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//===- IRSymtab.cpp - implementation of IR symbol tables ------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/Object/IRSymtab.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Analysis/ObjectUtils.h"
#include "llvm/IR/Comdat.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/GlobalObject.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/StringTableBuilder.h"
#include "llvm/Object/ModuleSymbolTable.h"
#include "llvm/Object/SymbolicFile.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/StringSaver.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <string>
#include <utility>
#include <vector>
using namespace llvm;
using namespace irsymtab;
namespace {
/// Stores the temporary state that is required to build an IR symbol table.
struct Builder {
SmallVector<char, 0> &Symtab;
SmallVector<char, 0> &Strtab;
Builder(SmallVector<char, 0> &Symtab, SmallVector<char, 0> &Strtab)
: Symtab(Symtab), Strtab(Strtab) {}
StringTableBuilder StrtabBuilder{StringTableBuilder::RAW};
BumpPtrAllocator Alloc;
StringSaver Saver{Alloc};
DenseMap<const Comdat *, unsigned> ComdatMap;
Mangler Mang;
Triple TT;
std::vector<storage::Comdat> Comdats;
std::vector<storage::Module> Mods;
std::vector<storage::Symbol> Syms;
std::vector<storage::Uncommon> Uncommons;
std::string COFFLinkerOpts;
raw_string_ostream COFFLinkerOptsOS{COFFLinkerOpts};
void setStr(storage::Str &S, StringRef Value) {
S.Offset = StrtabBuilder.add(Value);
S.Size = Value.size();
}
template <typename T>
void writeRange(storage::Range<T> &R, const std::vector<T> &Objs) {
R.Offset = Symtab.size();
R.Size = Objs.size();
Symtab.insert(Symtab.end(), reinterpret_cast<const char *>(Objs.data()),
reinterpret_cast<const char *>(Objs.data() + Objs.size()));
}
Error addModule(Module *M);
Error addSymbol(const ModuleSymbolTable &Msymtab,
const SmallPtrSet<GlobalValue *, 8> &Used,
ModuleSymbolTable::Symbol Sym);
Error build(ArrayRef<Module *> Mods);
};
Error Builder::addModule(Module *M) {
SmallPtrSet<GlobalValue *, 8> Used;
collectUsedGlobalVariables(*M, Used, /*CompilerUsed*/ false);
ModuleSymbolTable Msymtab;
Msymtab.addModule(M);
storage::Module Mod;
Mod.Begin = Syms.size();
Mod.End = Syms.size() + Msymtab.symbols().size();
Mod.UncBegin = Uncommons.size();
Mods.push_back(Mod);
if (TT.isOSBinFormatCOFF()) {
if (auto E = M->materializeMetadata())
return E;
if (Metadata *Val = M->getModuleFlag("Linker Options")) {
MDNode *LinkerOptions = cast<MDNode>(Val);
for (const MDOperand &MDOptions : LinkerOptions->operands())
for (const MDOperand &MDOption : cast<MDNode>(MDOptions)->operands())
COFFLinkerOptsOS << " " << cast<MDString>(MDOption)->getString();
}
}
for (ModuleSymbolTable::Symbol Msym : Msymtab.symbols())
if (Error Err = addSymbol(Msymtab, Used, Msym))
return Err;
return Error::success();
}
Error Builder::addSymbol(const ModuleSymbolTable &Msymtab,
const SmallPtrSet<GlobalValue *, 8> &Used,
ModuleSymbolTable::Symbol Msym) {
Syms.emplace_back();
storage::Symbol &Sym = Syms.back();
Sym = {};
storage::Uncommon *Unc = nullptr;
auto Uncommon = [&]() -> storage::Uncommon & {
if (Unc)
return *Unc;
Sym.Flags |= 1 << storage::Symbol::FB_has_uncommon;
Uncommons.emplace_back();
Unc = &Uncommons.back();
*Unc = {};
setStr(Unc->COFFWeakExternFallbackName, "");
return *Unc;
};
SmallString<64> Name;
{
raw_svector_ostream OS(Name);
Msymtab.printSymbolName(OS, Msym);
}
setStr(Sym.Name, Saver.save(StringRef(Name)));
auto Flags = Msymtab.getSymbolFlags(Msym);
if (Flags & object::BasicSymbolRef::SF_Undefined)
Sym.Flags |= 1 << storage::Symbol::FB_undefined;
if (Flags & object::BasicSymbolRef::SF_Weak)
Sym.Flags |= 1 << storage::Symbol::FB_weak;
if (Flags & object::BasicSymbolRef::SF_Common)
Sym.Flags |= 1 << storage::Symbol::FB_common;
if (Flags & object::BasicSymbolRef::SF_Indirect)
Sym.Flags |= 1 << storage::Symbol::FB_indirect;
if (Flags & object::BasicSymbolRef::SF_Global)
Sym.Flags |= 1 << storage::Symbol::FB_global;
if (Flags & object::BasicSymbolRef::SF_FormatSpecific)
Sym.Flags |= 1 << storage::Symbol::FB_format_specific;
if (Flags & object::BasicSymbolRef::SF_Executable)
Sym.Flags |= 1 << storage::Symbol::FB_executable;
Sym.ComdatIndex = -1;
auto *GV = Msym.dyn_cast<GlobalValue *>();
if (!GV) {
// Undefined module asm symbols act as GC roots and are implicitly used.
if (Flags & object::BasicSymbolRef::SF_Undefined)
Sym.Flags |= 1 << storage::Symbol::FB_used;
setStr(Sym.IRName, "");
return Error::success();
}
setStr(Sym.IRName, GV->getName());
if (Used.count(GV))
Sym.Flags |= 1 << storage::Symbol::FB_used;
if (GV->isThreadLocal())
Sym.Flags |= 1 << storage::Symbol::FB_tls;
if (GV->hasGlobalUnnamedAddr())
Sym.Flags |= 1 << storage::Symbol::FB_unnamed_addr;
if (canBeOmittedFromSymbolTable(GV))
Sym.Flags |= 1 << storage::Symbol::FB_may_omit;
Sym.Flags |= unsigned(GV->getVisibility()) << storage::Symbol::FB_visibility;
if (Flags & object::BasicSymbolRef::SF_Common) {
Uncommon().CommonSize = GV->getParent()->getDataLayout().getTypeAllocSize(
GV->getType()->getElementType());
Uncommon().CommonAlign = GV->getAlignment();
}
const GlobalObject *Base = GV->getBaseObject();
if (!Base)
return make_error<StringError>("Unable to determine comdat of alias!",
inconvertibleErrorCode());
if (const Comdat *C = Base->getComdat()) {
auto P = ComdatMap.insert(std::make_pair(C, Comdats.size()));
Sym.ComdatIndex = P.first->second;
if (P.second) {
storage::Comdat Comdat;
setStr(Comdat.Name, C->getName());
Comdats.push_back(Comdat);
}
}
if (TT.isOSBinFormatCOFF()) {
emitLinkerFlagsForGlobalCOFF(COFFLinkerOptsOS, GV, TT, Mang);
if ((Flags & object::BasicSymbolRef::SF_Weak) &&
(Flags & object::BasicSymbolRef::SF_Indirect)) {
std::string FallbackName;
raw_string_ostream OS(FallbackName);
Msymtab.printSymbolName(
OS, cast<GlobalValue>(
cast<GlobalAlias>(GV)->getAliasee()->stripPointerCasts()));
OS.flush();
setStr(Uncommon().COFFWeakExternFallbackName, Saver.save(FallbackName));
}
}
return Error::success();
}
Error Builder::build(ArrayRef<Module *> IRMods) {
storage::Header Hdr;
assert(!IRMods.empty());
setStr(Hdr.TargetTriple, IRMods[0]->getTargetTriple());
setStr(Hdr.SourceFileName, IRMods[0]->getSourceFileName());
TT = Triple(IRMods[0]->getTargetTriple());
for (auto *M : IRMods)
if (Error Err = addModule(M))
return Err;
COFFLinkerOptsOS.flush();
setStr(Hdr.COFFLinkerOpts, COFFLinkerOpts);
// We are about to fill in the header's range fields, so reserve space for it
// and copy it in afterwards.
Symtab.resize(sizeof(storage::Header));
writeRange(Hdr.Modules, Mods);
writeRange(Hdr.Comdats, Comdats);
writeRange(Hdr.Symbols, Syms);
writeRange(Hdr.Uncommons, Uncommons);
*reinterpret_cast<storage::Header *>(Symtab.data()) = Hdr;
raw_svector_ostream OS(Strtab);
StrtabBuilder.finalizeInOrder();
StrtabBuilder.write(OS);
return Error::success();
}
} // end anonymous namespace
Error irsymtab::build(ArrayRef<Module *> Mods, SmallVector<char, 0> &Symtab,
SmallVector<char, 0> &Strtab) {
return Builder(Symtab, Strtab).build(Mods);
}