llvm-jitlink-elf.cpp

//===---- llvm-jitlink-elf.cpp -- ELF parsing support for llvm-jitlink ----===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// ELF parsing support for llvm-jitlink.
//
//===----------------------------------------------------------------------===//

#include "llvm-jitlink.h"

#include "llvm/Support/Error.h"
#include "llvm/Support/Path.h"

#define DEBUG_TYPE "llvm_jitlink"

using namespace llvm;
using namespace llvm::jitlink;

namespace llvm {

Error registerELFGraphInfo(Session &S, LinkGraph &G) {
  auto FileName = sys::path::filename(G.getName());
  if (S.FileInfos.count(FileName)) {
    return make_error<StringError>("When -check is passed, file names must be "
                                   "distinct (duplicate: \"" +
                                       FileName + "\")",
                                   inconvertibleErrorCode());
  }

  auto &FileInfo = S.FileInfos[FileName];
  LLVM_DEBUG({
    dbgs() << "Registering ELF file info for \"" << FileName << "\"\n";
  });
  for (auto &Sec : G.sections()) {
    LLVM_DEBUG({
      dbgs() << "  Section \"" << Sec.getName() << "\": "
             << (llvm::empty(Sec.symbols()) ? "empty. skipping."
                                            : "processing...")
             << "\n";
    });

    // Skip empty sections.
    if (llvm::empty(Sec.symbols()))
      continue;

    if (FileInfo.SectionInfos.count(Sec.getName()))
      return make_error<StringError>("Encountered duplicate section name \"" +
                                         Sec.getName() + "\" in \"" + FileName +
                                         "\"",
                                     inconvertibleErrorCode());

    bool SectionContainsContent = false;
    bool SectionContainsZeroFill = false;

    auto *FirstSym = *Sec.symbols().begin();
    auto *LastSym = FirstSym;
    for (auto *Sym : Sec.symbols()) {
      if (Sym->getAddress() < FirstSym->getAddress())
        FirstSym = Sym;
      if (Sym->getAddress() > LastSym->getAddress())
        LastSym = Sym;

      if (Sym->hasName()) {
        dbgs() << "Symbol: " << Sym->getName() << "\n";
        if (Sym->isSymbolZeroFill()) {
          S.SymbolInfos[Sym->getName()] = {Sym->getSize(), Sym->getAddress()};
          SectionContainsZeroFill = true;
        } else {
          S.SymbolInfos[Sym->getName()] = {Sym->getSymbolContent(),
                                           Sym->getAddress()};
          SectionContainsContent = true;
        }
      }
    }

    JITTargetAddress SecAddr = FirstSym->getAddress();
    uint64_t SecSize =
        (LastSym->getBlock().getAddress() + LastSym->getBlock().getSize()) -
        SecAddr;

    if (SectionContainsZeroFill && SectionContainsContent)
      return make_error<StringError>("Mixed zero-fill and content sections not "
                                     "supported yet",
                                     inconvertibleErrorCode());
    if (SectionContainsZeroFill)
      FileInfo.SectionInfos[Sec.getName()] = {SecSize, SecAddr};
    else
      FileInfo.SectionInfos[Sec.getName()] = {
          StringRef(FirstSym->getBlock().getContent().data(), SecSize),
          SecAddr};
  }

  return Error::success();
}

} // end namespace llvm