llvm-objdump -m -D should disassemble all text segments

Summary:
When running llvm-objdump with the -macho option objdump will by default
disassemble only the __TEXT,__text section (or __TEXT_EXEC,__text when
disassembling MH_KEXT_BUNDLE files). The -disassemble-all option is
treated no diferently than -disassemble.

This change upates llvm-objdump's MachO parsing code to disassemble all
__text sections found in a file when -disassemble-all is specified. This
is useful for disassembling files with more than one __text section, or
when disassembling files whose __text section is not present in __TEXT.

I added a lit test case that verifies "llvm-objdump -m -d" and 
"llvm-objdump -m -D" produce the expected results on a reference binary. 
I also updated the CommandGuide documentation for llvm-objdump.rst and
verified it renders correctly as man and html.

rdar://42899338

Reviewers: ab, pete, lhames

Reviewed By: lhames

Subscribers: rupprecht, llvm-commits

Differential Revision: https://reviews.llvm.org/D56649

llvm-svn: 351238

1 files changed, 13 insertions, 2 deletions

diff --git a/llvm/tools/llvm-objdump/MachODump.cpp b/llvm/tools/llvm-objdump/MachODump.cpp
index c8707ac1183..5ef7058ec9d 100644
--- a/llvm/tools/llvm-objdump/MachODump.cpp
+++ b/llvm/tools/llvm-objdump/MachODump.cpp
@@ -1610,8 +1610,19 @@ static void ProcessMachO(StringRef Name, MachOObjectFile *MachOOF,
   if (Disassemble || IndirectSymbols || !FilterSections.empty() || UnwindInfo)
     if (Error Err = MachOOF->checkSymbolTable())
       report_error(ArchiveName, FileName, std::move(Err), ArchitectureName);
-
-  if (Disassemble) {
+  
+  if (DisassembleAll) {
+    for (const SectionRef &Section : MachOOF->sections()) {
+      StringRef SectName;
+      Section.getName(SectName);
+      if (SectName.equals("__text")) {
+        DataRefImpl Ref = Section.getRawDataRefImpl();
+        StringRef SegName = MachOOF->getSectionFinalSegmentName(Ref);
+        DisassembleMachO(FileName, MachOOF, SegName, SectName);
+      }
+    }
+  }
+  else if (Disassemble) {
     if (MachOOF->getHeader().filetype == MachO::MH_KEXT_BUNDLE &&
         MachOOF->getHeader().cputype == MachO::CPU_TYPE_ARM64)
       DisassembleMachO(FileName, MachOOF, "__TEXT_EXEC", "__text");