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Diffstat (limited to 'contrib/llvm/lib/CodeGen/RegisterCoalescer.h')
| -rw-r--r-- | contrib/llvm/lib/CodeGen/RegisterCoalescer.h | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/contrib/llvm/lib/CodeGen/RegisterCoalescer.h b/contrib/llvm/lib/CodeGen/RegisterCoalescer.h new file mode 100644 index 0000000..4131d91 --- /dev/null +++ b/contrib/llvm/lib/CodeGen/RegisterCoalescer.h @@ -0,0 +1,243 @@ +//===-- RegisterCoalescer.h - Register Coalescing Interface ------*- 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 abstract interface for register coalescers, +// allowing them to interact with and query register allocators. +// +//===----------------------------------------------------------------------===// + +#include "RegisterClassInfo.h" +#include "llvm/Support/IncludeFile.h" +#include "llvm/CodeGen/LiveInterval.h" +#include "llvm/ADT/SmallPtrSet.h" + +#ifndef LLVM_CODEGEN_REGISTER_COALESCER_H +#define LLVM_CODEGEN_REGISTER_COALESCER_H + +namespace llvm { + + class MachineFunction; + class RegallocQuery; + class AnalysisUsage; + class MachineInstr; + class TargetRegisterInfo; + class TargetRegisterClass; + class TargetInstrInfo; + class LiveDebugVariables; + class VirtRegMap; + class MachineLoopInfo; + + class CoalescerPair; + + /// An abstract interface for register coalescers. Coalescers must + /// implement this interface to be part of the coalescer analysis + /// group. + class RegisterCoalescer : public MachineFunctionPass { + MachineFunction* mf_; + MachineRegisterInfo* mri_; + const TargetMachine* tm_; + const TargetRegisterInfo* tri_; + const TargetInstrInfo* tii_; + LiveIntervals *li_; + LiveDebugVariables *ldv_; + const MachineLoopInfo* loopInfo; + AliasAnalysis *AA; + RegisterClassInfo RegClassInfo; + + /// 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; + + /// 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<MachineInstr*> &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(MachineInstr *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); + + public: + static char ID; // Class identification, replacement for typeinfo + RegisterCoalescer() : MachineFunctionPass(ID) { + initializeRegisterCoalescerPass(*PassRegistry::getPassRegistry()); + } + + /// Register allocators must call this from their own + /// getAnalysisUsage to cover the case where the coalescer is not + /// a Pass in the proper sense and isn't managed by PassManager. + /// PassManager needs to know which analyses to make available and + /// which to invalidate when running the register allocator or any + /// pass that might call coalescing. The long-term solution is to + /// allow hierarchies of PassManagers. + virtual void getAnalysisUsage(AnalysisUsage &AU) const; + + virtual void releaseMemory(); + + /// runOnMachineFunction - pass entry point + virtual bool runOnMachineFunction(MachineFunction&); + + /// print - Implement the dump method. + virtual void print(raw_ostream &O, const Module* = 0) const; + }; + + /// CoalescerPair - A helper class for register coalescers. When deciding if + /// two registers can be coalesced, CoalescerPair can determine if a copy + /// instruction would become an identity copy after coalescing. + class CoalescerPair { + const TargetInstrInfo &tii_; + const TargetRegisterInfo &tri_; + + /// dstReg_ - The register that will be left after coalescing. It can be a + /// virtual or physical register. + unsigned dstReg_; + + /// srcReg_ - the virtual register that will be coalesced into dstReg. + unsigned srcReg_; + + /// subReg_ - The subregister index of srcReg in dstReg_. It is possible the + /// coalesce srcReg_ into a subreg of the larger dstReg_ when dstReg_ is a + /// virtual register. + unsigned subIdx_; + + /// partial_ - True when the original copy was a partial subregister copy. + bool partial_; + + /// crossClass_ - True when both regs are virtual, and newRC is constrained. + bool crossClass_; + + /// flipped_ - True when DstReg and SrcReg are reversed from the oriignal copy + /// instruction. + bool flipped_; + + /// newRC_ - The register class of the coalesced register, or NULL if dstReg_ + /// is a physreg. + const TargetRegisterClass *newRC_; + + public: + CoalescerPair(const TargetInstrInfo &tii, const TargetRegisterInfo &tri) + : tii_(tii), tri_(tri), dstReg_(0), srcReg_(0), subIdx_(0), + partial_(false), crossClass_(false), flipped_(false), newRC_(0) {} + + /// setRegisters - set registers to match the copy instruction MI. Return + /// false if MI is not a coalescable copy instruction. + bool setRegisters(const MachineInstr*); + + /// flip - Swap srcReg_ and dstReg_. Return false if swapping is impossible + /// because dstReg_ is a physical register, or subIdx_ is set. + bool flip(); + + /// isCoalescable - Return true if MI is a copy instruction that will become + /// an identity copy after coalescing. + bool isCoalescable(const MachineInstr*) const; + + /// isPhys - Return true if DstReg is a physical register. + bool isPhys() const { return !newRC_; } + + /// isPartial - Return true if the original copy instruction did not copy the + /// full register, but was a subreg operation. + bool isPartial() const { return partial_; } + + /// isCrossClass - Return true if DstReg is virtual and NewRC is a smaller register class than DstReg's. + bool isCrossClass() const { return crossClass_; } + + /// isFlipped - Return true when getSrcReg is the register being defined by + /// the original copy instruction. + bool isFlipped() const { return flipped_; } + + /// getDstReg - Return the register (virtual or physical) that will remain + /// after coalescing. + unsigned getDstReg() const { return dstReg_; } + + /// getSrcReg - Return the virtual register that will be coalesced away. + unsigned getSrcReg() const { return srcReg_; } + + /// getSubIdx - Return the subregister index in DstReg that SrcReg will be + /// coalesced into, or 0. + unsigned getSubIdx() const { return subIdx_; } + + /// getNewRC - Return the register class of the coalesced register. + const TargetRegisterClass *getNewRC() const { return newRC_; } + }; +} // End llvm namespace + +#endif |
