LLVM  12.0.0git
LiveIntervalCalc.h
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1 //===- LiveIntervalCalc.h - Calculate live intervals -----------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // The LiveIntervalCalc class is an extension of LiveRangeCalc targeted to the
10 // computation and modification of the LiveInterval variants of LiveRanges.
11 // LiveIntervals are meant to track liveness of registers and stack slots and
12 // LiveIntervalCalc adds to LiveRangeCalc all the machinery requied to
13 // construct the liveness of virtual registers tracked by a LiveInterval.
14 //
15 //===----------------------------------------------------------------------===//
16 
17 #ifndef LLVM_LIB_CODEGEN_LIVEINTERVALCALC_H
18 #define LLVM_LIB_CODEGEN_LIVEINTERVALCALC_H
19 
21 
22 namespace llvm {
23 
24 template <class NodeT> class DomTreeNodeBase;
25 
27 
29  /// Extend the live range of @p LR to reach all uses of Reg.
30  ///
31  /// If @p LR is a main range, or if @p LI is null, then all uses must be
32  /// jointly dominated by the definitions from @p LR. If @p LR is a subrange
33  /// of the live interval @p LI, corresponding to lane mask @p LaneMask,
34  /// all uses must be jointly dominated by the definitions from @p LR
35  /// together with definitions of other lanes where @p LR becomes undefined
36  /// (via <def,read-undef> operands).
37  /// If @p LR is a main range, the @p LaneMask should be set to ~0, i.e.
38  /// LaneBitmask::getAll().
39  void extendToUses(LiveRange &LR, Register Reg, LaneBitmask LaneMask,
40  LiveInterval *LI = nullptr);
41 
42 public:
43  LiveIntervalCalc() = default;
44 
45  /// createDeadDefs - Create a dead def in LI for every def operand of Reg.
46  /// Each instruction defining Reg gets a new VNInfo with a corresponding
47  /// minimal live range.
48  void createDeadDefs(LiveRange &LR, Register Reg);
49 
50  /// Extend the live range of @p LR to reach all uses of Reg.
51  ///
52  /// All uses must be jointly dominated by existing liveness. PHI-defs are
53  /// inserted as needed to preserve SSA form.
54  void extendToUses(LiveRange &LR, MCRegister PhysReg) {
55  extendToUses(LR, PhysReg, LaneBitmask::getAll());
56  }
57 
58  /// Calculates liveness for the register specified in live interval @p LI.
59  /// Creates subregister live ranges as needed if subreg liveness tracking is
60  /// enabled.
61  void calculate(LiveInterval &LI, bool TrackSubRegs);
62 
63  /// For live interval \p LI with correct SubRanges construct matching
64  /// information for the main live range. Expects the main live range to not
65  /// have any segments or value numbers.
67 };
68 
69 } // end namespace llvm
70 
71 #endif // LLVM_LIB_CODEGEN_LIVEINTERVALCALC_H
Wrapper class representing physical registers. Should be passed by value.
Definition: MCRegister.h:22
void constructMainRangeFromSubranges(LiveInterval &LI)
For live interval LI with correct SubRanges construct matching information for the main live range...
This class represents lattice values for constants.
Definition: AllocatorList.h:23
LiveInterval - This class represents the liveness of a register, or stack slot.
Definition: LiveInterval.h:680
unsigned Reg
This class represents the liveness of a register, stack slot, etc.
Definition: LiveInterval.h:156
static constexpr LaneBitmask getAll()
Definition: LaneBitmask.h:83
void createDeadDefs(LiveRange &LR, Register Reg)
createDeadDefs - Create a dead def in LI for every def operand of Reg.
Base class for the actual dominator tree node.
void calculate(LiveInterval &LI, bool TrackSubRegs)
Calculates liveness for the register specified in live interval LI.
void extendToUses(LiveRange &LR, MCRegister PhysReg)
Extend the live range of LR to reach all uses of Reg.
Wrapper class representing virtual and physical registers.
Definition: Register.h:19