Add a function to get the segment name of a section.

On MachO, sections also have segment names. When a tool looking at a .o file
prints a segment name, this is what they mean. In reality, a .o has only one
anonymous, segment.

This patch adds a MachO only function to fetch that segment name. I named it
getSectionFinalSegmentName since the main use for the name seems to be inform
the linker with segment this section should go to.

The patch also changes MachOObjectFile::getSectionName to return just the
section name instead of computing SegmentName,SectionName.

The main difference from the previous patch is that it doesn't use
InMemoryStruct. It is extremely dangerous: if the endians match it returns
a pointer to the file buffer, if not, it returns a pointer to an internal buffer
that is overwritten in the next API call.

We should change all of this code to use
support::detail::packed_endian_specific_integral like ELF, but since these
functions only handle strings, they work with big and little endian machines
as is.

I have tested this by installing ubuntu 12.10 ppc on qemu, that is why it took
so long :-)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170838 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 21 insertions, 4 deletions

diff --git a/tools/llvm-objdump/llvm-objdump.cpp b/tools/llvm-objdump/llvm-objdump.cpp
index 2838a2a2b3..24dc9c91a3 100644
--- a/tools/llvm-objdump/llvm-objdump.cpp
+++ b/tools/llvm-objdump/llvm-objdump.cpp
@@ -28,6 +28,7 @@
 #include "llvm/MC/MCSubtargetInfo.h"
 #include "llvm/Object/Archive.h"
 #include "llvm/Object/COFF.h"
+#include "llvm/Object/MachO.h"
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/CommandLine.h"
@@ -72,9 +73,9 @@ static cl::opt<bool>
 SymbolTable("t", cl::desc("Display the symbol table"));
 
 static cl::opt<bool>
-MachO("macho", cl::desc("Use MachO specific object file parser"));
+MachOOpt("macho", cl::desc("Use MachO specific object file parser"));
 static cl::alias
-MachOm("m", cl::desc("Alias for --macho"), cl::aliasopt(MachO));
+MachOm("m", cl::desc("Alias for --macho"), cl::aliasopt(MachOOpt));
 
 cl::opt<std::string>
 llvm::TripleName("triple", cl::desc("Target triple to disassemble for, "
@@ -241,9 +242,18 @@ static void DisassembleObject(const ObjectFile *Obj, bool InlineRelocs) {
     // Sort relocations by address.
     std::sort(Rels.begin(), Rels.end(), RelocAddressLess);
 
+    StringRef SegmentName = "";
+    if (const MachOObjectFile *MachO = dyn_cast<const MachOObjectFile>(Obj)) {
+      DataRefImpl DR = i->getRawDataRefImpl();
+      if (error(MachO->getSectionFinalSegmentName(DR, SegmentName)))
+        break;
+    }
     StringRef name;
     if (error(i->getName(name))) break;
-    outs() << "Disassembly of section " << name << ':';
+    outs() << "Disassembly of section ";
+    if (!SegmentName.empty())
+      outs() << SegmentName << ",";
+    outs() << name << ':';
 
     // If the section has no symbols just insert a dummy one and disassemble
     // the whole section.
@@ -567,6 +577,13 @@ static void PrintSymbolTable(const ObjectFile *o) {
       else if (Section == o->end_sections())
         outs() << "*UND*";
       else {
+        if (const MachOObjectFile *MachO = dyn_cast<const MachOObjectFile>(o)) {
+          StringRef SegmentName;
+          DataRefImpl DR = Section->getRawDataRefImpl();
+          if (error(MachO->getSectionFinalSegmentName(DR, SegmentName)))
+            SegmentName = "";
+          outs() << SegmentName << ",";
+        }
         StringRef SectionName;
         if (error(Section->getName(SectionName)))
           SectionName = "";
@@ -640,7 +657,7 @@ static void DumpInput(StringRef file) {
     return;
   }
 
-  if (MachO && Disassemble) {
+  if (MachOOpt && Disassemble) {
     DisassembleInputMachO(file);
     return;
   }