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   void dumpAddress(raw_ostream &OS, uint64_t Address) const;
86   static void dumpAddress(raw_ostream &OS, uint8_t AddressSize,
87                           uint64_t Address);
88   static void dumpAddressSection(const DWARFObject &Obj, raw_ostream &OS,
89                                  DIDumpOptions DumpOpts, uint64_t SectionIndex);
90 
91   /// Extracts a value in \p Data at offset \p *OffsetPtr. The information
92   /// in \p FormParams is needed to interpret some forms. The optional
93   /// \p Context and \p Unit allows extracting information if the form refers
94   /// to other sections (e.g., .debug_str).
95   bool extractValue(const DWARFDataExtractor &Data, uint64_t *OffsetPtr,
96                     dwarf::FormParams FormParams,
97                     const DWARFContext *Context = nullptr,
98                     const DWARFUnit *Unit = nullptr);
99 
100   bool extractValue(const DWARFDataExtractor &Data, uint64_t *OffsetPtr,
101                     dwarf::FormParams FormParams, const DWARFUnit *U) {
102     return extractValue(Data, OffsetPtr, FormParams, nullptr, U);
103   }
104 
105   bool isInlinedCStr() const {
106     return Value.data != nullptr && Value.data == (const uint8_t *)Value.cstr;
107   }
108 
109   /// getAsFoo functions below return the extracted value as Foo if only
110   /// DWARFFormValue has form class is suitable for representing Foo.
111   Optional<uint64_t> getAsReference() const;
112   struct UnitOffset {
113     DWARFUnit *Unit;
114     uint64_t Offset;
115   };
116   Optional<UnitOffset> getAsRelativeReference() const;
117   Optional<uint64_t> getAsUnsignedConstant() const;
118   Optional<int64_t> getAsSignedConstant() const;
119   Optional<const char *> getAsCString() const;
120   Optional<uint64_t> getAsAddress() const;
121   Optional<object::SectionedAddress> getAsSectionedAddress() const;
122   Optional<uint64_t> getAsSectionOffset() const;
123   Optional<ArrayRef<uint8_t>> getAsBlock() const;
124   Optional<uint64_t> getAsCStringOffset() const;
125   Optional<uint64_t> getAsReferenceUVal() const;
126 
127   /// Skip a form's value in \p DebugInfoData at the offset specified by
128   /// \p OffsetPtr.
129   ///
130   /// Skips the bytes for the current form and updates the offset.
131   ///
132   /// \param DebugInfoData The data where we want to skip the value.
133   /// \param OffsetPtr A reference to the offset that will be updated.
134   /// \param Params DWARF parameters to help interpret forms.
135   /// \returns true on success, false if the form was not skipped.
136   bool skipValue(DataExtractor DebugInfoData, uint64_t *OffsetPtr,
137                  const dwarf::FormParams Params) const {
138     return DWARFFormValue::skipValue(Form, DebugInfoData, OffsetPtr, Params);
139   }
140 
141   /// Skip a form's value in \p DebugInfoData at the offset specified by
142   /// \p OffsetPtr.
143   ///
144   /// Skips the bytes for the specified form and updates the offset.
145   ///
146   /// \param Form The DW_FORM enumeration that indicates the form to skip.
147   /// \param DebugInfoData The data where we want to skip the value.
148   /// \param OffsetPtr A reference to the offset that will be updated.
149   /// \param FormParams DWARF parameters to help interpret forms.
150   /// \returns true on success, false if the form was not skipped.
151   static bool skipValue(dwarf::Form Form, DataExtractor DebugInfoData,
152                         uint64_t *OffsetPtr,
153                         const dwarf::FormParams FormParams);
154 
155 private:
156   void dumpString(raw_ostream &OS) const;
157 };
158 
159 namespace dwarf {
160 
161 /// Take an optional DWARFFormValue and try to extract a string value from it.
162 ///
163 /// \param V and optional DWARFFormValue to attempt to extract the value from.
164 /// \returns an optional value that contains a value if the form value
165 /// was valid and was a string.
166 inline Optional<const char *> toString(const Optional<DWARFFormValue> &V) {
167   if (V)
168     return V->getAsCString();
169   return None;
170 }
171 
172 /// Take an optional DWARFFormValue and try to extract a string value from it.
173 ///
174 /// \param V and optional DWARFFormValue to attempt to extract the value from.
175 /// \returns an optional value that contains a value if the form value
176 /// was valid and was a string.
177 inline StringRef toStringRef(const Optional<DWARFFormValue> &V,
178                              StringRef Default = {}) {
179   if (V)
180     if (auto S = V->getAsCString())
181       return *S;
182   return Default;
183 }
184 
185 /// Take an optional DWARFFormValue and extract a string value from it.
186 ///
187 /// \param V and optional DWARFFormValue to attempt to extract the value from.
188 /// \param Default the default value to return in case of failure.
189 /// \returns the string value or Default if the V doesn't have a value or the
190 /// form value's encoding wasn't a string.
191 inline const char *toString(const Optional<DWARFFormValue> &V,
192                             const char *Default) {
193   return toString(V).getValueOr(Default);
194 }
195 
196 /// Take an optional DWARFFormValue and try to extract an unsigned constant.
197 ///
198 /// \param V and optional DWARFFormValue to attempt to extract the value from.
199 /// \returns an optional value that contains a value if the form value
200 /// was valid and has a unsigned constant form.
201 inline Optional<uint64_t> toUnsigned(const Optional<DWARFFormValue> &V) {
202   if (V)
203     return V->getAsUnsignedConstant();
204   return None;
205 }
206 
207 /// Take an optional DWARFFormValue and extract a unsigned constant.
208 ///
209 /// \param V and optional DWARFFormValue to attempt to extract the value from.
210 /// \param Default the default value to return in case of failure.
211 /// \returns the extracted unsigned value or Default if the V doesn't have a
212 /// value or the form value's encoding wasn't an unsigned constant form.
213 inline uint64_t toUnsigned(const Optional<DWARFFormValue> &V,
214                            uint64_t Default) {
215   return toUnsigned(V).getValueOr(Default);
216 }
217 
218 /// Take an optional DWARFFormValue and try to extract an reference.
219 ///
220 /// \param V and optional DWARFFormValue to attempt to extract the value from.
221 /// \returns an optional value that contains a value if the form value
222 /// was valid and has a reference form.
223 inline Optional<uint64_t> toReference(const Optional<DWARFFormValue> &V) {
224   if (V)
225     return V->getAsReference();
226   return None;
227 }
228 
229 /// Take an optional DWARFFormValue and extract a reference.
230 ///
231 /// \param V and optional DWARFFormValue to attempt to extract the value from.
232 /// \param Default the default value to return in case of failure.
233 /// \returns the extracted reference value or Default if the V doesn't have a
234 /// value or the form value's encoding wasn't a reference form.
235 inline uint64_t toReference(const Optional<DWARFFormValue> &V,
236                             uint64_t Default) {
237   return toReference(V).getValueOr(Default);
238 }
239 
240 /// Take an optional DWARFFormValue and try to extract an signed constant.
241 ///
242 /// \param V and optional DWARFFormValue to attempt to extract the value from.
243 /// \returns an optional value that contains a value if the form value
244 /// was valid and has a signed constant form.
245 inline Optional<int64_t> toSigned(const Optional<DWARFFormValue> &V) {
246   if (V)
247     return V->getAsSignedConstant();
248   return None;
249 }
250 
251 /// Take an optional DWARFFormValue and extract a signed integer.
252 ///
253 /// \param V and optional DWARFFormValue to attempt to extract the value from.
254 /// \param Default the default value to return in case of failure.
255 /// \returns the extracted signed integer value or Default if the V doesn't
256 /// have a value or the form value's encoding wasn't a signed integer form.
257 inline int64_t toSigned(const Optional<DWARFFormValue> &V, int64_t Default) {
258   return toSigned(V).getValueOr(Default);
259 }
260 
261 /// Take an optional DWARFFormValue and try to extract an address.
262 ///
263 /// \param V and optional DWARFFormValue to attempt to extract the value from.
264 /// \returns an optional value that contains a value if the form value
265 /// was valid and has a address form.
266 inline Optional<uint64_t> toAddress(const Optional<DWARFFormValue> &V) {
267   if (V)
268     return V->getAsAddress();
269   return None;
270 }
271 
272 inline Optional<object::SectionedAddress>
273 toSectionedAddress(const Optional<DWARFFormValue> &V) {
274   if (V)
275     return V->getAsSectionedAddress();
276   return None;
277 }
278 
279 /// Take an optional DWARFFormValue and extract a address.
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 address value or Default if the V doesn't have a
284 /// value or the form value's encoding wasn't an address form.
285 inline uint64_t toAddress(const Optional<DWARFFormValue> &V, uint64_t Default) {
286   return toAddress(V).getValueOr(Default);
287 }
288 
289 /// Take an optional DWARFFormValue and try to extract an section offset.
290 ///
291 /// \param V and optional DWARFFormValue to attempt to extract the value from.
292 /// \returns an optional value that contains a value if the form value
293 /// was valid and has a section offset form.
294 inline Optional<uint64_t> toSectionOffset(const Optional<DWARFFormValue> &V) {
295   if (V)
296     return V->getAsSectionOffset();
297   return None;
298 }
299 
300 /// Take an optional DWARFFormValue and extract a section offset.
301 ///
302 /// \param V and optional DWARFFormValue to attempt to extract the value from.
303 /// \param Default the default value to return in case of failure.
304 /// \returns the extracted section offset value or Default if the V doesn't
305 /// have a value or the form value's encoding wasn't a section offset form.
306 inline uint64_t toSectionOffset(const Optional<DWARFFormValue> &V,
307                                 uint64_t Default) {
308   return toSectionOffset(V).getValueOr(Default);
309 }
310 
311 /// Take an optional DWARFFormValue and try to extract block data.
312 ///
313 /// \param V and optional DWARFFormValue to attempt to extract the value from.
314 /// \returns an optional value that contains a value if the form value
315 /// was valid and has a block form.
316 inline Optional<ArrayRef<uint8_t>> toBlock(const Optional<DWARFFormValue> &V) {
317   if (V)
318     return V->getAsBlock();
319   return None;
320 }
321 
322 } // end namespace dwarf
323 
324 } // end namespace llvm
325 
326 #endif // LLVM_DEBUGINFO_DWARFFORMVALUE_H
327