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//===-- 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"
namespace llvm {
class SimpleRegisterCoalescing;
class LiveDebugVariables;
class TargetRegisterInfo;
class TargetInstrInfo;
class VirtRegMap;
class MachineLoopInfo;
/// CopyRec - Representation for copy instructions in coalescer queue.
///
struct CopyRec {
MachineInstr *MI;
unsigned LoopDepth;
CopyRec(MachineInstr *mi, unsigned depth)
: MI(mi), LoopDepth(depth) {}
};
class SimpleRegisterCoalescing : public MachineFunctionPass,
public RegisterCoalescer {
MachineFunction* mf_;
MachineRegisterInfo* mri_;
const TargetMachine* tm_;
const TargetRegisterInfo* tri_;
const TargetInstrInfo* tii_;
LiveIntervals *li_;
LiveDebugVariables *ldv_;
const MachineLoopInfo* loopInfo;
AliasAnalysis *AA;
DenseMap<const TargetRegisterClass*, BitVector> allocatableRCRegs_;
/// 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) {
initializeSimpleRegisterCoalescingPass(*PassRegistry::getPassRegistry());
}
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;
}
/// print - Implement the dump method.
virtual void print(raw_ostream &O, const Module* = 0) const;
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. The output "SrcInt" will not have been modified, so we can
/// use this information below to update aliases.
bool JoinIntervals(CoalescerPair &CP);
/// 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(const CoalescerPair &CP, 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(const CoalescerPair &CP,MachineInstr *CopyMI);
/// ReMaterializeTrivialDef - If the source of a copy is defined by a trivial
/// computation, replace the copy by rematerialize the definition.
/// If PreserveSrcInt is true, make sure SrcInt is valid after the call.
bool ReMaterializeTrivialDef(LiveInterval &SrcInt, bool PreserveSrcInt,
unsigned DstReg, unsigned DstSubIdx,
MachineInstr *CopyMI);
/// shouldJoinPhys - Return true if a physreg copy should be joined.
bool shouldJoinPhys(CoalescerPair &CP);
/// isWinToJoinCrossClass - Return true if it's profitable to coalesce
/// two virtual registers from different register classes.
bool isWinToJoinCrossClass(unsigned SrcReg,
unsigned DstReg,
const TargetRegisterClass *SrcRC,
const TargetRegisterClass *DstRC,
const TargetRegisterClass *NewRC);
/// 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(const CoalescerPair &CP);
/// 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);
/// RemoveCopyFlag - If DstReg is no longer defined by CopyMI, clear the
/// VNInfo copy flag for DstReg and all aliases.
void RemoveCopyFlag(unsigned DstReg, const MachineInstr *CopyMI);
/// markAsJoined - Remember that CopyMI has already been joined.
void markAsJoined(MachineInstr *CopyMI);
};
} // End llvm namespace
#endif
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