[llvm-readobj] Install llvm-readelf alias

[mcgrathr]

Summary

Install an llvm-readelf symlink to llvm-readobj.
When invoked as *readelf*, default to -elf-output-style=GNU.

[davide]

I'd split this in several patches.

tools/llvm-readobj/llvm-readobj.cpp

54–57

What about the --wide alias?

[mcgrathr]

Split out:

-S https://reviews.llvm.org/D33872
-W https://reviews.llvm.org/D33873

[mcgrathr]

PTAL and land it for me if approved.

[mcgrathr]

One line from the -W patch crept into this one.

test/tools/llvm-readobj/gnu-sections.test

 RUN: llvm-readobj -s %p/Inputs/relocs.obj.elf-i386 --elf-output-style=GNU \
 RUN:   | FileCheck %s -check-prefix ELF32
 RUN: llvm-readobj -S %p/Inputs/relocs.obj.elf-x86_64 --elf-output-style=GNU \
 RUN:   | FileCheck %s -check-prefix ELF64
 RUN: llvm-readobj --wide --sections \
 RUN:   %p/Inputs/relocs.obj.elf-x86_64 --elf-output-style=GNU \
 RUN:   | FileCheck %s -check-prefix ELF64
 RUN: llvm-readobj -W --sections \
 RUN:   %p/Inputs/relocs.obj.elf-x86_64 --elf-output-style=GNU \
 RUN:   | FileCheck %s -check-prefix ELF64
+RUN: llvm-readelf -W -S %p/Inputs/relocs.obj.elf-x86_64 \
+RUN:   | FileCheck %s -check-prefix ELF64
 
 ELF32:    Section Headers:
 ELF32-NEXT:      [Nr] Name              Type            Address  Off    Size   ES Flg Lk Inf Al
 ELF32-NEXT:      [ 0]                   NULL            00000000 000000 000000 00      0   0  0
 ELF32-NEXT:      [ 1] .text             PROGBITS        00000000 000034 0000f6 00  AX  0   0  4
 ELF32-NEXT:      [ 2] .rel.text         REL             00000000 000318 000148 08      6   1  4
 ELF32-NEXT:      [ 3] .data             PROGBITS        00000000 00012c 000000 00  WA  0   0  4
 ELF32-NEXT:      [ 4] .bss              NOBITS          00000000 00012c 000000 00  WA  0   0  4

tools/llvm-readobj/CMakeLists.txt

add_llvm_tool(llvm-readobj
   ELFDumper.cpp
   Error.cpp
   llvm-readobj.cpp
   MachODumper.cpp
   ObjDumper.cpp
   WasmDumper.cpp
   Win64EHDumper.cpp
   )
+
+add_llvm_tool_symlink(llvm-readelf llvm-readobj)

tools/llvm-readobj/llvm-readobj.cpp

 #include "llvm/Object/MachOUniversal.h"
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/DataTypes.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/Path.h"
 #include "llvm/Support/PrettyStackTrace.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/TargetSelect.h"
 #include <string>
 #include <system_error>
 
 using namespace llvm;
 using namespace llvm::object;
 
 namespace opts {
   cl::list<std::string> InputFilenames(cl::Positional,
     cl::desc("<input object files>"),
     cl::ZeroOrMore);
 
   // -wide, -W
   cl::opt<bool> WideOutput("wide",
     cl::desc("Ignored for compatibility with GNU readelf"));
   cl::alias WideOutputShort("W",
     cl::desc("Alias for --wide"),
     cl::aliasopt(WideOutput));
 
   // -file-headers, -h
   cl::opt<bool> FileHeaders("file-headers",
     cl::desc("Display file headers "));
   cl::alias FileHeadersShort("h",
     cl::desc("Alias for --file-headers"),
else if (ObjectFile *Obj = dyn_cast<ObjectFile>(&Binary))
     dumpObject(Obj);
   else if (COFFImportFile *Import = dyn_cast<COFFImportFile>(&Binary))
     dumpCOFFImportFile(Import);
   else
     reportError(File, readobj_error::unrecognized_file_format);
 }
 
 int main(int argc, const char *argv[]) {
-  sys::PrintStackTraceOnErrorSignal(argv[0]);
+  StringRef ToolName = argv[0];
+  sys::PrintStackTraceOnErrorSignal(ToolName);
   PrettyStackTraceProgram X(argc, argv);
   llvm_shutdown_obj Y;
 
   // Register the target printer for --version.
   cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
 
   opts::WideOutput.setHiddenFlag(cl::Hidden);
 
+  if (sys::path::stem(ToolName).find("readelf") != StringRef::npos)
+    opts::Output = opts::GNU;
+
   cl::ParseCommandLineOptions(argc, argv, "LLVM Object Reader\n");
 
   // Default to stdin if no filename is specified.
   if (opts::InputFilenames.size() == 0)
     opts::InputFilenames.push_back("-");
 
   std::for_each(opts::InputFilenames.begin(), opts::InputFilenames.end(),
                 dumpInput);
 
   if (opts::CodeViewMergedTypes) {
     ScopedPrinter W(outs());
     dumpCodeViewMergedTypes(W, CVTypes.IDTable, CVTypes.TypeTable);
   }
 
   return 0;
 }