1 //===-- SimpleRegisterCoalescing.h - Register Coalescing --------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements a simple register copy coalescing phase.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CODEGEN_SIMPLE_REGISTER_COALESCING_H
15 #define LLVM_CODEGEN_SIMPLE_REGISTER_COALESCING_H
17 #include "llvm/CodeGen/MachineFunctionPass.h"
18 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
19 #include "llvm/CodeGen/RegisterCoalescer.h"
20 #include "llvm/ADT/BitVector.h"
23 class SimpleRegisterCoalescing;
24 class LiveDebugVariables;
25 class TargetRegisterInfo;
26 class TargetInstrInfo;
28 class MachineLoopInfo;
30 /// CopyRec - Representation for copy instructions in coalescer queue.
35 CopyRec(MachineInstr *mi, unsigned depth)
36 : MI(mi), LoopDepth(depth) {}
39 class SimpleRegisterCoalescing : public MachineFunctionPass,
40 public RegisterCoalescer {
42 MachineRegisterInfo* mri_;
43 const TargetMachine* tm_;
44 const TargetRegisterInfo* tri_;
45 const TargetInstrInfo* tii_;
47 LiveDebugVariables *ldv_;
48 const MachineLoopInfo* loopInfo;
51 DenseMap<const TargetRegisterClass*, BitVector> allocatableRCRegs_;
53 /// JoinedCopies - Keep track of copies eliminated due to coalescing.
55 SmallPtrSet<MachineInstr*, 32> JoinedCopies;
57 /// ReMatCopies - Keep track of copies eliminated due to remat.
59 SmallPtrSet<MachineInstr*, 32> ReMatCopies;
61 /// ReMatDefs - Keep track of definition instructions which have
63 SmallPtrSet<MachineInstr*, 8> ReMatDefs;
66 static char ID; // Pass identifcation, replacement for typeid
67 SimpleRegisterCoalescing() : MachineFunctionPass(ID) {
68 initializeSimpleRegisterCoalescingPass(*PassRegistry::getPassRegistry());
71 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
72 virtual void releaseMemory();
74 /// runOnMachineFunction - pass entry point
75 virtual bool runOnMachineFunction(MachineFunction&);
77 bool coalesceFunction(MachineFunction &mf, RegallocQuery &) {
78 // This runs as an independent pass, so don't do anything.
82 /// print - Implement the dump method.
83 virtual void print(raw_ostream &O, const Module* = 0) const;
86 /// joinIntervals - join compatible live intervals
89 /// CopyCoalesceInMBB - Coalesce copies in the specified MBB, putting
90 /// copies that cannot yet be coalesced into the "TryAgain" list.
91 void CopyCoalesceInMBB(MachineBasicBlock *MBB,
92 std::vector<CopyRec> &TryAgain);
94 /// JoinCopy - Attempt to join intervals corresponding to SrcReg/DstReg,
95 /// which are the src/dst of the copy instruction CopyMI. This returns true
96 /// if the copy was successfully coalesced away. If it is not currently
97 /// possible to coalesce this interval, but it may be possible if other
98 /// things get coalesced, then it returns true by reference in 'Again'.
99 bool JoinCopy(CopyRec &TheCopy, bool &Again);
101 /// JoinIntervals - Attempt to join these two intervals. On failure, this
102 /// returns false. The output "SrcInt" will not have been modified, so we can
103 /// use this information below to update aliases.
104 bool JoinIntervals(CoalescerPair &CP);
106 /// AdjustCopiesBackFrom - We found a non-trivially-coalescable copy. If
107 /// the source value number is defined by a copy from the destination reg
108 /// see if we can merge these two destination reg valno# into a single
109 /// value number, eliminating a copy.
110 bool AdjustCopiesBackFrom(const CoalescerPair &CP, MachineInstr *CopyMI);
112 /// HasOtherReachingDefs - Return true if there are definitions of IntB
113 /// other than BValNo val# that can reach uses of AValno val# of IntA.
114 bool HasOtherReachingDefs(LiveInterval &IntA, LiveInterval &IntB,
115 VNInfo *AValNo, VNInfo *BValNo);
117 /// RemoveCopyByCommutingDef - We found a non-trivially-coalescable copy.
118 /// If the source value number is defined by a commutable instruction and
119 /// its other operand is coalesced to the copy dest register, see if we
120 /// can transform the copy into a noop by commuting the definition.
121 bool RemoveCopyByCommutingDef(const CoalescerPair &CP,MachineInstr *CopyMI);
123 /// ReMaterializeTrivialDef - If the source of a copy is defined by a trivial
124 /// computation, replace the copy by rematerialize the definition.
125 /// If PreserveSrcInt is true, make sure SrcInt is valid after the call.
126 bool ReMaterializeTrivialDef(LiveInterval &SrcInt, bool PreserveSrcInt,
127 unsigned DstReg, unsigned DstSubIdx,
128 MachineInstr *CopyMI);
130 /// shouldJoinPhys - Return true if a physreg copy should be joined.
131 bool shouldJoinPhys(CoalescerPair &CP);
133 /// isWinToJoinCrossClass - Return true if it's profitable to coalesce
134 /// two virtual registers from different register classes.
135 bool isWinToJoinCrossClass(unsigned SrcReg,
137 const TargetRegisterClass *SrcRC,
138 const TargetRegisterClass *DstRC,
139 const TargetRegisterClass *NewRC);
141 /// UpdateRegDefsUses - Replace all defs and uses of SrcReg to DstReg and
142 /// update the subregister number if it is not zero. If DstReg is a
143 /// physical register and the existing subregister number of the def / use
144 /// being updated is not zero, make sure to set it to the correct physical
146 void UpdateRegDefsUses(const CoalescerPair &CP);
148 /// RemoveDeadDef - If a def of a live interval is now determined dead,
149 /// remove the val# it defines. If the live interval becomes empty, remove
151 bool RemoveDeadDef(LiveInterval &li, MachineInstr *DefMI);
153 /// RemoveCopyFlag - If DstReg is no longer defined by CopyMI, clear the
154 /// VNInfo copy flag for DstReg and all aliases.
155 void RemoveCopyFlag(unsigned DstReg, const MachineInstr *CopyMI);
157 /// markAsJoined - Remember that CopyMI has already been joined.
158 void markAsJoined(MachineInstr *CopyMI);
161 } // End llvm namespace