1//===- DWARFFormValue.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#ifndef LLVM_DEBUGINFO_DWARF_DWARFFORMVALUE_H
10#define LLVM_DEBUGINFO_DWARF_DWARFFORMVALUE_H
11
12#include "llvm/ADT/ArrayRef.h"
13#include "llvm/BinaryFormat/Dwarf.h"
14#include "llvm/DebugInfo/DIContext.h"
15#include "llvm/Support/DataExtractor.h"
16#include <cstdint>
17
18namespace llvm {
19
20class DWARFContext;
21class DWARFObject;
22class DWARFDataExtractor;
23class DWARFUnit;
24class raw_ostream;
25
26class DWARFFormValue {
27public:
28  enum FormClass {
29    FC_Unknown,
30    FC_Address,
31    FC_Block,
32    FC_Constant,
33    FC_String,
34    FC_Flag,
35    FC_Reference,
36    FC_Indirect,
37    FC_SectionOffset,
38    FC_Exprloc
39  };
40
41  struct ValueType {
42    ValueType() { uval = 0; }
43    ValueType(int64_t V) : sval(V) {}
44    ValueType(uint64_t V) : uval(V) {}
45    ValueType(const char *V) : cstr(V) {}
46
47    union {
48      uint64_t uval;
49      int64_t sval;
50      const char *cstr;
51    };
52    const uint8_t *data = nullptr;
53    uint64_t SectionIndex; /// Section index for reference forms.
54  };
55
56private:
57  dwarf::Form Form; /// Form for this value.
58  dwarf::DwarfFormat Format =
59      dwarf::DWARF32;           /// Remember the DWARF format at extract time.
60  ValueType Value;              /// Contains all data for the form.
61  const DWARFUnit *U = nullptr; /// Remember the DWARFUnit at extract time.
62  const DWARFContext *C = nullptr; /// Context for extract time.
63
64  DWARFFormValue(dwarf::Form F, ValueType V) : Form(F), Value(V) {}
65
66public:
67  DWARFFormValue(dwarf::Form F = dwarf::Form(0)) : Form(F) {}
68
69  static DWARFFormValue createFromSValue(dwarf::Form F, int64_t V);
70  static DWARFFormValue createFromUValue(dwarf::Form F, uint64_t V);
71  static DWARFFormValue createFromPValue(dwarf::Form F, const char *V);
72  static DWARFFormValue createFromBlockValue(dwarf::Form F,
73                                             ArrayRef<uint8_t> D);
74  static DWARFFormValue createFromUnit(dwarf::Form F, const DWARFUnit *Unit,
75                                       uint64_t *OffsetPtr);
76  static std::optional<object::SectionedAddress>
77  getAsSectionedAddress(const ValueType &Val, const dwarf::Form Form,
78                        const DWARFUnit *U);
79
80  dwarf::Form getForm() const { return Form; }
81  uint64_t getRawUValue() const { return Value.uval; }
82
83  bool isFormClass(FormClass FC) const;
84  const DWARFUnit *getUnit() const { return U; }
85  void dump(raw_ostream &OS, DIDumpOptions DumpOpts = DIDumpOptions()) const;
86  void dumpSectionedAddress(raw_ostream &OS, DIDumpOptions DumpOpts,
87                            object::SectionedAddress SA) const;
88  void dumpAddress(raw_ostream &OS, uint64_t Address) const;
89  static void dumpAddress(raw_ostream &OS, uint8_t AddressSize,
90                          uint64_t Address);
91  static void dumpAddressSection(const DWARFObject &Obj, raw_ostream &OS,
92                                 DIDumpOptions DumpOpts, uint64_t SectionIndex);
93
94  /// Extracts a value in \p Data at offset \p *OffsetPtr. The information
95  /// in \p FormParams is needed to interpret some forms. The optional
96  /// \p Context and \p Unit allows extracting information if the form refers
97  /// to other sections (e.g., .debug_str).
98  bool extractValue(const DWARFDataExtractor &Data, uint64_t *OffsetPtr,
99                    dwarf::FormParams FormParams,
100                    const DWARFContext *Context = nullptr,
101                    const DWARFUnit *Unit = nullptr);
102
103  bool extractValue(const DWARFDataExtractor &Data, uint64_t *OffsetPtr,
104                    dwarf::FormParams FormParams, const DWARFUnit *U) {
105    return extractValue(Data, OffsetPtr, FormParams, nullptr, U);
106  }
107
108  /// getAsFoo functions below return the extracted value as Foo if only
109  /// DWARFFormValue has form class is suitable for representing Foo.
110  std::optional<uint64_t> getAsReference() const;
111  struct UnitOffset {
112    DWARFUnit *Unit;
113    uint64_t Offset;
114  };
115  std::optional<UnitOffset> getAsRelativeReference() const;
116  std::optional<uint64_t> getAsUnsignedConstant() const;
117  std::optional<int64_t> getAsSignedConstant() const;
118  Expected<const char *> getAsCString() const;
119  std::optional<uint64_t> getAsAddress() const;
120  std::optional<object::SectionedAddress> getAsSectionedAddress() const;
121  std::optional<uint64_t> getAsSectionOffset() const;
122  std::optional<ArrayRef<uint8_t>> getAsBlock() const;
123  std::optional<uint64_t> getAsCStringOffset() const;
124  std::optional<uint64_t> getAsReferenceUVal() const;
125  /// Correctly extract any file paths from a form value.
126  ///
127  /// These attributes can be in the from DW_AT_decl_file or DW_AT_call_file
128  /// attributes. We need to use the file index in the correct DWARFUnit's line
129  /// table prologue, and each DWARFFormValue has the DWARFUnit the form value
130  /// was extracted from.
131  ///
132  /// \param Kind The kind of path to extract.
133  ///
134  /// \returns A valid string value on success, or std::nullopt if the form
135  /// class is not FC_Constant, or if the file index is not valid.
136  std::optional<std::string>
137  getAsFile(DILineInfoSpecifier::FileLineInfoKind Kind) const;
138
139  /// Skip a form's value in \p DebugInfoData at the offset specified by
140  /// \p OffsetPtr.
141  ///
142  /// Skips the bytes for the current form and updates the offset.
143  ///
144  /// \param DebugInfoData The data where we want to skip the value.
145  /// \param OffsetPtr A reference to the offset that will be updated.
146  /// \param Params DWARF parameters to help interpret forms.
147  /// \returns true on success, false if the form was not skipped.
148  bool skipValue(DataExtractor DebugInfoData, uint64_t *OffsetPtr,
149                 const dwarf::FormParams Params) const {
150    return DWARFFormValue::skipValue(Form, DebugInfoData, OffsetPtr, Params);
151  }
152
153  /// Skip a form's value in \p DebugInfoData at the offset specified by
154  /// \p OffsetPtr.
155  ///
156  /// Skips the bytes for the specified form and updates the offset.
157  ///
158  /// \param Form The DW_FORM enumeration that indicates the form to skip.
159  /// \param DebugInfoData The data where we want to skip the value.
160  /// \param OffsetPtr A reference to the offset that will be updated.
161  /// \param FormParams DWARF parameters to help interpret forms.
162  /// \returns true on success, false if the form was not skipped.
163  static bool skipValue(dwarf::Form Form, DataExtractor DebugInfoData,
164                        uint64_t *OffsetPtr,
165                        const dwarf::FormParams FormParams);
166
167private:
168  void dumpString(raw_ostream &OS) const;
169};
170
171namespace dwarf {
172
173/// Take an optional DWARFFormValue and try to extract a string value from it.
174///
175/// \param V and optional DWARFFormValue to attempt to extract the value from.
176/// \returns an optional value that contains a value if the form value
177/// was valid and was a string.
178inline std::optional<const char *>
179toString(const std::optional<DWARFFormValue> &V) {
180  if (!V)
181    return std::nullopt;
182  Expected<const char*> E = V->getAsCString();
183  if (!E) {
184    consumeError(E.takeError());
185    return std::nullopt;
186  }
187  return *E;
188}
189
190/// Take an optional DWARFFormValue and try to extract a string value from it.
191///
192/// \param V and optional DWARFFormValue to attempt to extract the value from.
193/// \returns an optional value that contains a value if the form value
194/// was valid and was a string.
195inline StringRef toStringRef(const std::optional<DWARFFormValue> &V,
196                             StringRef Default = {}) {
197  if (!V)
198    return Default;
199  auto S = V->getAsCString();
200  if (!S) {
201    consumeError(S.takeError());
202    return Default;
203  }
204  if (!*S)
205    return Default;
206  return *S;
207}
208
209/// Take an optional DWARFFormValue and extract a string value from it.
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 string value or Default if the V doesn't have a value or the
214/// form value's encoding wasn't a string.
215inline const char *toString(const std::optional<DWARFFormValue> &V,
216                            const char *Default) {
217  if (auto E = toString(V))
218    return *E;
219  return Default;
220}
221
222/// Take an optional DWARFFormValue and try to extract an unsigned constant.
223///
224/// \param V and optional DWARFFormValue to attempt to extract the value from.
225/// \returns an optional value that contains a value if the form value
226/// was valid and has a unsigned constant form.
227inline std::optional<uint64_t>
228toUnsigned(const std::optional<DWARFFormValue> &V) {
229  if (V)
230    return V->getAsUnsignedConstant();
231  return std::nullopt;
232}
233
234/// Take an optional DWARFFormValue and extract a unsigned constant.
235///
236/// \param V and optional DWARFFormValue to attempt to extract the value from.
237/// \param Default the default value to return in case of failure.
238/// \returns the extracted unsigned value or Default if the V doesn't have a
239/// value or the form value's encoding wasn't an unsigned constant form.
240inline uint64_t toUnsigned(const std::optional<DWARFFormValue> &V,
241                           uint64_t Default) {
242  return toUnsigned(V).value_or(Default);
243}
244
245/// Take an optional DWARFFormValue and try to extract an reference.
246///
247/// \param V and optional DWARFFormValue to attempt to extract the value from.
248/// \returns an optional value that contains a value if the form value
249/// was valid and has a reference form.
250inline std::optional<uint64_t>
251toReference(const std::optional<DWARFFormValue> &V) {
252  if (V)
253    return V->getAsReference();
254  return std::nullopt;
255}
256
257/// Take an optional DWARFFormValue and extract a reference.
258///
259/// \param V and optional DWARFFormValue to attempt to extract the value from.
260/// \param Default the default value to return in case of failure.
261/// \returns the extracted reference value or Default if the V doesn't have a
262/// value or the form value's encoding wasn't a reference form.
263inline uint64_t toReference(const std::optional<DWARFFormValue> &V,
264                            uint64_t Default) {
265  return toReference(V).value_or(Default);
266}
267
268/// Take an optional DWARFFormValue and try to extract an signed constant.
269///
270/// \param V and optional DWARFFormValue to attempt to extract the value from.
271/// \returns an optional value that contains a value if the form value
272/// was valid and has a signed constant form.
273inline std::optional<int64_t> toSigned(const std::optional<DWARFFormValue> &V) {
274  if (V)
275    return V->getAsSignedConstant();
276  return std::nullopt;
277}
278
279/// Take an optional DWARFFormValue and extract a signed integer.
280///
281/// \param V and optional DWARFFormValue to attempt to extract the value from.
282/// \param Default the default value to return in case of failure.
283/// \returns the extracted signed integer value or Default if the V doesn't
284/// have a value or the form value's encoding wasn't a signed integer form.
285inline int64_t toSigned(const std::optional<DWARFFormValue> &V,
286                        int64_t Default) {
287  return toSigned(V).value_or(Default);
288}
289
290/// Take an optional DWARFFormValue and try to extract an address.
291///
292/// \param V and optional DWARFFormValue to attempt to extract the value from.
293/// \returns an optional value that contains a value if the form value
294/// was valid and has a address form.
295inline std::optional<uint64_t>
296toAddress(const std::optional<DWARFFormValue> &V) {
297  if (V)
298    return V->getAsAddress();
299  return std::nullopt;
300}
301
302inline std::optional<object::SectionedAddress>
303toSectionedAddress(const std::optional<DWARFFormValue> &V) {
304  if (V)
305    return V->getAsSectionedAddress();
306  return std::nullopt;
307}
308
309/// Take an optional DWARFFormValue and extract a address.
310///
311/// \param V and optional DWARFFormValue to attempt to extract the value from.
312/// \param Default the default value to return in case of failure.
313/// \returns the extracted address value or Default if the V doesn't have a
314/// value or the form value's encoding wasn't an address form.
315inline uint64_t toAddress(const std::optional<DWARFFormValue> &V,
316                          uint64_t Default) {
317  return toAddress(V).value_or(Default);
318}
319
320/// Take an optional DWARFFormValue and try to extract an section offset.
321///
322/// \param V and optional DWARFFormValue to attempt to extract the value from.
323/// \returns an optional value that contains a value if the form value
324/// was valid and has a section offset form.
325inline std::optional<uint64_t>
326toSectionOffset(const std::optional<DWARFFormValue> &V) {
327  if (V)
328    return V->getAsSectionOffset();
329  return std::nullopt;
330}
331
332/// Take an optional DWARFFormValue and extract a section offset.
333///
334/// \param V and optional DWARFFormValue to attempt to extract the value from.
335/// \param Default the default value to return in case of failure.
336/// \returns the extracted section offset value or Default if the V doesn't
337/// have a value or the form value's encoding wasn't a section offset form.
338inline uint64_t toSectionOffset(const std::optional<DWARFFormValue> &V,
339                                uint64_t Default) {
340  return toSectionOffset(V).value_or(Default);
341}
342
343/// Take an optional DWARFFormValue and try to extract block data.
344///
345/// \param V and optional DWARFFormValue to attempt to extract the value from.
346/// \returns an optional value that contains a value if the form value
347/// was valid and has a block form.
348inline std::optional<ArrayRef<uint8_t>>
349toBlock(const std::optional<DWARFFormValue> &V) {
350  if (V)
351    return V->getAsBlock();
352  return std::nullopt;
353}
354
355/// Check whether specified \p Form belongs to the \p FC class.
356/// \param Form an attribute form.
357/// \param FC an attribute form class to check.
358/// \param DwarfVersion the version of DWARF debug info keeping the attribute.
359/// \returns true if specified \p Form belongs to the \p FC class.
360bool doesFormBelongToClass(dwarf::Form Form, DWARFFormValue::FormClass FC,
361                           uint16_t DwarfVersion);
362
363} // end namespace dwarf
364
365} // end namespace llvm
366
367#endif // LLVM_DEBUGINFO_DWARF_DWARFFORMVALUE_H
368