/Users/buildslave/jenkins/sharedspace/clang-stage2-coverage-R@2/llvm/include/llvm/CodeGen/LiveRegMatrix.h
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1 | | //===- LiveRegMatrix.h - Track register interference ----------*- C++ -*---===// |
2 | | // |
3 | | // The LLVM Compiler Infrastructure |
4 | | // |
5 | | // This file is distributed under the University of Illinois Open Source |
6 | | // License. See LICENSE.TXT for details. |
7 | | // |
8 | | //===----------------------------------------------------------------------===// |
9 | | // |
10 | | // The LiveRegMatrix analysis pass keeps track of virtual register interference |
11 | | // along two dimensions: Slot indexes and register units. The matrix is used by |
12 | | // register allocators to ensure that no interfering virtual registers get |
13 | | // assigned to overlapping physical registers. |
14 | | // |
15 | | // Register units are defined in MCRegisterInfo.h, they represent the smallest |
16 | | // unit of interference when dealing with overlapping physical registers. The |
17 | | // LiveRegMatrix is represented as a LiveIntervalUnion per register unit. When |
18 | | // a virtual register is assigned to a physical register, the live range for |
19 | | // the virtual register is inserted into the LiveIntervalUnion for each regunit |
20 | | // in the physreg. |
21 | | // |
22 | | //===----------------------------------------------------------------------===// |
23 | | |
24 | | #ifndef LLVM_CODEGEN_LIVEREGMATRIX_H |
25 | | #define LLVM_CODEGEN_LIVEREGMATRIX_H |
26 | | |
27 | | #include "llvm/ADT/BitVector.h" |
28 | | #include "llvm/CodeGen/LiveIntervalUnion.h" |
29 | | #include "llvm/CodeGen/MachineFunctionPass.h" |
30 | | #include <memory> |
31 | | |
32 | | namespace llvm { |
33 | | |
34 | | class AnalysisUsage; |
35 | | class LiveInterval; |
36 | | class LiveIntervals; |
37 | | class MachineFunction; |
38 | | class TargetRegisterInfo; |
39 | | class VirtRegMap; |
40 | | |
41 | | class LiveRegMatrix : public MachineFunctionPass { |
42 | | const TargetRegisterInfo *TRI; |
43 | | LiveIntervals *LIS; |
44 | | VirtRegMap *VRM; |
45 | | |
46 | | // UserTag changes whenever virtual registers have been modified. |
47 | | unsigned UserTag = 0; |
48 | | |
49 | | // The matrix is represented as a LiveIntervalUnion per register unit. |
50 | | LiveIntervalUnion::Allocator LIUAlloc; |
51 | | LiveIntervalUnion::Array Matrix; |
52 | | |
53 | | // Cached queries per register unit. |
54 | | std::unique_ptr<LiveIntervalUnion::Query[]> Queries; |
55 | | |
56 | | // Cached register mask interference info. |
57 | | unsigned RegMaskTag = 0; |
58 | | unsigned RegMaskVirtReg = 0; |
59 | | BitVector RegMaskUsable; |
60 | | |
61 | | // MachineFunctionPass boilerplate. |
62 | | void getAnalysisUsage(AnalysisUsage &) const override; |
63 | | bool runOnMachineFunction(MachineFunction &) override; |
64 | | void releaseMemory() override; |
65 | | |
66 | | public: |
67 | | static char ID; |
68 | | |
69 | | LiveRegMatrix(); |
70 | | |
71 | | //===--------------------------------------------------------------------===// |
72 | | // High-level interface. |
73 | | //===--------------------------------------------------------------------===// |
74 | | // |
75 | | // Check for interference before assigning virtual registers to physical |
76 | | // registers. |
77 | | // |
78 | | |
79 | | /// Invalidate cached interference queries after modifying virtual register |
80 | | /// live ranges. Interference checks may return stale information unless |
81 | | /// caches are invalidated. |
82 | 11.7M | void invalidateVirtRegs() { ++UserTag; } |
83 | | |
84 | | enum InterferenceKind { |
85 | | /// No interference, go ahead and assign. |
86 | | IK_Free = 0, |
87 | | |
88 | | /// Virtual register interference. There are interfering virtual registers |
89 | | /// assigned to PhysReg or its aliases. This interference could be resolved |
90 | | /// by unassigning those other virtual registers. |
91 | | IK_VirtReg, |
92 | | |
93 | | /// Register unit interference. A fixed live range is in the way, typically |
94 | | /// argument registers for a call. This can't be resolved by unassigning |
95 | | /// other virtual registers. |
96 | | IK_RegUnit, |
97 | | |
98 | | /// RegMask interference. The live range is crossing an instruction with a |
99 | | /// regmask operand that doesn't preserve PhysReg. This typically means |
100 | | /// VirtReg is live across a call, and PhysReg isn't call-preserved. |
101 | | IK_RegMask |
102 | | }; |
103 | | |
104 | | /// Check for interference before assigning VirtReg to PhysReg. |
105 | | /// If this function returns IK_Free, it is legal to assign(VirtReg, PhysReg). |
106 | | /// When there is more than one kind of interference, the InterferenceKind |
107 | | /// with the highest enum value is returned. |
108 | | InterferenceKind checkInterference(LiveInterval &VirtReg, unsigned PhysReg); |
109 | | |
110 | | /// Assign VirtReg to PhysReg. |
111 | | /// This will mark VirtReg's live range as occupied in the LiveRegMatrix and |
112 | | /// update VirtRegMap. The live range is expected to be available in PhysReg. |
113 | | void assign(LiveInterval &VirtReg, unsigned PhysReg); |
114 | | |
115 | | /// Unassign VirtReg from its PhysReg. |
116 | | /// Assuming that VirtReg was previously assigned to a PhysReg, this undoes |
117 | | /// the assignment and updates VirtRegMap accordingly. |
118 | | void unassign(LiveInterval &VirtReg); |
119 | | |
120 | | /// Returns true if the given \p PhysReg has any live intervals assigned. |
121 | | bool isPhysRegUsed(unsigned PhysReg) const; |
122 | | |
123 | | //===--------------------------------------------------------------------===// |
124 | | // Low-level interface. |
125 | | //===--------------------------------------------------------------------===// |
126 | | // |
127 | | // Provide access to the underlying LiveIntervalUnions. |
128 | | // |
129 | | |
130 | | /// Check for regmask interference only. |
131 | | /// Return true if VirtReg crosses a regmask operand that clobbers PhysReg. |
132 | | /// If PhysReg is null, check if VirtReg crosses any regmask operands. |
133 | | bool checkRegMaskInterference(LiveInterval &VirtReg, unsigned PhysReg = 0); |
134 | | |
135 | | /// Check for regunit interference only. |
136 | | /// Return true if VirtReg overlaps a fixed assignment of one of PhysRegs's |
137 | | /// register units. |
138 | | bool checkRegUnitInterference(LiveInterval &VirtReg, unsigned PhysReg); |
139 | | |
140 | | /// Query a line of the assigned virtual register matrix directly. |
141 | | /// Use MCRegUnitIterator to enumerate all regunits in the desired PhysReg. |
142 | | /// This returns a reference to an internal Query data structure that is only |
143 | | /// valid until the next query() call. |
144 | | LiveIntervalUnion::Query &query(const LiveRange &LR, unsigned RegUnit); |
145 | | |
146 | | /// Directly access the live interval unions per regunit. |
147 | | /// This returns an array indexed by the regunit number. |
148 | 155M | LiveIntervalUnion *getLiveUnions() { return &Matrix[0]; } |
149 | | }; |
150 | | |
151 | | } // end namespace llvm |
152 | | |
153 | | #endif // LLVM_CODEGEN_LIVEREGMATRIX_H |