From 85b7a66eee81b0b2ff42aa6aeac14eb7bdac0b24 Mon Sep 17 00:00:00 2001
From: Kevin Enderby <enderby@apple.com>
Date: Tue, 20 Mar 2018 20:29:52 +0000
Subject: [PATCH] For llvm-objdump and Mach-O files, fix the printing of module
 init and term sections from .o files to look to see if the pointers have a
 relocation entry and if so print the symbol name from the relocation entry. 
 If not fall back to the existing code and use the pointer value to look up
 that value in the symbol table.

rdar://38337506

llvm-svn: 328037
---
 .../X86/Inputs/objModInit.macho-x86_64             | Bin 0 -> 828 bytes
 .../test/tools/llvm-objdump/X86/macho-section.test |   4 ++
 llvm/tools/llvm-objdump/MachODump.cpp              |  52 +++++++++++++++++----
 3 files changed, 47 insertions(+), 9 deletions(-)
 create mode 100644 llvm/test/tools/llvm-objdump/X86/Inputs/objModInit.macho-x86_64

diff --git a/llvm/test/tools/llvm-objdump/X86/Inputs/objModInit.macho-x86_64 b/llvm/test/tools/llvm-objdump/X86/Inputs/objModInit.macho-x86_64
new file mode 100644
index 0000000000000000000000000000000000000000..52dd9ca101186f48b3d910ad15cbf9f9d143a6db
GIT binary patch
literal 828
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l9FVu;g7OY(2>d+}S`Ki=S#H>*3EoF`Y5IfM<bC(#=nI(aP4@r*

literal 0
HcmV?d00001

diff --git a/llvm/test/tools/llvm-objdump/X86/macho-section.test b/llvm/test/tools/llvm-objdump/X86/macho-section.test
index e4d7857..a8eaa49 100644
--- a/llvm/test/tools/llvm-objdump/X86/macho-section.test
+++ b/llvm/test/tools/llvm-objdump/X86/macho-section.test
@@ -1,8 +1,12 @@
 // RUN: llvm-objdump -m -section __DATA,__mod_init_func %p/Inputs/dylibModInit.macho-x86_64 | FileCheck %s -check-prefix=MODINIT
 // RUN: llvm-objdump -m -section __DATA,__mod_init_func -non-verbose %p/Inputs/dylibModInit.macho-x86_64 | FileCheck %s -check-prefix=NON_VERBOSE
+// RUN: llvm-objdump -m -section __DATA,__mod_init_func %p/Inputs/objModInit.macho-x86_64 | FileCheck %s -check-prefix=OBJ_MODINIT
 
 MODINIT: Contents of (__DATA,__mod_init_func) section
 MODINIT: 0x0000000000001000 0x0000000000000f30 _libinit
 
 NON_VERBOSE: Contents of (__DATA,__mod_init_func) section
 NON_VERBOSE: 0000000000001000	30 0f 00 00 00 00 00 00 
+
+OBJ_MODINIT: Contents of (__DATA,__mod_init_func) section
+OBJ_MODINIT: 0x0000000000000018 0x0000000000000000 _constructor_func
diff --git a/llvm/tools/llvm-objdump/MachODump.cpp b/llvm/tools/llvm-objdump/MachODump.cpp
index c5aba86..69e95b4 100644
--- a/llvm/tools/llvm-objdump/MachODump.cpp
+++ b/llvm/tools/llvm-objdump/MachODump.cpp
@@ -1284,14 +1284,35 @@ static void DumpLiteralPointerSection(MachOObjectFile *O,
   }
 }
 
-static void DumpInitTermPointerSection(MachOObjectFile *O, const char *sect,
+static void DumpInitTermPointerSection(MachOObjectFile *O,
+                                       const SectionRef &Section,
+                                       const char *sect,
                                        uint32_t sect_size, uint64_t sect_addr,
                                        SymbolAddressMap *AddrMap,
                                        bool verbose) {
   uint32_t stride;
   stride = (O->is64Bit()) ? sizeof(uint64_t) : sizeof(uint32_t);
+
+  // Collect the external relocation symbols for the pointers.
+  std::vector<std::pair<uint64_t, SymbolRef>> Relocs;
+  for (const RelocationRef &Reloc : Section.relocations()) {
+    DataRefImpl Rel;
+    MachO::any_relocation_info RE;
+    bool isExtern = false;
+    Rel = Reloc.getRawDataRefImpl();
+    RE = O->getRelocation(Rel);
+    isExtern = O->getPlainRelocationExternal(RE);
+    if (isExtern) {
+      uint64_t RelocOffset = Reloc.getOffset();
+      symbol_iterator RelocSym = Reloc.getSymbol();
+      Relocs.push_back(std::make_pair(RelocOffset, *RelocSym));
+    }
+  }
+  array_pod_sort(Relocs.begin(), Relocs.end());
+
   for (uint32_t i = 0; i < sect_size; i += stride) {
     const char *SymbolName = nullptr;
+    uint64_t p;
     if (O->is64Bit()) {
       outs() << format("0x%016" PRIx64, sect_addr + i * stride) << " ";
       uint64_t pointer_value;
@@ -1299,8 +1320,7 @@ static void DumpInitTermPointerSection(MachOObjectFile *O, const char *sect,
       if (O->isLittleEndian() != sys::IsLittleEndianHost)
         sys::swapByteOrder(pointer_value);
       outs() << format("0x%016" PRIx64, pointer_value);
-      if (verbose)
-        SymbolName = GuessSymbolName(pointer_value, AddrMap);
+      p = pointer_value;
     } else {
       outs() << format("0x%08" PRIx64, sect_addr + i * stride) << " ";
       uint32_t pointer_value;
@@ -1308,11 +1328,25 @@ static void DumpInitTermPointerSection(MachOObjectFile *O, const char *sect,
       if (O->isLittleEndian() != sys::IsLittleEndianHost)
         sys::swapByteOrder(pointer_value);
       outs() << format("0x%08" PRIx32, pointer_value);
-      if (verbose)
-        SymbolName = GuessSymbolName(pointer_value, AddrMap);
+      p = pointer_value;
+    }
+    if (verbose) {
+      // First look for an external relocation entry for this pointer.
+      auto Reloc = find_if(Relocs, [&](const std::pair<uint64_t, SymbolRef> &P) {
+        return P.first == i;
+      });
+      if (Reloc != Relocs.end()) {
+        symbol_iterator RelocSym = Reloc->second;
+        Expected<StringRef> SymName = RelocSym->getName();
+        if (!SymName)
+          report_error(O->getFileName(), SymName.takeError());
+        outs() << " " << *SymName;
+      } else {
+        SymbolName = GuessSymbolName(p, AddrMap);
+        if (SymbolName)
+          outs() << " " << SymbolName;
+      }
     }
-    if (SymbolName)
-      outs() << " " << SymbolName;
     outs() << "\n";
   }
 }
@@ -1463,8 +1497,8 @@ static void DumpSectionContents(StringRef Filename, MachOObjectFile *O,
             break;
           case MachO::S_MOD_INIT_FUNC_POINTERS:
           case MachO::S_MOD_TERM_FUNC_POINTERS:
-            DumpInitTermPointerSection(O, sect, sect_size, sect_addr, &AddrMap,
-                                       verbose);
+            DumpInitTermPointerSection(O, Section, sect, sect_size, sect_addr,
+                                       &AddrMap, verbose);
             break;
           default:
             outs() << "Unknown section type ("
-- 
2.7.4