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_DWARFFORMVALUE_H
10 #define LLVM_DEBUGINFO_DWARFFORMVALUE_H
11 
12 #include "llvm/ADT/ArrayRef.h"
13 #include "llvm/ADT/None.h"
14 #include "llvm/ADT/Optional.h"
15 #include "llvm/BinaryFormat/Dwarf.h"
16 #include "llvm/DebugInfo/DIContext.h"
17 #include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
18 #include <cstdint>
19 
20 namespace llvm {
21 
22 class DWARFContext;
23 class DWARFUnit;
24 class raw_ostream;
25 
26 class DWARFFormValue {
27 public:
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 private:
42   struct ValueType {
43     ValueType() { uval = 0; }
44     ValueType(int64_t V) : sval(V) {}
45     ValueType(uint64_t V) : uval(V) {}
46     ValueType(const char *V) : cstr(V) {}
47 
48     union {
49       uint64_t uval;
50       int64_t sval;
51       const char *cstr;
52     };
53     const uint8_t *data = nullptr;
54     uint64_t SectionIndex;      /// Section index for reference forms.
55   };
56 
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 
66 public:
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 
77   dwarf::Form getForm() const { return Form; }
78   uint64_t getRawUValue() const { return Value.uval; }
79 
80   bool isFormClass(FormClass FC) const;
81   const DWARFUnit *getUnit() const { return U; }
82   void dump(raw_ostream &OS, DIDumpOptions DumpOpts = DIDumpOptions()) const;
83   void dumpSectionedAddress(raw_ostream &OS, DIDumpOptions DumpOpts,
84                             object::SectionedAddress SA) const;
85   static void dumpAddressSection(const DWARFObject &Obj, raw_ostream &OS,
86                                  DIDumpOptions DumpOpts, uint64_t SectionIndex);
87 
88   /// Extracts a value in \p Data at offset \p *OffsetPtr. The information
89   /// in \p FormParams is needed to interpret some forms. The optional
90   /// \p Context and \p Unit allows extracting information if the form refers
91   /// to other sections (e.g., .debug_str).
92   bool extractValue(const DWARFDataExtractor &Data, uint64_t *OffsetPtr,
93                     dwarf::FormParams FormParams,
94                     const DWARFContext *Context = nullptr,
95                     const DWARFUnit *Unit = nullptr);
96 
97   bool extractValue(const DWARFDataExtractor &Data, uint64_t *OffsetPtr,
98                     dwarf::FormParams FormParams, const DWARFUnit *U) {
99     return extractValue(Data, OffsetPtr, FormParams, nullptr, U);
100   }
101 
102   bool isInlinedCStr() const {
103     return Value.data != nullptr && Value.data == (const uint8_t *)Value.cstr;
104   }
105 
106   /// getAsFoo functions below return the extracted value as Foo if only
107   /// DWARFFormValue has form class is suitable for representing Foo.
108   Optional<uint64_t> getAsReference() const;
109   struct UnitOffset {
110     DWARFUnit *Unit;
111     uint64_t Offset;
112   };
113   Optional<UnitOffset> getAsRelativeReference() const;
114   Optional<uint64_t> getAsUnsignedConstant() const;
115   Optional<int64_t> getAsSignedConstant() const;
116   Optional<const char *> getAsCString() const;
117   Optional<uint64_t> getAsAddress() const;
118   Optional<object::SectionedAddress> getAsSectionedAddress() const;
119   Optional<uint64_t> getAsSectionOffset() const;
120   Optional<ArrayRef<uint8_t>> getAsBlock() const;
121   Optional<uint64_t> getAsCStringOffset() const;
122   Optional<uint64_t> getAsReferenceUVal() const;
123 
124   /// Skip a form's value in \p DebugInfoData at the offset specified by
125   /// \p OffsetPtr.
126   ///
127   /// Skips the bytes for the current form and updates the offset.
128   ///
129   /// \param DebugInfoData The data where we want to skip the value.
130   /// \param OffsetPtr A reference to the offset that will be updated.
131   /// \param Params DWARF parameters to help interpret forms.
132   /// \returns true on success, false if the form was not skipped.
133   bool skipValue(DataExtractor DebugInfoData, uint64_t *OffsetPtr,
134                  const dwarf::FormParams Params) const {
135     return DWARFFormValue::skipValue(Form, DebugInfoData, OffsetPtr, Params);
136   }
137 
138   /// Skip a form's value in \p DebugInfoData at the offset specified by
139   /// \p OffsetPtr.
140   ///
141   /// Skips the bytes for the specified form and updates the offset.
142   ///
143   /// \param Form The DW_FORM enumeration that indicates the form to skip.
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 FormParams DWARF parameters to help interpret forms.
147   /// \returns true on success, false if the form was not skipped.
148   static bool skipValue(dwarf::Form Form, DataExtractor DebugInfoData,
149                         uint64_t *OffsetPtr,
150                         const dwarf::FormParams FormParams);
151 
152 private:
153   void dumpString(raw_ostream &OS) const;
154 };
155 
156 namespace dwarf {
157 
158 /// Take an optional DWARFFormValue and try to extract a string value from it.
159 ///
160 /// \param V and optional DWARFFormValue to attempt to extract the value from.
161 /// \returns an optional value that contains a value if the form value
162 /// was valid and was a string.
163 inline Optional<const char *> toString(const Optional<DWARFFormValue> &V) {
164   if (V)
165     return V->getAsCString();
166   return None;
167 }
168 
169 /// Take an optional DWARFFormValue and try to extract a string value from it.
170 ///
171 /// \param V and optional DWARFFormValue to attempt to extract the value from.
172 /// \returns an optional value that contains a value if the form value
173 /// was valid and was a string.
174 inline StringRef toStringRef(const Optional<DWARFFormValue> &V,
175                              StringRef Default = {}) {
176   if (V)
177     if (auto S = V->getAsCString())
178       return *S;
179   return Default;
180 }
181 
182 /// Take an optional DWARFFormValue and extract a string value from it.
183 ///
184 /// \param V and optional DWARFFormValue to attempt to extract the value from.
185 /// \param Default the default value to return in case of failure.
186 /// \returns the string value or Default if the V doesn't have a value or the
187 /// form value's encoding wasn't a string.
188 inline const char *toString(const Optional<DWARFFormValue> &V,
189                             const char *Default) {
190   return toString(V).getValueOr(Default);
191 }
192 
193 /// Take an optional DWARFFormValue and try to extract an unsigned constant.
194 ///
195 /// \param V and optional DWARFFormValue to attempt to extract the value from.
196 /// \returns an optional value that contains a value if the form value
197 /// was valid and has a unsigned constant form.
198 inline Optional<uint64_t> toUnsigned(const Optional<DWARFFormValue> &V) {
199   if (V)
200     return V->getAsUnsignedConstant();
201   return None;
202 }
203 
204 /// Take an optional DWARFFormValue and extract a unsigned constant.
205 ///
206 /// \param V and optional DWARFFormValue to attempt to extract the value from.
207 /// \param Default the default value to return in case of failure.
208 /// \returns the extracted unsigned value or Default if the V doesn't have a
209 /// value or the form value's encoding wasn't an unsigned constant form.
210 inline uint64_t toUnsigned(const Optional<DWARFFormValue> &V,
211                            uint64_t Default) {
212   return toUnsigned(V).getValueOr(Default);
213 }
214 
215 /// Take an optional DWARFFormValue and try to extract an reference.
216 ///
217 /// \param V and optional DWARFFormValue to attempt to extract the value from.
218 /// \returns an optional value that contains a value if the form value
219 /// was valid and has a reference form.
220 inline Optional<uint64_t> toReference(const Optional<DWARFFormValue> &V) {
221   if (V)
222     return V->getAsReference();
223   return None;
224 }
225 
226 /// Take an optional DWARFFormValue and extract a reference.
227 ///
228 /// \param V and optional DWARFFormValue to attempt to extract the value from.
229 /// \param Default the default value to return in case of failure.
230 /// \returns the extracted reference value or Default if the V doesn't have a
231 /// value or the form value's encoding wasn't a reference form.
232 inline uint64_t toReference(const Optional<DWARFFormValue> &V,
233                             uint64_t Default) {
234   return toReference(V).getValueOr(Default);
235 }
236 
237 /// Take an optional DWARFFormValue and try to extract an signed constant.
238 ///
239 /// \param V and optional DWARFFormValue to attempt to extract the value from.
240 /// \returns an optional value that contains a value if the form value
241 /// was valid and has a signed constant form.
242 inline Optional<int64_t> toSigned(const Optional<DWARFFormValue> &V) {
243   if (V)
244     return V->getAsSignedConstant();
245   return None;
246 }
247 
248 /// Take an optional DWARFFormValue and extract a signed integer.
249 ///
250 /// \param V and optional DWARFFormValue to attempt to extract the value from.
251 /// \param Default the default value to return in case of failure.
252 /// \returns the extracted signed integer value or Default if the V doesn't
253 /// have a value or the form value's encoding wasn't a signed integer form.
254 inline int64_t toSigned(const Optional<DWARFFormValue> &V, int64_t Default) {
255   return toSigned(V).getValueOr(Default);
256 }
257 
258 /// Take an optional DWARFFormValue and try to extract an address.
259 ///
260 /// \param V and optional DWARFFormValue to attempt to extract the value from.
261 /// \returns an optional value that contains a value if the form value
262 /// was valid and has a address form.
263 inline Optional<uint64_t> toAddress(const Optional<DWARFFormValue> &V) {
264   if (V)
265     return V->getAsAddress();
266   return None;
267 }
268 
269 inline Optional<object::SectionedAddress>
270 toSectionedAddress(const Optional<DWARFFormValue> &V) {
271   if (V)
272     return V->getAsSectionedAddress();
273   return None;
274 }
275 
276 /// Take an optional DWARFFormValue and extract a address.
277 ///
278 /// \param V and optional DWARFFormValue to attempt to extract the value from.
279 /// \param Default the default value to return in case of failure.
280 /// \returns the extracted address value or Default if the V doesn't have a
281 /// value or the form value's encoding wasn't an address form.
282 inline uint64_t toAddress(const Optional<DWARFFormValue> &V, uint64_t Default) {
283   return toAddress(V).getValueOr(Default);
284 }
285 
286 /// Take an optional DWARFFormValue and try to extract an section offset.
287 ///
288 /// \param V and optional DWARFFormValue to attempt to extract the value from.
289 /// \returns an optional value that contains a value if the form value
290 /// was valid and has a section offset form.
291 inline Optional<uint64_t> toSectionOffset(const Optional<DWARFFormValue> &V) {
292   if (V)
293     return V->getAsSectionOffset();
294   return None;
295 }
296 
297 /// Take an optional DWARFFormValue and extract a section offset.
298 ///
299 /// \param V and optional DWARFFormValue to attempt to extract the value from.
300 /// \param Default the default value to return in case of failure.
301 /// \returns the extracted section offset value or Default if the V doesn't
302 /// have a value or the form value's encoding wasn't a section offset form.
303 inline uint64_t toSectionOffset(const Optional<DWARFFormValue> &V,
304                                 uint64_t Default) {
305   return toSectionOffset(V).getValueOr(Default);
306 }
307 
308 /// Take an optional DWARFFormValue and try to extract block data.
309 ///
310 /// \param V and optional DWARFFormValue to attempt to extract the value from.
311 /// \returns an optional value that contains a value if the form value
312 /// was valid and has a block form.
313 inline Optional<ArrayRef<uint8_t>> toBlock(const Optional<DWARFFormValue> &V) {
314   if (V)
315     return V->getAsBlock();
316   return None;
317 }
318 
319 } // end namespace dwarf
320 
321 } // end namespace llvm
322 
323 #endif // LLVM_DEBUGINFO_DWARFFORMVALUE_H
324