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/ADT/ArrayRef.h"
11 #include "llvm/ADT/DenseMap.h"
12 #include "llvm/ADT/SmallPtrSet.h"
13 #include "llvm/ADT/SmallString.h"
14 #include "llvm/ADT/SmallVector.h"
15 #include "llvm/ADT/StringRef.h"
16 #include "llvm/ADT/Triple.h"
17 #include "llvm/Analysis/ObjectUtils.h"
18 #include "llvm/IR/Comdat.h"
19 #include "llvm/IR/DataLayout.h"
20 #include "llvm/IR/GlobalAlias.h"
21 #include "llvm/IR/GlobalObject.h"
22 #include "llvm/IR/Mangler.h"
23 #include "llvm/IR/Metadata.h"
24 #include "llvm/IR/Module.h"
25 #include "llvm/MC/StringTableBuilder.h"
26 #include "llvm/Object/IRSymtab.h"
27 #include "llvm/Object/ModuleSymbolTable.h"
28 #include "llvm/Object/SymbolicFile.h"
29 #include "llvm/Support/Allocator.h"
30 #include "llvm/Support/Casting.h"
31 #include "llvm/Support/Error.h"
32 #include "llvm/Support/raw_ostream.h"
33 #include "llvm/Support/StringSaver.h"
40 using namespace irsymtab;
44 /// Stores the temporary state that is required to build an IR symbol table.
46 SmallVector<char, 0> &Symtab;
47 SmallVector<char, 0> &Strtab;
49 Builder(SmallVector<char, 0> &Symtab, SmallVector<char, 0> &Strtab)
50 : Symtab(Symtab), Strtab(Strtab) {}
52 StringTableBuilder StrtabBuilder{StringTableBuilder::RAW};
54 BumpPtrAllocator Alloc;
55 StringSaver Saver{Alloc};
57 DenseMap<const Comdat *, unsigned> ComdatMap;
61 std::vector<storage::Comdat> Comdats;
62 std::vector<storage::Module> Mods;
63 std::vector<storage::Symbol> Syms;
64 std::vector<storage::Uncommon> Uncommons;
66 std::string COFFLinkerOpts;
67 raw_string_ostream COFFLinkerOptsOS{COFFLinkerOpts};
69 void setStr(storage::Str &S, StringRef Value) {
70 S.Offset = StrtabBuilder.add(Value);
71 S.Size = Value.size();
75 void writeRange(storage::Range<T> &R, const std::vector<T> &Objs) {
76 R.Offset = Symtab.size();
78 Symtab.insert(Symtab.end(), reinterpret_cast<const char *>(Objs.data()),
79 reinterpret_cast<const char *>(Objs.data() + Objs.size()));
82 Error addModule(Module *M);
83 Error addSymbol(const ModuleSymbolTable &Msymtab,
84 const SmallPtrSet<GlobalValue *, 8> &Used,
85 ModuleSymbolTable::Symbol Sym);
87 Error build(ArrayRef<Module *> Mods);
90 Error Builder::addModule(Module *M) {
91 SmallPtrSet<GlobalValue *, 8> Used;
92 collectUsedGlobalVariables(*M, Used, /*CompilerUsed*/ false);
94 ModuleSymbolTable Msymtab;
98 Mod.Begin = Syms.size();
99 Mod.End = Syms.size() + Msymtab.symbols().size();
100 Mod.UncBegin = Uncommons.size();
103 if (TT.isOSBinFormatCOFF()) {
104 if (auto E = M->materializeMetadata())
106 if (Metadata *Val = M->getModuleFlag("Linker Options")) {
107 MDNode *LinkerOptions = cast<MDNode>(Val);
108 for (const MDOperand &MDOptions : LinkerOptions->operands())
109 for (const MDOperand &MDOption : cast<MDNode>(MDOptions)->operands())
110 COFFLinkerOptsOS << " " << cast<MDString>(MDOption)->getString();
114 for (ModuleSymbolTable::Symbol Msym : Msymtab.symbols())
115 if (Error Err = addSymbol(Msymtab, Used, Msym))
118 return Error::success();
121 Error Builder::addSymbol(const ModuleSymbolTable &Msymtab,
122 const SmallPtrSet<GlobalValue *, 8> &Used,
123 ModuleSymbolTable::Symbol Msym) {
125 storage::Symbol &Sym = Syms.back();
128 storage::Uncommon *Unc = nullptr;
129 auto Uncommon = [&]() -> storage::Uncommon & {
132 Sym.Flags |= 1 << storage::Symbol::FB_has_uncommon;
133 Uncommons.emplace_back();
134 Unc = &Uncommons.back();
136 setStr(Unc->COFFWeakExternFallbackName, "");
140 SmallString<64> Name;
142 raw_svector_ostream OS(Name);
143 Msymtab.printSymbolName(OS, Msym);
145 setStr(Sym.Name, Saver.save(StringRef(Name)));
147 auto Flags = Msymtab.getSymbolFlags(Msym);
148 if (Flags & object::BasicSymbolRef::SF_Undefined)
149 Sym.Flags |= 1 << storage::Symbol::FB_undefined;
150 if (Flags & object::BasicSymbolRef::SF_Weak)
151 Sym.Flags |= 1 << storage::Symbol::FB_weak;
152 if (Flags & object::BasicSymbolRef::SF_Common)
153 Sym.Flags |= 1 << storage::Symbol::FB_common;
154 if (Flags & object::BasicSymbolRef::SF_Indirect)
155 Sym.Flags |= 1 << storage::Symbol::FB_indirect;
156 if (Flags & object::BasicSymbolRef::SF_Global)
157 Sym.Flags |= 1 << storage::Symbol::FB_global;
158 if (Flags & object::BasicSymbolRef::SF_FormatSpecific)
159 Sym.Flags |= 1 << storage::Symbol::FB_format_specific;
160 if (Flags & object::BasicSymbolRef::SF_Executable)
161 Sym.Flags |= 1 << storage::Symbol::FB_executable;
163 Sym.ComdatIndex = -1;
164 auto *GV = Msym.dyn_cast<GlobalValue *>();
166 // Undefined module asm symbols act as GC roots and are implicitly used.
167 if (Flags & object::BasicSymbolRef::SF_Undefined)
168 Sym.Flags |= 1 << storage::Symbol::FB_used;
169 setStr(Sym.IRName, "");
170 return Error::success();
173 setStr(Sym.IRName, GV->getName());
176 Sym.Flags |= 1 << storage::Symbol::FB_used;
177 if (GV->isThreadLocal())
178 Sym.Flags |= 1 << storage::Symbol::FB_tls;
179 if (GV->hasGlobalUnnamedAddr())
180 Sym.Flags |= 1 << storage::Symbol::FB_unnamed_addr;
181 if (canBeOmittedFromSymbolTable(GV))
182 Sym.Flags |= 1 << storage::Symbol::FB_may_omit;
183 Sym.Flags |= unsigned(GV->getVisibility()) << storage::Symbol::FB_visibility;
185 if (Flags & object::BasicSymbolRef::SF_Common) {
186 Uncommon().CommonSize = GV->getParent()->getDataLayout().getTypeAllocSize(
187 GV->getType()->getElementType());
188 Uncommon().CommonAlign = GV->getAlignment();
191 const GlobalObject *Base = GV->getBaseObject();
193 return make_error<StringError>("Unable to determine comdat of alias!",
194 inconvertibleErrorCode());
195 if (const Comdat *C = Base->getComdat()) {
196 auto P = ComdatMap.insert(std::make_pair(C, Comdats.size()));
197 Sym.ComdatIndex = P.first->second;
200 storage::Comdat Comdat;
201 setStr(Comdat.Name, C->getName());
202 Comdats.push_back(Comdat);
206 if (TT.isOSBinFormatCOFF()) {
207 emitLinkerFlagsForGlobalCOFF(COFFLinkerOptsOS, GV, TT, Mang);
209 if ((Flags & object::BasicSymbolRef::SF_Weak) &&
210 (Flags & object::BasicSymbolRef::SF_Indirect)) {
211 std::string FallbackName;
212 raw_string_ostream OS(FallbackName);
213 Msymtab.printSymbolName(
214 OS, cast<GlobalValue>(
215 cast<GlobalAlias>(GV)->getAliasee()->stripPointerCasts()));
217 setStr(Uncommon().COFFWeakExternFallbackName, Saver.save(FallbackName));
221 return Error::success();
224 Error Builder::build(ArrayRef<Module *> IRMods) {
227 assert(!IRMods.empty());
228 setStr(Hdr.TargetTriple, IRMods[0]->getTargetTriple());
229 setStr(Hdr.SourceFileName, IRMods[0]->getSourceFileName());
230 TT = Triple(IRMods[0]->getTargetTriple());
232 for (auto *M : IRMods)
233 if (Error Err = addModule(M))
236 COFFLinkerOptsOS.flush();
237 setStr(Hdr.COFFLinkerOpts, COFFLinkerOpts);
239 // We are about to fill in the header's range fields, so reserve space for it
240 // and copy it in afterwards.
241 Symtab.resize(sizeof(storage::Header));
242 writeRange(Hdr.Modules, Mods);
243 writeRange(Hdr.Comdats, Comdats);
244 writeRange(Hdr.Symbols, Syms);
245 writeRange(Hdr.Uncommons, Uncommons);
247 *reinterpret_cast<storage::Header *>(Symtab.data()) = Hdr;
249 raw_svector_ostream OS(Strtab);
250 StrtabBuilder.finalizeInOrder();
251 StrtabBuilder.write(OS);
253 return Error::success();
256 } // end anonymous namespace
258 Error irsymtab::build(ArrayRef<Module *> Mods, SmallVector<char, 0> &Symtab,
259 SmallVector<char, 0> &Strtab) {
260 return Builder(Symtab, Strtab).build(Mods);