xref: /freebsd/contrib/llvm-project/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp (revision 04eeddc0aa8e0a417a16eaf9d7d095207f4a8623)
1 //===- DWARFFormValue.cpp -------------------------------------------------===//
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 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
10 #include "llvm/ADT/ArrayRef.h"
11 #include "llvm/ADT/None.h"
12 #include "llvm/ADT/Optional.h"
13 #include "llvm/ADT/StringRef.h"
14 #include "llvm/BinaryFormat/Dwarf.h"
15 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
16 #include "llvm/DebugInfo/DWARF/DWARFRelocMap.h"
17 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
18 #include "llvm/Support/ErrorHandling.h"
19 #include "llvm/Support/Format.h"
20 #include "llvm/Support/WithColor.h"
21 #include "llvm/Support/raw_ostream.h"
22 #include <cinttypes>
23 #include <cstdint>
24 #include <limits>
25 
26 using namespace llvm;
27 using namespace dwarf;
28 
29 static const DWARFFormValue::FormClass DWARF5FormClasses[] = {
30     DWARFFormValue::FC_Unknown,  // 0x0
31     DWARFFormValue::FC_Address,  // 0x01 DW_FORM_addr
32     DWARFFormValue::FC_Unknown,  // 0x02 unused
33     DWARFFormValue::FC_Block,    // 0x03 DW_FORM_block2
34     DWARFFormValue::FC_Block,    // 0x04 DW_FORM_block4
35     DWARFFormValue::FC_Constant, // 0x05 DW_FORM_data2
36     // --- These can be FC_SectionOffset in DWARF3 and below:
37     DWARFFormValue::FC_Constant, // 0x06 DW_FORM_data4
38     DWARFFormValue::FC_Constant, // 0x07 DW_FORM_data8
39     // ---
40     DWARFFormValue::FC_String,        // 0x08 DW_FORM_string
41     DWARFFormValue::FC_Block,         // 0x09 DW_FORM_block
42     DWARFFormValue::FC_Block,         // 0x0a DW_FORM_block1
43     DWARFFormValue::FC_Constant,      // 0x0b DW_FORM_data1
44     DWARFFormValue::FC_Flag,          // 0x0c DW_FORM_flag
45     DWARFFormValue::FC_Constant,      // 0x0d DW_FORM_sdata
46     DWARFFormValue::FC_String,        // 0x0e DW_FORM_strp
47     DWARFFormValue::FC_Constant,      // 0x0f DW_FORM_udata
48     DWARFFormValue::FC_Reference,     // 0x10 DW_FORM_ref_addr
49     DWARFFormValue::FC_Reference,     // 0x11 DW_FORM_ref1
50     DWARFFormValue::FC_Reference,     // 0x12 DW_FORM_ref2
51     DWARFFormValue::FC_Reference,     // 0x13 DW_FORM_ref4
52     DWARFFormValue::FC_Reference,     // 0x14 DW_FORM_ref8
53     DWARFFormValue::FC_Reference,     // 0x15 DW_FORM_ref_udata
54     DWARFFormValue::FC_Indirect,      // 0x16 DW_FORM_indirect
55     DWARFFormValue::FC_SectionOffset, // 0x17 DW_FORM_sec_offset
56     DWARFFormValue::FC_Exprloc,       // 0x18 DW_FORM_exprloc
57     DWARFFormValue::FC_Flag,          // 0x19 DW_FORM_flag_present
58     DWARFFormValue::FC_String,        // 0x1a DW_FORM_strx
59     DWARFFormValue::FC_Address,       // 0x1b DW_FORM_addrx
60     DWARFFormValue::FC_Reference,     // 0x1c DW_FORM_ref_sup4
61     DWARFFormValue::FC_String,        // 0x1d DW_FORM_strp_sup
62     DWARFFormValue::FC_Constant,      // 0x1e DW_FORM_data16
63     DWARFFormValue::FC_String,        // 0x1f DW_FORM_line_strp
64     DWARFFormValue::FC_Reference,     // 0x20 DW_FORM_ref_sig8
65     DWARFFormValue::FC_Constant,      // 0x21 DW_FORM_implicit_const
66     DWARFFormValue::FC_SectionOffset, // 0x22 DW_FORM_loclistx
67     DWARFFormValue::FC_SectionOffset, // 0x23 DW_FORM_rnglistx
68     DWARFFormValue::FC_Reference,     // 0x24 DW_FORM_ref_sup8
69     DWARFFormValue::FC_String,        // 0x25 DW_FORM_strx1
70     DWARFFormValue::FC_String,        // 0x26 DW_FORM_strx2
71     DWARFFormValue::FC_String,        // 0x27 DW_FORM_strx3
72     DWARFFormValue::FC_String,        // 0x28 DW_FORM_strx4
73     DWARFFormValue::FC_Address,       // 0x29 DW_FORM_addrx1
74     DWARFFormValue::FC_Address,       // 0x2a DW_FORM_addrx2
75     DWARFFormValue::FC_Address,       // 0x2b DW_FORM_addrx3
76     DWARFFormValue::FC_Address,       // 0x2c DW_FORM_addrx4
77     DWARFFormValue::FC_Address,       // 0x2001 DW_FORM_addrx_offset
78 };
79 
80 DWARFFormValue DWARFFormValue::createFromSValue(dwarf::Form F, int64_t V) {
81   return DWARFFormValue(F, ValueType(V));
82 }
83 
84 DWARFFormValue DWARFFormValue::createFromUValue(dwarf::Form F, uint64_t V) {
85   return DWARFFormValue(F, ValueType(V));
86 }
87 
88 DWARFFormValue DWARFFormValue::createFromPValue(dwarf::Form F, const char *V) {
89   return DWARFFormValue(F, ValueType(V));
90 }
91 
92 DWARFFormValue DWARFFormValue::createFromBlockValue(dwarf::Form F,
93                                                     ArrayRef<uint8_t> D) {
94   ValueType V;
95   V.uval = D.size();
96   V.data = D.data();
97   return DWARFFormValue(F, V);
98 }
99 
100 DWARFFormValue DWARFFormValue::createFromUnit(dwarf::Form F, const DWARFUnit *U,
101                                               uint64_t *OffsetPtr) {
102   DWARFFormValue FormValue(F);
103   FormValue.extractValue(U->getDebugInfoExtractor(), OffsetPtr,
104                          U->getFormParams(), U);
105   return FormValue;
106 }
107 
108 bool DWARFFormValue::skipValue(dwarf::Form Form, DataExtractor DebugInfoData,
109                                uint64_t *OffsetPtr,
110                                const dwarf::FormParams Params) {
111   bool Indirect = false;
112   do {
113     switch (Form) {
114     // Blocks of inlined data that have a length field and the data bytes
115     // inlined in the .debug_info.
116     case DW_FORM_exprloc:
117     case DW_FORM_block: {
118       uint64_t size = DebugInfoData.getULEB128(OffsetPtr);
119       *OffsetPtr += size;
120       return true;
121     }
122     case DW_FORM_block1: {
123       uint8_t size = DebugInfoData.getU8(OffsetPtr);
124       *OffsetPtr += size;
125       return true;
126     }
127     case DW_FORM_block2: {
128       uint16_t size = DebugInfoData.getU16(OffsetPtr);
129       *OffsetPtr += size;
130       return true;
131     }
132     case DW_FORM_block4: {
133       uint32_t size = DebugInfoData.getU32(OffsetPtr);
134       *OffsetPtr += size;
135       return true;
136     }
137 
138     // Inlined NULL terminated C-strings.
139     case DW_FORM_string:
140       DebugInfoData.getCStr(OffsetPtr);
141       return true;
142 
143     case DW_FORM_addr:
144     case DW_FORM_ref_addr:
145     case DW_FORM_flag_present:
146     case DW_FORM_data1:
147     case DW_FORM_data2:
148     case DW_FORM_data4:
149     case DW_FORM_data8:
150     case DW_FORM_data16:
151     case DW_FORM_flag:
152     case DW_FORM_ref1:
153     case DW_FORM_ref2:
154     case DW_FORM_ref4:
155     case DW_FORM_ref8:
156     case DW_FORM_ref_sig8:
157     case DW_FORM_ref_sup4:
158     case DW_FORM_ref_sup8:
159     case DW_FORM_strx1:
160     case DW_FORM_strx2:
161     case DW_FORM_strx4:
162     case DW_FORM_addrx1:
163     case DW_FORM_addrx2:
164     case DW_FORM_addrx4:
165     case DW_FORM_sec_offset:
166     case DW_FORM_strp:
167     case DW_FORM_strp_sup:
168     case DW_FORM_line_strp:
169     case DW_FORM_GNU_ref_alt:
170     case DW_FORM_GNU_strp_alt:
171     case DW_FORM_implicit_const:
172       if (Optional<uint8_t> FixedSize =
173               dwarf::getFixedFormByteSize(Form, Params)) {
174         *OffsetPtr += *FixedSize;
175         return true;
176       }
177       return false;
178 
179     // signed or unsigned LEB 128 values.
180     case DW_FORM_sdata:
181       DebugInfoData.getSLEB128(OffsetPtr);
182       return true;
183 
184     case DW_FORM_udata:
185     case DW_FORM_ref_udata:
186     case DW_FORM_strx:
187     case DW_FORM_addrx:
188     case DW_FORM_loclistx:
189     case DW_FORM_rnglistx:
190     case DW_FORM_GNU_addr_index:
191     case DW_FORM_GNU_str_index:
192       DebugInfoData.getULEB128(OffsetPtr);
193       return true;
194 
195     case DW_FORM_LLVM_addrx_offset:
196       DebugInfoData.getULEB128(OffsetPtr);
197       *OffsetPtr += 4;
198       return true;
199 
200     case DW_FORM_indirect:
201       Indirect = true;
202       Form = static_cast<dwarf::Form>(DebugInfoData.getULEB128(OffsetPtr));
203       break;
204 
205     default:
206       return false;
207     }
208   } while (Indirect);
209   return true;
210 }
211 
212 bool DWARFFormValue::isFormClass(DWARFFormValue::FormClass FC) const {
213   // First, check DWARF5 form classes.
214   if (Form < makeArrayRef(DWARF5FormClasses).size() &&
215       DWARF5FormClasses[Form] == FC)
216     return true;
217   // Check more forms from extensions and proposals.
218   switch (Form) {
219   case DW_FORM_GNU_ref_alt:
220     return (FC == FC_Reference);
221   case DW_FORM_GNU_addr_index:
222     return (FC == FC_Address);
223   case DW_FORM_GNU_str_index:
224   case DW_FORM_GNU_strp_alt:
225     return (FC == FC_String);
226   case DW_FORM_LLVM_addrx_offset:
227     return (FC == FC_Address);
228   default:
229     break;
230   }
231 
232   if (FC == FC_SectionOffset) {
233     if (Form == DW_FORM_strp || Form == DW_FORM_line_strp)
234       return true;
235     // In DWARF3 DW_FORM_data4 and DW_FORM_data8 served also as a section
236     // offset. If we don't have a DWARFUnit, default to the old behavior.
237     if (Form == DW_FORM_data4 || Form == DW_FORM_data8)
238       return !U || U->getVersion() <= 3;
239   }
240 
241   return false;
242 }
243 
244 bool DWARFFormValue::extractValue(const DWARFDataExtractor &Data,
245                                   uint64_t *OffsetPtr, dwarf::FormParams FP,
246                                   const DWARFContext *Ctx,
247                                   const DWARFUnit *CU) {
248   if (!Ctx && CU)
249     Ctx = &CU->getContext();
250   C = Ctx;
251   U = CU;
252   Format = FP.Format;
253   bool Indirect = false;
254   bool IsBlock = false;
255   Value.data = nullptr;
256   // Read the value for the form into value and follow and DW_FORM_indirect
257   // instances we run into
258   Error Err = Error::success();
259   do {
260     Indirect = false;
261     switch (Form) {
262     case DW_FORM_addr:
263     case DW_FORM_ref_addr: {
264       uint16_t Size =
265           (Form == DW_FORM_addr) ? FP.AddrSize : FP.getRefAddrByteSize();
266       Value.uval =
267           Data.getRelocatedValue(Size, OffsetPtr, &Value.SectionIndex, &Err);
268       break;
269     }
270     case DW_FORM_exprloc:
271     case DW_FORM_block:
272       Value.uval = Data.getULEB128(OffsetPtr, &Err);
273       IsBlock = true;
274       break;
275     case DW_FORM_block1:
276       Value.uval = Data.getU8(OffsetPtr, &Err);
277       IsBlock = true;
278       break;
279     case DW_FORM_block2:
280       Value.uval = Data.getU16(OffsetPtr, &Err);
281       IsBlock = true;
282       break;
283     case DW_FORM_block4:
284       Value.uval = Data.getU32(OffsetPtr, &Err);
285       IsBlock = true;
286       break;
287     case DW_FORM_data1:
288     case DW_FORM_ref1:
289     case DW_FORM_flag:
290     case DW_FORM_strx1:
291     case DW_FORM_addrx1:
292       Value.uval = Data.getU8(OffsetPtr, &Err);
293       break;
294     case DW_FORM_data2:
295     case DW_FORM_ref2:
296     case DW_FORM_strx2:
297     case DW_FORM_addrx2:
298       Value.uval = Data.getU16(OffsetPtr, &Err);
299       break;
300     case DW_FORM_strx3:
301       Value.uval = Data.getU24(OffsetPtr, &Err);
302       break;
303     case DW_FORM_data4:
304     case DW_FORM_ref4:
305     case DW_FORM_ref_sup4:
306     case DW_FORM_strx4:
307     case DW_FORM_addrx4:
308       Value.uval = Data.getRelocatedValue(4, OffsetPtr, nullptr, &Err);
309       break;
310     case DW_FORM_data8:
311     case DW_FORM_ref8:
312     case DW_FORM_ref_sup8:
313       Value.uval = Data.getRelocatedValue(8, OffsetPtr, nullptr, &Err);
314       break;
315     case DW_FORM_data16:
316       // Treat this like a 16-byte block.
317       Value.uval = 16;
318       IsBlock = true;
319       break;
320     case DW_FORM_sdata:
321       Value.sval = Data.getSLEB128(OffsetPtr, &Err);
322       break;
323     case DW_FORM_udata:
324     case DW_FORM_ref_udata:
325     case DW_FORM_rnglistx:
326     case DW_FORM_loclistx:
327     case DW_FORM_GNU_addr_index:
328     case DW_FORM_GNU_str_index:
329     case DW_FORM_addrx:
330     case DW_FORM_strx:
331       Value.uval = Data.getULEB128(OffsetPtr, &Err);
332       break;
333     case DW_FORM_LLVM_addrx_offset:
334       Value.uval = Data.getULEB128(OffsetPtr, &Err) << 32;
335       Value.uval |= Data.getU32(OffsetPtr, &Err);
336       break;
337     case DW_FORM_string:
338       Value.cstr = Data.getCStr(OffsetPtr, &Err);
339       break;
340     case DW_FORM_indirect:
341       Form = static_cast<dwarf::Form>(Data.getULEB128(OffsetPtr, &Err));
342       Indirect = true;
343       break;
344     case DW_FORM_strp:
345     case DW_FORM_sec_offset:
346     case DW_FORM_GNU_ref_alt:
347     case DW_FORM_GNU_strp_alt:
348     case DW_FORM_line_strp:
349     case DW_FORM_strp_sup: {
350       Value.uval = Data.getRelocatedValue(FP.getDwarfOffsetByteSize(),
351                                           OffsetPtr, nullptr, &Err);
352       break;
353     }
354     case DW_FORM_flag_present:
355       Value.uval = 1;
356       break;
357     case DW_FORM_ref_sig8:
358       Value.uval = Data.getU64(OffsetPtr, &Err);
359       break;
360     case DW_FORM_implicit_const:
361       // Value has been already set by DWARFFormValue::createFromSValue.
362       break;
363     default:
364       // DWARFFormValue::skipValue() will have caught this and caused all
365       // DWARF DIEs to fail to be parsed, so this code is not be reachable.
366       llvm_unreachable("unsupported form");
367     }
368   } while (Indirect && !Err);
369 
370   if (IsBlock)
371     Value.data = Data.getBytes(OffsetPtr, Value.uval, &Err).bytes_begin();
372 
373   return !errorToBool(std::move(Err));
374 }
375 
376 void DWARFFormValue::dumpAddress(raw_ostream &OS, uint8_t AddressSize,
377                                  uint64_t Address) {
378   uint8_t HexDigits = AddressSize * 2;
379   OS << format("0x%*.*" PRIx64, HexDigits, HexDigits, Address);
380 }
381 
382 void DWARFFormValue::dumpSectionedAddress(raw_ostream &OS,
383                                           DIDumpOptions DumpOpts,
384                                           object::SectionedAddress SA) const {
385   dumpAddress(OS, U->getAddressByteSize(), SA.Address);
386   dumpAddressSection(U->getContext().getDWARFObj(), OS, DumpOpts,
387                      SA.SectionIndex);
388 }
389 
390 void DWARFFormValue::dumpAddressSection(const DWARFObject &Obj, raw_ostream &OS,
391                                         DIDumpOptions DumpOpts,
392                                         uint64_t SectionIndex) {
393   if (!DumpOpts.Verbose || SectionIndex == -1ULL)
394     return;
395   ArrayRef<SectionName> SectionNames = Obj.getSectionNames();
396   const auto &SecRef = SectionNames[SectionIndex];
397 
398   OS << " \"" << SecRef.Name << '\"';
399 
400   // Print section index if name is not unique.
401   if (!SecRef.IsNameUnique)
402     OS << format(" [%" PRIu64 "]", SectionIndex);
403 }
404 
405 void DWARFFormValue::dump(raw_ostream &OS, DIDumpOptions DumpOpts) const {
406   uint64_t UValue = Value.uval;
407   bool CURelativeOffset = false;
408   raw_ostream &AddrOS = DumpOpts.ShowAddresses
409                             ? WithColor(OS, HighlightColor::Address).get()
410                             : nulls();
411   int OffsetDumpWidth = 2 * dwarf::getDwarfOffsetByteSize(Format);
412   switch (Form) {
413   case DW_FORM_addr:
414     dumpSectionedAddress(AddrOS, DumpOpts, {Value.uval, Value.SectionIndex});
415     break;
416   case DW_FORM_addrx:
417   case DW_FORM_addrx1:
418   case DW_FORM_addrx2:
419   case DW_FORM_addrx3:
420   case DW_FORM_addrx4:
421   case DW_FORM_GNU_addr_index: {
422     if (U == nullptr) {
423       OS << "<invalid dwarf unit>";
424       break;
425     }
426     Optional<object::SectionedAddress> A = U->getAddrOffsetSectionItem(UValue);
427     if (!A || DumpOpts.Verbose)
428       AddrOS << format("indexed (%8.8x) address = ", (uint32_t)UValue);
429     if (A)
430       dumpSectionedAddress(AddrOS, DumpOpts, *A);
431     else
432       OS << "<unresolved>";
433     break;
434   }
435   case DW_FORM_LLVM_addrx_offset: {
436     if (U == nullptr) {
437       OS << "<invalid dwarf unit>";
438       break;
439     }
440     uint32_t Index = UValue >> 32;
441     uint32_t Offset = UValue & 0xffffffff;
442     Optional<object::SectionedAddress> A = U->getAddrOffsetSectionItem(Index);
443     if (!A || DumpOpts.Verbose)
444       AddrOS << format("indexed (%8.8x) + 0x%x address = ", Index, Offset);
445     if (A) {
446       A->Address += Offset;
447       dumpSectionedAddress(AddrOS, DumpOpts, *A);
448     } else
449       OS << "<unresolved>";
450     break;
451   }
452   case DW_FORM_flag_present:
453     OS << "true";
454     break;
455   case DW_FORM_flag:
456   case DW_FORM_data1:
457     OS << format("0x%02x", (uint8_t)UValue);
458     break;
459   case DW_FORM_data2:
460     OS << format("0x%04x", (uint16_t)UValue);
461     break;
462   case DW_FORM_data4:
463     OS << format("0x%08x", (uint32_t)UValue);
464     break;
465   case DW_FORM_ref_sig8:
466     AddrOS << format("0x%016" PRIx64, UValue);
467     break;
468   case DW_FORM_data8:
469     OS << format("0x%016" PRIx64, UValue);
470     break;
471   case DW_FORM_data16:
472     OS << format_bytes(ArrayRef<uint8_t>(Value.data, 16), None, 16, 16);
473     break;
474   case DW_FORM_string:
475     OS << '"';
476     OS.write_escaped(Value.cstr);
477     OS << '"';
478     break;
479   case DW_FORM_exprloc:
480   case DW_FORM_block:
481   case DW_FORM_block1:
482   case DW_FORM_block2:
483   case DW_FORM_block4:
484     if (UValue > 0) {
485       switch (Form) {
486       case DW_FORM_exprloc:
487       case DW_FORM_block:
488         AddrOS << format("<0x%" PRIx64 "> ", UValue);
489         break;
490       case DW_FORM_block1:
491         AddrOS << format("<0x%2.2x> ", (uint8_t)UValue);
492         break;
493       case DW_FORM_block2:
494         AddrOS << format("<0x%4.4x> ", (uint16_t)UValue);
495         break;
496       case DW_FORM_block4:
497         AddrOS << format("<0x%8.8x> ", (uint32_t)UValue);
498         break;
499       default:
500         break;
501       }
502 
503       const uint8_t *DataPtr = Value.data;
504       if (DataPtr) {
505         // UValue contains size of block
506         const uint8_t *EndDataPtr = DataPtr + UValue;
507         while (DataPtr < EndDataPtr) {
508           AddrOS << format("%2.2x ", *DataPtr);
509           ++DataPtr;
510         }
511       } else
512         OS << "NULL";
513     }
514     break;
515 
516   case DW_FORM_sdata:
517   case DW_FORM_implicit_const:
518     OS << Value.sval;
519     break;
520   case DW_FORM_udata:
521     OS << Value.uval;
522     break;
523   case DW_FORM_strp:
524     if (DumpOpts.Verbose)
525       OS << format(" .debug_str[0x%0*" PRIx64 "] = ", OffsetDumpWidth, UValue);
526     dumpString(OS);
527     break;
528   case DW_FORM_line_strp:
529     if (DumpOpts.Verbose)
530       OS << format(" .debug_line_str[0x%0*" PRIx64 "] = ", OffsetDumpWidth,
531                    UValue);
532     dumpString(OS);
533     break;
534   case DW_FORM_strx:
535   case DW_FORM_strx1:
536   case DW_FORM_strx2:
537   case DW_FORM_strx3:
538   case DW_FORM_strx4:
539   case DW_FORM_GNU_str_index:
540     if (DumpOpts.Verbose)
541       OS << format("indexed (%8.8x) string = ", (uint32_t)UValue);
542     dumpString(OS);
543     break;
544   case DW_FORM_GNU_strp_alt:
545     if (DumpOpts.Verbose)
546       OS << format("alt indirect string, offset: 0x%" PRIx64 "", UValue);
547     dumpString(OS);
548     break;
549   case DW_FORM_ref_addr:
550     AddrOS << format("0x%016" PRIx64, UValue);
551     break;
552   case DW_FORM_ref1:
553     CURelativeOffset = true;
554     if (DumpOpts.Verbose)
555       AddrOS << format("cu + 0x%2.2x", (uint8_t)UValue);
556     break;
557   case DW_FORM_ref2:
558     CURelativeOffset = true;
559     if (DumpOpts.Verbose)
560       AddrOS << format("cu + 0x%4.4x", (uint16_t)UValue);
561     break;
562   case DW_FORM_ref4:
563     CURelativeOffset = true;
564     if (DumpOpts.Verbose)
565       AddrOS << format("cu + 0x%4.4x", (uint32_t)UValue);
566     break;
567   case DW_FORM_ref8:
568     CURelativeOffset = true;
569     if (DumpOpts.Verbose)
570       AddrOS << format("cu + 0x%8.8" PRIx64, UValue);
571     break;
572   case DW_FORM_ref_udata:
573     CURelativeOffset = true;
574     if (DumpOpts.Verbose)
575       AddrOS << format("cu + 0x%" PRIx64, UValue);
576     break;
577   case DW_FORM_GNU_ref_alt:
578     AddrOS << format("<alt 0x%" PRIx64 ">", UValue);
579     break;
580 
581   // All DW_FORM_indirect attributes should be resolved prior to calling
582   // this function
583   case DW_FORM_indirect:
584     OS << "DW_FORM_indirect";
585     break;
586 
587   case DW_FORM_rnglistx:
588     OS << format("indexed (0x%x) rangelist = ", (uint32_t)UValue);
589     break;
590 
591   case DW_FORM_loclistx:
592     OS << format("indexed (0x%x) loclist = ", (uint32_t)UValue);
593     break;
594 
595   case DW_FORM_sec_offset:
596     AddrOS << format("0x%0*" PRIx64, OffsetDumpWidth, UValue);
597     break;
598 
599   default:
600     OS << format("DW_FORM(0x%4.4x)", Form);
601     break;
602   }
603 
604   if (CURelativeOffset) {
605     if (DumpOpts.Verbose)
606       OS << " => {";
607     if (DumpOpts.ShowAddresses)
608       WithColor(OS, HighlightColor::Address).get()
609           << format("0x%8.8" PRIx64, UValue + (U ? U->getOffset() : 0));
610     if (DumpOpts.Verbose)
611       OS << "}";
612   }
613 }
614 
615 void DWARFFormValue::dumpString(raw_ostream &OS) const {
616   if (auto DbgStr = dwarf::toString(*this)) {
617     auto COS = WithColor(OS, HighlightColor::String);
618     COS.get() << '"';
619     COS.get().write_escaped(*DbgStr);
620     COS.get() << '"';
621   }
622 }
623 
624 Expected<const char *> DWARFFormValue::getAsCString() const {
625   if (!isFormClass(FC_String))
626     return make_error<StringError>("Invalid form for string attribute",
627                                    inconvertibleErrorCode());
628   if (Form == DW_FORM_string)
629     return Value.cstr;
630   // FIXME: Add support for DW_FORM_GNU_strp_alt
631   if (Form == DW_FORM_GNU_strp_alt || C == nullptr)
632     return make_error<StringError>("Unsupported form for string attribute",
633                                    inconvertibleErrorCode());
634   uint64_t Offset = Value.uval;
635   Optional<uint32_t> Index;
636   if (Form == DW_FORM_GNU_str_index || Form == DW_FORM_strx ||
637       Form == DW_FORM_strx1 || Form == DW_FORM_strx2 || Form == DW_FORM_strx3 ||
638       Form == DW_FORM_strx4) {
639     if (!U)
640       return make_error<StringError>("API limitation - string extraction not "
641                                      "available without a DWARFUnit",
642                                      inconvertibleErrorCode());
643     Expected<uint64_t> StrOffset = U->getStringOffsetSectionItem(Offset);
644     Index = Offset;
645     if (!StrOffset)
646       return StrOffset.takeError();
647     Offset = *StrOffset;
648   }
649   // Prefer the Unit's string extractor, because for .dwo it will point to
650   // .debug_str.dwo, while the Context's extractor always uses .debug_str.
651   DataExtractor StrData = Form == DW_FORM_line_strp
652                               ? C->getLineStringExtractor()
653                           : U ? U->getStringExtractor()
654                               : C->getStringExtractor();
655   if (const char *Str = StrData.getCStr(&Offset))
656     return Str;
657   std::string Msg = FormEncodingString(Form).str();
658   if (Index)
659     Msg += (" uses index " + Twine(*Index) + ", but the referenced string").str();
660   Msg += (" offset " + Twine(Offset) + " is beyond .debug_str bounds").str();
661   return make_error<StringError>(Msg,
662       inconvertibleErrorCode());
663 }
664 
665 Optional<uint64_t> DWARFFormValue::getAsAddress() const {
666   if (auto SA = getAsSectionedAddress())
667     return SA->Address;
668   return None;
669 }
670 
671 Optional<object::SectionedAddress>
672 DWARFFormValue::getAsSectionedAddress() const {
673   if (!isFormClass(FC_Address))
674     return None;
675   bool AddrOffset = Form == dwarf::DW_FORM_LLVM_addrx_offset;
676   if (Form == DW_FORM_GNU_addr_index || Form == DW_FORM_addrx || AddrOffset) {
677 
678     uint32_t Index = AddrOffset ? (Value.uval >> 32) : Value.uval;
679     if (!U)
680       return None;
681     Optional<object::SectionedAddress> SA = U->getAddrOffsetSectionItem(Index);
682     if (!SA)
683       return None;
684     if (AddrOffset)
685       SA->Address += (Value.uval & 0xffffffff);
686     return SA;
687   }
688   return {{Value.uval, Value.SectionIndex}};
689 }
690 
691 Optional<uint64_t> DWARFFormValue::getAsReference() const {
692   if (auto R = getAsRelativeReference())
693     return R->Unit ? R->Unit->getOffset() + R->Offset : R->Offset;
694   return None;
695 }
696 
697 Optional<DWARFFormValue::UnitOffset> DWARFFormValue::getAsRelativeReference() const {
698   if (!isFormClass(FC_Reference))
699     return None;
700   switch (Form) {
701   case DW_FORM_ref1:
702   case DW_FORM_ref2:
703   case DW_FORM_ref4:
704   case DW_FORM_ref8:
705   case DW_FORM_ref_udata:
706     if (!U)
707       return None;
708     return UnitOffset{const_cast<DWARFUnit*>(U), Value.uval};
709   case DW_FORM_ref_addr:
710   case DW_FORM_ref_sig8:
711   case DW_FORM_GNU_ref_alt:
712     return UnitOffset{nullptr, Value.uval};
713   default:
714     return None;
715   }
716 }
717 
718 Optional<uint64_t> DWARFFormValue::getAsSectionOffset() const {
719   if (!isFormClass(FC_SectionOffset))
720     return None;
721   return Value.uval;
722 }
723 
724 Optional<uint64_t> DWARFFormValue::getAsUnsignedConstant() const {
725   if ((!isFormClass(FC_Constant) && !isFormClass(FC_Flag)) ||
726       Form == DW_FORM_sdata)
727     return None;
728   return Value.uval;
729 }
730 
731 Optional<int64_t> DWARFFormValue::getAsSignedConstant() const {
732   if ((!isFormClass(FC_Constant) && !isFormClass(FC_Flag)) ||
733       (Form == DW_FORM_udata &&
734        uint64_t(std::numeric_limits<int64_t>::max()) < Value.uval))
735     return None;
736   switch (Form) {
737   case DW_FORM_data4:
738     return int32_t(Value.uval);
739   case DW_FORM_data2:
740     return int16_t(Value.uval);
741   case DW_FORM_data1:
742     return int8_t(Value.uval);
743   case DW_FORM_sdata:
744   case DW_FORM_data8:
745   default:
746     return Value.sval;
747   }
748 }
749 
750 Optional<ArrayRef<uint8_t>> DWARFFormValue::getAsBlock() const {
751   if (!isFormClass(FC_Block) && !isFormClass(FC_Exprloc) &&
752       Form != DW_FORM_data16)
753     return None;
754   return makeArrayRef(Value.data, Value.uval);
755 }
756 
757 Optional<uint64_t> DWARFFormValue::getAsCStringOffset() const {
758   if (!isFormClass(FC_String) && Form == DW_FORM_string)
759     return None;
760   return Value.uval;
761 }
762 
763 Optional<uint64_t> DWARFFormValue::getAsReferenceUVal() const {
764   if (!isFormClass(FC_Reference))
765     return None;
766   return Value.uval;
767 }
768 
769 Optional<std::string>
770 DWARFFormValue::getAsFile(DILineInfoSpecifier::FileLineInfoKind Kind) const {
771   if (U == nullptr || !isFormClass(FC_Constant))
772     return None;
773   DWARFUnit *DLU = const_cast<DWARFUnit *>(U)->getLinkedUnit();
774   if (auto *LT = DLU->getContext().getLineTableForUnit(DLU)) {
775     std::string FileName;
776     if (LT->getFileNameByIndex(Value.uval, DLU->getCompilationDir(), Kind,
777                                FileName))
778       return FileName;
779   }
780   return None;
781 }
782