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

17 files changed, 46 insertions, 14 deletions

diff --git a/lib/AsmParser/LLLexer.cpp b/lib/AsmParser/LLLexer.cpp
index 9b4370fbb4..3e8414af45 100644
--- a/lib/AsmParser/LLLexer.cpp
+++ b/lib/AsmParser/LLLexer.cpp
@@ -492,6 +492,7 @@ lltok::Kind LLLexer::LexIdentifier() {
 
   KEYWORD(private);
   KEYWORD(linker_private);
+  KEYWORD(linker_weak);
   KEYWORD(internal);
   KEYWORD(available_externally);
   KEYWORD(linkonce);
diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index 1cd66e536e..9a9bd12269 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -198,6 +198,7 @@ bool LLParser::ParseTopLevelEntities() {
     //               OptionalAddrSpace ('constant'|'global') ...
     case lltok::kw_private :       // OptionalLinkage
     case lltok::kw_linker_private: // OptionalLinkage
+    case lltok::kw_linker_weak:    // OptionalLinkage
     case lltok::kw_internal:       // OptionalLinkage
     case lltok::kw_weak:           // OptionalLinkage
     case lltok::kw_weak_odr:       // OptionalLinkage
@@ -629,7 +630,8 @@ bool LLParser::ParseAlias(const std::string &Name, LocTy NameLoc,
       Linkage != GlobalValue::WeakODRLinkage &&
       Linkage != GlobalValue::InternalLinkage &&
       Linkage != GlobalValue::PrivateLinkage &&
-      Linkage != GlobalValue::LinkerPrivateLinkage)
+      Linkage != GlobalValue::LinkerPrivateLinkage &&
+      Linkage != GlobalValue::LinkerWeakLinkage)
     return Error(LinkageLoc, "invalid linkage type for alias");
 
   Constant *Aliasee;
@@ -1013,6 +1015,7 @@ bool LLParser::ParseOptionalAttrs(unsigned &Attrs, unsigned AttrKind) {
 ///   ::= /*empty*/
 ///   ::= 'private'
 ///   ::= 'linker_private'
+///   ::= 'linker_weak'
 ///   ::= 'internal'
 ///   ::= 'weak'
 ///   ::= 'weak_odr'
@@ -1030,6 +1033,7 @@ bool LLParser::ParseOptionalLinkage(unsigned &Res, bool &HasLinkage) {
   default:                       Res=GlobalValue::ExternalLinkage; return false;
   case lltok::kw_private:        Res = GlobalValue::PrivateLinkage;       break;
   case lltok::kw_linker_private: Res = GlobalValue::LinkerPrivateLinkage; break;
+  case lltok::kw_linker_weak:    Res = GlobalValue::LinkerWeakLinkage;    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;
@@ -2704,6 +2708,7 @@ bool LLParser::ParseFunctionHeader(Function *&Fn, bool isDefine) {
     break;
   case GlobalValue::PrivateLinkage:
   case GlobalValue::LinkerPrivateLinkage:
+  case GlobalValue::LinkerWeakLinkage:
   case GlobalValue::InternalLinkage:
   case GlobalValue::AvailableExternallyLinkage:
   case GlobalValue::LinkOnceAnyLinkage:
diff --git a/lib/AsmParser/LLToken.h b/lib/AsmParser/LLToken.h
index 5eed170908..9430f5d43c 100644
--- a/lib/AsmParser/LLToken.h
+++ b/lib/AsmParser/LLToken.h
@@ -37,8 +37,9 @@ namespace lltok {
     kw_declare, kw_define,
     kw_global,  kw_constant,
 
-    kw_private, kw_linker_private, kw_internal, kw_linkonce, kw_linkonce_odr,
-    kw_weak, kw_weak_odr, kw_appending, kw_dllimport, kw_dllexport, kw_common,
+    kw_private, kw_linker_private, kw_linker_weak, kw_internal, kw_linkonce,
+    kw_linkonce_odr, kw_weak, kw_weak_odr, kw_appending, kw_dllimport,
+    kw_dllexport, kw_common,
     kw_available_externally,
     kw_default, kw_hidden, kw_protected,
     kw_extern_weak,
diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index a252da26f1..71efeff4d3 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -75,6 +75,7 @@ static GlobalValue::LinkageTypes GetDecodedLinkage(unsigned Val) {
   case 11: return GlobalValue::LinkOnceODRLinkage;
   case 12: return GlobalValue::AvailableExternallyLinkage;
   case 13: return GlobalValue::LinkerPrivateLinkage;
+  case 14: return GlobalValue::LinkerWeakLinkage;
   }
 }
 
diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
index cdeb854d7d..4655a65e19 100644
--- a/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -313,6 +313,7 @@ static unsigned getEncodedLinkage(const GlobalValue *GV) {
   case GlobalValue::LinkOnceODRLinkage:         return 11;
   case GlobalValue::AvailableExternallyLinkage: return 12;
   case GlobalValue::LinkerPrivateLinkage:       return 13;
+  case GlobalValue::LinkerWeakLinkage:          return 14;
   }
 }
 
diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index ffccd9e2c0..fa9b777cd8 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -199,6 +199,7 @@ void AsmPrinter::EmitLinkage(unsigned Linkage, MCSymbol *GVSym) const {
   case GlobalValue::LinkOnceODRLinkage:
   case GlobalValue::WeakAnyLinkage:
   case GlobalValue::WeakODRLinkage:
+  case GlobalValue::LinkerWeakLinkage:
   case GlobalValue::LinkerPrivateLinkage:
     if (MAI->getWeakDefDirective() != 0) {
       // .globl _foo
@@ -1610,8 +1611,8 @@ MCSymbol *AsmPrinter::GetCPISymbol(unsigned CPID) const {
 }
 
 /// GetJTISymbol - Return the symbol for the specified jump table entry.
-MCSymbol *AsmPrinter::GetJTISymbol(unsigned JTID, bool isLinkerPrivate) const {
-  return MF->getJTISymbol(JTID, OutContext, isLinkerPrivate);
+MCSymbol *AsmPrinter::GetJTISymbol(unsigned JTID, bool PassToLinker) const {
+  return MF->getJTISymbol(JTID, OutContext, PassToLinker);
 }
 
 /// GetJTSetSymbol - Return the symbol for the specified jump table .set
diff --git a/lib/CodeGen/MachineFunction.cpp b/lib/CodeGen/MachineFunction.cpp
index a38c881982..c84c31ec10 100644
--- a/lib/CodeGen/MachineFunction.cpp
+++ b/lib/CodeGen/MachineFunction.cpp
@@ -410,17 +410,18 @@ unsigned MachineFunction::addLiveIn(unsigned PReg,
 }
 
 /// 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 *MachineFunction::getJTISymbol(unsigned JTI, MCContext &Ctx, 
-                                        bool isLinkerPrivate) const {
+/// If isLinkerPrivate or isLinkerWeak is specified, an 'l' label is returned,
+/// otherwise a normal 'L' label is returned.
+MCSymbol *MachineFunction::getJTISymbol(unsigned JTI, MCContext &Ctx,
+                                        bool PassToLinker) const {
   assert(JumpTableInfo && "No jump tables");
   
   assert(JTI < JumpTableInfo->getJumpTables().size() && "Invalid JTI!");
   const MCAsmInfo &MAI = *getTarget().getMCAsmInfo();
   
-  const char *Prefix = isLinkerPrivate ? MAI.getLinkerPrivateGlobalPrefix() :
-                                         MAI.getPrivateGlobalPrefix();
+  const char *Prefix = PassToLinker ?
+    MAI.getLinkerPrivateGlobalPrefix() :
+    MAI.getPrivateGlobalPrefix();
   SmallString<60> Name;
   raw_svector_ostream(Name)
     << Prefix << "JTI" << getFunctionNumber() << '_' << JTI;
diff --git a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 71ad3fb6f9..56420539b7 100644
--- a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -755,11 +755,12 @@ shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
   /// the directive emitted (this occurs in ObjC metadata).
   if (!GV) return false;
 
-  // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
+  // Check whether the mangled name has the "Private", "LinkerPrivate", or
+  // "LinkerWeak" prefix.
   if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
     // FIXME: ObjC metadata is currently emitted as internal symbols that have
-    // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
-    // this horrible hack can go away.
+    // \1L and \1l prefixes on them.  Fix them to be Private / LinkerPrivate /
+    // LinkerWeak and this horrible hack can go away.
     MCSymbol *Sym = Mang->getSymbol(GV);
     if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
       return false;
diff --git a/lib/Linker/LinkModules.cpp b/lib/Linker/LinkModules.cpp
index 8487c83ce3..d741245d77 100644
--- a/lib/Linker/LinkModules.cpp
+++ b/lib/Linker/LinkModules.cpp
@@ -735,6 +735,9 @@ CalculateAliasLinkage(const GlobalValue *SGV, const GlobalValue *DGV) {
   else if (SL == GlobalValue::LinkerPrivateLinkage &&
            DL == GlobalValue::LinkerPrivateLinkage)
     return GlobalValue::LinkerPrivateLinkage;
+  else if (SL == GlobalValue::LinkerWeakLinkage &&
+           DL == GlobalValue::LinkerWeakLinkage)
+    return GlobalValue::LinkerWeakLinkage;
   else {
     assert (SL == GlobalValue::PrivateLinkage &&
             DL == GlobalValue::PrivateLinkage && "Unexpected linkage type");
diff --git a/lib/MC/MCAsmInfo.cpp b/lib/MC/MCAsmInfo.cpp
index a275be2c53..79c09a94b9 100644
--- a/lib/MC/MCAsmInfo.cpp
+++ b/lib/MC/MCAsmInfo.cpp
@@ -31,6 +31,7 @@ MCAsmInfo::MCAsmInfo() {
   GlobalPrefix = "";
   PrivateGlobalPrefix = ".";
   LinkerPrivateGlobalPrefix = "";
+  LinkerWeakGlobalPrefix = "";
   InlineAsmStart = "APP";
   InlineAsmEnd = "NO_APP";
   AssemblerDialect = 0;
diff --git a/lib/MC/MCAsmInfoDarwin.cpp b/lib/MC/MCAsmInfoDarwin.cpp
index 0bd3b2d001..aef4b22067 100644
--- a/lib/MC/MCAsmInfoDarwin.cpp
+++ b/lib/MC/MCAsmInfoDarwin.cpp
@@ -21,6 +21,7 @@ MCAsmInfoDarwin::MCAsmInfoDarwin() {
   GlobalPrefix = "_";
   PrivateGlobalPrefix = "L";
   LinkerPrivateGlobalPrefix = "l";
+  LinkerWeakGlobalPrefix = "l";
   AllowQuotesInName = true;
   HasSingleParameterDotFile = false;
   HasSubsectionsViaSymbols = true;
diff --git a/lib/Target/CppBackend/CPPBackend.cpp b/lib/Target/CppBackend/CPPBackend.cpp
index eda08e7a88..e72763bbf1 100644
--- a/lib/Target/CppBackend/CPPBackend.cpp
+++ b/lib/Target/CppBackend/CPPBackend.cpp
@@ -286,6 +286,8 @@ void CppWriter::printLinkageType(GlobalValue::LinkageTypes LT) {
     Out << "GlobalValue::PrivateLinkage"; break;
   case GlobalValue::LinkerPrivateLinkage:
     Out << "GlobalValue::LinkerPrivateLinkage"; break;
+  case GlobalValue::LinkerWeakLinkage:
+    Out << "GlobalValue::LinkerWeakLinkage"; break;
   case GlobalValue::AvailableExternallyLinkage:
     Out << "GlobalValue::AvailableExternallyLinkage "; break;
   case GlobalValue::LinkOnceAnyLinkage:
diff --git a/lib/Target/Mangler.cpp b/lib/Target/Mangler.cpp
index 4ef017ab92..fc2f78d5b6 100644
--- a/lib/Target/Mangler.cpp
+++ b/lib/Target/Mangler.cpp
@@ -118,6 +118,9 @@ void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
     } else if (PrefixTy == Mangler::LinkerPrivate) {
       const char *Prefix = MAI.getLinkerPrivateGlobalPrefix();
       OutName.append(Prefix, Prefix+strlen(Prefix));
+    } else if (PrefixTy == Mangler::LinkerWeak) {
+      const char *Prefix = MAI.getLinkerWeakGlobalPrefix();
+      OutName.append(Prefix, Prefix+strlen(Prefix));
     }
 
     const char *Prefix = MAI.getGlobalPrefix();
@@ -182,6 +185,8 @@ void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
     PrefixTy = Mangler::Private;
   else if (GV->hasLinkerPrivateLinkage())
     PrefixTy = Mangler::LinkerPrivate;
+  else if (GV->hasLinkerWeakLinkage())
+    PrefixTy = Mangler::LinkerWeak;
   
   // If this global has a name, handle it simply.
   if (GV->hasName()) {
diff --git a/lib/Target/XCore/AsmPrinter/XCoreAsmPrinter.cpp b/lib/Target/XCore/AsmPrinter/XCoreAsmPrinter.cpp
index c100c59013..33a11d09f2 100644
--- a/lib/Target/XCore/AsmPrinter/XCoreAsmPrinter.cpp
+++ b/lib/Target/XCore/AsmPrinter/XCoreAsmPrinter.cpp
@@ -129,6 +129,7 @@ void XCoreAsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
   case GlobalValue::WeakAnyLinkage:
   case GlobalValue::WeakODRLinkage:
   case GlobalValue::ExternalLinkage:
+  case GlobalValue::LinkerWeakLinkage:
     emitArrayBound(GVSym, GV);
     OutStreamer.EmitSymbolAttribute(GVSym, MCSA_Global);
 
diff --git a/lib/Transforms/IPO/MergeFunctions.cpp b/lib/Transforms/IPO/MergeFunctions.cpp
index 622a9b529c..7bb4d9d74f 100644
--- a/lib/Transforms/IPO/MergeFunctions.cpp
+++ b/lib/Transforms/IPO/MergeFunctions.cpp
@@ -535,6 +535,7 @@ static LinkageCategory categorize(const Function *F) {
   case GlobalValue::WeakAnyLinkage:
   case GlobalValue::WeakODRLinkage:
   case GlobalValue::ExternalWeakLinkage:
+  case GlobalValue::LinkerWeakLinkage:
     return ExternalWeak;
 
   case GlobalValue::ExternalLinkage:
diff --git a/lib/VMCore/AsmWriter.cpp b/lib/VMCore/AsmWriter.cpp
index 057ad916c7..8b6aabb53a 100644
--- a/lib/VMCore/AsmWriter.cpp
+++ b/lib/VMCore/AsmWriter.cpp
@@ -1419,6 +1419,7 @@ static void PrintLinkage(GlobalValue::LinkageTypes LT,
   case GlobalValue::ExternalLinkage: break;
   case GlobalValue::PrivateLinkage:       Out << "private ";        break;
   case GlobalValue::LinkerPrivateLinkage: Out << "linker_private "; break;
+  case GlobalValue::LinkerWeakLinkage:    Out << "linker_weak ";    break;
   case GlobalValue::InternalLinkage:      Out << "internal ";       break;
   case GlobalValue::LinkOnceAnyLinkage:   Out << "linkonce ";       break;
   case GlobalValue::LinkOnceODRLinkage:   Out << "linkonce_odr ";   break;
diff --git a/lib/VMCore/Core.cpp b/lib/VMCore/Core.cpp
index 295d14868f..faf62ad6cc 100644
--- a/lib/VMCore/Core.cpp
+++ b/lib/VMCore/Core.cpp
@@ -1058,6 +1058,8 @@ LLVMLinkage LLVMGetLinkage(LLVMValueRef Global) {
     return LLVMPrivateLinkage;
   case GlobalValue::LinkerPrivateLinkage:
     return LLVMLinkerPrivateLinkage;
+  case GlobalValue::LinkerWeakLinkage:
+    return LLVMLinkerWeakLinkage;
   case GlobalValue::DLLImportLinkage:
     return LLVMDLLImportLinkage;
   case GlobalValue::DLLExportLinkage:
@@ -1108,6 +1110,9 @@ void LLVMSetLinkage(LLVMValueRef Global, LLVMLinkage Linkage) {
   case LLVMLinkerPrivateLinkage:
     GV->setLinkage(GlobalValue::LinkerPrivateLinkage);
     break;
+  case LLVMLinkerWeakLinkage:
+    GV->setLinkage(GlobalValue::LinkerWeakLinkage);
+    break;
   case LLVMDLLImportLinkage:
     GV->setLinkage(GlobalValue::DLLImportLinkage);
     break;