From 07e3f81e931605d2cdc853c583b61e99defae4c6 Mon Sep 17 00:00:00 2001
From: Lang Hames <lhames@gmail.com>
Date: Thu, 15 Jan 2015 22:33:30 +0000
Subject: [PATCH] [Object] Add SF_Exported flag. This flag will be set on all
 symbols that would be exported from a dylib if their containing object file
 were linked into one.

No test case: No command line tools query this flag, and there are no Object
unit tests.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226217 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Object/ELFObjectFile.h | 17 +++++++++++++++++
 include/llvm/Object/SymbolicFile.h  |  5 +++--
 lib/Object/MachOObjectFile.cpp      |  3 +++
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/include/llvm/Object/ELFObjectFile.h b/include/llvm/Object/ELFObjectFile.h
index c2d6438f45b..07f9542263b 100644
--- a/include/llvm/Object/ELFObjectFile.h
+++ b/include/llvm/Object/ELFObjectFile.h
@@ -177,6 +177,20 @@ protected:
     return DRI;
   }
 
+  bool isExportedToOtherDSO(const Elf_Sym *ESym) const {
+    unsigned char Binding = ESym->getBinding();
+    unsigned char Visibility = ESym->getVisibility();
+
+    // A symbol is exported if its binding is either GLOBAL or WEAK, and its
+    // visibility is either DEFAULT or PROTECTED. All other symbols are not
+    // exported.
+    if ((Binding == ELF::STB_GLOBAL || Binding == ELF::STB_WEAK) &&
+        (Visibility == ELF::STV_DEFAULT && Visibility == ELF::STV_PROTECTED))
+      return true;
+
+    return false;
+  }
+
   // This flag is used for classof, to distinguish ELFObjectFile from
   // its subclass. If more subclasses will be created, this flag will
   // have to become an enum.
@@ -389,6 +403,9 @@ uint32_t ELFObjectFile<ELFT>::getSymbolFlags(DataRefImpl Symb) const {
       EF.getSymbolTableIndex(ESym) == ELF::SHN_COMMON)
     Result |= SymbolRef::SF_Common;
 
+  if (isExportedToOtherDSO(ESym))
+    Result |= SymbolRef::SF_Exported;
+
   return Result;
 }
 
diff --git a/include/llvm/Object/SymbolicFile.h b/include/llvm/Object/SymbolicFile.h
index 435799a34eb..f7b7cb422dd 100644
--- a/include/llvm/Object/SymbolicFile.h
+++ b/include/llvm/Object/SymbolicFile.h
@@ -87,9 +87,10 @@ public:
     SF_Absolute = 1U << 3,       // Absolute symbol
     SF_Common = 1U << 4,         // Symbol has common linkage
     SF_Indirect = 1U << 5,       // Symbol is an alias to another symbol
-    SF_FormatSpecific = 1U << 6, // Specific to the object file format
+    SF_Exported = 1U << 6,       // Symbol is visible to other DSOs
+    SF_FormatSpecific = 1U << 7, // Specific to the object file format
                                  // (e.g. section symbols)
-    SF_Thumb = 1U << 7           // Thumb symbol in a 32-bit ARM binary
+    SF_Thumb = 1U << 8,          // Thumb symbol in a 32-bit ARM binary
   };
 
   BasicSymbolRef() : OwningObject(nullptr) { }
diff --git a/lib/Object/MachOObjectFile.cpp b/lib/Object/MachOObjectFile.cpp
index e4769762be4..978988c2569 100644
--- a/lib/Object/MachOObjectFile.cpp
+++ b/lib/Object/MachOObjectFile.cpp
@@ -478,6 +478,9 @@ uint32_t MachOObjectFile::getSymbolFlags(DataRefImpl DRI) const {
       if (Value && Value != UnknownAddressOrSize)
         Result |= SymbolRef::SF_Common;
     }
+
+    if (!(MachOType & MachO::N_PEXT))
+      Result |= SymbolRef::SF_Exported;
   }
 
   if (MachOFlags & (MachO::N_WEAK_REF | MachO::N_WEAK_DEF))
-- 
2.11.0