Add r170095 back.

I cannot reproduce it the failures locally, so I will keep an eye at the ppc
bots. This patch does add the change to the "Disassembly of section" message,
but that is not what was failing on the bots.

Original message:

Add a funciton 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 infor
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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170545 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Object/MachO.h

@@ -44,6 +44,11 @@ public:
   virtual unsigned getArch() const;
   virtual StringRef getLoadName() const;
 
+  // In a MachO file, sections have a segment name. This is used in the .o
+  // files. They have a single segment, but this field specifies which segment
+  // a section should be put in in the final object.
+  error_code getSectionFinalSegmentName(DataRefImpl Sec, StringRef &Res) const;
+
   MachOObject *getObject() { return MachOObj.get(); }
 
   static inline bool classof(const Binary *v) {

lib/Object/MachOObjectFile.cpp

@@ -473,28 +473,43 @@ static bool is64BitLoadCommand(const MachOObject *MachOObj, DataRefImpl DRI) {
   return false;
 }
 
+static StringRef parseSegmentOrSectionName(const char *P) {
+  if (P[15] == 0)
+    // Null terminated.
+    return P;
+  // Not null terminated, so this is a 16 char string.
+  return StringRef(P, 16);
+}
+
 error_code MachOObjectFile::getSectionName(DataRefImpl DRI,
                                            StringRef &Result) const {
-  // FIXME: thread safety.
-  static char result[34];
   if (is64BitLoadCommand(MachOObj.get(), DRI)) {
     LoadCommandInfo LCI = MachOObj->getLoadCommandInfo(DRI.d.a);
     InMemoryStruct<macho::Section64> Sect;
     MachOObj->ReadSection64(LCI, DRI.d.b, Sect);
-
-    strcpy(result, Sect->SegmentName);
-    strcat(result, ",");
-    strcat(result, Sect->Name);
+    Result = parseSegmentOrSectionName(Sect->Name);
   } else {
     LoadCommandInfo LCI = MachOObj->getLoadCommandInfo(DRI.d.a);
     InMemoryStruct<macho::Section> Sect;
     MachOObj->ReadSection(LCI, DRI.d.b, Sect);
-
-    strcpy(result, Sect->SegmentName);
-    strcat(result, ",");
-    strcat(result, Sect->Name);
+    Result = parseSegmentOrSectionName(Sect->Name);
+  }
+  return object_error::success;
+}
+
+error_code MachOObjectFile::getSectionFinalSegmentName(DataRefImpl Sec,
+                                                       StringRef &Res) const {
+  if (is64BitLoadCommand(MachOObj.get(), Sec)) {
+    LoadCommandInfo LCI = MachOObj->getLoadCommandInfo(Sec.d.a);
+    InMemoryStruct<macho::Section64> Sect;
+    MachOObj->ReadSection64(LCI, Sec.d.b, Sect);
+    Res = parseSegmentOrSectionName(Sect->SegmentName);
+  } else {
+    LoadCommandInfo LCI = MachOObj->getLoadCommandInfo(Sec.d.a);
+    InMemoryStruct<macho::Section> Sect;
+    MachOObj->ReadSection(LCI, Sec.d.b, Sect);
+    Res = parseSegmentOrSectionName(Sect->SegmentName);
   }
-  Result = StringRef(result);
   return object_error::success;
 }
 

tools/llvm-objdump/MachODump.cpp

@@ -334,9 +334,15 @@ void llvm::DisassembleInputMachO(StringRef Filename) {
   for (unsigned SectIdx = 0; SectIdx != Sections.size(); SectIdx++) {
     StringRef SectName;
     if (Sections[SectIdx].getName(SectName) ||
-        SectName.compare("__TEXT,__text"))
+        SectName != "__text")
       continue; // Skip non-text sections
 
+    StringRef SegmentName;
+    DataRefImpl DR = Sections[SectIdx].getRawDataRefImpl();
+    if (MachOOF->getSectionFinalSegmentName(DR, SegmentName) ||
+        SegmentName != "__TEXT")
+      continue;
+
     // Insert the functions from the function starts segment into our map.
     uint64_t VMAddr;
     Sections[SectIdx].getAddress(VMAddr);

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;
   }