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     case DW_FORM_rnglistx:
284       Value.uval = Data.getULEB128(OffsetPtr);
285       break;
286     case DW_FORM_string:
287       Value.cstr = Data.getCStr(OffsetPtr);
288       break;
289     case DW_FORM_indirect:
290       Form = static_cast<dwarf::Form>(Data.getULEB128(OffsetPtr));
291       Indirect = true;
292       break;
293     case DW_FORM_strp:
294     case DW_FORM_sec_offset:
295     case DW_FORM_GNU_ref_alt:
296     case DW_FORM_GNU_strp_alt:
297     case DW_FORM_line_strp:
298     case DW_FORM_strp_sup: {
299       Value.uval =
300           Data.getRelocatedValue(FP.getDwarfOffsetByteSize(), OffsetPtr);
301       break;
302     }
303     case DW_FORM_flag_present:
304       Value.uval = 1;
305       break;
306     case DW_FORM_ref_sig8:
307       Value.uval = Data.getU64(OffsetPtr);
308       break;
309     case DW_FORM_GNU_addr_index:
310     case DW_FORM_GNU_str_index:
311     case DW_FORM_addrx:
312     case DW_FORM_strx:
313       Value.uval = Data.getULEB128(OffsetPtr);
314       break;
315     default:
316       // DWARFFormValue::skipValue() will have caught this and caused all
317       // DWARF DIEs to fail to be parsed, so this code is not be reachable.
318       llvm_unreachable("unsupported form");
319     }
320   } while (Indirect);
321 
322   if (IsBlock) {
323     StringRef Str = Data.getData().substr(*OffsetPtr, Value.uval);
324     Value.data = nullptr;
325     if (!Str.empty()) {
326       Value.data = reinterpret_cast<const uint8_t *>(Str.data());
327       *OffsetPtr += Value.uval;
328     }
329   }
330 
331   return true;
332 }
333 
334 void DWARFFormValue::dump(raw_ostream &OS, DIDumpOptions DumpOpts) const {
335   uint64_t UValue = Value.uval;
336   bool CURelativeOffset = false;
337   raw_ostream &AddrOS = DumpOpts.ShowAddresses
338                             ? WithColor(OS, HighlightColor::Address).get()
339                             : nulls();
340   switch (Form) {
341   case DW_FORM_addr:
342     AddrOS << format("0x%016" PRIx64, UValue);
343     break;
344   case DW_FORM_addrx:
345   case DW_FORM_addrx1:
346   case DW_FORM_addrx2:
347   case DW_FORM_addrx3:
348   case DW_FORM_addrx4:
349   case DW_FORM_GNU_addr_index: {
350     AddrOS << format(" indexed (%8.8x) address = ", (uint32_t)UValue);
351     if (U == nullptr)
352       OS << "<invalid dwarf unit>";
353     else if (Optional<SectionedAddress> A = U->getAddrOffsetSectionItem(UValue))
354       AddrOS << format("0x%016" PRIx64, A->Address);
355     else
356       OS << "<no .debug_addr section>";
357     break;
358   }
359   case DW_FORM_flag_present:
360     OS << "true";
361     break;
362   case DW_FORM_flag:
363   case DW_FORM_data1:
364     OS << format("0x%02x", (uint8_t)UValue);
365     break;
366   case DW_FORM_data2:
367     OS << format("0x%04x", (uint16_t)UValue);
368     break;
369   case DW_FORM_data4:
370     OS << format("0x%08x", (uint32_t)UValue);
371     break;
372   case DW_FORM_ref_sig8:
373     AddrOS << format("0x%016" PRIx64, UValue);
374     break;
375   case DW_FORM_data8:
376     OS << format("0x%016" PRIx64, UValue);
377     break;
378   case DW_FORM_data16:
379     OS << format_bytes(ArrayRef<uint8_t>(Value.data, 16), None, 16, 16);
380     break;
381   case DW_FORM_string:
382     OS << '"';
383     OS.write_escaped(Value.cstr);
384     OS << '"';
385     break;
386   case DW_FORM_exprloc:
387   case DW_FORM_block:
388   case DW_FORM_block1:
389   case DW_FORM_block2:
390   case DW_FORM_block4:
391     if (UValue > 0) {
392       switch (Form) {
393       case DW_FORM_exprloc:
394       case DW_FORM_block:
395         AddrOS << format("<0x%" PRIx64 "> ", UValue);
396         break;
397       case DW_FORM_block1:
398         AddrOS << format("<0x%2.2x> ", (uint8_t)UValue);
399         break;
400       case DW_FORM_block2:
401         AddrOS << format("<0x%4.4x> ", (uint16_t)UValue);
402         break;
403       case DW_FORM_block4:
404         AddrOS << format("<0x%8.8x> ", (uint32_t)UValue);
405         break;
406       default:
407         break;
408       }
409 
410       const uint8_t *DataPtr = Value.data;
411       if (DataPtr) {
412         // UValue contains size of block
413         const uint8_t *EndDataPtr = DataPtr + UValue;
414         while (DataPtr < EndDataPtr) {
415           AddrOS << format("%2.2x ", *DataPtr);
416           ++DataPtr;
417         }
418       } else
419         OS << "NULL";
420     }
421     break;
422 
423   case DW_FORM_sdata:
424     OS << Value.sval;
425     break;
426   case DW_FORM_udata:
427     OS << Value.uval;
428     break;
429   case DW_FORM_strp:
430     if (DumpOpts.Verbose)
431       OS << format(" .debug_str[0x%8.8x] = ", (uint32_t)UValue);
432     dumpString(OS);
433     break;
434   case DW_FORM_line_strp:
435     if (DumpOpts.Verbose)
436       OS << format(" .debug_line_str[0x%8.8x] = ", (uint32_t)UValue);
437     dumpString(OS);
438     break;
439   case DW_FORM_strx:
440   case DW_FORM_strx1:
441   case DW_FORM_strx2:
442   case DW_FORM_strx3:
443   case DW_FORM_strx4:
444   case DW_FORM_GNU_str_index:
445     if (DumpOpts.Verbose)
446       OS << format(" indexed (%8.8x) string = ", (uint32_t)UValue);
447     dumpString(OS);
448     break;
449   case DW_FORM_GNU_strp_alt:
450     if (DumpOpts.Verbose)
451       OS << format("alt indirect string, offset: 0x%" PRIx64 "", UValue);
452     dumpString(OS);
453     break;
454   case DW_FORM_ref_addr:
455     AddrOS << format("0x%016" PRIx64, UValue);
456     break;
457   case DW_FORM_ref1:
458     CURelativeOffset = true;
459     if (DumpOpts.Verbose)
460       AddrOS << format("cu + 0x%2.2x", (uint8_t)UValue);
461     break;
462   case DW_FORM_ref2:
463     CURelativeOffset = true;
464     if (DumpOpts.Verbose)
465       AddrOS << format("cu + 0x%4.4x", (uint16_t)UValue);
466     break;
467   case DW_FORM_ref4:
468     CURelativeOffset = true;
469     if (DumpOpts.Verbose)
470       AddrOS << format("cu + 0x%4.4x", (uint32_t)UValue);
471     break;
472   case DW_FORM_ref8:
473     CURelativeOffset = true;
474     if (DumpOpts.Verbose)
475       AddrOS << format("cu + 0x%8.8" PRIx64, UValue);
476     break;
477   case DW_FORM_ref_udata:
478     CURelativeOffset = true;
479     if (DumpOpts.Verbose)
480       AddrOS << format("cu + 0x%" PRIx64, UValue);
481     break;
482   case DW_FORM_GNU_ref_alt:
483     AddrOS << format("<alt 0x%" PRIx64 ">", UValue);
484     break;
485 
486   // All DW_FORM_indirect attributes should be resolved prior to calling
487   // this function
488   case DW_FORM_indirect:
489     OS << "DW_FORM_indirect";
490     break;
491 
492   case DW_FORM_rnglistx:
493     OS << format("indexed (0x%x) rangelist = ", (uint32_t)UValue);
494     break;
495 
496   // Should be formatted to 64-bit for DWARF64.
497   case DW_FORM_sec_offset:
498     AddrOS << format("0x%08x", (uint32_t)UValue);
499     break;
500 
501   default:
502     OS << format("DW_FORM(0x%4.4x)", Form);
503     break;
504   }
505 
506   if (CURelativeOffset) {
507     if (DumpOpts.Verbose)
508       OS << " => {";
509     if (DumpOpts.ShowAddresses)
510       WithColor(OS, HighlightColor::Address).get()
511           << format("0x%8.8" PRIx64, UValue + (U ? U->getOffset() : 0));
512     if (DumpOpts.Verbose)
513       OS << "}";
514   }
515 }
516 
517 void DWARFFormValue::dumpString(raw_ostream &OS) const {
518   Optional<const char *> DbgStr = getAsCString();
519   if (DbgStr.hasValue()) {
520     auto COS = WithColor(OS, HighlightColor::String);
521     COS.get() << '"';
522     COS.get().write_escaped(DbgStr.getValue());
523     COS.get() << '"';
524   }
525 }
526 
527 Optional<const char *> DWARFFormValue::getAsCString() const {
528   if (!isFormClass(FC_String))
529     return None;
530   if (Form == DW_FORM_string)
531     return Value.cstr;
532   // FIXME: Add support for DW_FORM_GNU_strp_alt
533   if (Form == DW_FORM_GNU_strp_alt || C == nullptr)
534     return None;
535   uint32_t Offset = Value.uval;
536   if (Form == DW_FORM_line_strp) {
537     // .debug_line_str is tracked in the Context.
538     if (const char *Str = C->getLineStringExtractor().getCStr(&Offset))
539       return Str;
540     return None;
541   }
542   if (Form == DW_FORM_GNU_str_index || Form == DW_FORM_strx ||
543       Form == DW_FORM_strx1 || Form == DW_FORM_strx2 || Form == DW_FORM_strx3 ||
544       Form == DW_FORM_strx4) {
545     if (!U)
546       return None;
547     Optional<uint64_t> StrOffset = U->getStringOffsetSectionItem(Offset);
548     if (!StrOffset)
549       return None;
550     Offset = *StrOffset;
551   }
552   // Prefer the Unit's string extractor, because for .dwo it will point to
553   // .debug_str.dwo, while the Context's extractor always uses .debug_str.
554   if (U) {
555     if (const char *Str = U->getStringExtractor().getCStr(&Offset))
556       return Str;
557     return None;
558   }
559   if (const char *Str = C->getStringExtractor().getCStr(&Offset))
560     return Str;
561   return None;
562 }
563 
564 Optional<uint64_t> DWARFFormValue::getAsAddress() const {
565   if (auto SA = getAsSectionedAddress())
566     return SA->Address;
567   return None;
568 }
569 Optional<SectionedAddress> DWARFFormValue::getAsSectionedAddress() const {
570   if (!isFormClass(FC_Address))
571     return None;
572   if (Form == DW_FORM_GNU_addr_index || Form == DW_FORM_addrx) {
573     uint32_t Index = Value.uval;
574     if (!U)
575       return None;
576     Optional<SectionedAddress> SA = U->getAddrOffsetSectionItem(Index);
577     if (!SA)
578       return None;
579     return SA;
580   }
581   return {{Value.uval, Value.SectionIndex}};
582 }
583 
584 Optional<uint64_t> DWARFFormValue::getAsReference() const {
585   if (!isFormClass(FC_Reference))
586     return None;
587   switch (Form) {
588   case DW_FORM_ref1:
589   case DW_FORM_ref2:
590   case DW_FORM_ref4:
591   case DW_FORM_ref8:
592   case DW_FORM_ref_udata:
593     if (!U)
594       return None;
595     return Value.uval + U->getOffset();
596   case DW_FORM_ref_addr:
597   case DW_FORM_ref_sig8:
598   case DW_FORM_GNU_ref_alt:
599     return Value.uval;
600   default:
601     return None;
602   }
603 }
604 
605 Optional<uint64_t> DWARFFormValue::getAsSectionOffset() const {
606   if (!isFormClass(FC_SectionOffset))
607     return None;
608   return Value.uval;
609 }
610 
611 Optional<uint64_t> DWARFFormValue::getAsUnsignedConstant() const {
612   if ((!isFormClass(FC_Constant) && !isFormClass(FC_Flag)) ||
613       Form == DW_FORM_sdata)
614     return None;
615   return Value.uval;
616 }
617 
618 Optional<int64_t> DWARFFormValue::getAsSignedConstant() const {
619   if ((!isFormClass(FC_Constant) && !isFormClass(FC_Flag)) ||
620       (Form == DW_FORM_udata &&
621        uint64_t(std::numeric_limits<int64_t>::max()) < Value.uval))
622     return None;
623   switch (Form) {
624   case DW_FORM_data4:
625     return int32_t(Value.uval);
626   case DW_FORM_data2:
627     return int16_t(Value.uval);
628   case DW_FORM_data1:
629     return int8_t(Value.uval);
630   case DW_FORM_sdata:
631   case DW_FORM_data8:
632   default:
633     return Value.sval;
634   }
635 }
636 
637 Optional<ArrayRef<uint8_t>> DWARFFormValue::getAsBlock() const {
638   if (!isFormClass(FC_Block) && !isFormClass(FC_Exprloc) &&
639       Form != DW_FORM_data16)
640     return None;
641   return makeArrayRef(Value.data, Value.uval);
642 }
643 
644 Optional<uint64_t> DWARFFormValue::getAsCStringOffset() const {
645   if (!isFormClass(FC_String) && Form == DW_FORM_string)
646     return None;
647   return Value.uval;
648 }
649 
650 Optional<uint64_t> DWARFFormValue::getAsReferenceUVal() const {
651   if (!isFormClass(FC_Reference))
652     return None;
653   return Value.uval;
654 }
655