1 //===- IRSymtab.cpp - implementation of IR symbol tables ------------------===//
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 #include "llvm/Object/IRSymtab.h"
11 #include "llvm/ADT/ArrayRef.h"
12 #include "llvm/ADT/DenseMap.h"
13 #include "llvm/ADT/SmallPtrSet.h"
14 #include "llvm/ADT/SmallString.h"
15 #include "llvm/ADT/SmallVector.h"
16 #include "llvm/ADT/StringRef.h"
17 #include "llvm/ADT/Triple.h"
18 #include "llvm/Analysis/ObjectUtils.h"
19 #include "llvm/IR/Comdat.h"
20 #include "llvm/IR/DataLayout.h"
21 #include "llvm/IR/GlobalAlias.h"
22 #include "llvm/IR/GlobalObject.h"
23 #include "llvm/IR/Mangler.h"
24 #include "llvm/IR/Metadata.h"
25 #include "llvm/IR/Module.h"
26 #include "llvm/Bitcode/BitcodeReader.h"
27 #include "llvm/MC/StringTableBuilder.h"
28 #include "llvm/Object/IRObjectFile.h"
29 #include "llvm/Object/ModuleSymbolTable.h"
30 #include "llvm/Object/SymbolicFile.h"
31 #include "llvm/Support/Allocator.h"
32 #include "llvm/Support/Casting.h"
33 #include "llvm/Support/Error.h"
34 #include "llvm/Support/StringSaver.h"
35 #include "llvm/Support/raw_ostream.h"
42 using namespace irsymtab;
46 /// Stores the temporary state that is required to build an IR symbol table.
48 SmallVector<char, 0> &Symtab;
49 SmallVector<char, 0> &Strtab;
51 Builder(SmallVector<char, 0> &Symtab, SmallVector<char, 0> &Strtab)
52 : Symtab(Symtab), Strtab(Strtab) {}
54 StringTableBuilder StrtabBuilder{StringTableBuilder::RAW};
56 BumpPtrAllocator Alloc;
57 StringSaver Saver{Alloc};
59 DenseMap<const Comdat *, unsigned> ComdatMap;
63 std::vector<storage::Comdat> Comdats;
64 std::vector<storage::Module> Mods;
65 std::vector<storage::Symbol> Syms;
66 std::vector<storage::Uncommon> Uncommons;
68 std::string COFFLinkerOpts;
69 raw_string_ostream COFFLinkerOptsOS{COFFLinkerOpts};
71 void setStr(storage::Str &S, StringRef Value) {
72 S.Offset = StrtabBuilder.add(Value);
73 S.Size = Value.size();
77 void writeRange(storage::Range<T> &R, const std::vector<T> &Objs) {
78 R.Offset = Symtab.size();
80 Symtab.insert(Symtab.end(), reinterpret_cast<const char *>(Objs.data()),
81 reinterpret_cast<const char *>(Objs.data() + Objs.size()));
84 Error addModule(Module *M);
85 Error addSymbol(const ModuleSymbolTable &Msymtab,
86 const SmallPtrSet<GlobalValue *, 8> &Used,
87 ModuleSymbolTable::Symbol Sym);
89 Error build(ArrayRef<Module *> Mods);
92 Error Builder::addModule(Module *M) {
93 if (M->getDataLayoutStr().empty())
94 return make_error<StringError>("input module has no datalayout",
95 inconvertibleErrorCode());
97 SmallPtrSet<GlobalValue *, 8> Used;
98 collectUsedGlobalVariables(*M, Used, /*CompilerUsed*/ false);
100 ModuleSymbolTable Msymtab;
101 Msymtab.addModule(M);
104 Mod.Begin = Syms.size();
105 Mod.End = Syms.size() + Msymtab.symbols().size();
106 Mod.UncBegin = Uncommons.size();
109 if (TT.isOSBinFormatCOFF()) {
110 if (auto E = M->materializeMetadata())
112 if (Metadata *Val = M->getModuleFlag("Linker Options")) {
113 MDNode *LinkerOptions = cast<MDNode>(Val);
114 for (const MDOperand &MDOptions : LinkerOptions->operands())
115 for (const MDOperand &MDOption : cast<MDNode>(MDOptions)->operands())
116 COFFLinkerOptsOS << " " << cast<MDString>(MDOption)->getString();
120 for (ModuleSymbolTable::Symbol Msym : Msymtab.symbols())
121 if (Error Err = addSymbol(Msymtab, Used, Msym))
124 return Error::success();
127 Error Builder::addSymbol(const ModuleSymbolTable &Msymtab,
128 const SmallPtrSet<GlobalValue *, 8> &Used,
129 ModuleSymbolTable::Symbol Msym) {
131 storage::Symbol &Sym = Syms.back();
134 storage::Uncommon *Unc = nullptr;
135 auto Uncommon = [&]() -> storage::Uncommon & {
138 Sym.Flags |= 1 << storage::Symbol::FB_has_uncommon;
139 Uncommons.emplace_back();
140 Unc = &Uncommons.back();
142 setStr(Unc->COFFWeakExternFallbackName, "");
146 SmallString<64> Name;
148 raw_svector_ostream OS(Name);
149 Msymtab.printSymbolName(OS, Msym);
151 setStr(Sym.Name, Saver.save(StringRef(Name)));
153 auto Flags = Msymtab.getSymbolFlags(Msym);
154 if (Flags & object::BasicSymbolRef::SF_Undefined)
155 Sym.Flags |= 1 << storage::Symbol::FB_undefined;
156 if (Flags & object::BasicSymbolRef::SF_Weak)
157 Sym.Flags |= 1 << storage::Symbol::FB_weak;
158 if (Flags & object::BasicSymbolRef::SF_Common)
159 Sym.Flags |= 1 << storage::Symbol::FB_common;
160 if (Flags & object::BasicSymbolRef::SF_Indirect)
161 Sym.Flags |= 1 << storage::Symbol::FB_indirect;
162 if (Flags & object::BasicSymbolRef::SF_Global)
163 Sym.Flags |= 1 << storage::Symbol::FB_global;
164 if (Flags & object::BasicSymbolRef::SF_FormatSpecific)
165 Sym.Flags |= 1 << storage::Symbol::FB_format_specific;
166 if (Flags & object::BasicSymbolRef::SF_Executable)
167 Sym.Flags |= 1 << storage::Symbol::FB_executable;
169 Sym.ComdatIndex = -1;
170 auto *GV = Msym.dyn_cast<GlobalValue *>();
172 // Undefined module asm symbols act as GC roots and are implicitly used.
173 if (Flags & object::BasicSymbolRef::SF_Undefined)
174 Sym.Flags |= 1 << storage::Symbol::FB_used;
175 setStr(Sym.IRName, "");
176 return Error::success();
179 setStr(Sym.IRName, GV->getName());
182 Sym.Flags |= 1 << storage::Symbol::FB_used;
183 if (GV->isThreadLocal())
184 Sym.Flags |= 1 << storage::Symbol::FB_tls;
185 if (GV->hasGlobalUnnamedAddr())
186 Sym.Flags |= 1 << storage::Symbol::FB_unnamed_addr;
187 if (canBeOmittedFromSymbolTable(GV))
188 Sym.Flags |= 1 << storage::Symbol::FB_may_omit;
189 Sym.Flags |= unsigned(GV->getVisibility()) << storage::Symbol::FB_visibility;
191 if (Flags & object::BasicSymbolRef::SF_Common) {
192 Uncommon().CommonSize = GV->getParent()->getDataLayout().getTypeAllocSize(
193 GV->getType()->getElementType());
194 Uncommon().CommonAlign = GV->getAlignment();
197 const GlobalObject *Base = GV->getBaseObject();
199 return make_error<StringError>("Unable to determine comdat of alias!",
200 inconvertibleErrorCode());
201 if (const Comdat *C = Base->getComdat()) {
202 auto P = ComdatMap.insert(std::make_pair(C, Comdats.size()));
203 Sym.ComdatIndex = P.first->second;
206 storage::Comdat Comdat;
207 setStr(Comdat.Name, C->getName());
208 Comdats.push_back(Comdat);
212 if (TT.isOSBinFormatCOFF()) {
213 emitLinkerFlagsForGlobalCOFF(COFFLinkerOptsOS, GV, TT, Mang);
215 if ((Flags & object::BasicSymbolRef::SF_Weak) &&
216 (Flags & object::BasicSymbolRef::SF_Indirect)) {
217 std::string FallbackName;
218 raw_string_ostream OS(FallbackName);
219 Msymtab.printSymbolName(
220 OS, cast<GlobalValue>(
221 cast<GlobalAlias>(GV)->getAliasee()->stripPointerCasts()));
223 setStr(Uncommon().COFFWeakExternFallbackName, Saver.save(FallbackName));
227 return Error::success();
230 Error Builder::build(ArrayRef<Module *> IRMods) {
233 assert(!IRMods.empty());
234 setStr(Hdr.TargetTriple, IRMods[0]->getTargetTriple());
235 setStr(Hdr.SourceFileName, IRMods[0]->getSourceFileName());
236 TT = Triple(IRMods[0]->getTargetTriple());
238 for (auto *M : IRMods)
239 if (Error Err = addModule(M))
242 COFFLinkerOptsOS.flush();
243 setStr(Hdr.COFFLinkerOpts, COFFLinkerOpts);
245 // We are about to fill in the header's range fields, so reserve space for it
246 // and copy it in afterwards.
247 Symtab.resize(sizeof(storage::Header));
248 writeRange(Hdr.Modules, Mods);
249 writeRange(Hdr.Comdats, Comdats);
250 writeRange(Hdr.Symbols, Syms);
251 writeRange(Hdr.Uncommons, Uncommons);
253 *reinterpret_cast<storage::Header *>(Symtab.data()) = Hdr;
255 raw_svector_ostream OS(Strtab);
256 StrtabBuilder.finalizeInOrder();
257 StrtabBuilder.write(OS);
259 return Error::success();
262 } // end anonymous namespace
264 Error irsymtab::build(ArrayRef<Module *> Mods, SmallVector<char, 0> &Symtab,
265 SmallVector<char, 0> &Strtab) {
266 return Builder(Symtab, Strtab).build(Mods);
269 // Upgrade a vector of bitcode modules created by an old version of LLVM by
270 // creating an irsymtab for them in the current format.
271 static Expected<FileContents> upgrade(ArrayRef<BitcodeModule> BMs) {
275 std::vector<Module *> Mods;
276 std::vector<std::unique_ptr<Module>> OwnedMods;
277 for (auto BM : BMs) {
278 Expected<std::unique_ptr<Module>> MOrErr =
279 BM.getLazyModule(Ctx, /*ShouldLazyLoadMetadata*/ true,
280 /*IsImporting*/ false);
282 return MOrErr.takeError();
284 Mods.push_back(MOrErr->get());
285 OwnedMods.push_back(std::move(*MOrErr));
288 if (Error E = build(Mods, FC.Symtab, FC.Strtab))
291 FC.TheReader = {{FC.Symtab.data(), FC.Symtab.size()},
292 {FC.Strtab.data(), FC.Strtab.size()}};
293 return std::move(FC);
296 Expected<FileContents> irsymtab::readBitcode(const BitcodeFileContents &BFC) {
297 if (BFC.Mods.empty())
298 return make_error<StringError>("Bitcode file does not contain any modules",
299 inconvertibleErrorCode());
301 // Right now we have no on-disk representation of symbol tables, so we always
303 return upgrade(BFC.Mods);