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
;
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 const MachineLoopInfo
* loopInfo
;
50 BitVector allocatableRegs_
;
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
) {}
79 virtual void getAnalysisUsage(AnalysisUsage
&AU
) const;
80 virtual void releaseMemory();
82 /// runOnMachineFunction - pass entry point
83 virtual bool runOnMachineFunction(MachineFunction
&);
85 bool coalesceFunction(MachineFunction
&mf
, RegallocQuery
&) {
86 // This runs as an independent pass, so don't do anything.
90 /// print - Implement the dump method.
91 virtual void print(raw_ostream
&O
, const Module
* = 0) const;
94 /// joinIntervals - join compatible live intervals
97 /// CopyCoalesceInMBB - Coalesce copies in the specified MBB, putting
98 /// copies that cannot yet be coalesced into the "TryAgain" list.
99 void CopyCoalesceInMBB(MachineBasicBlock
*MBB
,
100 std::vector
<CopyRec
> &TryAgain
);
102 /// JoinCopy - Attempt to join intervals corresponding to SrcReg/DstReg,
103 /// which are the src/dst of the copy instruction CopyMI. This returns true
104 /// if the copy was successfully coalesced away. If it is not currently
105 /// possible to coalesce this interval, but it may be possible if other
106 /// things get coalesced, then it returns true by reference in 'Again'.
107 bool JoinCopy(CopyRec
&TheCopy
, bool &Again
);
109 /// JoinIntervals - Attempt to join these two intervals. On failure, this
110 /// returns false. The output "SrcInt" will not have been modified, so we can
111 /// use this information below to update aliases.
112 bool JoinIntervals(CoalescerPair
&CP
);
114 /// Return true if the two specified registers belong to different register
115 /// classes. The registers may be either phys or virt regs.
116 bool differingRegisterClasses(unsigned RegA
, unsigned RegB
) const;
118 /// AdjustCopiesBackFrom - We found a non-trivially-coalescable copy. If
119 /// the source value number is defined by a copy from the destination reg
120 /// see if we can merge these two destination reg valno# into a single
121 /// value number, eliminating a copy.
122 bool AdjustCopiesBackFrom(const CoalescerPair
&CP
, MachineInstr
*CopyMI
);
124 /// HasOtherReachingDefs - Return true if there are definitions of IntB
125 /// other than BValNo val# that can reach uses of AValno val# of IntA.
126 bool HasOtherReachingDefs(LiveInterval
&IntA
, LiveInterval
&IntB
,
127 VNInfo
*AValNo
, VNInfo
*BValNo
);
129 /// RemoveCopyByCommutingDef - We found a non-trivially-coalescable copy.
130 /// If the source value number is defined by a commutable instruction and
131 /// its other operand is coalesced to the copy dest register, see if we
132 /// can transform the copy into a noop by commuting the definition.
133 bool RemoveCopyByCommutingDef(const CoalescerPair
&CP
,MachineInstr
*CopyMI
);
135 /// TrimLiveIntervalToLastUse - If there is a last use in the same basic
136 /// block as the copy instruction, trim the ive interval to the last use
138 bool TrimLiveIntervalToLastUse(SlotIndex CopyIdx
,
139 MachineBasicBlock
*CopyMBB
,
140 LiveInterval
&li
, const LiveRange
*LR
);
142 /// ReMaterializeTrivialDef - If the source of a copy is defined by a trivial
143 /// computation, replace the copy by rematerialize the definition.
144 bool ReMaterializeTrivialDef(LiveInterval
&SrcInt
, unsigned DstReg
,
145 unsigned DstSubIdx
, MachineInstr
*CopyMI
);
147 /// isWinToJoinCrossClass - Return true if it's profitable to coalesce
148 /// two virtual registers from different register classes.
149 bool isWinToJoinCrossClass(unsigned SrcReg
,
151 const TargetRegisterClass
*SrcRC
,
152 const TargetRegisterClass
*DstRC
,
153 const TargetRegisterClass
*NewRC
);
155 /// UpdateRegDefsUses - Replace all defs and uses of SrcReg to DstReg and
156 /// update the subregister number if it is not zero. If DstReg is a
157 /// physical register and the existing subregister number of the def / use
158 /// being updated is not zero, make sure to set it to the correct physical
160 void UpdateRegDefsUses(const CoalescerPair
&CP
);
162 /// ShortenDeadCopyLiveRange - Shorten a live range defined by a dead copy.
163 /// Return true if live interval is removed.
164 bool ShortenDeadCopyLiveRange(LiveInterval
&li
, MachineInstr
*CopyMI
);
166 /// ShortenDeadCopyLiveRange - Shorten a live range as it's artificially
167 /// extended by a dead copy. Mark the last use (if any) of the val# as kill
168 /// as ends the live range there. If there isn't another use, then this
169 /// live range is dead. Return true if live interval is removed.
170 bool ShortenDeadCopySrcLiveRange(LiveInterval
&li
, MachineInstr
*CopyMI
);
172 /// RemoveDeadDef - If a def of a live interval is now determined dead,
173 /// remove the val# it defines. If the live interval becomes empty, remove
175 bool RemoveDeadDef(LiveInterval
&li
, MachineInstr
*DefMI
);
177 /// RemoveCopyFlag - If DstReg is no longer defined by CopyMI, clear the
178 /// VNInfo copy flag for DstReg and all aliases.
179 void RemoveCopyFlag(unsigned DstReg
, const MachineInstr
*CopyMI
);
181 /// lastRegisterUse - Returns the last use of the specific register between
182 /// cycles Start and End or NULL if there are no uses.
183 MachineOperand
*lastRegisterUse(SlotIndex Start
, SlotIndex End
,
184 unsigned Reg
, SlotIndex
&LastUseIdx
) const;
187 } // End llvm namespace