[objdump][macho] Emit segment names along with section names

[dsanders]

Summary

I recently came across a MachO with multiple sections of the same name but
different segments. We should emit the segment name alongside the section name
for MachO's.

[pete]

LGTM

llvm/test/MC/AArch64/arm64_32-compact-unwind.s

 ; RUN: llvm-mc -triple=arm64_32-ios7.0 -filetype=obj %s -o %t
 ; RUN: llvm-objdump -s %t | FileCheck %s
 
 ; The compact unwind format in ILP32 mode is pretty much the same, except
 ; references to addresses (function, personality, LSDA) are pointer-sized.
 
-; CHECK: Contents of section __compact_unwind:
+; CHECK: Contents of section __LD,__compact_unwind:
 ; CHECK-NEXT:  0004 00000000 04000000 00000002 00000000
 ; CHECK-NEXT:  0014 00000000
         .globl  _test_compact_unwind
         .align  2
 _test_compact_unwind:
         .cfi_startproc
         ret
         .cfi_endproc

llvm/test/tools/llvm-objdump/MachO/section-contents.test

 RUN: llvm-objdump --macho -s %p/Inputs/hello.obj.macho-x86_64 | FileCheck %s
 
-CHECK: Contents of section __text:
+CHECK: Contents of section __TEXT,__text:
 CHECK:  0000 554889e5 4883ec20 488d0500 000000c7  UH..H.. H.......
 CHECK:  0010 45fc0000 0000897d f8488975 f0488955  E......}.H.u.H.U
 CHECK:  0020 e84889c7 b000e800 000000b9 00000000  .H..............
 CHECK:  0030 8945e489 c84883c4 205dc3             .E...H.. ].
-CHECK: Contents of section __cstring:
+CHECK: Contents of section __TEXT,__cstring:
 CHECK:  003b 48656c6c 6f20776f 726c640a 00        Hello world..
-CHECK: Contents of section __compact_unwind:
+CHECK: Contents of section __LD,__compact_unwind:
 CHECK:  0048 00000000 00000000 3b000000 00000001  ........;.......
 CHECK:  0058 00000000 00000000 00000000 00000000  ................
-CHECK: Contents of section __eh_frame:
+CHECK: Contents of section __TEXT,__eh_frame:
 CHECK:  0068 14000000 00000000 017a5200 01781001  .........zR..x..
 CHECK:  0078 100c0708 90010000 24000000 1c000000  ........$.......
 CHECK:  0088 78ffffff ffffffff 3b000000 00000000  x.......;.......
 CHECK:  0098 00410e10 8602430d 06000000 00000000  .A....C.........

llvm/tools/llvm-objdump/llvm-objdump.cpp

if (Disassembled && MIA) {
           !Labels.count(Target))
         Labels[Target] = ("L" + Twine(LabelCount++)).str();
     }
 
     Index += Size;
   }
 }
 
+static StringRef getSegmentName(const MachOObjectFile *MachO,
+                                const SectionRef &Section) {
+  if (MachO) {
+    DataRefImpl DR = Section.getRawDataRefImpl();
+    StringRef SegmentName = MachO->getSectionFinalSegmentName(DR);
+    return SegmentName;
+  }
+  return "";
+}
+
 static void disassembleObject(const Target *TheTarget, const ObjectFile *Obj,
                               MCContext &Ctx, MCDisassembler *PrimaryDisAsm,
                               MCDisassembler *SecondaryDisAsm,
                               const MCInstrAnalysis *MIA, MCInstPrinter *IP,
                               const MCSubtargetInfo *PrimarySTI,
                               const MCSubtargetInfo *SecondarySTI,
                               PrettyPrinter &PIP,
                               SourcePrinter &SP, bool InlineRelocs) {
if (Obj->isELF() && Obj->getArch() == Triple::amdgcn) {
       if (RelInfo) {
         std::unique_ptr<MCSymbolizer> Symbolizer(
           TheTarget->createMCSymbolizer(
             TripleName, nullptr, nullptr, &Symbols, &Ctx, std::move(RelInfo)));
         DisAsm->setSymbolizer(std::move(Symbolizer));
       }
     }
 
-    StringRef SegmentName = "";
-    if (MachO) {
-      DataRefImpl DR = Section.getRawDataRefImpl();
-      SegmentName = MachO->getSectionFinalSegmentName(DR);
-    }
-
+    StringRef SegmentName = getSegmentName(MachO, Section);
     StringRef SectionName = unwrapOrError(Section.getName(), Obj->getFileName());
     // If the section has no symbol at the start, just insert a dummy one.
     if (Symbols.empty() || Symbols[0].Addr != 0) {
       Symbols.insert(Symbols.begin(),
                      createDummySymbolInfo(Obj, SectionAddr, SectionName,
                                            Section.isText() ? ELF::STT_FUNC
                                                             : ELF::STT_OBJECT));
     }
else
       outs() << format("%3" PRIu64 " %-*s %08" PRIx64 " ", Idx, NameWidth,
                        Name.str().c_str(), Size)
              << format_hex_no_prefix(VMA, AddressWidth) << " " << Type << "\n";
   }
   outs() << "\n";
 }
 
 void objdump::printSectionContents(const ObjectFile *Obj) {
+  const MachOObjectFile *MachO = dyn_cast<const MachOObjectFile>(Obj);
+
   for (const SectionRef &Section : ToolSectionFilter(*Obj)) {
     StringRef Name = unwrapOrError(Section.getName(), Obj->getFileName());
     uint64_t BaseAddr = Section.getAddress();
     uint64_t Size = Section.getSize();
     if (!Size)
       continue;
 
-    outs() << "Contents of section " << Name << ":\n";
+    outs() << "Contents of section ";
+    StringRef SegmentName = getSegmentName(MachO, Section);
+    if (!SegmentName.empty())
+      outs() << SegmentName << ",";
+    outs() << Name << ":\n";
     if (Section.isBSS()) {
       outs() << format("<skipping contents of bss section at [%04" PRIx64
                        ", %04" PRIx64 ")>\n",
                        BaseAddr, BaseAddr + Size);
       continue;
     }
 
     StringRef Contents = unwrapOrError(Section.getContents(), Obj->getFileName());
outs() << format(Fmt, Address) << " "
          << ' ';
   if (Absolute) {
     outs() << "*ABS*";
   } else if (Common) {
     outs() << "*COM*";
   } else if (Section == O->section_end()) {
     outs() << "*UND*";
   } else {
-    if (MachO) {
-      DataRefImpl DR = Section->getRawDataRefImpl();
-      StringRef SegmentName = MachO->getSectionFinalSegmentName(DR);
+    StringRef SegmentName = getSegmentName(MachO, *Section);
+    if (!SegmentName.empty())
       outs() << SegmentName << ",";
-    }
     StringRef SectionName = unwrapOrError(Section->getName(), FileName);
     outs() << SectionName;
   }
 
   if (Common || O->isELF()) {
     uint64_t Val =
         Common ? Symbol.getAlignment() : ELFSymbolRef(Symbol).getSize();
     outs() << '\t' << format(Fmt, Val);