1 //===- DWARFFormValue.cpp -------------------------------------------------===//
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 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
11 #include "llvm/ADT/ArrayRef.h"
12 #include "llvm/ADT/None.h"
13 #include "llvm/ADT/Optional.h"
14 #include "llvm/ADT/StringRef.h"
15 #include "llvm/BinaryFormat/Dwarf.h"
16 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
17 #include "llvm/DebugInfo/DWARF/DWARFRelocMap.h"
18 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
19 #include "llvm/Support/ErrorHandling.h"
20 #include "llvm/Support/Format.h"
21 #include "llvm/Support/WithColor.h"
22 #include "llvm/Support/raw_ostream.h"
23 #include <cinttypes>
24 #include <cstdint>
25 #include <limits>
26 
27 using namespace llvm;
28 using namespace dwarf;
29 
30 static const DWARFFormValue::FormClass DWARF5FormClasses[] = {
31     DWARFFormValue::FC_Unknown,  // 0x0
32     DWARFFormValue::FC_Address,  // 0x01 DW_FORM_addr
33     DWARFFormValue::FC_Unknown,  // 0x02 unused
34     DWARFFormValue::FC_Block,    // 0x03 DW_FORM_block2
35     DWARFFormValue::FC_Block,    // 0x04 DW_FORM_block4
36     DWARFFormValue::FC_Constant, // 0x05 DW_FORM_data2
37     // --- These can be FC_SectionOffset in DWARF3 and below:
38     DWARFFormValue::FC_Constant, // 0x06 DW_FORM_data4
39     DWARFFormValue::FC_Constant, // 0x07 DW_FORM_data8
40     // ---
41     DWARFFormValue::FC_String,        // 0x08 DW_FORM_string
42     DWARFFormValue::FC_Block,         // 0x09 DW_FORM_block
43     DWARFFormValue::FC_Block,         // 0x0a DW_FORM_block1
44     DWARFFormValue::FC_Constant,      // 0x0b DW_FORM_data1
45     DWARFFormValue::FC_Flag,          // 0x0c DW_FORM_flag
46     DWARFFormValue::FC_Constant,      // 0x0d DW_FORM_sdata
47     DWARFFormValue::FC_String,        // 0x0e DW_FORM_strp
48     DWARFFormValue::FC_Constant,      // 0x0f DW_FORM_udata
49     DWARFFormValue::FC_Reference,     // 0x10 DW_FORM_ref_addr
50     DWARFFormValue::FC_Reference,     // 0x11 DW_FORM_ref1
51     DWARFFormValue::FC_Reference,     // 0x12 DW_FORM_ref2
52     DWARFFormValue::FC_Reference,     // 0x13 DW_FORM_ref4
53     DWARFFormValue::FC_Reference,     // 0x14 DW_FORM_ref8
54     DWARFFormValue::FC_Reference,     // 0x15 DW_FORM_ref_udata
55     DWARFFormValue::FC_Indirect,      // 0x16 DW_FORM_indirect
56     DWARFFormValue::FC_SectionOffset, // 0x17 DW_FORM_sec_offset
57     DWARFFormValue::FC_Exprloc,       // 0x18 DW_FORM_exprloc
58     DWARFFormValue::FC_Flag,          // 0x19 DW_FORM_flag_present
59     DWARFFormValue::FC_String,        // 0x1a DW_FORM_strx
60     DWARFFormValue::FC_Address,       // 0x1b DW_FORM_addrx
61     DWARFFormValue::FC_Reference,     // 0x1c DW_FORM_ref_sup4
62     DWARFFormValue::FC_String,        // 0x1d DW_FORM_strp_sup
63     DWARFFormValue::FC_Constant,      // 0x1e DW_FORM_data16
64     DWARFFormValue::FC_String,        // 0x1f DW_FORM_line_strp
65     DWARFFormValue::FC_Reference,     // 0x20 DW_FORM_ref_sig8
66     DWARFFormValue::FC_Constant,      // 0x21 DW_FORM_implicit_const
67     DWARFFormValue::FC_SectionOffset, // 0x22 DW_FORM_loclistx
68     DWARFFormValue::FC_SectionOffset, // 0x23 DW_FORM_rnglistx
69     DWARFFormValue::FC_Reference,     // 0x24 DW_FORM_ref_sup8
70     DWARFFormValue::FC_String,        // 0x25 DW_FORM_strx1
71     DWARFFormValue::FC_String,        // 0x26 DW_FORM_strx2
72     DWARFFormValue::FC_String,        // 0x27 DW_FORM_strx3
73     DWARFFormValue::FC_String,        // 0x28 DW_FORM_strx4
74     DWARFFormValue::FC_Address,       // 0x29 DW_FORM_addrx1
75     DWARFFormValue::FC_Address,       // 0x2a DW_FORM_addrx2
76     DWARFFormValue::FC_Address,       // 0x2b DW_FORM_addrx3
77     DWARFFormValue::FC_Address,       // 0x2c DW_FORM_addrx4
78 
79 };
80 
81 bool DWARFFormValue::skipValue(dwarf::Form Form, DataExtractor DebugInfoData,
82                                uint32_t *OffsetPtr,
83                                const dwarf::FormParams Params) {
84   bool Indirect = false;
85   do {
86     switch (Form) {
87     // Blocks of inlined data that have a length field and the data bytes
88     // inlined in the .debug_info.
89     case DW_FORM_exprloc:
90     case DW_FORM_block: {
91       uint64_t size = DebugInfoData.getULEB128(OffsetPtr);
92       *OffsetPtr += size;
93       return true;
94     }
95     case DW_FORM_block1: {
96       uint8_t size = DebugInfoData.getU8(OffsetPtr);
97       *OffsetPtr += size;
98       return true;
99     }
100     case DW_FORM_block2: {
101       uint16_t size = DebugInfoData.getU16(OffsetPtr);
102       *OffsetPtr += size;
103       return true;
104     }
105     case DW_FORM_block4: {
106       uint32_t size = DebugInfoData.getU32(OffsetPtr);
107       *OffsetPtr += size;
108       return true;
109     }
110 
111     // Inlined NULL terminated C-strings.
112     case DW_FORM_string:
113       DebugInfoData.getCStr(OffsetPtr);
114       return true;
115 
116     case DW_FORM_addr:
117     case DW_FORM_ref_addr:
118     case DW_FORM_flag_present:
119     case DW_FORM_data1:
120     case DW_FORM_data2:
121     case DW_FORM_data4:
122     case DW_FORM_data8:
123     case DW_FORM_data16:
124     case DW_FORM_flag:
125     case DW_FORM_ref1:
126     case DW_FORM_ref2:
127     case DW_FORM_ref4:
128     case DW_FORM_ref8:
129     case DW_FORM_ref_sig8:
130     case DW_FORM_ref_sup4:
131     case DW_FORM_ref_sup8:
132     case DW_FORM_strx1:
133     case DW_FORM_strx2:
134     case DW_FORM_strx4:
135     case DW_FORM_addrx1:
136     case DW_FORM_addrx2:
137     case DW_FORM_addrx4:
138     case DW_FORM_sec_offset:
139     case DW_FORM_strp:
140     case DW_FORM_strp_sup:
141     case DW_FORM_line_strp:
142     case DW_FORM_GNU_ref_alt:
143     case DW_FORM_GNU_strp_alt:
144       if (Optional<uint8_t> FixedSize =
145               dwarf::getFixedFormByteSize(Form, Params)) {
146         *OffsetPtr += *FixedSize;
147         return true;
148       }
149       return false;
150 
151     // signed or unsigned LEB 128 values.
152     case DW_FORM_sdata:
153       DebugInfoData.getSLEB128(OffsetPtr);
154       return true;
155 
156     case DW_FORM_udata:
157     case DW_FORM_ref_udata:
158     case DW_FORM_strx:
159     case DW_FORM_addrx:
160     case DW_FORM_loclistx:
161     case DW_FORM_rnglistx:
162     case DW_FORM_GNU_addr_index:
163     case DW_FORM_GNU_str_index:
164       DebugInfoData.getULEB128(OffsetPtr);
165       return true;
166 
167     case DW_FORM_indirect:
168       Indirect = true;
169       Form = static_cast<dwarf::Form>(DebugInfoData.getULEB128(OffsetPtr));
170       break;
171 
172     default:
173       return false;
174     }
175   } while (Indirect);
176   return true;
177 }
178 
179 bool DWARFFormValue::isFormClass(DWARFFormValue::FormClass FC) const {
180   // First, check DWARF5 form classes.
181   if (Form < makeArrayRef(DWARF5FormClasses).size() &&
182       DWARF5FormClasses[Form] == FC)
183     return true;
184   // Check more forms from extensions and proposals.
185   switch (Form) {
186   case DW_FORM_GNU_ref_alt:
187     return (FC == FC_Reference);
188   case DW_FORM_GNU_addr_index:
189     return (FC == FC_Address);
190   case DW_FORM_GNU_str_index:
191   case DW_FORM_GNU_strp_alt:
192     return (FC == FC_String);
193   default:
194     break;
195   }
196   // In DWARF3 DW_FORM_data4 and DW_FORM_data8 served also as a section offset.
197   // Don't check for DWARF version here, as some producers may still do this
198   // by mistake. Also accept DW_FORM_[line_]strp since these are
199   // .debug_[line_]str section offsets.
200   return (Form == DW_FORM_data4 || Form == DW_FORM_data8 ||
201           Form == DW_FORM_strp || Form == DW_FORM_line_strp) &&
202          FC == FC_SectionOffset;
203 }
204 
205 bool DWARFFormValue::extractValue(const DWARFDataExtractor &Data,
206                                   uint32_t *OffsetPtr, dwarf::FormParams FP,
207                                   const DWARFContext *Ctx,
208                                   const DWARFUnit *CU) {
209   if (!Ctx && CU)
210     Ctx = &CU->getContext();
211   C = Ctx;
212   U = CU;
213   bool Indirect = false;
214   bool IsBlock = false;
215   Value.data = nullptr;
216   // Read the value for the form into value and follow and DW_FORM_indirect
217   // instances we run into
218   do {
219     Indirect = false;
220     switch (Form) {
221     case DW_FORM_addr:
222     case DW_FORM_ref_addr: {
223       uint16_t Size =
224           (Form == DW_FORM_addr) ? FP.AddrSize : FP.getRefAddrByteSize();
225       Value.uval = Data.getRelocatedValue(Size, OffsetPtr, &Value.SectionIndex);
226       break;
227     }
228     case DW_FORM_exprloc:
229     case DW_FORM_block:
230       Value.uval = Data.getULEB128(OffsetPtr);
231       IsBlock = true;
232       break;
233     case DW_FORM_block1:
234       Value.uval = Data.getU8(OffsetPtr);
235       IsBlock = true;
236       break;
237     case DW_FORM_block2:
238       Value.uval = Data.getU16(OffsetPtr);
239       IsBlock = true;
240       break;
241     case DW_FORM_block4:
242       Value.uval = Data.getU32(OffsetPtr);
243       IsBlock = true;
244       break;
245     case DW_FORM_data1:
246     case DW_FORM_ref1:
247     case DW_FORM_flag:
248     case DW_FORM_strx1:
249     case DW_FORM_addrx1:
250       Value.uval = Data.getU8(OffsetPtr);
251       break;
252     case DW_FORM_data2:
253     case DW_FORM_ref2:
254     case DW_FORM_strx2:
255     case DW_FORM_addrx2:
256       Value.uval = Data.getU16(OffsetPtr);
257       break;
258     case DW_FORM_strx3:
259       Value.uval = Data.getU24(OffsetPtr);
260       break;
261     case DW_FORM_data4:
262     case DW_FORM_ref4:
263     case DW_FORM_ref_sup4:
264     case DW_FORM_strx4:
265     case DW_FORM_addrx4:
266       Value.uval = Data.getRelocatedValue(4, OffsetPtr);
267       break;
268     case DW_FORM_data8:
269     case DW_FORM_ref8:
270     case DW_FORM_ref_sup8:
271       Value.uval = Data.getU64(OffsetPtr);
272       break;
273     case DW_FORM_data16:
274       // Treat this like a 16-byte block.
275       Value.uval = 16;
276       IsBlock = true;
277       break;
278     case DW_FORM_sdata:
279       Value.sval = Data.getSLEB128(OffsetPtr);
280       break;
281     case DW_FORM_udata:
282     case DW_FORM_ref_udata:
283       Value.uval = Data.getULEB128(OffsetPtr);
284       break;
285     case DW_FORM_string:
286       Value.cstr = Data.getCStr(OffsetPtr);
287       break;
288     case DW_FORM_indirect:
289       Form = static_cast<dwarf::Form>(Data.getULEB128(OffsetPtr));
290       Indirect = true;
291       break;
292     case DW_FORM_strp:
293     case DW_FORM_sec_offset:
294     case DW_FORM_GNU_ref_alt:
295     case DW_FORM_GNU_strp_alt:
296     case DW_FORM_line_strp:
297     case DW_FORM_strp_sup: {
298       Value.uval =
299           Data.getRelocatedValue(FP.getDwarfOffsetByteSize(), OffsetPtr);
300       break;
301     }
302     case DW_FORM_flag_present:
303       Value.uval = 1;
304       break;
305     case DW_FORM_ref_sig8:
306       Value.uval = Data.getU64(OffsetPtr);
307       break;
308     case DW_FORM_GNU_addr_index:
309     case DW_FORM_GNU_str_index:
310     case DW_FORM_strx:
311       Value.uval = Data.getULEB128(OffsetPtr);
312       break;
313     default:
314       // DWARFFormValue::skipValue() will have caught this and caused all
315       // DWARF DIEs to fail to be parsed, so this code is not be reachable.
316       llvm_unreachable("unsupported form");
317     }
318   } while (Indirect);
319 
320   if (IsBlock) {
321     StringRef Str = Data.getData().substr(*OffsetPtr, Value.uval);
322     Value.data = nullptr;
323     if (!Str.empty()) {
324       Value.data = reinterpret_cast<const uint8_t *>(Str.data());
325       *OffsetPtr += Value.uval;
326     }
327   }
328 
329   return true;
330 }
331 
332 void DWARFFormValue::dump(raw_ostream &OS, DIDumpOptions DumpOpts) const {
333   uint64_t UValue = Value.uval;
334   bool CURelativeOffset = false;
335   raw_ostream &AddrOS = DumpOpts.ShowAddresses
336                             ? WithColor(OS, HighlightColor::Address).get()
337                             : nulls();
338   switch (Form) {
339   case DW_FORM_addr:
340     AddrOS << format("0x%016" PRIx64, UValue);
341     break;
342   case DW_FORM_GNU_addr_index: {
343     AddrOS << format(" indexed (%8.8x) address = ", (uint32_t)UValue);
344     uint64_t Address;
345     if (U == nullptr)
346       OS << "<invalid dwarf unit>";
347     else if (U->getAddrOffsetSectionItem(UValue, Address))
348       AddrOS << format("0x%016" PRIx64, Address);
349     else
350       OS << "<no .debug_addr section>";
351     break;
352   }
353   case DW_FORM_flag_present:
354     OS << "true";
355     break;
356   case DW_FORM_flag:
357   case DW_FORM_data1:
358     OS << format("0x%02x", (uint8_t)UValue);
359     break;
360   case DW_FORM_data2:
361     OS << format("0x%04x", (uint16_t)UValue);
362     break;
363   case DW_FORM_data4:
364     OS << format("0x%08x", (uint32_t)UValue);
365     break;
366   case DW_FORM_ref_sig8:
367     AddrOS << format("0x%016" PRIx64, UValue);
368     break;
369   case DW_FORM_data8:
370     OS << format("0x%016" PRIx64, UValue);
371     break;
372   case DW_FORM_data16:
373     OS << format_bytes(ArrayRef<uint8_t>(Value.data, 16), None, 16, 16);
374     break;
375   case DW_FORM_string:
376     OS << '"';
377     OS.write_escaped(Value.cstr);
378     OS << '"';
379     break;
380   case DW_FORM_exprloc:
381   case DW_FORM_block:
382   case DW_FORM_block1:
383   case DW_FORM_block2:
384   case DW_FORM_block4:
385     if (UValue > 0) {
386       switch (Form) {
387       case DW_FORM_exprloc:
388       case DW_FORM_block:
389         OS << format("<0x%" PRIx64 "> ", UValue);
390         break;
391       case DW_FORM_block1:
392         OS << format("<0x%2.2x> ", (uint8_t)UValue);
393         break;
394       case DW_FORM_block2:
395         OS << format("<0x%4.4x> ", (uint16_t)UValue);
396         break;
397       case DW_FORM_block4:
398         OS << format("<0x%8.8x> ", (uint32_t)UValue);
399         break;
400       default:
401         break;
402       }
403 
404       const uint8_t *DataPtr = Value.data;
405       if (DataPtr) {
406         // UValue contains size of block
407         const uint8_t *EndDataPtr = DataPtr + UValue;
408         while (DataPtr < EndDataPtr) {
409           OS << format("%2.2x ", *DataPtr);
410           ++DataPtr;
411         }
412       } else
413         OS << "NULL";
414     }
415     break;
416 
417   case DW_FORM_sdata:
418     OS << Value.sval;
419     break;
420   case DW_FORM_udata:
421     OS << Value.uval;
422     break;
423   case DW_FORM_strp:
424     if (DumpOpts.Verbose)
425       OS << format(" .debug_str[0x%8.8x] = ", (uint32_t)UValue);
426     dumpString(OS);
427     break;
428   case DW_FORM_line_strp:
429     if (DumpOpts.Verbose)
430       OS << format(" .debug_line_str[0x%8.8x] = ", (uint32_t)UValue);
431     dumpString(OS);
432     break;
433   case DW_FORM_strx:
434   case DW_FORM_strx1:
435   case DW_FORM_strx2:
436   case DW_FORM_strx3:
437   case DW_FORM_strx4:
438   case DW_FORM_GNU_str_index:
439     if (DumpOpts.Verbose)
440       OS << format(" indexed (%8.8x) string = ", (uint32_t)UValue);
441     dumpString(OS);
442     break;
443   case DW_FORM_GNU_strp_alt:
444     if (DumpOpts.Verbose)
445       OS << format("alt indirect string, offset: 0x%" PRIx64 "", UValue);
446     dumpString(OS);
447     break;
448   case DW_FORM_ref_addr:
449     AddrOS << format("0x%016" PRIx64, UValue);
450     break;
451   case DW_FORM_ref1:
452     CURelativeOffset = true;
453     if (DumpOpts.Verbose)
454       AddrOS << format("cu + 0x%2.2x", (uint8_t)UValue);
455     break;
456   case DW_FORM_ref2:
457     CURelativeOffset = true;
458     if (DumpOpts.Verbose)
459       AddrOS << format("cu + 0x%4.4x", (uint16_t)UValue);
460     break;
461   case DW_FORM_ref4:
462     CURelativeOffset = true;
463     if (DumpOpts.Verbose)
464       AddrOS << format("cu + 0x%4.4x", (uint32_t)UValue);
465     break;
466   case DW_FORM_ref8:
467     CURelativeOffset = true;
468     if (DumpOpts.Verbose)
469       AddrOS << format("cu + 0x%8.8" PRIx64, UValue);
470     break;
471   case DW_FORM_ref_udata:
472     CURelativeOffset = true;
473     if (DumpOpts.Verbose)
474       AddrOS << format("cu + 0x%" PRIx64, UValue);
475     break;
476   case DW_FORM_GNU_ref_alt:
477     AddrOS << format("<alt 0x%" PRIx64 ">", UValue);
478     break;
479 
480   // All DW_FORM_indirect attributes should be resolved prior to calling
481   // this function
482   case DW_FORM_indirect:
483     OS << "DW_FORM_indirect";
484     break;
485 
486   // Should be formatted to 64-bit for DWARF64.
487   case DW_FORM_sec_offset:
488     AddrOS << format("0x%08x", (uint32_t)UValue);
489     break;
490 
491   default:
492     OS << format("DW_FORM(0x%4.4x)", Form);
493     break;
494   }
495 
496   if (CURelativeOffset) {
497     if (DumpOpts.Verbose)
498       OS << " => {";
499     WithColor(OS, HighlightColor::Address).get()
500         << format("0x%8.8" PRIx64, UValue + (U ? U->getOffset() : 0));
501     if (DumpOpts.Verbose)
502       OS << "}";
503   }
504 }
505 
506 void DWARFFormValue::dumpString(raw_ostream &OS) const {
507   Optional<const char *> DbgStr = getAsCString();
508   if (DbgStr.hasValue()) {
509     auto COS = WithColor(OS, HighlightColor::String);
510     COS.get() << '"';
511     COS.get().write_escaped(DbgStr.getValue());
512     COS.get() << '"';
513   }
514 }
515 
516 Optional<const char *> DWARFFormValue::getAsCString() const {
517   if (!isFormClass(FC_String))
518     return None;
519   if (Form == DW_FORM_string)
520     return Value.cstr;
521   // FIXME: Add support for DW_FORM_GNU_strp_alt
522   if (Form == DW_FORM_GNU_strp_alt || C == nullptr)
523     return None;
524   uint32_t Offset = Value.uval;
525   if (Form == DW_FORM_line_strp) {
526     // .debug_line_str is tracked in the Context.
527     if (const char *Str = C->getLineStringExtractor().getCStr(&Offset))
528       return Str;
529     return None;
530   }
531   if (Form == DW_FORM_GNU_str_index || Form == DW_FORM_strx ||
532       Form == DW_FORM_strx1 || Form == DW_FORM_strx2 || Form == DW_FORM_strx3 ||
533       Form == DW_FORM_strx4) {
534     uint64_t StrOffset;
535     if (!U || !U->getStringOffsetSectionItem(Offset, StrOffset))
536       return None;
537     Offset = StrOffset;
538   }
539   // Prefer the Unit's string extractor, because for .dwo it will point to
540   // .debug_str.dwo, while the Context's extractor always uses .debug_str.
541   if (U) {
542     if (const char *Str = U->getStringExtractor().getCStr(&Offset))
543       return Str;
544     return None;
545   }
546   if (const char *Str = C->getStringExtractor().getCStr(&Offset))
547     return Str;
548   return None;
549 }
550 
551 Optional<uint64_t> DWARFFormValue::getAsAddress() const {
552   if (!isFormClass(FC_Address))
553     return None;
554   if (Form == DW_FORM_GNU_addr_index) {
555     uint32_t Index = Value.uval;
556     uint64_t Result;
557     if (!U || !U->getAddrOffsetSectionItem(Index, Result))
558       return None;
559     return Result;
560   }
561   return Value.uval;
562 }
563 
564 Optional<uint64_t> DWARFFormValue::getAsReference() const {
565   if (!isFormClass(FC_Reference))
566     return None;
567   switch (Form) {
568   case DW_FORM_ref1:
569   case DW_FORM_ref2:
570   case DW_FORM_ref4:
571   case DW_FORM_ref8:
572   case DW_FORM_ref_udata:
573     if (!U)
574       return None;
575     return Value.uval + U->getOffset();
576   case DW_FORM_ref_addr:
577   case DW_FORM_ref_sig8:
578   case DW_FORM_GNU_ref_alt:
579     return Value.uval;
580   default:
581     return None;
582   }
583 }
584 
585 Optional<uint64_t> DWARFFormValue::getAsSectionOffset() const {
586   if (!isFormClass(FC_SectionOffset))
587     return None;
588   return Value.uval;
589 }
590 
591 Optional<uint64_t> DWARFFormValue::getAsUnsignedConstant() const {
592   if ((!isFormClass(FC_Constant) && !isFormClass(FC_Flag)) ||
593       Form == DW_FORM_sdata)
594     return None;
595   return Value.uval;
596 }
597 
598 Optional<int64_t> DWARFFormValue::getAsSignedConstant() const {
599   if ((!isFormClass(FC_Constant) && !isFormClass(FC_Flag)) ||
600       (Form == DW_FORM_udata &&
601        uint64_t(std::numeric_limits<int64_t>::max()) < Value.uval))
602     return None;
603   switch (Form) {
604   case DW_FORM_data4:
605     return int32_t(Value.uval);
606   case DW_FORM_data2:
607     return int16_t(Value.uval);
608   case DW_FORM_data1:
609     return int8_t(Value.uval);
610   case DW_FORM_sdata:
611   case DW_FORM_data8:
612   default:
613     return Value.sval;
614   }
615 }
616 
617 Optional<ArrayRef<uint8_t>> DWARFFormValue::getAsBlock() const {
618   if (!isFormClass(FC_Block) && !isFormClass(FC_Exprloc) &&
619       Form != DW_FORM_data16)
620     return None;
621   return makeArrayRef(Value.data, Value.uval);
622 }
623 
624 Optional<uint64_t> DWARFFormValue::getAsCStringOffset() const {
625   if (!isFormClass(FC_String) && Form == DW_FORM_string)
626     return None;
627   return Value.uval;
628 }
629 
630 Optional<uint64_t> DWARFFormValue::getAsReferenceUVal() const {
631   if (!isFormClass(FC_Reference))
632     return None;
633   return Value.uval;
634 }
635