1 //===- IRSymtab.cpp - implementation of IR symbol 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 #include "llvm/Object/IRSymtab.h"
11 #include "llvm/Analysis/ObjectUtils.h"
12 #include "llvm/IR/Mangler.h"
13 #include "llvm/IR/Module.h"
14 #include "llvm/MC/StringTableBuilder.h"
15 #include "llvm/Object/ModuleSymbolTable.h"
16 #include "llvm/Support/Allocator.h"
17 #include "llvm/Support/StringSaver.h"
20 using namespace irsymtab;
24 /// Stores the temporary state that is required to build an IR symbol table.
26 SmallVector<char, 0> &Symtab;
27 SmallVector<char, 0> &Strtab;
28 Builder(SmallVector<char, 0> &Symtab, SmallVector<char, 0> &Strtab)
29 : Symtab(Symtab), Strtab(Strtab) {}
31 StringTableBuilder StrtabBuilder{StringTableBuilder::ELF};
33 BumpPtrAllocator Alloc;
34 StringSaver Saver{Alloc};
36 DenseMap<const Comdat *, unsigned> ComdatMap;
37 ModuleSymbolTable Msymtab;
38 SmallPtrSet<GlobalValue *, 8> Used;
42 std::vector<storage::Comdat> Comdats;
43 std::vector<storage::Module> Mods;
44 std::vector<storage::Symbol> Syms;
45 std::vector<storage::Uncommon> Uncommons;
47 std::string COFFLinkerOpts;
48 raw_string_ostream COFFLinkerOptsOS{COFFLinkerOpts};
50 void setStr(storage::Str &S, StringRef Value) {
51 S.Offset = StrtabBuilder.add(Value);
54 void writeRange(storage::Range<T> &R, const std::vector<T> &Objs) {
55 R.Offset = Symtab.size();
57 Symtab.insert(Symtab.end(), reinterpret_cast<const char *>(Objs.data()),
58 reinterpret_cast<const char *>(Objs.data() + Objs.size()));
61 Error addModule(Module *M);
62 Error addSymbol(ModuleSymbolTable::Symbol Sym);
64 Error build(ArrayRef<Module *> Mods);
67 Error Builder::addModule(Module *M) {
68 collectUsedGlobalVariables(*M, Used, /*CompilerUsed*/ false);
71 Mod.Begin = Msymtab.symbols().size();
73 Mod.End = Msymtab.symbols().size();
76 if (TT.isOSBinFormatCOFF()) {
77 if (auto E = M->materializeMetadata())
79 if (Metadata *Val = M->getModuleFlag("Linker Options")) {
80 MDNode *LinkerOptions = cast<MDNode>(Val);
81 for (const MDOperand &MDOptions : LinkerOptions->operands())
82 for (const MDOperand &MDOption : cast<MDNode>(MDOptions)->operands())
83 COFFLinkerOptsOS << " " << cast<MDString>(MDOption)->getString();
87 return Error::success();
90 Error Builder::addSymbol(ModuleSymbolTable::Symbol Msym) {
92 storage::Symbol &Sym = Syms.back();
95 Sym.UncommonIndex = -1;
96 storage::Uncommon *Unc = nullptr;
97 auto Uncommon = [&]() -> storage::Uncommon & {
100 Sym.UncommonIndex = Uncommons.size();
101 Uncommons.emplace_back();
102 Unc = &Uncommons.back();
104 setStr(Unc->COFFWeakExternFallbackName, "");
108 SmallString<64> Name;
110 raw_svector_ostream OS(Name);
111 Msymtab.printSymbolName(OS, Msym);
113 setStr(Sym.Name, Saver.save(StringRef(Name)));
115 auto Flags = Msymtab.getSymbolFlags(Msym);
116 if (Flags & object::BasicSymbolRef::SF_Undefined)
117 Sym.Flags |= 1 << storage::Symbol::FB_undefined;
118 if (Flags & object::BasicSymbolRef::SF_Weak)
119 Sym.Flags |= 1 << storage::Symbol::FB_weak;
120 if (Flags & object::BasicSymbolRef::SF_Common)
121 Sym.Flags |= 1 << storage::Symbol::FB_common;
122 if (Flags & object::BasicSymbolRef::SF_Indirect)
123 Sym.Flags |= 1 << storage::Symbol::FB_indirect;
124 if (Flags & object::BasicSymbolRef::SF_Global)
125 Sym.Flags |= 1 << storage::Symbol::FB_global;
126 if (Flags & object::BasicSymbolRef::SF_FormatSpecific)
127 Sym.Flags |= 1 << storage::Symbol::FB_format_specific;
128 if (Flags & object::BasicSymbolRef::SF_Executable)
129 Sym.Flags |= 1 << storage::Symbol::FB_executable;
131 Sym.ComdatIndex = -1;
132 auto *GV = Msym.dyn_cast<GlobalValue *>();
134 setStr(Sym.IRName, "");
135 return Error::success();
138 setStr(Sym.IRName, GV->getName());
141 Sym.Flags |= 1 << storage::Symbol::FB_used;
142 if (GV->isThreadLocal())
143 Sym.Flags |= 1 << storage::Symbol::FB_tls;
144 if (GV->hasGlobalUnnamedAddr())
145 Sym.Flags |= 1 << storage::Symbol::FB_unnamed_addr;
146 if (canBeOmittedFromSymbolTable(GV))
147 Sym.Flags |= 1 << storage::Symbol::FB_may_omit;
148 Sym.Flags |= unsigned(GV->getVisibility()) << storage::Symbol::FB_visibility;
150 if (Flags & object::BasicSymbolRef::SF_Common) {
151 Uncommon().CommonSize = GV->getParent()->getDataLayout().getTypeAllocSize(
152 GV->getType()->getElementType());
153 Uncommon().CommonAlign = GV->getAlignment();
156 const GlobalObject *Base = GV->getBaseObject();
158 return make_error<StringError>("Unable to determine comdat of alias!",
159 inconvertibleErrorCode());
160 if (const Comdat *C = Base->getComdat()) {
161 auto P = ComdatMap.insert(std::make_pair(C, Comdats.size()));
162 Sym.ComdatIndex = P.first->second;
165 storage::Comdat Comdat;
166 setStr(Comdat.Name, C->getName());
167 Comdats.push_back(Comdat);
171 if (TT.isOSBinFormatCOFF()) {
172 emitLinkerFlagsForGlobalCOFF(COFFLinkerOptsOS, GV, TT, Mang);
174 if ((Flags & object::BasicSymbolRef::SF_Weak) &&
175 (Flags & object::BasicSymbolRef::SF_Indirect)) {
176 std::string FallbackName;
177 raw_string_ostream OS(FallbackName);
178 Msymtab.printSymbolName(
179 OS, cast<GlobalValue>(
180 cast<GlobalAlias>(GV)->getAliasee()->stripPointerCasts()));
182 setStr(Uncommon().COFFWeakExternFallbackName, Saver.save(FallbackName));
186 return Error::success();
189 Error Builder::build(ArrayRef<Module *> IRMods) {
192 assert(!IRMods.empty());
193 setStr(Hdr.TargetTriple, IRMods[0]->getTargetTriple());
194 setStr(Hdr.SourceFileName, IRMods[0]->getSourceFileName());
195 TT = Triple(IRMods[0]->getTargetTriple());
197 // This adds the symbols for each module to Msymtab.
198 for (auto *M : IRMods)
199 if (Error Err = addModule(M))
202 for (ModuleSymbolTable::Symbol Msym : Msymtab.symbols())
203 if (Error Err = addSymbol(Msym))
206 COFFLinkerOptsOS.flush();
207 setStr(Hdr.COFFLinkerOpts, COFFLinkerOpts);
209 // We are about to fill in the header's range fields, so reserve space for it
210 // and copy it in afterwards.
211 Symtab.resize(sizeof(storage::Header));
212 writeRange(Hdr.Modules, Mods);
213 writeRange(Hdr.Comdats, Comdats);
214 writeRange(Hdr.Symbols, Syms);
215 writeRange(Hdr.Uncommons, Uncommons);
217 *reinterpret_cast<storage::Header *>(Symtab.data()) = Hdr;
219 raw_svector_ostream OS(Strtab);
220 StrtabBuilder.finalizeInOrder();
221 StrtabBuilder.write(OS);
223 return Error::success();
226 } // anonymous namespace
228 Error irsymtab::build(ArrayRef<Module *> Mods, SmallVector<char, 0> &Symtab,
229 SmallVector<char, 0> &Strtab) {
230 return Builder(Symtab, Strtab).build(Mods);