1//===-- llvm/CodeGen/DebugHandlerBase.h -----------------------*- 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// Common functionality for different debug information format backends.
10// LLVM currently supports DWARF and CodeView.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CODEGEN_DEBUGHANDLERBASE_H
15#define LLVM_CODEGEN_DEBUGHANDLERBASE_H
16
17#include "llvm/CodeGen/AsmPrinterHandler.h"
18#include "llvm/CodeGen/DbgEntityHistoryCalculator.h"
19#include "llvm/CodeGen/LexicalScopes.h"
20#include "llvm/IR/DebugInfoMetadata.h"
21#include "llvm/IR/DebugLoc.h"
22#include <optional>
23
24namespace llvm {
25
26class AsmPrinter;
27class MachineInstr;
28class MachineModuleInfo;
29
30/// Represents the location at which a variable is stored.
31struct DbgVariableLocation {
32 /// Base register.
33 MCRegister Register;
34
35 /// Chain of offsetted loads necessary to load the value if it lives in
36 /// memory. Every load except for the last is pointer-sized.
37 SmallVector<int64_t, 1> LoadChain;
38
39 /// Present if the location is part of a larger variable.
40 std::optional<llvm::DIExpression::FragmentInfo> FragmentInfo;
41
42 /// Extract a VariableLocation from a MachineInstr.
43 /// This will only work if Instruction is a debug value instruction
44 /// and the associated DIExpression is in one of the supported forms.
45 /// If these requirements are not met, the returned Optional will not
46 /// have a value.
47 static std::optional<DbgVariableLocation>
48 extractFromMachineInstruction(const MachineInstr &Instruction);
49};
50
51/// Base class for debug information backends. Common functionality related to
52/// tracking which variables and scopes are alive at a given PC live here.
53class DebugHandlerBase : public AsmPrinterHandler {
54protected:
55 DebugHandlerBase(AsmPrinter *A);
56
57 /// Target of debug info emission.
58 AsmPrinter *Asm = nullptr;
59
60 /// Collected machine module information.
61 MachineModuleInfo *MMI = nullptr;
62
63 /// Previous instruction's location information. This is used to
64 /// determine label location to indicate scope boundaries in debug info.
65 /// We track the previous instruction's source location (if not line 0),
66 /// whether it was a label, and its parent BB.
67 DebugLoc PrevInstLoc;
68 MCSymbol *PrevLabel = nullptr;
69 const MachineBasicBlock *PrevInstBB = nullptr;
70
71 /// This location indicates end of function prologue and beginning of
72 /// function body.
73 const MachineInstr *PrologEndLoc;
74
75 /// This block includes epilogue instructions.
76 const MachineBasicBlock *EpilogBeginBlock = nullptr;
77
78 /// If nonnull, stores the current machine instruction we're processing.
79 const MachineInstr *CurMI = nullptr;
80
81 LexicalScopes LScopes;
82
83 /// History of DBG_VALUE and clobber instructions for each user
84 /// variable. Variables are listed in order of appearance.
85 DbgValueHistoryMap DbgValues;
86
87 /// Mapping of inlined labels and DBG_LABEL machine instruction.
88 DbgLabelInstrMap DbgLabels;
89
90 /// Maps instruction with label emitted before instruction.
91 /// FIXME: Make this private from DwarfDebug, we have the necessary accessors
92 /// for it.
93 DenseMap<const MachineInstr *, MCSymbol *> LabelsBeforeInsn;
94
95 /// Maps instruction with label emitted after instruction.
96 DenseMap<const MachineInstr *, MCSymbol *> LabelsAfterInsn;
97
98 /// Indentify instructions that are marking the beginning of or
99 /// ending of a scope.
100 void identifyScopeMarkers();
101
102 /// Ensure that a label will be emitted before MI.
103 void requestLabelBeforeInsn(const MachineInstr *MI) {
104 LabelsBeforeInsn.try_emplace(Key: MI);
105 }
106
107 /// Ensure that a label will be emitted after MI.
108 void requestLabelAfterInsn(const MachineInstr *MI) {
109 LabelsAfterInsn.try_emplace(Key: MI);
110 }
111
112 virtual void beginFunctionImpl(const MachineFunction *MF) = 0;
113 virtual void endFunctionImpl(const MachineFunction *MF) = 0;
114 virtual void skippedNonDebugFunction() {}
115
116private:
117 InstructionOrdering InstOrdering;
118
119 // AsmPrinterHandler overrides.
120public:
121 ~DebugHandlerBase() override;
122
123 void beginModule(Module *M) override;
124
125 void beginInstruction(const MachineInstr *MI) override;
126 void endInstruction() override;
127
128 void beginFunction(const MachineFunction *MF) override;
129 void endFunction(const MachineFunction *MF) override;
130
131 void beginBasicBlockSection(const MachineBasicBlock &MBB) override;
132 void endBasicBlockSection(const MachineBasicBlock &MBB) override;
133
134 /// Return Label preceding the instruction.
135 MCSymbol *getLabelBeforeInsn(const MachineInstr *MI);
136
137 /// Return Label immediately following the instruction.
138 MCSymbol *getLabelAfterInsn(const MachineInstr *MI);
139
140 /// If this type is derived from a base type then return base type size.
141 static uint64_t getBaseTypeSize(const DIType *Ty);
142
143 /// Return true if type encoding is unsigned.
144 static bool isUnsignedDIType(const DIType *Ty);
145
146 const InstructionOrdering &getInstOrdering() const { return InstOrdering; }
147
148 const LexicalScopes &getLexicalScopes() const { return LScopes; }
149};
150
151} // namespace llvm
152
153#endif
154