llvm-project/llvm/lib/Object/ModuleSymbolTable.cpp

263 lines
8.1 KiB
C++

//===- ModuleSymbolTable.cpp - symbol table for in-memory IR ----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This class represents a symbol table built from in-memory IR. It provides
// access to GlobalValues and should only be used if such access is required
// (e.g. in the LTO implementation).
//
//===----------------------------------------------------------------------===//
#include "llvm/Object/IRObjectFile.h"
#include "RecordStreamer.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Bitcode/BitcodeReader.h"
#include "llvm/IR/GVMaterializer.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCParser/MCAsmParser.h"
#include "llvm/MC/MCParser/MCTargetAsmParser.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
using namespace object;
void ModuleSymbolTable::addModule(Module *M) {
if (FirstMod)
assert(FirstMod->getTargetTriple() == M->getTargetTriple());
else
FirstMod = M;
for (GlobalValue &GV : M->global_values())
SymTab.push_back(&GV);
CollectAsmSymbols(*M, [this](StringRef Name, BasicSymbolRef::Flags Flags) {
SymTab.push_back(new (AsmSymbols.Allocate()) AsmSymbol(Name, Flags));
});
}
// Ensure ELF .symver aliases get the same binding as the defined symbol
// they alias with.
static void handleSymverAliases(const Module &M, RecordStreamer &Streamer) {
if (Streamer.symverAliases().empty())
return;
// The name in the assembler will be mangled, but the name in the IR
// might not, so we first compute a mapping from mangled name to GV.
Mangler Mang;
SmallString<64> MangledName;
StringMap<const GlobalValue *> MangledNameMap;
auto GetMangledName = [&](const GlobalValue &GV) {
if (!GV.hasName())
return;
MangledName.clear();
MangledName.reserve(GV.getName().size() + 1);
Mang.getNameWithPrefix(MangledName, &GV, /*CannotUsePrivateLabel=*/false);
MangledNameMap[MangledName] = &GV;
};
for (const Function &F : M)
GetMangledName(F);
for (const GlobalVariable &GV : M.globals())
GetMangledName(GV);
for (const GlobalAlias &GA : M.aliases())
GetMangledName(GA);
// Walk all the recorded .symver aliases, and set up the binding
// for each alias.
for (auto &Symver : Streamer.symverAliases()) {
const MCSymbol *Aliasee = Symver.first;
MCSymbolAttr Attr = MCSA_Invalid;
// First check if the aliasee binding was recorded in the asm.
RecordStreamer::State state = Streamer.getSymbolState(Aliasee);
switch (state) {
case RecordStreamer::Global:
case RecordStreamer::DefinedGlobal:
Attr = MCSA_Global;
break;
case RecordStreamer::UndefinedWeak:
case RecordStreamer::DefinedWeak:
Attr = MCSA_Weak;
break;
default:
break;
}
// If we don't have a symbol attribute from assembly, then check if
// the aliasee was defined in the IR.
if (Attr == MCSA_Invalid) {
const auto *GV = M.getNamedValue(Aliasee->getName());
if (!GV) {
auto MI = MangledNameMap.find(Aliasee->getName());
if (MI != MangledNameMap.end())
GV = MI->second;
else
continue;
}
if (GV->hasExternalLinkage())
Attr = MCSA_Global;
else if (GV->hasLocalLinkage())
Attr = MCSA_Local;
else if (GV->isWeakForLinker())
Attr = MCSA_Weak;
}
if (Attr == MCSA_Invalid)
continue;
// Set the detected binding on each alias with this aliasee.
for (auto &Alias : Symver.second)
Streamer.EmitSymbolAttribute(Alias, Attr);
}
}
void ModuleSymbolTable::CollectAsmSymbols(
const Module &M,
function_ref<void(StringRef, BasicSymbolRef::Flags)> AsmSymbol) {
StringRef InlineAsm = M.getModuleInlineAsm();
if (InlineAsm.empty())
return;
std::string Err;
const Triple TT(M.getTargetTriple());
const Target *T = TargetRegistry::lookupTarget(TT.str(), Err);
assert(T && T->hasMCAsmParser());
std::unique_ptr<MCRegisterInfo> MRI(T->createMCRegInfo(TT.str()));
if (!MRI)
return;
std::unique_ptr<MCAsmInfo> MAI(T->createMCAsmInfo(*MRI, TT.str()));
if (!MAI)
return;
std::unique_ptr<MCSubtargetInfo> STI(
T->createMCSubtargetInfo(TT.str(), "", ""));
if (!STI)
return;
std::unique_ptr<MCInstrInfo> MCII(T->createMCInstrInfo());
if (!MCII)
return;
MCObjectFileInfo MOFI;
MCContext MCCtx(MAI.get(), MRI.get(), &MOFI);
MOFI.InitMCObjectFileInfo(TT, /*PIC*/ false, CodeModel::Default, MCCtx);
RecordStreamer Streamer(MCCtx);
T->createNullTargetStreamer(Streamer);
std::unique_ptr<MemoryBuffer> Buffer(MemoryBuffer::getMemBuffer(InlineAsm));
SourceMgr SrcMgr;
SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc());
std::unique_ptr<MCAsmParser> Parser(
createMCAsmParser(SrcMgr, MCCtx, Streamer, *MAI));
MCTargetOptions MCOptions;
std::unique_ptr<MCTargetAsmParser> TAP(
T->createMCAsmParser(*STI, *Parser, *MCII, MCOptions));
if (!TAP)
return;
Parser->setTargetParser(*TAP);
if (Parser->Run(false))
return;
handleSymverAliases(M, Streamer);
for (auto &KV : Streamer) {
StringRef Key = KV.first();
RecordStreamer::State Value = KV.second;
// FIXME: For now we just assume that all asm symbols are executable.
uint32_t Res = BasicSymbolRef::SF_Executable;
switch (Value) {
case RecordStreamer::NeverSeen:
llvm_unreachable("NeverSeen should have been replaced earlier");
case RecordStreamer::DefinedGlobal:
Res |= BasicSymbolRef::SF_Global;
break;
case RecordStreamer::Defined:
break;
case RecordStreamer::Global:
case RecordStreamer::Used:
Res |= BasicSymbolRef::SF_Undefined;
Res |= BasicSymbolRef::SF_Global;
break;
case RecordStreamer::DefinedWeak:
Res |= BasicSymbolRef::SF_Weak;
Res |= BasicSymbolRef::SF_Global;
break;
case RecordStreamer::UndefinedWeak:
Res |= BasicSymbolRef::SF_Weak;
Res |= BasicSymbolRef::SF_Undefined;
}
AsmSymbol(Key, BasicSymbolRef::Flags(Res));
}
}
void ModuleSymbolTable::printSymbolName(raw_ostream &OS, Symbol S) const {
if (S.is<AsmSymbol *>()) {
OS << S.get<AsmSymbol *>()->first;
return;
}
auto *GV = S.get<GlobalValue *>();
if (GV->hasDLLImportStorageClass())
OS << "__imp_";
Mang.getNameWithPrefix(OS, GV, false);
}
uint32_t ModuleSymbolTable::getSymbolFlags(Symbol S) const {
if (S.is<AsmSymbol *>())
return S.get<AsmSymbol *>()->second;
auto *GV = S.get<GlobalValue *>();
uint32_t Res = BasicSymbolRef::SF_None;
if (GV->isDeclarationForLinker())
Res |= BasicSymbolRef::SF_Undefined;
else if (GV->hasHiddenVisibility() && !GV->hasLocalLinkage())
Res |= BasicSymbolRef::SF_Hidden;
if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV)) {
if (GVar->isConstant())
Res |= BasicSymbolRef::SF_Const;
}
if (dyn_cast_or_null<Function>(GV->getBaseObject()))
Res |= BasicSymbolRef::SF_Executable;
if (isa<GlobalAlias>(GV))
Res |= BasicSymbolRef::SF_Indirect;
if (GV->hasPrivateLinkage())
Res |= BasicSymbolRef::SF_FormatSpecific;
if (!GV->hasLocalLinkage())
Res |= BasicSymbolRef::SF_Global;
if (GV->hasCommonLinkage())
Res |= BasicSymbolRef::SF_Common;
if (GV->hasLinkOnceLinkage() || GV->hasWeakLinkage() ||
GV->hasExternalWeakLinkage())
Res |= BasicSymbolRef::SF_Weak;
if (GV->getName().startswith("llvm."))
Res |= BasicSymbolRef::SF_FormatSpecific;
else if (auto *Var = dyn_cast<GlobalVariable>(GV)) {
if (Var->getSection() == "llvm.metadata")
Res |= BasicSymbolRef::SF_FormatSpecific;
}
return Res;
}