1 //===-- DWARFCompileUnit.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 "DWARFCompileUnit.h"
11 #include "DWARFContext.h"
12 #include "DWARFFormValue.h"
13 #include "llvm/Support/Dwarf.h"
14 #include "llvm/Support/Format.h"
15 #include "llvm/Support/raw_ostream.h"
16 using namespace llvm;
17 using namespace dwarf;
18
getDebugInfoExtractor() const19 DataExtractor DWARFCompileUnit::getDebugInfoExtractor() const {
20 return DataExtractor(Context.getInfoSection(),
21 Context.isLittleEndian(), getAddressByteSize());
22 }
23
extract(DataExtractor debug_info,uint32_t * offset_ptr)24 bool DWARFCompileUnit::extract(DataExtractor debug_info, uint32_t *offset_ptr) {
25 clear();
26
27 Offset = *offset_ptr;
28
29 if (debug_info.isValidOffset(*offset_ptr)) {
30 uint64_t abbrOffset;
31 const DWARFDebugAbbrev *abbr = Context.getDebugAbbrev();
32 Length = debug_info.getU32(offset_ptr);
33 Version = debug_info.getU16(offset_ptr);
34 abbrOffset = debug_info.getU32(offset_ptr);
35 AddrSize = debug_info.getU8(offset_ptr);
36
37 bool lengthOK = debug_info.isValidOffset(getNextCompileUnitOffset()-1);
38 bool versionOK = DWARFContext::isSupportedVersion(Version);
39 bool abbrOffsetOK = Context.getAbbrevSection().size() > abbrOffset;
40 bool addrSizeOK = AddrSize == 4 || AddrSize == 8;
41
42 if (lengthOK && versionOK && addrSizeOK && abbrOffsetOK && abbr != NULL) {
43 Abbrevs = abbr->getAbbreviationDeclarationSet(abbrOffset);
44 return true;
45 }
46
47 // reset the offset to where we tried to parse from if anything went wrong
48 *offset_ptr = Offset;
49 }
50
51 return false;
52 }
53
54 uint32_t
extract(uint32_t offset,DataExtractor debug_info_data,const DWARFAbbreviationDeclarationSet * abbrevs)55 DWARFCompileUnit::extract(uint32_t offset, DataExtractor debug_info_data,
56 const DWARFAbbreviationDeclarationSet *abbrevs) {
57 clear();
58
59 Offset = offset;
60
61 if (debug_info_data.isValidOffset(offset)) {
62 Length = debug_info_data.getU32(&offset);
63 Version = debug_info_data.getU16(&offset);
64 bool abbrevsOK = debug_info_data.getU32(&offset) == abbrevs->getOffset();
65 Abbrevs = abbrevs;
66 AddrSize = debug_info_data.getU8 (&offset);
67
68 bool versionOK = DWARFContext::isSupportedVersion(Version);
69 bool addrSizeOK = AddrSize == 4 || AddrSize == 8;
70
71 if (versionOK && addrSizeOK && abbrevsOK &&
72 debug_info_data.isValidOffset(offset))
73 return offset;
74 }
75 return 0;
76 }
77
clear()78 void DWARFCompileUnit::clear() {
79 Offset = 0;
80 Length = 0;
81 Version = 0;
82 Abbrevs = 0;
83 AddrSize = 0;
84 BaseAddr = 0;
85 DieArray.clear();
86 }
87
dump(raw_ostream & OS)88 void DWARFCompileUnit::dump(raw_ostream &OS) {
89 OS << format("0x%08x", Offset) << ": Compile Unit:"
90 << " length = " << format("0x%08x", Length)
91 << " version = " << format("0x%04x", Version)
92 << " abbr_offset = " << format("0x%04x", Abbrevs->getOffset())
93 << " addr_size = " << format("0x%02x", AddrSize)
94 << " (next CU at " << format("0x%08x", getNextCompileUnitOffset())
95 << ")\n";
96
97 getCompileUnitDIE(false)->dump(OS, this, -1U);
98 }
99
setDIERelations()100 void DWARFCompileUnit::setDIERelations() {
101 if (DieArray.empty())
102 return;
103 DWARFDebugInfoEntryMinimal *die_array_begin = &DieArray.front();
104 DWARFDebugInfoEntryMinimal *die_array_end = &DieArray.back();
105 DWARFDebugInfoEntryMinimal *curr_die;
106 // We purposely are skipping the last element in the array in the loop below
107 // so that we can always have a valid next item
108 for (curr_die = die_array_begin; curr_die < die_array_end; ++curr_die) {
109 // Since our loop doesn't include the last element, we can always
110 // safely access the next die in the array.
111 DWARFDebugInfoEntryMinimal *next_die = curr_die + 1;
112
113 const DWARFAbbreviationDeclaration *curr_die_abbrev =
114 curr_die->getAbbreviationDeclarationPtr();
115
116 if (curr_die_abbrev) {
117 // Normal DIE
118 if (curr_die_abbrev->hasChildren())
119 next_die->setParent(curr_die);
120 else
121 curr_die->setSibling(next_die);
122 } else {
123 // NULL DIE that terminates a sibling chain
124 DWARFDebugInfoEntryMinimal *parent = curr_die->getParent();
125 if (parent)
126 parent->setSibling(next_die);
127 }
128 }
129
130 // Since we skipped the last element, we need to fix it up!
131 if (die_array_begin < die_array_end)
132 curr_die->setParent(die_array_begin);
133 }
134
extractDIEsIfNeeded(bool cu_die_only)135 size_t DWARFCompileUnit::extractDIEsIfNeeded(bool cu_die_only) {
136 const size_t initial_die_array_size = DieArray.size();
137 if ((cu_die_only && initial_die_array_size > 0) ||
138 initial_die_array_size > 1)
139 return 0; // Already parsed
140
141 // Set the offset to that of the first DIE and calculate the start of the
142 // next compilation unit header.
143 uint32_t offset = getFirstDIEOffset();
144 uint32_t next_cu_offset = getNextCompileUnitOffset();
145
146 DWARFDebugInfoEntryMinimal die;
147 // Keep a flat array of the DIE for binary lookup by DIE offset
148 uint32_t depth = 0;
149 // We are in our compile unit, parse starting at the offset
150 // we were told to parse
151
152 const uint8_t *fixed_form_sizes =
153 DWARFFormValue::getFixedFormSizesForAddressSize(getAddressByteSize());
154
155 while (offset < next_cu_offset &&
156 die.extractFast(this, fixed_form_sizes, &offset)) {
157
158 if (depth == 0) {
159 uint64_t base_addr =
160 die.getAttributeValueAsUnsigned(this, DW_AT_low_pc, -1U);
161 if (base_addr == -1U)
162 base_addr = die.getAttributeValueAsUnsigned(this, DW_AT_entry_pc, 0);
163 setBaseAddress(base_addr);
164 }
165
166 if (cu_die_only) {
167 addDIE(die);
168 return 1;
169 }
170 else if (depth == 0 && initial_die_array_size == 1) {
171 // Don't append the CU die as we already did that
172 } else {
173 addDIE (die);
174 }
175
176 const DWARFAbbreviationDeclaration *abbrDecl =
177 die.getAbbreviationDeclarationPtr();
178 if (abbrDecl) {
179 // Normal DIE
180 if (abbrDecl->hasChildren())
181 ++depth;
182 } else {
183 // NULL DIE.
184 if (depth > 0)
185 --depth;
186 if (depth == 0)
187 break; // We are done with this compile unit!
188 }
189
190 }
191
192 // Give a little bit of info if we encounter corrupt DWARF (our offset
193 // should always terminate at or before the start of the next compilation
194 // unit header).
195 if (offset > next_cu_offset) {
196 fprintf (stderr, "warning: DWARF compile unit extends beyond its bounds cu 0x%8.8x at 0x%8.8x'\n", getOffset(), offset);
197 }
198
199 setDIERelations();
200 return DieArray.size();
201 }
202
clearDIEs(bool keep_compile_unit_die)203 void DWARFCompileUnit::clearDIEs(bool keep_compile_unit_die) {
204 if (DieArray.size() > 1) {
205 // std::vectors never get any smaller when resized to a smaller size,
206 // or when clear() or erase() are called, the size will report that it
207 // is smaller, but the memory allocated remains intact (call capacity()
208 // to see this). So we need to create a temporary vector and swap the
209 // contents which will cause just the internal pointers to be swapped
210 // so that when "tmp_array" goes out of scope, it will destroy the
211 // contents.
212
213 // Save at least the compile unit DIE
214 std::vector<DWARFDebugInfoEntryMinimal> tmpArray;
215 DieArray.swap(tmpArray);
216 if (keep_compile_unit_die)
217 DieArray.push_back(tmpArray.front());
218 }
219 }
220
221 void
buildAddressRangeTable(DWARFDebugAranges * debug_aranges,bool clear_dies_if_already_not_parsed)222 DWARFCompileUnit::buildAddressRangeTable(DWARFDebugAranges *debug_aranges,
223 bool clear_dies_if_already_not_parsed){
224 // This function is usually called if there in no .debug_aranges section
225 // in order to produce a compile unit level set of address ranges that
226 // is accurate. If the DIEs weren't parsed, then we don't want all dies for
227 // all compile units to stay loaded when they weren't needed. So we can end
228 // up parsing the DWARF and then throwing them all away to keep memory usage
229 // down.
230 const bool clear_dies = extractDIEsIfNeeded(false) > 1;
231
232 DieArray[0].buildAddressRangeTable(this, debug_aranges);
233
234 // Keep memory down by clearing DIEs if this generate function
235 // caused them to be parsed.
236 if (clear_dies)
237 clearDIEs(true);
238 }
239