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: 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
---
 llvm/tools/llvm-objdump/MachODump.cpp | 52 +++++++++++++++++++++++++++++------
 1 file changed, 43 insertions(+), 9 deletions(-)

(limited to 'llvm/tools/llvm-objdump')

diff --git a/llvm/tools/llvm-objdump/MachODump.cpp b/llvm/tools/llvm-objdump/MachODump.cpp
index c5aba86b20e..69e95b4a29e 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 ("
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