[llvm-objdump] - Move getRelocationValueString and dependenices out of the llvm-objdump.cpp

getRelocationValueString is a dispatcher function that calls the
corresponding ELF/COFF/Wasm/MachO implementations
that currently live in the llvm-objdump.cpp file.

These implementations better be moved to ELFDump.cpp,
COFFDump.cpp and other corresponding files, to move platform specific
implementation out from the common logic.

The patch does that. Also, I had to move ToolSectionFilter helper
and SectionFilterIterator, SectionFilter to a header to make them
available across the objdump code.

Differential revision: https://reviews.llvm.org/D56842

llvm-svn: 351545

Author: George Rimar

llvm/tools/llvm-objdump/COFFDump.cpp

@@ -469,6 +469,19 @@ static bool getPDataSection(const COFFObjectFile *Obj,
   return false;
 }
 
+std::error_code
+llvm::getCOFFRelocationValueString(const COFFObjectFile *Obj,
+                                   const RelocationRef &Rel,
+                                   SmallVectorImpl<char> &Result) {
+  symbol_iterator SymI = Rel.getSymbol();
+  Expected<StringRef> SymNameOrErr = SymI->getName();
+  if (!SymNameOrErr)
+    return errorToErrorCode(SymNameOrErr.takeError());
+  StringRef SymName = *SymNameOrErr;
+  Result.append(SymName.begin(), SymName.end());
+  return std::error_code();
+}
+
 static void printWin64EHUnwindInfo(const Win64EH::UnwindInfo *UI) {
   // The casts to int are required in order to output the value as number.
   // Without the casts the value would be interpreted as char data (which

llvm/tools/llvm-objdump/ELFDump.cpp

@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm-objdump.h"
+#include "llvm/Demangle/Demangle.h"
 #include "llvm/Object/ELFObjectFile.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/MathExtras.h"
@@ -51,6 +52,87 @@ Expected<StringRef> getDynamicStrTab(const ELFFile<ELFT> *Elf) {
   return createError("dynamic string table not found");
 }
 
+template <class ELFT>
+static std::error_code getRelocationValueString(const ELFObjectFile<ELFT> *Obj,
+                                                const RelocationRef &RelRef,
+                                                SmallVectorImpl<char> &Result) {
+  typedef typename ELFObjectFile<ELFT>::Elf_Sym Elf_Sym;
+  typedef typename ELFObjectFile<ELFT>::Elf_Shdr Elf_Shdr;
+  typedef typename ELFObjectFile<ELFT>::Elf_Rela Elf_Rela;
+
+  const ELFFile<ELFT> &EF = *Obj->getELFFile();
+  DataRefImpl Rel = RelRef.getRawDataRefImpl();
+  auto SecOrErr = EF.getSection(Rel.d.a);
+  if (!SecOrErr)
+    return errorToErrorCode(SecOrErr.takeError());
+
+  int64_t Addend = 0;
+  // If there is no Symbol associated with the relocation, we set the undef
+  // boolean value to 'true'. This will prevent us from calling functions that
+  // requires the relocation to be associated with a symbol.
+  //
+  // In SHT_REL case we would need to read the addend from section data.
+  // GNU objdump does not do that and we just follow for simplicity atm.
+  bool Undef = false;
+  if ((*SecOrErr)->sh_type == ELF::SHT_RELA) {
+    const Elf_Rela *ERela = Obj->getRela(Rel);
+    Addend = ERela->r_addend;
+    Undef = ERela->getSymbol(false) == 0;
+  } else if ((*SecOrErr)->sh_type != ELF::SHT_REL) {
+    return object_error::parse_failed;
+  }
+
+  // Default scheme is to print Target, as well as "+ <addend>" for nonzero
+  // addend. Should be acceptable for all normal purposes.
+  std::string FmtBuf;
+  raw_string_ostream Fmt(FmtBuf);
+
+  if (!Undef) {
+    symbol_iterator SI = RelRef.getSymbol();
+    const Elf_Sym *Sym = Obj->getSymbol(SI->getRawDataRefImpl());
+    if (Sym->getType() == ELF::STT_SECTION) {
+      Expected<section_iterator> SymSI = SI->getSection();
+      if (!SymSI)
+        return errorToErrorCode(SymSI.takeError());
+      const Elf_Shdr *SymSec = Obj->getSection((*SymSI)->getRawDataRefImpl());
+      auto SecName = EF.getSectionName(SymSec);
+      if (!SecName)
+        return errorToErrorCode(SecName.takeError());
+      Fmt << *SecName;
+    } else {
+      Expected<StringRef> SymName = SI->getName();
+      if (!SymName)
+        return errorToErrorCode(SymName.takeError());
+      if (Demangle)
+        Fmt << demangle(*SymName);
+      else
+        Fmt << *SymName;
+    }
+  } else {
+    Fmt << "*ABS*";
+  }
+
+  if (Addend != 0)
+    Fmt << (Addend < 0 ? "" : "+") << Addend;
+  Fmt.flush();
+  Result.append(FmtBuf.begin(), FmtBuf.end());
+  return std::error_code();
+}
+
+std::error_code
+llvm::getELFRelocationValueString(const ELFObjectFileBase *Obj,
+                                  const RelocationRef &Rel,
+                                  SmallVectorImpl<char> &Result) {
+  if (auto *ELF32LE = dyn_cast<ELF32LEObjectFile>(Obj))
+    return getRelocationValueString(ELF32LE, Rel, Result);
+  if (auto *ELF64LE = dyn_cast<ELF64LEObjectFile>(Obj))
+    return getRelocationValueString(ELF64LE, Rel, Result);
+  if (auto *ELF32BE = dyn_cast<ELF32BEObjectFile>(Obj))
+    return getRelocationValueString(ELF32BE, Rel, Result);
+  auto *ELF64BE = cast<ELF64BEObjectFile>(Obj);
+  return getRelocationValueString(ELF64BE, Rel, Result);
+}
+
 template <class ELFT>
 void printDynamicSection(const ELFFile<ELFT> *Elf, StringRef Filename) {
   auto ProgramHeaderOrError = Elf->program_headers();

llvm/tools/llvm-objdump/MachODump.cpp

@@ -342,6 +342,264 @@ static void getSectionsAndSymbols(MachOObjectFile *MachOObj,
   }
 }
 
+static void printRelocationTargetName(const MachOObjectFile *O,
+                                      const MachO::any_relocation_info &RE,
+                                      raw_string_ostream &Fmt) {
+  // Target of a scattered relocation is an address.  In the interest of
+  // generating pretty output, scan through the symbol table looking for a
+  // symbol that aligns with that address.  If we find one, print it.
+  // Otherwise, we just print the hex address of the target.
+  if (O->isRelocationScattered(RE)) {
+    uint32_t Val = O->getPlainRelocationSymbolNum(RE);
+
+    for (const SymbolRef &Symbol : O->symbols()) {
+      Expected<uint64_t> Addr = Symbol.getAddress();
+      if (!Addr)
+        report_error(O->getFileName(), Addr.takeError());
+      if (*Addr != Val)
+        continue;
+      Expected<StringRef> Name = Symbol.getName();
+      if (!Name)
+        report_error(O->getFileName(), Name.takeError());
+      Fmt << *Name;
+      return;
+    }
+
+    // If we couldn't find a symbol that this relocation refers to, try
+    // to find a section beginning instead.
+    for (const SectionRef &Section : ToolSectionFilter(*O)) {
+      std::error_code ec;
+
+      StringRef Name;
+      uint64_t Addr = Section.getAddress();
+      if (Addr != Val)
+        continue;
+      if ((ec = Section.getName(Name)))
+        report_error(O->getFileName(), ec);
+      Fmt << Name;
+      return;
+    }
+
+    Fmt << format("0x%x", Val);
+    return;
+  }
+
+  StringRef S;
+  bool isExtern = O->getPlainRelocationExternal(RE);
+  uint64_t Val = O->getPlainRelocationSymbolNum(RE);
+
+  if (O->getAnyRelocationType(RE) == MachO::ARM64_RELOC_ADDEND) {
+    Fmt << format("0x%0" PRIx64, Val);
+    return;
+  }
+
+  if (isExtern) {
+    symbol_iterator SI = O->symbol_begin();
+    advance(SI, Val);
+    Expected<StringRef> SOrErr = SI->getName();
+    if (!SOrErr)
+      report_error(O->getFileName(), SOrErr.takeError());
+    S = *SOrErr;
+  } else {
+    section_iterator SI = O->section_begin();
+    // Adjust for the fact that sections are 1-indexed.
+    if (Val == 0) {
+      Fmt << "0 (?,?)";
+      return;
+    }
+    uint32_t I = Val - 1;
+    while (I != 0 && SI != O->section_end()) {
+      --I;
+      advance(SI, 1);
+    }
+    if (SI == O->section_end())
+      Fmt << Val << " (?,?)";
+    else
+      SI->getName(S);
+  }
+
+  Fmt << S;
+}
+
+std::error_code
+llvm::getMachORelocationValueString(const MachOObjectFile *Obj,
+                                    const RelocationRef &RelRef,
+                                    SmallVectorImpl<char> &Result) {
+  DataRefImpl Rel = RelRef.getRawDataRefImpl();
+  MachO::any_relocation_info RE = Obj->getRelocation(Rel);
+
+  unsigned Arch = Obj->getArch();
+
+  std::string FmtBuf;
+  raw_string_ostream Fmt(FmtBuf);
+  unsigned Type = Obj->getAnyRelocationType(RE);
+  bool IsPCRel = Obj->getAnyRelocationPCRel(RE);
+
+  // Determine any addends that should be displayed with the relocation.
+  // These require decoding the relocation type, which is triple-specific.
+
+  // X86_64 has entirely custom relocation types.
+  if (Arch == Triple::x86_64) {
+    switch (Type) {
+    case MachO::X86_64_RELOC_GOT_LOAD:
+    case MachO::X86_64_RELOC_GOT: {
+      printRelocationTargetName(Obj, RE, Fmt);
+      Fmt << "@GOT";
+      if (IsPCRel)
+        Fmt << "PCREL";
+      break;
+    }
+    case MachO::X86_64_RELOC_SUBTRACTOR: {
+      DataRefImpl RelNext = Rel;
+      Obj->moveRelocationNext(RelNext);
+      MachO::any_relocation_info RENext = Obj->getRelocation(RelNext);
+
+      // X86_64_RELOC_SUBTRACTOR must be followed by a relocation of type
+      // X86_64_RELOC_UNSIGNED.
+      // NOTE: Scattered relocations don't exist on x86_64.
+      unsigned RType = Obj->getAnyRelocationType(RENext);
+      if (RType != MachO::X86_64_RELOC_UNSIGNED)
+        report_error(Obj->getFileName(), "Expected X86_64_RELOC_UNSIGNED after "
+                                         "X86_64_RELOC_SUBTRACTOR.");
+
+      // The X86_64_RELOC_UNSIGNED contains the minuend symbol;
+      // X86_64_RELOC_SUBTRACTOR contains the subtrahend.
+      printRelocationTargetName(Obj, RENext, Fmt);
+      Fmt << "-";
+      printRelocationTargetName(Obj, RE, Fmt);
+      break;
+    }
+    case MachO::X86_64_RELOC_TLV:
+      printRelocationTargetName(Obj, RE, Fmt);
+      Fmt << "@TLV";
+      if (IsPCRel)
+        Fmt << "P";
+      break;
+    case MachO::X86_64_RELOC_SIGNED_1:
+      printRelocationTargetName(Obj, RE, Fmt);
+      Fmt << "-1";
+      break;
+    case MachO::X86_64_RELOC_SIGNED_2:
+      printRelocationTargetName(Obj, RE, Fmt);
+      Fmt << "-2";
+      break;
+    case MachO::X86_64_RELOC_SIGNED_4:
+      printRelocationTargetName(Obj, RE, Fmt);
+      Fmt << "-4";
+      break;
+    default:
+      printRelocationTargetName(Obj, RE, Fmt);
+      break;
+    }
+    // X86 and ARM share some relocation types in common.
+  } else if (Arch == Triple::x86 || Arch == Triple::arm ||
+             Arch == Triple::ppc) {
+    // Generic relocation types...
+    switch (Type) {
+    case MachO::GENERIC_RELOC_PAIR: // prints no info
+      return std::error_code();
+    case MachO::GENERIC_RELOC_SECTDIFF: {
+      DataRefImpl RelNext = Rel;
+      Obj->moveRelocationNext(RelNext);
+      MachO::any_relocation_info RENext = Obj->getRelocation(RelNext);
+
+      // X86 sect diff's must be followed by a relocation of type
+      // GENERIC_RELOC_PAIR.
+      unsigned RType = Obj->getAnyRelocationType(RENext);
+
+      if (RType != MachO::GENERIC_RELOC_PAIR)
+        report_error(Obj->getFileName(), "Expected GENERIC_RELOC_PAIR after "
+                                         "GENERIC_RELOC_SECTDIFF.");
+
+      printRelocationTargetName(Obj, RE, Fmt);
+      Fmt << "-";
+      printRelocationTargetName(Obj, RENext, Fmt);
+      break;
+    }
+    }
+
+    if (Arch == Triple::x86 || Arch == Triple::ppc) {
+      switch (Type) {
+      case MachO::GENERIC_RELOC_LOCAL_SECTDIFF: {
+        DataRefImpl RelNext = Rel;
+        Obj->moveRelocationNext(RelNext);
+        MachO::any_relocation_info RENext = Obj->getRelocation(RelNext);
+
+        // X86 sect diff's must be followed by a relocation of type
+        // GENERIC_RELOC_PAIR.
+        unsigned RType = Obj->getAnyRelocationType(RENext);
+        if (RType != MachO::GENERIC_RELOC_PAIR)
+          report_error(Obj->getFileName(), "Expected GENERIC_RELOC_PAIR after "
+                                           "GENERIC_RELOC_LOCAL_SECTDIFF.");
+
+        printRelocationTargetName(Obj, RE, Fmt);
+        Fmt << "-";
+        printRelocationTargetName(Obj, RENext, Fmt);
+        break;
+      }
+      case MachO::GENERIC_RELOC_TLV: {
+        printRelocationTargetName(Obj, RE, Fmt);
+        Fmt << "@TLV";
+        if (IsPCRel)
+          Fmt << "P";
+        break;
+      }
+      default:
+        printRelocationTargetName(Obj, RE, Fmt);
+      }
+    } else { // ARM-specific relocations
+      switch (Type) {
+      case MachO::ARM_RELOC_HALF:
+      case MachO::ARM_RELOC_HALF_SECTDIFF: {
+        // Half relocations steal a bit from the length field to encode
+        // whether this is an upper16 or a lower16 relocation.
+        bool isUpper = (Obj->getAnyRelocationLength(RE) & 0x1) == 1;
+
+        if (isUpper)
+          Fmt << ":upper16:(";
+        else
+          Fmt << ":lower16:(";
+        printRelocationTargetName(Obj, RE, Fmt);
+
+        DataRefImpl RelNext = Rel;
+        Obj->moveRelocationNext(RelNext);
+        MachO::any_relocation_info RENext = Obj->getRelocation(RelNext);
+
+        // ARM half relocs must be followed by a relocation of type
+        // ARM_RELOC_PAIR.
+        unsigned RType = Obj->getAnyRelocationType(RENext);
+        if (RType != MachO::ARM_RELOC_PAIR)
+          report_error(Obj->getFileName(), "Expected ARM_RELOC_PAIR after "
+                                           "ARM_RELOC_HALF");
+
+        // NOTE: The half of the target virtual address is stashed in the
+        // address field of the secondary relocation, but we can't reverse
+        // engineer the constant offset from it without decoding the movw/movt
+        // instruction to find the other half in its immediate field.
+
+        // ARM_RELOC_HALF_SECTDIFF encodes the second section in the
+        // symbol/section pointer of the follow-on relocation.
+        if (Type == MachO::ARM_RELOC_HALF_SECTDIFF) {
+          Fmt << "-";
+          printRelocationTargetName(Obj, RENext, Fmt);
+        }
+
+        Fmt << ")";
+        break;
+      }
+      default: {
+        printRelocationTargetName(Obj, RE, Fmt);
+      }
+      }
+    }
+  } else
+    printRelocationTargetName(Obj, RE, Fmt);
+
+  Fmt.flush();
+  Result.append(FmtBuf.begin(), FmtBuf.end());
+  return std::error_code();
+}
+
 static void PrintIndirectSymbolTable(MachOObjectFile *O, bool verbose,
                                      uint32_t n, uint32_t count,
                                      uint32_t stride, uint64_t addr) {