Introduce new linkage types linkonce_odr, weak_odr, common_odr

and extern_weak_odr.  These are the same as the non-odr versions,
except that they indicate that the global will only be overridden
by an *equivalent* global.  In C, a function with weak linkage can
be overridden by a function which behaves completely differently.
This means that IP passes have to skip weak functions, since any
deductions made from the function definition might be wrong, since
the definition could be replaced by something completely different
at link time.   This is not allowed in C++, thanks to the ODR
(One-Definition-Rule): if a function is replaced by another at
link-time, then the new function must be the same as the original
function.  If a language knows that a function or other global can
only be overridden by an equivalent global, it can give it the
weak_odr linkage type, and the optimizers will understand that it
is alright to make deductions based on the function body.  The
code generators on the other hand map weak and weak_odr linkage
to the same thing.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66339 91177308-0d34-0410-b5e6-96231b3b80d8

43 files changed, 370 insertions, 192 deletions

diff --git a/docs/LangRef.html b/docs/LangRef.html
index 83ea026c6b..0985cbd61e 100644
--- a/docs/LangRef.html
+++ b/docs/LangRef.html
@@ -545,11 +545,26 @@ All Global Variables and Functions have one of the following types of linkage:
   </dd>
 
   <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
+
   <dd>The semantics of this linkage follow the ELF object file model: the
     symbol is weak until linked, if not linked, the symbol becomes null instead
     of being an undefined reference.
   </dd>
 
+  <dt><tt><b><a name="linkage_linkonce">linkonce_odr</a></b></tt>: </dt>
+  <dt><tt><b><a name="linkage_common">common_odr</a></b></tt>: </dt>
+  <dt><tt><b><a name="linkage_weak">weak_odr</a></b></tt>: </dt>
+  <dt><tt><b><a name="linkage_externweak">extern_weak_odr</a></b></tt>: </dt>
+  <dd>Some languages allow inequivalent globals to be merged, such as two
+    functions with different semantics.  Other languages, such as <tt>C++</tt>,
+    ensure that only equivalent globals are ever merged (the "one definition
+    rule" - <tt>odr</tt>).  Such languages can use the <tt>linkonce_odr</tt>,
+    <tt>common_odr</tt>, <tt>weak_odr</tt> and <tt>extern_weak_odr</tt> linkage
+    types to indicate that the global will only be merged with equivalent
+    globals.  These linkage types are otherwise the same as their
+    non-<tt>odr</tt> versions.
+  </dd>
+
   <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
 
   <dd>If none of the above identifiers are used, the global is externally
@@ -592,9 +607,9 @@ external (i.e., lacking any linkage declarations), they are accessible
 outside of the current module.</p>
 <p>It is illegal for a function <i>declaration</i>
 to have any linkage type other than "externally visible", <tt>dllimport</tt>,
-or <tt>extern_weak</tt>.</p>
-<p>Aliases can have only <tt>external</tt>, <tt>internal</tt> and <tt>weak</tt>
-linkages.</p>
+<tt>extern_weak</tt> or <tt>extern_weak_odr</tt>.</p>
+<p>Aliases can have only <tt>external</tt>, <tt>internal</tt>, <tt>weak</tt>
+or <tt>weak_odr</tt> linkages.</p>
 </div>
 
 <!-- ======================================================================= -->
diff --git a/docs/ProgrammersManual.html b/docs/ProgrammersManual.html
index 289a569024..cf46a97e68 100644
--- a/docs/ProgrammersManual.html
+++ b/docs/ProgrammersManual.html
@@ -3322,11 +3322,12 @@ never change at runtime).</p>
     <p>Create a new global variable of the specified type. If
     <tt>isConstant</tt> is true then the global variable will be marked as
     unchanging for the program. The Linkage parameter specifies the type of
-    linkage (internal, external, weak, linkonce, appending) for the variable. If
-    the linkage is InternalLinkage, WeakLinkage, or LinkOnceLinkage,&nbsp; then
-    the resultant global variable will have internal linkage.  AppendingLinkage
-    concatenates together all instances (in different translation units) of the
-    variable into a single variable but is only applicable to arrays.  &nbsp;See
+    linkage (internal, external, weak, linkonce, appending) for the variable.
+    If the linkage is InternalLinkage, WeakAnyLinkage, WeakODRLinkage,
+    LinkOnceAnyLinkage or LinkOnceODRLinkage,&nbsp; then the resultant
+    global variable will have internal linkage.  AppendingLinkage concatenates
+    together all instances (in different translation units) of the variable
+    into a single variable but is only applicable to arrays.  &nbsp;See
     the <a href="LangRef.html#modulestructure">LLVM Language Reference</a> for
     further details on linkage types. Optionally an initializer, a name, and the
     module to put the variable into may be specified for the global variable as
diff --git a/include/llvm-c/Core.h b/include/llvm-c/Core.h
index 6016ac61b5..5d8cff414f 100644
--- a/include/llvm-c/Core.h
+++ b/include/llvm-c/Core.h
@@ -115,16 +115,26 @@ typedef enum {
 
 typedef enum {
   LLVMExternalLinkage,    /**< Externally visible function */
-  LLVMLinkOnceLinkage,    /**< Keep one copy of function when linking (inline)*/
-  LLVMWeakLinkage,        /**< Keep one copy of function when linking (weak) */
+  LLVMLinkOnceAnyLinkage, /**< Keep one copy of function when linking (inline)*/
+  LLVMLinkOnceODRLinkage, /**< Same, but only replaced by something
+                            equivalent. */
+  LLVMWeakAnyLinkage,     /**< Keep one copy of function when linking (weak) */
+  LLVMWeakODRLinkage,     /**< Same, but only replaced by something
+                            equivalent. */
   LLVMAppendingLinkage,   /**< Special purpose, only applies to global arrays */
   LLVMInternalLinkage,    /**< Rename collisions when linking (static
                                functions) */
+  LLVMPrivateLinkage,     /**< Like Internal, but omit from symbol table */
   LLVMDLLImportLinkage,   /**< Function to be imported from DLL */
   LLVMDLLExportLinkage,   /**< Function to be accessible from DLL */
-  LLVMExternalWeakLinkage,/**< ExternalWeak linkage description */
-  LLVMGhostLinkage        /**< Stand-in functions for streaming fns from
+  LLVMExternalWeakAnyLinkage,/**< ExternalWeak linkage description */
+  LLVMExternalWeakODRLinkage,/**< Same, but only replaced by something
+                               equivalent. */
+  LLVMGhostLinkage,       /**< Stand-in functions for streaming fns from
                                bitcode */
+  LLVMCommonAnyLinkage,   /**< Tentative definitions */
+  LLVMCommonODRLinkage    /**< Same, but only replaced by something
+                            equivalent. */
 } LLVMLinkage;
 
 typedef enum {
diff --git a/include/llvm/GlobalValue.h b/include/llvm/GlobalValue.h
index 8fb5580d0d..33f50c907b 100644
--- a/include/llvm/GlobalValue.h
+++ b/include/llvm/GlobalValue.h
@@ -31,16 +31,20 @@ public:
   /// @brief An enumeration for the kinds of linkage for global values.
   enum LinkageTypes {
     ExternalLinkage = 0,///< Externally visible function
-    LinkOnceLinkage,    ///< Keep one copy of function when linking (inline)
-    WeakLinkage,        ///< Keep one copy of named function when linking (weak)
+    LinkOnceAnyLinkage, ///< Keep one copy of function when linking (inline)
+    LinkOnceODRLinkage, ///< Same, but only replaced by something equivalent.
+    WeakAnyLinkage,     ///< Keep one copy of named function when linking (weak)
+    WeakODRLinkage,     ///< Same, but only replaced by something equivalent.
     AppendingLinkage,   ///< Special purpose, only applies to global arrays
     InternalLinkage,    ///< Rename collisions when linking (static functions)
     PrivateLinkage,     ///< Like Internal, but omit from symbol table
     DLLImportLinkage,   ///< Function to be imported from DLL
     DLLExportLinkage,   ///< Function to be accessible from DLL
-    ExternalWeakLinkage,///< ExternalWeak linkage description
+    ExternalWeakAnyLinkage,///< ExternalWeak linkage description
+    ExternalWeakODRLinkage,///< Same, but only replaced by something equivalent.
     GhostLinkage,       ///< Stand-in functions for streaming fns from BC files
-    CommonLinkage       ///< Tentative definitions
+    CommonAnyLinkage,   ///< Tentative definitions
+    CommonODRLinkage    ///< Same, but only replaced by something equivalent.
   };
 
   /// @brief An enumeration for the kinds of visibility of global values.
@@ -99,31 +103,67 @@ public:
     return reinterpret_cast<const PointerType*>(User::getType());
   }
 
-  bool hasExternalLinkage()   const { return Linkage == ExternalLinkage; }
-  bool hasLinkOnceLinkage()   const { return Linkage == LinkOnceLinkage; }
-  bool hasWeakLinkage()       const { return Linkage == WeakLinkage; }
-  bool hasCommonLinkage()     const { return Linkage == CommonLinkage; }
-  bool hasAppendingLinkage()  const { return Linkage == AppendingLinkage; }
-  bool hasInternalLinkage()   const { return Linkage == InternalLinkage; }
-  bool hasPrivateLinkage()    const { return Linkage == PrivateLinkage; }
-  bool hasLocalLinkage()      const {
+  static LinkageTypes getLinkOnceLinkage(bool ODR) {
+    return ODR ? LinkOnceODRLinkage : LinkOnceAnyLinkage;
+  }
+  static LinkageTypes getWeakLinkage(bool ODR) {
+    return ODR ? WeakODRLinkage : WeakAnyLinkage;
+  }
+  static LinkageTypes getCommonLinkage(bool ODR) {
+    return ODR ? CommonODRLinkage : CommonAnyLinkage;
+  }
+  static LinkageTypes getExternalWeakLinkage(bool ODR) {
+    return ODR ? ExternalWeakODRLinkage : ExternalWeakAnyLinkage;
+  }
+
+  bool hasExternalLinkage() const { return Linkage == ExternalLinkage; }
+  bool hasLinkOnceLinkage() const {
+    return Linkage == LinkOnceAnyLinkage || Linkage == LinkOnceODRLinkage;
+  }
+  bool hasWeakLinkage() const {
+    return Linkage == WeakAnyLinkage || Linkage == WeakODRLinkage;
+  }
+  bool hasAppendingLinkage() const { return Linkage == AppendingLinkage; }
+  bool hasInternalLinkage() const { return Linkage == InternalLinkage; }
+  bool hasPrivateLinkage() const { return Linkage == PrivateLinkage; }
+  bool hasLocalLinkage() const {
     return Linkage == InternalLinkage || Linkage == PrivateLinkage;
   }
-  bool hasDLLImportLinkage()  const { return Linkage == DLLImportLinkage; }
-  bool hasDLLExportLinkage()  const { return Linkage == DLLExportLinkage; }
-  bool hasExternalWeakLinkage() const { return Linkage == ExternalWeakLinkage; }
-  bool hasGhostLinkage()      const { return Linkage == GhostLinkage; }
+  bool hasDLLImportLinkage() const { return Linkage == DLLImportLinkage; }
+  bool hasDLLExportLinkage() const { return Linkage == DLLExportLinkage; }
+  bool hasExternalWeakLinkage() const {
+    return Linkage == ExternalWeakAnyLinkage ||
+      Linkage == ExternalWeakODRLinkage;
+  }
+  bool hasGhostLinkage() const { return Linkage == GhostLinkage; }
+  bool hasCommonLinkage() const {
+    return Linkage == CommonAnyLinkage || Linkage == CommonODRLinkage;
+  }
+
   void setLinkage(LinkageTypes LT) { Linkage = LT; }
   LinkageTypes getLinkage() const { return Linkage; }
 
   /// mayBeOverridden - Whether the definition of this global may be replaced
-  /// at link time.  For example, if a function has weak linkage then the code
-  /// defining it may be replaced by different code.
+  /// by something non-equivalent at link time.  For example, if a function has
+  /// weak linkage then the code defining it may be replaced by different code.
   bool mayBeOverridden() const {
-    return (Linkage == WeakLinkage ||
-            Linkage == LinkOnceLinkage ||
-            Linkage == CommonLinkage ||
-            Linkage == ExternalWeakLinkage);
+    return (Linkage == WeakAnyLinkage ||
+            Linkage == LinkOnceAnyLinkage ||
+            Linkage == CommonAnyLinkage ||
+            Linkage == ExternalWeakAnyLinkage);
+  }
+
+  /// isWeakForLinker - Whether the definition of this global may be replaced at
+  /// link time, whether the replacement is equivalent to the original or not.
+  bool isWeakForLinker() const {
+    return (Linkage == WeakAnyLinkage ||
+            Linkage == WeakODRLinkage ||
+            Linkage == LinkOnceAnyLinkage ||
+            Linkage == LinkOnceODRLinkage ||
+            Linkage == CommonAnyLinkage ||
+            Linkage == CommonODRLinkage ||
+            Linkage == ExternalWeakAnyLinkage ||
+            Linkage == ExternalWeakODRLinkage);
   }
 
   /// copyAttributesFrom - copy all additional attributes (those not needed to
diff --git a/lib/Analysis/DebugInfo.cpp b/lib/Analysis/DebugInfo.cpp
index deb5c9bbfb..a063aa53ba 100644
--- a/lib/Analysis/DebugInfo.cpp
+++ b/lib/Analysis/DebugInfo.cpp
@@ -344,7 +344,7 @@ DIAnchor DIFactory::GetOrCreateAnchor(unsigned TAG, const char *Name) {
   if (GV->hasInitializer()) 
     return SubProgramAnchor = DIAnchor(GV);
   
-  GV->setLinkage(GlobalValue::LinkOnceLinkage);
+  GV->setLinkage(GlobalValue::LinkOnceAnyLinkage);
   GV->setSection("llvm.metadata");
   GV->setConstant(true);
   M.addTypeName("llvm.dbg.anchor.type", EltTy);
diff --git a/lib/AsmParser/LLLexer.cpp b/lib/AsmParser/LLLexer.cpp
index fb491d3278..6f1d5eefe8 100644
--- a/lib/AsmParser/LLLexer.cpp
+++ b/lib/AsmParser/LLLexer.cpp
@@ -456,15 +456,19 @@ lltok::Kind LLLexer::LexIdentifier() {
   KEYWORD(private);
   KEYWORD(internal);
   KEYWORD(linkonce);
+  KEYWORD(linkonce_odr);
   KEYWORD(weak);
+  KEYWORD(weak_odr);
   KEYWORD(appending);
   KEYWORD(dllimport);
   KEYWORD(dllexport);
   KEYWORD(common);
+  KEYWORD(common_odr);
   KEYWORD(default);
   KEYWORD(hidden);
   KEYWORD(protected);
   KEYWORD(extern_weak);
+  KEYWORD(extern_weak_odr);
   KEYWORD(external);
   KEYWORD(thread_local);
   KEYWORD(zeroinitializer);
diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index 19f8415bba..90dd50743a 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -116,12 +116,16 @@ bool LLParser::ParseTopLevelEntities() {
     case lltok::kw_private:       // OptionalLinkage
     case lltok::kw_internal:      // OptionalLinkage
     case lltok::kw_weak:          // OptionalLinkage
+    case lltok::kw_weak_odr:      // OptionalLinkage
     case lltok::kw_linkonce:      // OptionalLinkage
+    case lltok::kw_linkonce_odr:  // OptionalLinkage
     case lltok::kw_appending:     // OptionalLinkage
     case lltok::kw_dllexport:     // OptionalLinkage
     case lltok::kw_common:        // OptionalLinkage
+    case lltok::kw_common_odr:    // OptionalLinkage
     case lltok::kw_dllimport:     // OptionalLinkage
     case lltok::kw_extern_weak:   // OptionalLinkage
+    case lltok::kw_extern_weak_odr: // OptionalLinkage
     case lltok::kw_external: {    // OptionalLinkage
       unsigned Linkage, Visibility;
       if (ParseOptionalLinkage(Linkage) ||
@@ -377,7 +381,8 @@ bool LLParser::ParseAlias(const std::string &Name, LocTy NameLoc,
     return true;
 
   if (Linkage != GlobalValue::ExternalLinkage &&
-      Linkage != GlobalValue::WeakLinkage &&
+      Linkage != GlobalValue::WeakAnyLinkage &&
+      Linkage != GlobalValue::WeakODRLinkage &&
       Linkage != GlobalValue::InternalLinkage &&
       Linkage != GlobalValue::PrivateLinkage)
     return Error(LinkageLoc, "invalid linkage type for alias");
@@ -461,7 +466,8 @@ bool LLParser::ParseGlobal(const std::string &Name, LocTy NameLoc,
   // present.
   Constant *Init = 0;
   if (!HasLinkage || (Linkage != GlobalValue::DLLImportLinkage &&
-                      Linkage != GlobalValue::ExternalWeakLinkage &&
+                      Linkage != GlobalValue::ExternalWeakAnyLinkage &&
+                      Linkage != GlobalValue::ExternalWeakODRLinkage &&
                       Linkage != GlobalValue::ExternalLinkage)) {
     if (ParseGlobalValue(Ty, Init))
       return true;
@@ -576,10 +582,10 @@ GlobalValue *LLParser::GetGlobalVal(const std::string &Name, const Type *Ty,
       return 0;
     }
     
-    FwdVal = Function::Create(FT, GlobalValue::ExternalWeakLinkage, Name, M);
+    FwdVal = Function::Create(FT, GlobalValue::ExternalWeakAnyLinkage, Name, M);
   } else {
     FwdVal = new GlobalVariable(PTy->getElementType(), false,
-                                GlobalValue::ExternalWeakLinkage, 0, Name, M);
+                                GlobalValue::ExternalWeakAnyLinkage, 0, Name, M);
   }
   
   ForwardRefVals[Name] = std::make_pair(FwdVal, Loc);
@@ -620,10 +626,10 @@ GlobalValue *LLParser::GetGlobalVal(unsigned ID, const Type *Ty, LocTy Loc) {
       Error(Loc, "function may not return opaque type");
       return 0;
     }
-    FwdVal = Function::Create(FT, GlobalValue::ExternalWeakLinkage, "", M);
+    FwdVal = Function::Create(FT, GlobalValue::ExternalWeakAnyLinkage, "", M);
   } else {
     FwdVal = new GlobalVariable(PTy->getElementType(), false,
-                                GlobalValue::ExternalWeakLinkage, 0, "", M);
+                                GlobalValue::ExternalWeakAnyLinkage, 0, "", M);
   }
   
   ForwardRefValIDs[ID] = std::make_pair(FwdVal, Loc);
@@ -746,27 +752,36 @@ bool LLParser::ParseOptionalAttrs(unsigned &Attrs, unsigned AttrKind) {
 ///   ::= 'private'
 ///   ::= 'internal'
 ///   ::= 'weak'
+///   ::= 'weak_odr'
 ///   ::= 'linkonce'
+///   ::= 'linkonce_odr'
 ///   ::= 'appending'
 ///   ::= 'dllexport'
 ///   ::= 'common'
+///   ::= 'common_odr'
 ///   ::= 'dllimport'
 ///   ::= 'extern_weak'
+///   ::= 'extern_weak_odr'
 ///   ::= 'external'
 bool LLParser::ParseOptionalLinkage(unsigned &Res, bool &HasLinkage) {
   HasLinkage = false;
   switch (Lex.getKind()) {
-  default:                    Res = GlobalValue::ExternalLinkage; return false;
-  case lltok::kw_private:     Res = GlobalValue::PrivateLinkage; break;
-  case lltok::kw_internal:    Res = GlobalValue::InternalLinkage; break;
-  case lltok::kw_weak:        Res = GlobalValue::WeakLinkage; break;
-  case lltok::kw_linkonce:    Res = GlobalValue::LinkOnceLinkage; break;
-  case lltok::kw_appending:   Res = GlobalValue::AppendingLinkage; break;
-  case lltok::kw_dllexport:   Res = GlobalValue::DLLExportLinkage; break;
-  case lltok::kw_common:      Res = GlobalValue::CommonLinkage; break;
-  case lltok::kw_dllimport:   Res = GlobalValue::DLLImportLinkage; break;
-  case lltok::kw_extern_weak: Res = GlobalValue::ExternalWeakLinkage; break;
-  case lltok::kw_external:    Res = GlobalValue::ExternalLinkage; break;
+  default:                     Res = GlobalValue::ExternalLinkage; return false;
+  case lltok::kw_private:      Res = GlobalValue::PrivateLinkage; break;
+  case lltok::kw_internal:     Res = GlobalValue::InternalLinkage; break;
+  case lltok::kw_weak:         Res = GlobalValue::WeakAnyLinkage; break;
+  case lltok::kw_weak_odr:     Res = GlobalValue::WeakODRLinkage; break;
+  case lltok::kw_linkonce:     Res = GlobalValue::LinkOnceAnyLinkage; break;
+  case lltok::kw_linkonce_odr: Res = GlobalValue::LinkOnceODRLinkage; break;
+  case lltok::kw_appending:    Res = GlobalValue::AppendingLinkage; break;
+  case lltok::kw_dllexport:    Res = GlobalValue::DLLExportLinkage; break;
+  case lltok::kw_common:       Res = GlobalValue::CommonAnyLinkage; break;
+  case lltok::kw_common_odr:   Res = GlobalValue::CommonODRLinkage; break;
+  case lltok::kw_dllimport:    Res = GlobalValue::DLLImportLinkage; break;
+  case lltok::kw_extern_weak:  Res = GlobalValue::ExternalWeakAnyLinkage; break;
+  case lltok::kw_extern_weak_odr:
+                               Res = GlobalValue::ExternalWeakODRLinkage; break;
+  case lltok::kw_external:     Res = GlobalValue::ExternalLinkage; break;
   }
   Lex.Lex();
   HasLinkage = true;
@@ -2074,21 +2089,25 @@ bool LLParser::ParseFunctionHeader(Function *&Fn, bool isDefine) {
   case GlobalValue::ExternalLinkage:
     break; // always ok.
   case GlobalValue::DLLImportLinkage:
-  case GlobalValue::ExternalWeakLinkage:
+  case GlobalValue::ExternalWeakAnyLinkage:
+  case GlobalValue::ExternalWeakODRLinkage:
     if (isDefine)
       return Error(LinkageLoc, "invalid linkage for function definition");
     break;
   case GlobalValue::PrivateLinkage:
   case GlobalValue::InternalLinkage:
-  case GlobalValue::LinkOnceLinkage:
-  case GlobalValue::WeakLinkage:
+  case GlobalValue::LinkOnceAnyLinkage:
+  case GlobalValue::LinkOnceODRLinkage:
+  case GlobalValue::WeakAnyLinkage:
+  case GlobalValue::WeakODRLinkage:
   case GlobalValue::DLLExportLinkage:
     if (!isDefine)
       return Error(LinkageLoc, "invalid linkage for function declaration");
     break;
   case GlobalValue::AppendingLinkage:
   case GlobalValue::GhostLinkage:
-  case GlobalValue::CommonLinkage:
+  case GlobalValue::CommonAnyLinkage:
+  case GlobalValue::CommonODRLinkage:
     return Error(LinkageLoc, "invalid function linkage type");
   }
   
diff --git a/lib/AsmParser/LLToken.h b/lib/AsmParser/LLToken.h
index e3bc908b6e..efdc77af81 100644
--- a/lib/AsmParser/LLToken.h
+++ b/lib/AsmParser/LLToken.h
@@ -36,9 +36,10 @@ namespace lltok {
     kw_declare, kw_define,
     kw_global,  kw_constant,
 
-    kw_private, kw_internal, kw_linkonce, kw_weak, kw_appending, kw_dllimport,
-    kw_dllexport, kw_common, kw_default, kw_hidden, kw_protected,
-    kw_extern_weak,
+    kw_private, kw_internal, kw_linkonce, kw_linkonce_odr, kw_weak, kw_weak_odr,
+    kw_appending, kw_dllimport, kw_dllexport, kw_common, kw_common_odr,
+    kw_default, kw_hidden, kw_protected,
+    kw_extern_weak, kw_extern_weak_odr,
     kw_external, kw_thread_local,
     kw_zeroinitializer,
     kw_undef, kw_null,
diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index 2ddfbe3a13..0fe6fc682c 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -59,15 +59,19 @@ static GlobalValue::LinkageTypes GetDecodedLinkage(unsigned Val) {
   switch (Val) {
   default: // Map unknown/new linkages to external
   case 0: return GlobalValue::ExternalLinkage;
-  case 1: return GlobalValue::WeakLinkage;
+  case 1: return GlobalValue::WeakAnyLinkage;
   case 2: return GlobalValue::AppendingLinkage;
   case 3: return GlobalValue::InternalLinkage;
-  case 4: return GlobalValue::LinkOnceLinkage;
+  case 4: return GlobalValue::LinkOnceAnyLinkage;
   case 5: return GlobalValue::DLLImportLinkage;
   case 6: return GlobalValue::DLLExportLinkage;
-  case 7: return GlobalValue::ExternalWeakLinkage;
-  case 8: return GlobalValue::CommonLinkage;
+  case 7: return GlobalValue::ExternalWeakAnyLinkage;
+  case 8: return GlobalValue::CommonAnyLinkage;
   case 9: return GlobalValue::PrivateLinkage;
+  case 10: return GlobalValue::WeakODRLinkage;
+  case 11: return GlobalValue::LinkOnceODRLinkage;
+  case 12: return GlobalValue::ExternalWeakODRLinkage;
+  case 13: return GlobalValue::CommonODRLinkage;
   }
 }
 
diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
index 5633f0ffad..fefffbedb6 100644
--- a/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -276,15 +276,19 @@ static unsigned getEncodedLinkage(const GlobalValue *GV) {
   default: assert(0 && "Invalid linkage!");
   case GlobalValue::GhostLinkage:  // Map ghost linkage onto external.
   case GlobalValue::ExternalLinkage:     return 0;
-  case GlobalValue::WeakLinkage:         return 1;
+  case GlobalValue::WeakAnyLinkage:      return 1;
   case GlobalValue::AppendingLinkage:    return 2;
   case GlobalValue::InternalLinkage:     return 3;
-  case GlobalValue::LinkOnceLinkage:     return 4;
+  case GlobalValue::LinkOnceAnyLinkage:  return 4;
   case GlobalValue::DLLImportLinkage:    return 5;
   case GlobalValue::DLLExportLinkage:    return 6;
-  case GlobalValue::ExternalWeakLinkage: return 7;
-  case GlobalValue::CommonLinkage:       return 8;
+  case GlobalValue::ExternalWeakAnyLinkage: return 7;
+  case GlobalValue::CommonAnyLinkage:    return 8;
   case GlobalValue::PrivateLinkage:      return 9;
+  case GlobalValue::WeakODRLinkage:      return 10;
+  case GlobalValue::LinkOnceODRLinkage:  return 11;
+  case GlobalValue::ExternalWeakODRLinkage: return 12;
+  case GlobalValue::CommonODRLinkage:    return 13;
   }
 }
 
diff --git a/lib/CodeGen/AsmPrinter/DwarfWriter.cpp b/lib/CodeGen/AsmPrinter/DwarfWriter.cpp
index 5c4957aba1..9181216b5a 100644
--- a/lib/CodeGen/AsmPrinter/DwarfWriter.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfWriter.cpp
@@ -3135,9 +3135,8 @@ public:
     GlobalVariable *GV = getGlobalVariable(V);
     if (!GV)
       return false;
-    
-    if (GV->getLinkage() != GlobalValue::InternalLinkage
-        && GV->getLinkage() != GlobalValue::LinkOnceLinkage)
+
+    if (!GV->hasInternalLinkage () && !GV->hasLinkOnceLinkage())
       return false;
 
     DIDescriptor DI(GV);
@@ -3449,8 +3448,10 @@ class DwarfException : public Dwarf  {
     }
 
     // If corresponding function is weak definition, this should be too.
-    if ((linkage == Function::WeakLinkage ||
-         linkage == Function::LinkOnceLinkage) &&
+    if ((linkage == Function::WeakAnyLinkage ||
+         linkage == Function::WeakODRLinkage ||
+         linkage == Function::LinkOnceAnyLinkage ||
+         linkage == Function::LinkOnceODRLinkage) &&
         TAI->getWeakDefDirective())
       O << TAI->getWeakDefDirective() << EHFrameInfo.FnName << "\n";
 
@@ -3461,8 +3462,10 @@ class DwarfException : public Dwarf  {
     // unwind info is to be available for non-EH uses.
     if (!EHFrameInfo.hasCalls &&
         !UnwindTablesMandatory &&
-        ((linkage != Function::WeakLinkage &&
-          linkage != Function::LinkOnceLinkage) ||
+        ((linkage != Function::WeakAnyLinkage &&
+          linkage != Function::WeakODRLinkage &&
+          linkage != Function::LinkOnceAnyLinkage &&
+          linkage != Function::LinkOnceODRLinkage) ||
          !TAI->getWeakDefDirective() ||
          TAI->getSupportsWeakOmittedEHFrame()))
     {
diff --git a/lib/CodeGen/ELFWriter.cpp b/lib/CodeGen/ELFWriter.cpp
index 7cca74b1fb..ddc4e3588b 100644
--- a/lib/CodeGen/ELFWriter.cpp
+++ b/lib/CodeGen/ELFWriter.cpp
@@ -174,8 +174,10 @@ bool ELFCodeEmitter::finishFunction(MachineFunction &F) {
   case GlobalValue::ExternalLinkage:
     FnSym.SetBind(ELFWriter::ELFSym::STB_GLOBAL);
     break;
-  case GlobalValue::LinkOnceLinkage:
-  case GlobalValue::WeakLinkage:
+  case GlobalValue::LinkOnceAnyLinkage:
+  case GlobalValue::LinkOnceODRLinkage:
+  case GlobalValue::WeakAnyLinkage:
+  case GlobalValue::WeakODRLinkage:
     FnSym.SetBind(ELFWriter::ELFSym::STB_WEAK);
     break;
   case GlobalValue::PrivateLinkage:
diff --git a/lib/CodeGen/IntrinsicLowering.cpp b/lib/CodeGen/Intrinsic