DWARFFormValue.h revision 327952 
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/ArrayRef.h"
14#include "llvm/ADT/None.h"
15#include "llvm/ADT/Optional.h"
16#include "llvm/BinaryFormat/Dwarf.h"
17#include "llvm/DebugInfo/DIContext.h"
18#include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
19#include <cstdint>
20
21namespace llvm {
22
23class DWARFUnit;
24class raw_ostream;
25
26/// A helper struct for DWARFFormValue methods, providing information that
27/// allows it to know the byte size of DW_FORM values that vary in size
28/// depending on the DWARF version, address byte size, or DWARF32/DWARF64.
29struct DWARFFormParams {
30  uint16_t Version;
31  uint8_t AddrSize;
32  dwarf::DwarfFormat Format;
33
34  /// The definition of the size of form DW_FORM_ref_addr depends on the
35  /// version. In DWARF v2 it's the size of an address; after that, it's the
36  /// size of a reference.
37  uint8_t getRefAddrByteSize() const {
38    if (Version == 2)
39      return AddrSize;
40    return getDwarfOffsetByteSize();
41  }
42
43  /// The size of a reference is determined by the DWARF 32/64-bit format.
44  uint8_t getDwarfOffsetByteSize() const {
45    switch (Format) {
46    case dwarf::DwarfFormat::DWARF32:
47      return 4;
48    case dwarf::DwarfFormat::DWARF64:
49      return 8;
50    }
51    llvm_unreachable("Invalid Format value");
52  }
53};
54
55class DWARFFormValue {
56public:
57  enum FormClass {
58    FC_Unknown,
59    FC_Address,
60    FC_Block,
61    FC_Constant,
62    FC_String,
63    FC_Flag,
64    FC_Reference,
65    FC_Indirect,
66    FC_SectionOffset,
67    FC_Exprloc
68  };
69
70private:
71  struct ValueType {
72    ValueType() { uval = 0; }
73
74    union {
75      uint64_t uval;
76      int64_t sval;
77      const char *cstr;
78    };
79    const uint8_t *data = nullptr;
80    uint64_t SectionIndex;      /// Section index for reference forms.
81  };
82
83  dwarf::Form Form;             /// Form for this value.
84  ValueType Value;              /// Contains all data for the form.
85  const DWARFUnit *U = nullptr; /// Remember the DWARFUnit at extract time.
86
87public:
88  DWARFFormValue(dwarf::Form F = dwarf::Form(0)) : Form(F) {}
89
90  dwarf::Form getForm() const { return Form; }
91  uint64_t getRawUValue() const { return Value.uval; }
92  uint64_t getSectionIndex() const { return Value.SectionIndex; }
93  void setForm(dwarf::Form F) { Form = F; }
94  void setUValue(uint64_t V) { Value.uval = V; }
95  void setSValue(int64_t V) { Value.sval = V; }
96  void setPValue(const char *V) { Value.cstr = V; }
97
98  void setBlockValue(const ArrayRef<uint8_t> &Data) {
99    Value.data = Data.data();
100    setUValue(Data.size());
101  }
102
103  bool isFormClass(FormClass FC) const;
104  const DWARFUnit *getUnit() const { return U; }
105  void dump(raw_ostream &OS, DIDumpOptions DumpOpts = DIDumpOptions()) const;
106
107  /// Extracts a value in \p Data at offset \p *OffsetPtr. The information
108  /// in \p FormParams is needed to interpret some forms. The optional
109  /// \p Unit allows extracting information if the form refers to other
110  /// sections (e.g., .debug_str).
111  bool extractValue(const DWARFDataExtractor &Data, uint32_t *OffsetPtr,
112                    DWARFFormParams FormParams, const DWARFUnit *U = nullptr);
113
114  bool isInlinedCStr() const {
115    return Value.data != nullptr && Value.data == (const uint8_t *)Value.cstr;
116  }
117
118  /// getAsFoo functions below return the extracted value as Foo if only
119  /// DWARFFormValue has form class is suitable for representing Foo.
120  Optional<uint64_t> getAsReference() const;
121  Optional<uint64_t> getAsUnsignedConstant() const;
122  Optional<int64_t> getAsSignedConstant() const;
123  Optional<const char *> getAsCString() const;
124  Optional<uint64_t> getAsAddress() const;
125  Optional<uint64_t> getAsSectionOffset() const;
126  Optional<ArrayRef<uint8_t>> getAsBlock() const;
127  Optional<uint64_t> getAsCStringOffset() const;
128  Optional<uint64_t> getAsReferenceUVal() const;
129
130  /// Get the fixed byte size for a given form.
131  ///
132  /// If the form has a fixed byte size, then an Optional with a value will be
133  /// returned. If the form is always encoded using a variable length storage
134  /// format (ULEB or SLEB numbers or blocks) then None will be returned.
135  ///
136  /// \param Form DWARF form to get the fixed byte size for.
137  /// \param FormParams DWARF parameters to help interpret forms.
138  /// \returns Optional<uint8_t> value with the fixed byte size or None if
139  /// \p Form doesn't have a fixed byte size.
140  static Optional<uint8_t> getFixedByteSize(dwarf::Form Form,
141                                            const DWARFFormParams FormParams);
142
143  /// Skip a form's value in \p DebugInfoData at the offset specified by
144  /// \p OffsetPtr.
145  ///
146  /// Skips the bytes for the current form and updates the offset.
147  ///
148  /// \param DebugInfoData The data where we want to skip the value.
149  /// \param OffsetPtr A reference to the offset that will be updated.
150  /// \param Params DWARF parameters to help interpret forms.
151  /// \returns true on success, false if the form was not skipped.
152  bool skipValue(DataExtractor DebugInfoData, uint32_t *OffsetPtr,
153                 const DWARFFormParams Params) const {
154    return DWARFFormValue::skipValue(Form, DebugInfoData, OffsetPtr, Params);
155  }
156
157  /// Skip a form's value in \p DebugInfoData at the offset specified by
158  /// \p OffsetPtr.
159  ///
160  /// Skips the bytes for the specified form and updates the offset.
161  ///
162  /// \param Form The DW_FORM enumeration that indicates the form to skip.
163  /// \param DebugInfoData The data where we want to skip the value.
164  /// \param OffsetPtr A reference to the offset that will be updated.
165  /// \param FormParams DWARF parameters to help interpret forms.
166  /// \returns true on success, false if the form was not skipped.
167  static bool skipValue(dwarf::Form Form, DataExtractor DebugInfoData,
168                        uint32_t *OffsetPtr, const DWARFFormParams FormParams);
169
170private:
171  void dumpString(raw_ostream &OS) const;
172};
173
174namespace dwarf {
175
176/// Take an optional DWARFFormValue and try to extract a string value from it.
177///
178/// \param V and optional DWARFFormValue to attempt to extract the value from.
179/// \returns an optional value that contains a value if the form value
180/// was valid and was a string.
181inline Optional<const char *> toString(const Optional<DWARFFormValue> &V) {
182  if (V)
183    return V->getAsCString();
184  return None;
185}
186
187/// Take an optional DWARFFormValue and extract a string value from it.
188///
189/// \param V and optional DWARFFormValue to attempt to extract the value from.
190/// \param Default the default value to return in case of failure.
191/// \returns the string value or Default if the V doesn't have a value or the
192/// form value's encoding wasn't a string.
193inline const char *toString(const Optional<DWARFFormValue> &V,
194                            const char *Default) {
195  return toString(V).getValueOr(Default);
196}
197
198/// Take an optional DWARFFormValue and try to extract an unsigned constant.
199///
200/// \param V and optional DWARFFormValue to attempt to extract the value from.
201/// \returns an optional value that contains a value if the form value
202/// was valid and has a unsigned constant form.
203inline Optional<uint64_t> toUnsigned(const Optional<DWARFFormValue> &V) {
204  if (V)
205    return V->getAsUnsignedConstant();
206  return None;
207}
208
209/// Take an optional DWARFFormValue and extract a unsigned constant.
210///
211/// \param V and optional DWARFFormValue to attempt to extract the value from.
212/// \param Default the default value to return in case of failure.
213/// \returns the extracted unsigned value or Default if the V doesn't have a
214/// value or the form value's encoding wasn't an unsigned constant form.
215inline uint64_t toUnsigned(const Optional<DWARFFormValue> &V,
216                           uint64_t Default) {
217  return toUnsigned(V).getValueOr(Default);
218}
219
220/// Take an optional DWARFFormValue and try to extract an reference.
221///
222/// \param V and optional DWARFFormValue to attempt to extract the value from.
223/// \returns an optional value that contains a value if the form value
224/// was valid and has a reference form.
225inline Optional<uint64_t> toReference(const Optional<DWARFFormValue> &V) {
226  if (V)
227    return V->getAsReference();
228  return None;
229}
230
231/// Take an optional DWARFFormValue and extract a reference.
232///
233/// \param V and optional DWARFFormValue to attempt to extract the value from.
234/// \param Default the default value to return in case of failure.
235/// \returns the extracted reference value or Default if the V doesn't have a
236/// value or the form value's encoding wasn't a reference form.
237inline uint64_t toReference(const Optional<DWARFFormValue> &V,
238                            uint64_t Default) {
239  return toReference(V).getValueOr(Default);
240}
241
242/// Take an optional DWARFFormValue and try to extract an signed constant.
243///
244/// \param V and optional DWARFFormValue to attempt to extract the value from.
245/// \returns an optional value that contains a value if the form value
246/// was valid and has a signed constant form.
247inline Optional<int64_t> toSigned(const Optional<DWARFFormValue> &V) {
248  if (V)
249    return V->getAsSignedConstant();
250  return None;
251}
252
253/// Take an optional DWARFFormValue and extract a signed integer.
254///
255/// \param V and optional DWARFFormValue to attempt to extract the value from.
256/// \param Default the default value to return in case of failure.
257/// \returns the extracted signed integer value or Default if the V doesn't
258/// have a value or the form value's encoding wasn't a signed integer form.
259inline int64_t toSigned(const Optional<DWARFFormValue> &V, int64_t Default) {
260  return toSigned(V).getValueOr(Default);
261}
262
263/// Take an optional DWARFFormValue and try to extract an address.
264///
265/// \param V and optional DWARFFormValue to attempt to extract the value from.
266/// \returns an optional value that contains a value if the form value
267/// was valid and has a address form.
268inline Optional<uint64_t> toAddress(const Optional<DWARFFormValue> &V) {
269  if (V)
270    return V->getAsAddress();
271  return None;
272}
273
274/// Take an optional DWARFFormValue and extract a address.
275///
276/// \param V and optional DWARFFormValue to attempt to extract the value from.
277/// \param Default the default value to return in case of failure.
278/// \returns the extracted address value or Default if the V doesn't have a
279/// value or the form value's encoding wasn't an address form.
280inline uint64_t toAddress(const Optional<DWARFFormValue> &V, uint64_t Default) {
281  return toAddress(V).getValueOr(Default);
282}
283
284/// Take an optional DWARFFormValue and try to extract an section offset.
285///
286/// \param V and optional DWARFFormValue to attempt to extract the value from.
287/// \returns an optional value that contains a value if the form value
288/// was valid and has a section offset form.
289inline Optional<uint64_t> toSectionOffset(const Optional<DWARFFormValue> &V) {
290  if (V)
291    return V->getAsSectionOffset();
292  return None;
293}
294
295/// Take an optional DWARFFormValue and extract a section offset.
296///
297/// \param V and optional DWARFFormValue to attempt to extract the value from.
298/// \param Default the default value to return in case of failure.
299/// \returns the extracted section offset value or Default if the V doesn't
300/// have a value or the form value's encoding wasn't a section offset form.
301inline uint64_t toSectionOffset(const Optional<DWARFFormValue> &V,
302                                uint64_t Default) {
303  return toSectionOffset(V).getValueOr(Default);
304}
305
306/// Take an optional DWARFFormValue and try to extract block data.
307///
308/// \param V and optional DWARFFormValue to attempt to extract the value from.
309/// \returns an optional value that contains a value if the form value
310/// was valid and has a block form.
311inline Optional<ArrayRef<uint8_t>> toBlock(const Optional<DWARFFormValue> &V) {
312  if (V)
313    return V->getAsBlock();
314  return None;
315}
316
317} // end namespace dwarf
318
319} // end namespace llvm
320
321#endif // LLVM_DEBUGINFO_DWARFFORMVALUE_H
322