1 //=-- llvm/CodeGen/DwarfAccelTable.cpp - Dwarf Accelerator Tables -*- C++ -*-=//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains support for writing dwarf accelerator tables.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/CodeGen/AsmPrinter.h"
15 #include "llvm/MC/MCExpr.h"
16 #include "llvm/MC/MCStreamer.h"
17 #include "llvm/MC/MCSymbol.h"
18 #include "llvm/Support/Debug.h"
19 #include "DwarfAccelTable.h"
20 #include "DwarfDebug.h"
25 const char *DwarfAccelTable::Atom::AtomTypeString(enum AtomType AT) {
27 default: llvm_unreachable("invalid AtomType!");
28 case eAtomTypeNULL: return "eAtomTypeNULL";
29 case eAtomTypeDIEOffset: return "eAtomTypeDIEOffset";
30 case eAtomTypeCUOffset: return "eAtomTypeCUOffset";
31 case eAtomTypeTag: return "eAtomTypeTag";
32 case eAtomTypeNameFlags: return "eAtomTypeNameFlags";
33 case eAtomTypeTypeFlags: return "eAtomTypeTypeFlags";
37 // The general case would need to have a less hard coded size for the
38 // length of the HeaderData, however, if we're constructing based on a
39 // single Atom then we know it will always be: 4 + 4 + 2 + 2.
40 DwarfAccelTable::DwarfAccelTable(DwarfAccelTable::Atom atom) :
45 DwarfAccelTable::~DwarfAccelTable() {
46 for (size_t i = 0, e = Data.size() ; i < e; ++i)
50 void DwarfAccelTable::AddName(StringRef Name, DIE* die) {
51 // If the string is in the list already then add this die to the list
52 // otherwise add a new one.
53 DIEArray &DIEs = Entries[Name];
57 void DwarfAccelTable::ComputeBucketCount(void) {
58 // First get the number of unique hashes.
59 std::vector<uint32_t> uniques;
60 uniques.resize(Data.size());
61 for (size_t i = 0, e = Data.size(); i < e; ++i)
62 uniques[i] = Data[i]->HashValue;
63 std::sort(uniques.begin(), uniques.end());
64 std::vector<uint32_t>::iterator p =
65 std::unique(uniques.begin(), uniques.end());
66 uint32_t num = std::distance(uniques.begin(), p);
68 // Then compute the bucket size, minimum of 1 bucket.
69 if (num > 1024) Header.bucket_count = num/4;
70 if (num > 16) Header.bucket_count = num/2;
71 else Header.bucket_count = num > 0 ? num : 1;
73 Header.hashes_count = num;
76 void DwarfAccelTable::FinalizeTable(AsmPrinter *Asm, const char *Prefix) {
77 // Create the individual hash data outputs.
78 for (StringMap<DIEArray>::iterator
79 EI = Entries.begin(), EE = Entries.end(); EI != EE; ++EI) {
80 struct HashData *Entry = new HashData((*EI).getKeyData());
82 // Unique the entries.
83 std::sort((*EI).second.begin(), (*EI).second.end());
84 (*EI).second.erase(std::unique((*EI).second.begin(), (*EI).second.end()),
87 for (DIEArray::const_iterator DI = (*EI).second.begin(),
88 DE = (*EI).second.end();
90 Entry->addOffset((*DI)->getOffset());
91 Data.push_back(Entry);
94 // Figure out how many buckets we need, then compute the bucket
95 // contents and the final ordering. We'll emit the hashes and offsets
96 // by doing a walk during the emission phase. We add temporary
97 // symbols to the data so that we can reference them during the offset
98 // later, we'll emit them when we emit the data.
101 // Compute bucket contents and final ordering.
102 Buckets.resize(Header.bucket_count);
103 for (size_t i = 0, e = Data.size(); i < e; ++i) {
104 uint32_t bucket = Data[i]->HashValue % Header.bucket_count;
105 Buckets[bucket].push_back(Data[i]);
106 Data[i]->Sym = Asm->GetTempSymbol(Prefix, i);
110 // Emits the header for the table via the AsmPrinter.
111 void DwarfAccelTable::EmitHeader(AsmPrinter *Asm) {
112 Asm->OutStreamer.AddComment("Header Magic");
113 Asm->EmitInt32(Header.magic);
114 Asm->OutStreamer.AddComment("Header Version");
115 Asm->EmitInt16(Header.version);
116 Asm->OutStreamer.AddComment("Header Hash Function");
117 Asm->EmitInt16(Header.hash_function);
118 Asm->OutStreamer.AddComment("Header Bucket Count");
119 Asm->EmitInt32(Header.bucket_count);
120 Asm->OutStreamer.AddComment("Header Hash Count");
121 Asm->EmitInt32(Header.hashes_count);
122 Asm->OutStreamer.AddComment("Header Data Length");
123 Asm->EmitInt32(Header.header_data_len);
124 Asm->OutStreamer.AddComment("HeaderData Die Offset Base");
125 Asm->EmitInt32(HeaderData.die_offset_base);
126 Asm->OutStreamer.AddComment("HeaderData Atom Count");
127 Asm->EmitInt32(HeaderData.Atoms.size());
128 for (size_t i = 0; i < HeaderData.Atoms.size(); i++) {
129 Atom A = HeaderData.Atoms[i];
130 Asm->OutStreamer.AddComment(Atom::AtomTypeString(A.type));
131 Asm->EmitInt16(A.type);
132 Asm->OutStreamer.AddComment(dwarf::FormEncodingString(A.form));
133 Asm->EmitInt16(A.form);
137 // Walk through and emit the buckets for the table. This will look
138 // like a list of numbers of how many elements are in each bucket.
139 void DwarfAccelTable::EmitBuckets(AsmPrinter *Asm) {
141 for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
142 Asm->OutStreamer.AddComment("Bucket " + Twine(i));
143 if (Buckets[i].size() != 0)
144 Asm->EmitInt32(index);
146 Asm->EmitInt32(UINT32_MAX);
147 index += Buckets[i].size();
151 // Walk through the buckets and emit the individual hashes for each
153 void DwarfAccelTable::EmitHashes(AsmPrinter *Asm) {
154 for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
155 for (HashList::const_iterator HI = Buckets[i].begin(),
156 HE = Buckets[i].end(); HI != HE; ++HI) {
157 Asm->OutStreamer.AddComment("Hash in Bucket " + Twine(i));
158 Asm->EmitInt32((*HI)->HashValue);
163 // Walk through the buckets and emit the individual offsets for each
164 // element in each bucket. This is done via a symbol subtraction from the
165 // beginning of the section. The non-section symbol will be output later
166 // when we emit the actual data.
167 void DwarfAccelTable::EmitOffsets(AsmPrinter *Asm, MCSymbol *SecBegin) {
168 for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
169 for (HashList::const_iterator HI = Buckets[i].begin(),
170 HE = Buckets[i].end(); HI != HE; ++HI) {
171 Asm->OutStreamer.AddComment("Offset in Bucket " + Twine(i));
172 MCContext &Context = Asm->OutStreamer.getContext();
174 MCBinaryExpr::CreateSub(MCSymbolRefExpr::Create((*HI)->Sym, Context),
175 MCSymbolRefExpr::Create(SecBegin, Context),
177 Asm->OutStreamer.EmitValue(Sub, sizeof(uint32_t), 0);
182 // Walk through the buckets and emit the full data for each element in
183 // the bucket. For the string case emit the dies and the various offsets.
184 // Terminate each HashData bucket with 0.
185 void DwarfAccelTable::EmitData(AsmPrinter *Asm, DwarfDebug *D) {
186 uint64_t PrevHash = UINT64_MAX;
187 for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
188 for (HashList::const_iterator HI = Buckets[i].begin(),
189 HE = Buckets[i].end(); HI != HE; ++HI) {
190 // Remember to emit the label for our offset.
191 Asm->OutStreamer.EmitLabel((*HI)->Sym);
192 Asm->OutStreamer.AddComment((*HI)->Str);
193 Asm->EmitSectionOffset(D->getStringPoolEntry((*HI)->Str),
195 Asm->OutStreamer.AddComment("Num DIEs");
196 Asm->EmitInt32((*HI)->DIEOffsets.size());
197 for (std::vector<uint32_t>::const_iterator
198 DI = (*HI)->DIEOffsets.begin(), DE = (*HI)->DIEOffsets.end();
200 Asm->EmitInt32((*DI));
202 // Emit a 0 to terminate the data unless we have a hash collision.
203 if (PrevHash != (*HI)->HashValue)
205 PrevHash = (*HI)->HashValue;
210 // Emit the entire data structure to the output file.
211 void DwarfAccelTable::Emit(AsmPrinter *Asm, MCSymbol *SecBegin,
223 EmitOffsets(Asm, SecBegin);
225 // Emit the hash data.
230 void DwarfAccelTable::print(raw_ostream &O) {
236 for (StringMap<DIEArray>::const_iterator
237 EI = Entries.begin(), EE = Entries.end(); EI != EE; ++EI) {
238 O << "Name: " << (*EI).getKeyData() << "\n";
239 for (DIEArray::const_iterator DI = (*EI).second.begin(),
240 DE = (*EI).second.end();
245 O << "Buckets and Hashes: \n";
246 for (size_t i = 0, e = Buckets.size(); i < e; ++i)
247 for (HashList::const_iterator HI = Buckets[i].begin(),
248 HE = Buckets[i].end(); HI != HE; ++HI)
252 for (std::vector<HashData*>::const_iterator
253 DI = Data.begin(), DE = Data.end(); DI != DE; ++DI)