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 // The length of the header data is always going to be 4 + 4 + 4*NumAtoms.
46 DwarfAccelTable::DwarfAccelTable(std::vector<DwarfAccelTable::Atom> &atomList) :
47 Header(8 + (atomList.size() * 4)),
48 HeaderData(atomList) {
51 DwarfAccelTable::~DwarfAccelTable() {
52 for (size_t i = 0, e = Data.size(); i < e; ++i)
56 void DwarfAccelTable::AddName(StringRef Name, DIE* die, char Flags) {
57 // If the string is in the list already then add this die to the list
58 // otherwise add a new one.
59 DataArray &DIEs = Entries[Name];
60 DIEs.push_back(new HashDataContents(die, Flags));
63 void DwarfAccelTable::ComputeBucketCount(void) {
64 // First get the number of unique hashes.
65 std::vector<uint32_t> uniques;
66 uniques.resize(Data.size());
67 for (size_t i = 0, e = Data.size(); i < e; ++i)
68 uniques[i] = Data[i]->HashValue;
69 std::stable_sort(uniques.begin(), uniques.end());
70 std::vector<uint32_t>::iterator p =
71 std::unique(uniques.begin(), uniques.end());
72 uint32_t num = std::distance(uniques.begin(), p);
74 // Then compute the bucket size, minimum of 1 bucket.
75 if (num > 1024) Header.bucket_count = num/4;
76 if (num > 16) Header.bucket_count = num/2;
77 else Header.bucket_count = num > 0 ? num : 1;
79 Header.hashes_count = num;
83 // DIESorter - comparison predicate that sorts DIEs by their offset.
85 bool operator()(const struct DwarfAccelTable::HashDataContents *A,
86 const struct DwarfAccelTable::HashDataContents *B) const {
87 return A->Die->getOffset() < B->Die->getOffset();
92 void DwarfAccelTable::FinalizeTable(AsmPrinter *Asm, const char *Prefix) {
93 // Create the individual hash data outputs.
94 for (StringMap<DataArray>::iterator
95 EI = Entries.begin(), EE = Entries.end(); EI != EE; ++EI) {
96 struct HashData *Entry = new HashData((*EI).getKeyData());
98 // Unique the entries.
99 std::stable_sort((*EI).second.begin(), (*EI).second.end(), DIESorter());
100 (*EI).second.erase(std::unique((*EI).second.begin(), (*EI).second.end()),
103 for (DataArray::const_iterator DI = (*EI).second.begin(),
104 DE = (*EI).second.end();
106 Entry->addData((*DI));
107 Data.push_back(Entry);
110 // Figure out how many buckets we need, then compute the bucket
111 // contents and the final ordering. We'll emit the hashes and offsets
112 // by doing a walk during the emission phase. We add temporary
113 // symbols to the data so that we can reference them during the offset
114 // later, we'll emit them when we emit the data.
115 ComputeBucketCount();
117 // Compute bucket contents and final ordering.
118 Buckets.resize(Header.bucket_count);
119 for (size_t i = 0, e = Data.size(); i < e; ++i) {
120 uint32_t bucket = Data[i]->HashValue % Header.bucket_count;
121 Buckets[bucket].push_back(Data[i]);
122 Data[i]->Sym = Asm->GetTempSymbol(Prefix, i);
126 // Emits the header for the table via the AsmPrinter.
127 void DwarfAccelTable::EmitHeader(AsmPrinter *Asm) {
128 Asm->OutStreamer.AddComment("Header Magic");
129 Asm->EmitInt32(Header.magic);
130 Asm->OutStreamer.AddComment("Header Version");
131 Asm->EmitInt16(Header.version);
132 Asm->OutStreamer.AddComment("Header Hash Function");
133 Asm->EmitInt16(Header.hash_function);
134 Asm->OutStreamer.AddComment("Header Bucket Count");
135 Asm->EmitInt32(Header.bucket_count);
136 Asm->OutStreamer.AddComment("Header Hash Count");
137 Asm->EmitInt32(Header.hashes_count);
138 Asm->OutStreamer.AddComment("Header Data Length");
139 Asm->EmitInt32(Header.header_data_len);
140 Asm->OutStreamer.AddComment("HeaderData Die Offset Base");
141 Asm->EmitInt32(HeaderData.die_offset_base);
142 Asm->OutStreamer.AddComment("HeaderData Atom Count");
143 Asm->EmitInt32(HeaderData.Atoms.size());
144 for (size_t i = 0; i < HeaderData.Atoms.size(); i++) {
145 Atom A = HeaderData.Atoms[i];
146 Asm->OutStreamer.AddComment(Atom::AtomTypeString(A.type));
147 Asm->EmitInt16(A.type);
148 Asm->OutStreamer.AddComment(dwarf::FormEncodingString(A.form));
149 Asm->EmitInt16(A.form);
153 // Walk through and emit the buckets for the table. This will look
154 // like a list of numbers of how many elements are in each bucket.
155 void DwarfAccelTable::EmitBuckets(AsmPrinter *Asm) {
157 for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
158 Asm->OutStreamer.AddComment("Bucket " + Twine(i));
159 if (Buckets[i].size() != 0)
160 Asm->EmitInt32(index);
162 Asm->EmitInt32(UINT32_MAX);
163 index += Buckets[i].size();
167 // Walk through the buckets and emit the individual hashes for each
169 void DwarfAccelTable::EmitHashes(AsmPrinter *Asm) {
170 for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
171 for (HashList::const_iterator HI = Buckets[i].begin(),
172 HE = Buckets[i].end(); HI != HE; ++HI) {
173 Asm->OutStreamer.AddComment("Hash in Bucket " + Twine(i));
174 Asm->EmitInt32((*HI)->HashValue);
179 // Walk through the buckets and emit the individual offsets for each
180 // element in each bucket. This is done via a symbol subtraction from the
181 // beginning of the section. The non-section symbol will be output later
182 // when we emit the actual data.
183 void DwarfAccelTable::EmitOffsets(AsmPrinter *Asm, MCSymbol *SecBegin) {
184 for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
185 for (HashList::const_iterator HI = Buckets[i].begin(),
186 HE = Buckets[i].end(); HI != HE; ++HI) {
187 Asm->OutStreamer.AddComment("Offset in Bucket " + Twine(i));
188 MCContext &Context = Asm->OutStreamer.getContext();
190 MCBinaryExpr::CreateSub(MCSymbolRefExpr::Create((*HI)->Sym, Context),
191 MCSymbolRefExpr::Create(SecBegin, Context),
193 Asm->OutStreamer.EmitValue(Sub, sizeof(uint32_t), 0);
198 // Walk through the buckets and emit the full data for each element in
199 // the bucket. For the string case emit the dies and the various offsets.
200 // Terminate each HashData bucket with 0.
201 void DwarfAccelTable::EmitData(AsmPrinter *Asm, DwarfDebug *D) {
202 uint64_t PrevHash = UINT64_MAX;
203 for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
204 for (HashList::const_iterator HI = Buckets[i].begin(),
205 HE = Buckets[i].end(); HI != HE; ++HI) {
206 // Remember to emit the label for our offset.
207 Asm->OutStreamer.EmitLabel((*HI)->Sym);
208 Asm->OutStreamer.AddComment((*HI)->Str);
209 Asm->EmitSectionOffset(D->getStringPoolEntry((*HI)->Str),
211 Asm->OutStreamer.AddComment("Num DIEs");
212 Asm->EmitInt32((*HI)->Data.size());
213 for (std::vector<struct HashDataContents*>::const_iterator
214 DI = (*HI)->Data.begin(), DE = (*HI)->Data.end();
216 // Emit the DIE offset
217 Asm->EmitInt32((*DI)->Die->getOffset());
218 // If we have multiple Atoms emit that info too.
219 // FIXME: A bit of a hack, we either emit only one atom or all info.
220 if (HeaderData.Atoms.size() > 1) {
221 Asm->EmitInt16((*DI)->Die->getTag());
222 Asm->EmitInt8((*DI)->Flags);
225 // Emit a 0 to terminate the data unless we have a hash collision.
226 if (PrevHash != (*HI)->HashValue)
228 PrevHash = (*HI)->HashValue;
233 // Emit the entire data structure to the output file.
234 void DwarfAccelTable::Emit(AsmPrinter *Asm, MCSymbol *SecBegin,
246 EmitOffsets(Asm, SecBegin);
248 // Emit the hash data.
253 void DwarfAccelTable::print(raw_ostream &O) {
259 for (StringMap<DataArray>::const_iterator
260 EI = Entries.begin(), EE = Entries.end(); EI != EE; ++EI) {
261 O << "Name: " << (*EI).getKeyData() << "\n";
262 for (DataArray::const_iterator DI = (*EI).second.begin(),
263 DE = (*EI).second.end();
268 O << "Buckets and Hashes: \n";
269 for (size_t i = 0, e = Buckets.size(); i < e; ++i)
270 for (HashList::const_iterator HI = Buckets[i].begin(),
271 HE = Buckets[i].end(); HI != HE; ++HI)
275 for (std::vector<HashData*>::const_iterator
276 DI = Data.begin(), DE = Data.end(); DI != DE; ++DI)