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1 //===-- DWARFFormValue.h ----------------------------------------*- 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 #ifndef LLVM_DEBUGINFO_DWARFFORMVALUE_H
11 #define LLVM_DEBUGINFO_DWARFFORMVALUE_H
12 
13 #include "llvm/ADT/Optional.h"
14 #include "llvm/Support/DataExtractor.h"
15 
16 namespace llvm {
17 
18 template <typename T> class ArrayRef;
19 class DWARFUnit;
20 class raw_ostream;
21 
22 class DWARFFormValue {
23 public:
24   enum FormClass {
25     FC_Unknown,
26     FC_Address,
27     FC_Block,
28     FC_Constant,
29     FC_String,
30     FC_Flag,
31     FC_Reference,
32     FC_Indirect,
33     FC_SectionOffset,
34     FC_Exprloc
35   };
36 
37 private:
38   struct ValueType {
ValueTypeValueType39     ValueType() : data(nullptr) {
40       uval = 0;
41     }
42 
43     union {
44       uint64_t uval;
45       int64_t sval;
46       const char* cstr;
47     };
48     const uint8_t* data;
49   };
50 
51   uint16_t Form;   // Form for this value.
52   ValueType Value; // Contains all data for the form.
53 
54 public:
Form(Form)55   DWARFFormValue(uint16_t Form = 0) : Form(Form) {}
getForm()56   uint16_t getForm() const { return Form; }
57   bool isFormClass(FormClass FC) const;
58 
59   void dump(raw_ostream &OS, const DWARFUnit *U) const;
60 
61   /// \brief extracts a value in data at offset *offset_ptr.
62   ///
63   /// The passed DWARFUnit is allowed to be nullptr, in which
64   /// case no relocation processing will be performed and some
65   /// kind of forms that depend on Unit information are disallowed.
66   /// \returns whether the extraction succeeded.
67   bool extractValue(DataExtractor data, uint32_t *offset_ptr,
68                     const DWARFUnit *u);
isInlinedCStr()69   bool isInlinedCStr() const {
70     return Value.data != nullptr && Value.data == (const uint8_t*)Value.cstr;
71   }
72 
73   /// getAsFoo functions below return the extracted value as Foo if only
74   /// DWARFFormValue has form class is suitable for representing Foo.
75   Optional<uint64_t> getAsReference(const DWARFUnit *U) const;
76   Optional<uint64_t> getAsUnsignedConstant() const;
77   Optional<int64_t> getAsSignedConstant() const;
78   Optional<const char *> getAsCString(const DWARFUnit *U) const;
79   Optional<uint64_t> getAsAddress(const DWARFUnit *U) const;
80   Optional<uint64_t> getAsSectionOffset() const;
81   Optional<ArrayRef<uint8_t>> getAsBlock() const;
82 
83   bool skipValue(DataExtractor debug_info_data, uint32_t *offset_ptr,
84                  const DWARFUnit *u) const;
85   static bool skipValue(uint16_t form, DataExtractor debug_info_data,
86                         uint32_t *offset_ptr, const DWARFUnit *u);
87   static bool skipValue(uint16_t form, DataExtractor debug_info_data,
88                         uint32_t *offset_ptr, uint16_t Version,
89                         uint8_t AddrSize);
90 
91   static ArrayRef<uint8_t> getFixedFormSizes(uint8_t AddrSize,
92                                              uint16_t Version);
93 private:
94   void dumpString(raw_ostream &OS, const DWARFUnit *U) const;
95 };
96 
97 }
98 
99 #endif
100