Vendor import of llvm trunk r135360:

http://llvm.org/svn/llvm-project/llvm/trunk@135360

1 files changed, 243 insertions, 0 deletions

diff --git a/lib/CodeGen/RegisterCoalescer.h b/lib/CodeGen/RegisterCoalescer.h
new file mode 100644
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+//===-- 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