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llvm-project/lld/ELF/MapFile.cpp

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//===- MapFile.cpp --------------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the -Map option. It shows lists in order and
// hierarchically the output sections, input sections, input files and
// symbol:
//
// Address Size Align Out In Symbol
// 00201000 00000015 4 .text
// 00201000 0000000e 4 test.o:(.text)
// 0020100e 00000000 0 local
// 00201005 00000000 0 f(int)
//
//===----------------------------------------------------------------------===//
#include "MapFile.h"
#include "InputFiles.h"
#include "LinkerScript.h"
#include "OutputSections.h"
#include "SymbolTable.h"
#include "Symbols.h"
#include "SyntheticSections.h"
#include "lld/Common/Strings.h"
#include "lld/Common/Threads.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
using namespace llvm::object;
using namespace lld;
using namespace lld::elf;
typedef DenseMap<const SectionBase *, SmallVector<Symbol *, 4>> SymbolMapTy;
static const std::string Indent8 = " "; // 8 spaces
static const std::string Indent16 = " "; // 16 spaces
// Print out the first three columns of a line.
static void writeHeader(raw_ostream &OS, uint64_t VMA, uint64_t LMA,
uint64_t Size, uint64_t Align) {
if (Config->Is64)
OS << format("%16llx %16llx %8llx %5lld ", VMA, LMA, Size, Align);
else
OS << format("%8llx %8llx %8llx %5lld ", VMA, LMA, Size, Align);
}
// Returns a list of all symbols that we want to print out.
static std::vector<Symbol *> getSymbols() {
std::vector<Symbol *> V;
for (InputFile *File : ObjectFiles) {
for (Symbol *B : File->getSymbols()) {
if (auto *SS = dyn_cast<SharedSymbol>(B))
if (SS->CopyRelSec || SS->NeedsPltAddr)
V.push_back(SS);
if (auto *DR = dyn_cast<Defined>(B))
if (DR->File == File && !DR->isSection() && DR->Section &&
DR->Section->Live)
V.push_back(DR);
}
}
return V;
}
// Returns a map from sections to their symbols.
static SymbolMapTy getSectionSyms(ArrayRef<Symbol *> Syms) {
SymbolMapTy Ret;
for (Symbol *S : Syms) {
if (auto *DR = dyn_cast<Defined>(S)) {
Ret[DR->Section].push_back(S);
continue;
}
SharedSymbol *SS = cast<SharedSymbol>(S);
if (SS->CopyRelSec)
Ret[SS->CopyRelSec].push_back(S);
else
Ret[InX::Plt].push_back(S);
}
// Sort symbols by address. We want to print out symbols in the
// order in the output file rather than the order they appeared
// in the input files.
for (auto &It : Ret) {
SmallVectorImpl<Symbol *> &V = It.second;
std::sort(V.begin(), V.end(),
[](Symbol *A, Symbol *B) { return A->getVA() < B->getVA(); });
}
return Ret;
}
// Construct a map from symbols to their stringified representations.
// Demangling symbols (which is what toString() does) is slow, so
// we do that in batch using parallel-for.
static DenseMap<Symbol *, std::string>
getSymbolStrings(ArrayRef<Symbol *> Syms) {
std::vector<std::string> Str(Syms.size());
parallelForEachN(0, Syms.size(), [&](size_t I) {
raw_string_ostream OS(Str[I]);
OutputSection *OSec = Syms[I]->getOutputSection();
uint64_t VMA = Syms[I]->getVA();
uint64_t LMA = OSec ? OSec->getLMA() + VMA - OSec->getVA(0) : 0;
writeHeader(OS, VMA, LMA, Syms[I]->getSize(), 1);
OS << Indent16 << toString(*Syms[I]);
});
DenseMap<Symbol *, std::string> Ret;
for (size_t I = 0, E = Syms.size(); I < E; ++I)
Ret[Syms[I]] = std::move(Str[I]);
return Ret;
}
// Print .eh_frame contents. Since the section consists of EhSectionPieces,
// we need a specialized printer for that section.
//
// .eh_frame tend to contain a lot of section pieces that are contiguous
// both in input file and output file. Such pieces are squashed before
// being displayed to make output compact.
static void printEhFrame(raw_ostream &OS, OutputSection *OSec) {
std::vector<EhSectionPiece> Pieces;
auto Add = [&](const EhSectionPiece &P) {
// If P is adjacent to Last, squash the two.
if (!Pieces.empty()) {
EhSectionPiece &Last = Pieces.back();
if (Last.Sec == P.Sec && Last.InputOff + Last.Size == P.InputOff &&
Last.OutputOff + Last.Size == P.OutputOff) {
Last.Size += P.Size;
return;
}
}
Pieces.push_back(P);
};
// Gather section pieces.
for (const CieRecord *Rec : InX::EhFrame->getCieRecords()) {
Add(*Rec->Cie);
for (const EhSectionPiece *Fde : Rec->Fdes)
Add(*Fde);
}
// Print out section pieces.
for (EhSectionPiece &P : Pieces) {
writeHeader(OS, OSec->Addr + P.OutputOff, OSec->getLMA() + P.OutputOff,
P.Size, 1);
OS << Indent8 << toString(P.Sec->File) << ":(" << P.Sec->Name << "+0x"
<< Twine::utohexstr(P.InputOff) + ")\n";
}
}
void elf::writeMapFile() {
if (Config->MapFile.empty())
return;
// Open a map file for writing.
std::error_code EC;
raw_fd_ostream OS(Config->MapFile, EC, sys::fs::F_None);
if (EC) {
error("cannot open " + Config->MapFile + ": " + EC.message());
return;
}
// Collect symbol info that we want to print out.
std::vector<Symbol *> Syms = getSymbols();
SymbolMapTy SectionSyms = getSectionSyms(Syms);
DenseMap<Symbol *, std::string> SymStr = getSymbolStrings(Syms);
// Print out the header line.
int W = Config->Is64 ? 16 : 8;
OS << right_justify("VMA", W) << ' ' << right_justify("LMA", W)
<< " Size Align Out In Symbol\n";
for (BaseCommand *Base : Script->SectionCommands) {
if (auto *Cmd = dyn_cast<SymbolAssignment>(Base)) {
if (Cmd->Provide && !Cmd->Sym)
continue;
//FIXME: calculate and print LMA.
writeHeader(OS, Cmd->Addr, 0, Cmd->Size, 1);
OS << Cmd->CommandString << '\n';
continue;
}
auto *OSec = dyn_cast<OutputSection>(Base);
if (!OSec)
continue;
writeHeader(OS, OSec->Addr, OSec->getLMA(), OSec->Size, OSec->Alignment);
OS << OSec->Name << '\n';
// Dump symbols for each input section.
for (BaseCommand *Base : OSec->SectionCommands) {
if (auto *ISD = dyn_cast<InputSectionDescription>(Base)) {
for (InputSection *IS : ISD->Sections) {
if (IS == InX::EhFrame) {
printEhFrame(OS, OSec);
continue;
}
writeHeader(OS, IS->getVA(0), OSec->getLMA() + IS->getOffset(0),
IS->getSize(), IS->Alignment);
OS << Indent8 << toString(IS) << '\n';
for (Symbol *Sym : SectionSyms[IS])
OS << SymStr[Sym] << '\n';
}
continue;
}
if (auto *Cmd = dyn_cast<ByteCommand>(Base)) {
writeHeader(OS, OSec->Addr + Cmd->Offset, OSec->getLMA() + Cmd->Offset,
Cmd->Size, 1);
OS << Indent8 << Cmd->CommandString << '\n';
continue;
}
if (auto *Cmd = dyn_cast<SymbolAssignment>(Base)) {
if (Cmd->Provide && !Cmd->Sym)
continue;
writeHeader(OS, Cmd->Addr, OSec->getLMA() + Cmd->Addr - OSec->getVA(0),
Cmd->Size, 1);
OS << Indent8 << Cmd->CommandString << '\n';
continue;
}
}
}
}
static void print(StringRef A, StringRef B) {
outs() << left_justify(A, 49) << " " << B << "\n";
}
// Output a cross reference table to stdout. This is for --cref.
//
// For each global symbol, we print out a file that defines the symbol
// followed by files that uses that symbol. Here is an example.
//
// strlen /lib/x86_64-linux-gnu/libc.so.6
// tools/lld/tools/lld/CMakeFiles/lld.dir/lld.cpp.o
// lib/libLLVMSupport.a(PrettyStackTrace.cpp.o)
//
// In this case, strlen is defined by libc.so.6 and used by other two
// files.
void elf::writeCrossReferenceTable() {
if (!Config->Cref)
return;
// Collect symbols and files.
MapVector<Symbol *, SetVector<InputFile *>> Map;
for (InputFile *File : ObjectFiles) {
for (Symbol *Sym : File->getSymbols()) {
if (isa<SharedSymbol>(Sym))
Map[Sym].insert(File);
if (auto *D = dyn_cast<Defined>(Sym))
if (!D->isLocal() && (!D->Section || D->Section->Live))
Map[D].insert(File);
}
}
// Print out a header.
outs() << "Cross Reference Table\n\n";
print("Symbol", "File");
// Print out a table.
for (auto KV : Map) {
Symbol *Sym = KV.first;
SetVector<InputFile *> &Files = KV.second;
print(toString(*Sym), toString(Sym->File));
for (InputFile *File : Files)
if (File != Sym->File)
print("", toString(File));
}
}
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