they will be removed.
void RemoveCopiesFromValNo(LiveInterval &li, VNInfo *VNI);
/// isProfitableToCoalesceToSubRC - Given that register class of DstReg is
/// a subset of the register class of SrcReg, return true if it's profitable
/// to coalesce the two registers.
bool isProfitableToCoalesceToSubRC(unsigned SrcReg, unsigned DstReg,
MachineBasicBlock *MBB);
/// HasIncompatibleSubRegDefUse - If we are trying to coalesce a virtual
/// register with a physical register, check if any of the virtual register
/// operand is a sub-register use or def. If so, make sure it won't result
/// in an illegal extract_subreg or insert_subreg instruction.
bool HasIncompatibleSubRegDefUse(MachineInstr *CopyMI,
unsigned VirtReg, unsigned PhysReg);
/// RangeIsDefinedByCopyFromReg - Return true if the specified live range of
/// the specified live interval is defined by a copy from the specified
/// register.
bool RangeIsDefinedByCopyFromReg(LiveInterval &li, LiveRange *LR,
unsigned Reg);
/// isBackEdgeCopy - Return true if CopyMI is a back edge copy.
///
bool isBackEdgeCopy(MachineInstr *CopyMI, unsigned DstReg) const;
/// UpdateRegDefsUses - Replace all defs and uses of SrcReg to DstReg and
/// update the subregister number if it is not zero. If DstReg is a
/// physical register and the existing subregister number of the def / use
/// being updated is not zero, make sure to set it to the correct physical
/// subregister.
void UpdateRegDefsUses(unsigned SrcReg, unsigned DstReg, unsigned SubIdx);
/// RemoveDeadImpDef - Remove implicit_def instructions which are
/// "re-defining" registers due to insert_subreg coalescing. e.g.
void RemoveDeadImpDef(unsigned Reg, LiveInterval &LI);
/// RemoveUnnecessaryKills - Remove kill markers that are no longer accurate
/// due to live range lengthening as the result of coalescing.
void RemoveUnnecessaryKills(unsigned Reg, LiveInterval &LI);
/// ShortenDeadCopyLiveRange - Shorten a live range defined by a dead copy.
/// Return true if live interval is removed.
bool ShortenDeadCopyLiveRange(LiveInterval &li, MachineInstr *CopyMI);
/// ShortenDeadCopyLiveRange - Shorten a live range as it's artificially
/// extended by a dead copy. Mark the last use (if any) of the val# as kill
/// as ends the live range there. If there isn't another use, then this
/// live range is dead. Return true if live interval is removed.
bool ShortenDeadCopySrcLiveRange(LiveInterval &li, MachineInstr *CopyMI);
/// RemoveDeadDef - If a def of a live interval is now determined dead,
/// remove the val# it defines. If the live interval becomes empty, remove
/// it as well.
bool RemoveDeadDef(LiveInterval &li, MachineInstr *DefMI);
/// lastRegisterUse - Returns the last use of the specific register between
/// cycles Start and End or NULL if there are no uses.
MachineOperand *lastRegisterUse(unsigned Start, unsigned End, unsigned Reg,
unsigned &LastUseIdx) const;
void printRegName(unsigned reg) const;
};
} // End llvm namespace
#endif