Introducing the "linker_weak" linkage type. This will be used for Objective-C

metadata types which should be marked as "weak", but which the linker will
remove upon final linkage. For example, the "objc_msgSend_fixup_alloc" symbol is
defined like this:

       .globl l_objc_msgSend_fixup_alloc
       .weak_definition l_objc_msgSend_fixup_alloc
       .section __DATA, __objc_msgrefs, coalesced
       .align 3
l_objc_msgSend_fixup_alloc:
        .quad   _objc_msgSend_fixup
        .quad   L_OBJC_METH_VAR_NAME_1

This is different from the "linker_private" linkage type, because it can't have
the metadata defined with ".weak_definition".


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107205 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 24 insertions, 9 deletions

diff --git a/include/llvm-c/Core.h b/include/llvm-c/Core.h
index d665c89377..23b4f83528 100644
--- a/include/llvm-c/Core.h
+++ b/include/llvm-c/Core.h
@@ -226,7 +226,8 @@ typedef enum {
   LLVMExternalWeakLinkage,/**< ExternalWeak linkage description */
   LLVMGhostLinkage,       /**< Obsolete */
   LLVMCommonLinkage,      /**< Tentative definitions */
-  LLVMLinkerPrivateLinkage /**< Like Private, but linker removes. */
+  LLVMLinkerPrivateLinkage, /**< Like private, but linker removes. */
+  LLVMLinkerWeakLinkage   /**< Like linker private, but weak. */
 } LLVMLinkage;
 
 typedef enum {
diff --git a/include/llvm/CodeGen/AsmPrinter.h b/include/llvm/CodeGen/AsmPrinter.h
index 243ddbb5da..32679b5374 100644
--- a/include/llvm/CodeGen/AsmPrinter.h
+++ b/include/llvm/CodeGen/AsmPrinter.h
@@ -285,7 +285,7 @@ namespace llvm {
     MCSymbol *GetCPISymbol(unsigned CPID) const;
 
     /// GetJTISymbol - Return the symbol for the specified jump table entry.
-    MCSymbol *GetJTISymbol(unsigned JTID, bool isLinkerPrivate = false) const;
+    MCSymbol *GetJTISymbol(unsigned JTID, bool PassToLinker = false) const;
 
     /// GetJTSetSymbol - Return the symbol for the specified jump table .set
     /// FIXME: privatize to AsmPrinter.
diff --git a/include/llvm/CodeGen/MachineFunction.h b/include/llvm/CodeGen/MachineFunction.h
index 409d13ee3f..ce8785857e 100644
--- a/include/llvm/CodeGen/MachineFunction.h
+++ b/include/llvm/CodeGen/MachineFunction.h
@@ -402,10 +402,10 @@ public:
   //
   
   /// getJTISymbol - Return the MCSymbol for the specified non-empty jump table.
-  /// If isLinkerPrivate is specified, an 'l' label is returned, otherwise a
-  /// normal 'L' label is returned.
-  MCSymbol *getJTISymbol(unsigned JTI, MCContext &Ctx, 
-                         bool isLinkerPrivate = false) const;
+  /// If PassToLinker is specified, an 'l' label is returned, otherwise a normal
+  /// 'L' label is returned.
+  MCSymbol *getJTISymbol(unsigned JTI, MCContext &Ctx,
+                         bool PassToLinker = false) const;
 };
 
 //===--------------------------------------------------------------------===//
diff --git a/include/llvm/GlobalValue.h b/include/llvm/GlobalValue.h
index 658967d81a..5132d395ef 100644
--- a/include/llvm/GlobalValue.h
+++ b/include/llvm/GlobalValue.h
@@ -39,7 +39,8 @@ public:
     AppendingLinkage,   ///< Special purpose, only applies to global arrays
     InternalLinkage,    ///< Rename collisions when linking (static functions).
     PrivateLinkage,     ///< Like Internal, but omit from symbol table.
-    LinkerPrivateLinkage, ///< Like Private, but linker removes.
+    LinkerPrivateLinkage, ///< Like private, but linker removes.
+    LinkerWeakLinkage,  ///< Like linker private, but weak.
     DLLImportLinkage,   ///< Function to be imported from DLL
     DLLExportLinkage,   ///< Function to be accessible from DLL.
     ExternalWeakLinkage,///< ExternalWeak linkage description.
@@ -132,7 +133,10 @@ public:
     return Linkage == PrivateLinkage;
   }
   static bool isLinkerPrivateLinkage(LinkageTypes Linkage) {
-    return Linkage==LinkerPrivateLinkage;
+    return Linkage == LinkerPrivateLinkage;
+  }
+  static bool isLinkerWeakLinkage(LinkageTypes Linkage) {
+    return Linkage == LinkerWeakLinkage;
   }
   static bool isLocalLinkage(LinkageTypes Linkage) {
     return isInternalLinkage(Linkage) || isPrivateLinkage(Linkage) ||
@@ -187,6 +191,7 @@ public:
   bool hasInternalLinkage() const { return isInternalLinkage(Linkage); }
   bool hasPrivateLinkage() const { return isPrivateLinkage(Linkage); }
   bool hasLinkerPrivateLinkage() const { return isLinkerPrivateLinkage(Linkage); }
+  bool hasLinkerWeakLinkage() const { return isLinkerWeakLinkage(Linkage); }
   bool hasLocalLinkage() const { return isLocalLinkage(Linkage); }
   bool hasDLLImportLinkage() const { return isDLLImportLinkage(Linkage); }
   bool hasDLLExportLinkage() const { return isDLLExportLinkage(Linkage); }
diff --git a/include/llvm/MC/MCAsmInfo.h b/include/llvm/MC/MCAsmInfo.h
index 8516de0188..b76be03fc6 100644
--- a/include/llvm/MC/MCAsmInfo.h
+++ b/include/llvm/MC/MCAsmInfo.h
@@ -85,6 +85,11 @@ namespace llvm {
     /// be passed through the assembler but be removed by the linker.  This
     /// is "l" on Darwin, currently used for some ObjC metadata.
     const char *LinkerPrivateGlobalPrefix;   // Defaults to ""
+
+    /// LinkerWeakGlobalPrefix - This prefix is used for symbols that are marked
+    /// "weak" and should be passed through the assembler, but be removed by the
+    /// linker.  This is "l" on Darwin, currently used for some ObjC metadata.
+    const char *LinkerWeakGlobalPrefix;      // Defaults to ""
     
     /// InlineAsmStart/End - If these are nonempty, they contain a directive to
     /// emit before and after an inline assembly statement.
@@ -335,6 +340,9 @@ namespace llvm {
     const char *getLinkerPrivateGlobalPrefix() const {
       return LinkerPrivateGlobalPrefix;
     }
+    const char *getLinkerWeakGlobalPrefix() const {
+      return LinkerWeakGlobalPrefix;
+    }
     const char *getInlineAsmStart() const {
       return InlineAsmStart;
     }
diff --git a/include/llvm/Target/Mangler.h b/include/llvm/Target/Mangler.h
index a9f3576559..167253e271 100644
--- a/include/llvm/Target/Mangler.h
+++ b/include/llvm/Target/Mangler.h
@@ -32,7 +32,8 @@ public:
   enum ManglerPrefixTy {
     Default,               ///< Emit default string before each symbol.
     Private,               ///< Emit "private" prefix before each symbol.
-    LinkerPrivate          ///< Emit "linker private" prefix before each symbol.
+    LinkerPrivate,         ///< Emit "linker private" prefix before each symbol.
+    LinkerWeak             ///< Emit "linker weak" prefix before each symbol.
   };
 
 private: