1 //===- llvm/CodeGen/VirtRegMap.h - Virtual Register Map ---------*- 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 // This file implements a virtual register map. This maps virtual registers to
10 // physical registers and virtual registers to stack slots. It is created and
11 // updated by a register allocator and then used by a machine code rewriter that
12 // adds spill code and rewrites virtual into physical register references.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #ifndef LLVM_CODEGEN_VIRTREGMAP_H
17 #define LLVM_CODEGEN_VIRTREGMAP_H
18 
19 #include "llvm/ADT/IndexedMap.h"
20 #include "llvm/CodeGen/MachineFunctionPass.h"
21 #include "llvm/CodeGen/TargetRegisterInfo.h"
22 #include "llvm/CodeGen/TileShapeInfo.h"
23 #include "llvm/Pass.h"
24 #include <cassert>
25 
26 namespace llvm {
27 
28 class MachineFunction;
29 class MachineRegisterInfo;
30 class raw_ostream;
31 class TargetInstrInfo;
32 
33   class VirtRegMap : public MachineFunctionPass {
34   public:
35     enum {
36       NO_PHYS_REG = 0,
37       NO_STACK_SLOT = (1L << 30)-1,
38       MAX_STACK_SLOT = (1L << 18)-1
39     };
40 
41   private:
42     MachineRegisterInfo *MRI = nullptr;
43     const TargetInstrInfo *TII = nullptr;
44     const TargetRegisterInfo *TRI = nullptr;
45     MachineFunction *MF = nullptr;
46 
47     /// Virt2PhysMap - This is a virtual to physical register
48     /// mapping. Each virtual register is required to have an entry in
49     /// it; even spilled virtual registers (the register mapped to a
50     /// spilled register is the temporary used to load it from the
51     /// stack).
52     IndexedMap<Register, VirtReg2IndexFunctor> Virt2PhysMap;
53 
54     /// Virt2StackSlotMap - This is virtual register to stack slot
55     /// mapping. Each spilled virtual register has an entry in it
56     /// which corresponds to the stack slot this register is spilled
57     /// at.
58     IndexedMap<int, VirtReg2IndexFunctor> Virt2StackSlotMap;
59 
60     /// Virt2SplitMap - This is virtual register to splitted virtual register
61     /// mapping.
62     IndexedMap<unsigned, VirtReg2IndexFunctor> Virt2SplitMap;
63 
64     /// Virt2ShapeMap - For X86 AMX register whose register is bound shape
65     /// information.
66     DenseMap<unsigned, ShapeT> Virt2ShapeMap;
67 
68     /// createSpillSlot - Allocate a spill slot for RC from MFI.
69     unsigned createSpillSlot(const TargetRegisterClass *RC);
70 
71   public:
72     static char ID;
73 
74     VirtRegMap()
75         : MachineFunctionPass(ID), Virt2PhysMap(NO_PHYS_REG),
76           Virt2StackSlotMap(NO_STACK_SLOT), Virt2SplitMap(0) {}
77     VirtRegMap(const VirtRegMap &) = delete;
78     VirtRegMap &operator=(const VirtRegMap &) = delete;
79 
80     bool runOnMachineFunction(MachineFunction &MF) override;
81 
82     void getAnalysisUsage(AnalysisUsage &AU) const override {
83       AU.setPreservesAll();
84       MachineFunctionPass::getAnalysisUsage(AU);
85     }
86 
87     MachineFunction &getMachineFunction() const {
88       assert(MF && "getMachineFunction called before runOnMachineFunction");
89       return *MF;
90     }
91 
92     MachineRegisterInfo &getRegInfo() const { return *MRI; }
93     const TargetRegisterInfo &getTargetRegInfo() const { return *TRI; }
94 
95     void grow();
96 
97     /// returns true if the specified virtual register is
98     /// mapped to a physical register
99     bool hasPhys(Register virtReg) const {
100       return getPhys(virtReg) != NO_PHYS_REG;
101     }
102 
103     /// returns the physical register mapped to the specified
104     /// virtual register
105     MCRegister getPhys(Register virtReg) const {
106       assert(virtReg.isVirtual());
107       return MCRegister::from(Virt2PhysMap[virtReg.id()]);
108     }
109 
110     /// creates a mapping for the specified virtual register to
111     /// the specified physical register
112     void assignVirt2Phys(Register virtReg, MCPhysReg physReg);
113 
114     bool isShapeMapEmpty() const { return Virt2ShapeMap.empty(); }
115 
116     bool hasShape(Register virtReg) const {
117       return getShape(virtReg).isValid();
118     }
119 
120     ShapeT getShape(Register virtReg) const {
121       assert(virtReg.isVirtual());
122       return Virt2ShapeMap.lookup(virtReg);
123     }
124 
125     void assignVirt2Shape(Register virtReg, ShapeT shape) {
126       Virt2ShapeMap[virtReg.id()] = shape;
127     }
128 
129     /// clears the specified virtual register's, physical
130     /// register mapping
131     void clearVirt(Register virtReg) {
132       assert(virtReg.isVirtual());
133       assert(Virt2PhysMap[virtReg.id()] != NO_PHYS_REG &&
134              "attempt to clear a not assigned virtual register");
135       Virt2PhysMap[virtReg.id()] = NO_PHYS_REG;
136     }
137 
138     /// clears all virtual to physical register mappings
139     void clearAllVirt() {
140       Virt2PhysMap.clear();
141       grow();
142     }
143 
144     /// returns true if VirtReg is assigned to its preferred physreg.
145     bool hasPreferredPhys(Register VirtReg) const;
146 
147     /// returns true if VirtReg has a known preferred register.
148     /// This returns false if VirtReg has a preference that is a virtual
149     /// register that hasn't been assigned yet.
150     bool hasKnownPreference(Register VirtReg) const;
151 
152     /// records virtReg is a split live interval from SReg.
153     void setIsSplitFromReg(Register virtReg, Register SReg) {
154       Virt2SplitMap[virtReg.id()] = SReg;
155       if (hasShape(SReg)) {
156         Virt2ShapeMap[virtReg.id()] = getShape(SReg);
157       }
158     }
159 
160     /// returns the live interval virtReg is split from.
161     Register getPreSplitReg(Register virtReg) const {
162       return Virt2SplitMap[virtReg.id()];
163     }
164 
165     /// getOriginal - Return the original virtual register that VirtReg descends
166     /// from through splitting.
167     /// A register that was not created by splitting is its own original.
168     /// This operation is idempotent.
169     Register getOriginal(Register VirtReg) const {
170       Register Orig = getPreSplitReg(VirtReg);
171       return Orig ? Orig : VirtReg;
172     }
173 
174     /// returns true if the specified virtual register is not
175     /// mapped to a stack slot or rematerialized.
176     bool isAssignedReg(Register virtReg) const {
177       if (getStackSlot(virtReg) == NO_STACK_SLOT)
178         return true;
179       // Split register can be assigned a physical register as well as a
180       // stack slot or remat id.
181       return (Virt2SplitMap[virtReg.id()] &&
182               Virt2PhysMap[virtReg.id()] != NO_PHYS_REG);
183     }
184 
185     /// returns the stack slot mapped to the specified virtual
186     /// register
187     int getStackSlot(Register virtReg) const {
188       assert(virtReg.isVirtual());
189       return Virt2StackSlotMap[virtReg.id()];
190     }
191 
192     /// create a mapping for the specifed virtual register to
193     /// the next available stack slot
194     int assignVirt2StackSlot(Register virtReg);
195 
196     /// create a mapping for the specified virtual register to
197     /// the specified stack slot
198     void assignVirt2StackSlot(Register virtReg, int SS);
199 
200     void print(raw_ostream &OS, const Module* M = nullptr) const override;
201     void dump() const;
202   };
203 
204   inline raw_ostream &operator<<(raw_ostream &OS, const VirtRegMap &VRM) {
205     VRM.print(OS);
206     return OS;
207   }
208 
209 } // end llvm namespace
210 
211 #endif // LLVM_CODEGEN_VIRTREGMAP_H
212