Use llvm.compiler.used instead of llvm.used for objc symbols.

LLVM currently has a hack (shouldEmitUsedDirectiveFor) that causes it to not
print no_dead_strip for symbols starting with 'l' or 'L'. These are exactly the
ones that the clang's objc codegen is producing. The net result, is that it is
equivalent to llvm.compiler.used.

The need for putting the private symbol in llvm.compiler.used should be clear
(the objc runtime uses them). The reason for also putting the weak symbols in
it is for LTO: ld64 will not ask us to preserve the it.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@203172 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/CGDecl.cpp b/lib/CodeGen/CGDecl.cpp
index 8ce03030b8bea6a81c92880364765de1a3729839..46de0e50b356be657d89881eb26660dff755d2d5 100644 (file)
--- a/lib/CodeGen/CGDecl.cpp
+++ b/lib/CodeGen/CGDecl.cpp
@@ -332,7 +332,7 @@ void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D,
     var->setSection(SA->getName());
 
   if (D.hasAttr<UsedAttr>())
-    CGM.AddUsedGlobal(var);
+    CGM.addUsedGlobal(var);
 
   // We may have to cast the constant because of the initializer
   // mismatch above.

diff --git a/lib/CodeGen/CGObjCMac.cpp b/lib/CodeGen/CGObjCMac.cpp
index 0cb38f27aa09dcf45f2b19e7e6c054243dca629e..bd7c8bf6e723da391a582093dcd664573770e6c8 100644 (file)
--- a/lib/CodeGen/CGObjCMac.cpp
+++ b/lib/CodeGen/CGObjCMac.cpp
@@ -2676,7 +2676,7 @@ llvm::Constant *CGObjCMac::GetOrEmitProtocol(const ObjCProtocolDecl *PD) {
     Protocols[PD->getIdentifier()] = Entry;
   }
   assertPrivateName(Entry);
-  CGM.AddUsedGlobal(Entry);
+  CGM.addCompilerUsedGlobal(Entry);
 
   return Entry;
 }
@@ -3156,7 +3156,7 @@ void CGObjCMac::GenerateClass(const ObjCImplementationDecl *ID) {
     GV->setInitializer(Init);
     GV->setSection(Section);
     GV->setAlignment(4);
-    CGM.AddUsedGlobal(GV);
+    CGM.addCompilerUsedGlobal(GV);
   } else
     GV = CreateMetadataVar(Name, Init, Section, 4, true);
   assertPrivateName(GV);
@@ -3229,7 +3229,7 @@ llvm::Constant *CGObjCMac::EmitMetaClass(const ObjCImplementationDecl *ID,
   assertPrivateName(GV);
   GV->setSection("__OBJC,__meta_class,regular,no_dead_strip");
   GV->setAlignment(4);
-  CGM.AddUsedGlobal(GV);
+  CGM.addCompilerUsedGlobal(GV);
 
   return GV;
 }
@@ -3446,7 +3446,7 @@ CGObjCCommonMac::CreateMetadataVar(Twine Name,
   if (Align)
     GV->setAlignment(Align);
   if (AddToUsed)
-    CGM.AddUsedGlobal(GV);
+    CGM.addCompilerUsedGlobal(GV);
   return GV;
 }
 
@@ -5006,7 +5006,7 @@ void CGObjCMac::FinishModule() {
     assertPrivateName(I->second);
     I->second->setInitializer(llvm::ConstantStruct::get(ObjCTypes.ProtocolTy,
                                                         Values));
-    CGM.AddUsedGlobal(I->second);
+    CGM.addCompilerUsedGlobal(I->second);
   }
 
   // Add assembler directives to add lazy undefined symbol references
@@ -5534,7 +5534,7 @@ AddModuleClassList(ArrayRef<llvm::GlobalValue*> Container,
   assertPrivateName(GV);
   GV->setAlignment(CGM.getDataLayout().getABITypeAlignment(Init->getType()));
   GV->setSection(SectionName);
-  CGM.AddUsedGlobal(GV);
+  CGM.addCompilerUsedGlobal(GV);
 }
 
 void CGObjCNonFragileABIMac::FinishNonFragileABIModule() {
@@ -5960,7 +5960,7 @@ llvm::Value *CGObjCNonFragileABIMac::GenerateProtocolRef(CodeGenFunction &CGF,
     ProtocolName);
   PTGV->setSection("__DATA, __objc_protorefs, coalesced, no_dead_strip");
   PTGV->setVisibility(llvm::GlobalValue::HiddenVisibility);
-  CGM.AddUsedGlobal(PTGV);
+  CGM.addCompilerUsedGlobal(PTGV);
   return CGF.Builder.CreateLoad(PTGV);
 }
 
@@ -6048,7 +6048,7 @@ void CGObjCNonFragileABIMac::GenerateCategory(const ObjCCategoryImplDecl *OCD) {
   GCATV->setAlignment(
     CGM.getDataLayout().getABITypeAlignment(ObjCTypes.CategorynfABITy));
   GCATV->setSection("__DATA, __objc_const");
-  CGM.AddUsedGlobal(GCATV);
+  CGM.addCompilerUsedGlobal(GCATV);
   DefinedCategories.push_back(GCATV);
 
   // Determine if this category is also "non-lazy".
@@ -6108,7 +6108,7 @@ CGObjCNonFragileABIMac::EmitMethodList(Twine Name,
   assertPrivateName(GV);
   GV->setAlignment(CGM.getDataLayout().getABITypeAlignment(Init->getType()));
   GV->setSection(Section);
-  CGM.AddUsedGlobal(GV);
+  CGM.addCompilerUsedGlobal(GV);
   return llvm::ConstantExpr::getBitCast(GV, ObjCTypes.MethodListnfABIPtrTy);
 }
 
@@ -6229,7 +6229,7 @@ llvm::Constant *CGObjCNonFragileABIMac::EmitIvarList(
     CGM.getDataLayout().getABITypeAlignment(Init->getType()));
   GV->setSection("__DATA, __objc_const");
 
-  CGM.AddUsedGlobal(GV);
+  CGM.addCompilerUsedGlobal(GV);
   return llvm::ConstantExpr::getBitCast(GV, ObjCTypes.IvarListnfABIPtrTy);
 }
 
@@ -6372,7 +6372,7 @@ llvm::Constant *CGObjCNonFragileABIMac::GetOrEmitProtocol(
     Protocols[PD->getIdentifier()] = Entry;
   }
   Entry->setVisibility(llvm::GlobalValue::HiddenVisibility);
-  CGM.AddUsedGlobal(Entry);
+  CGM.addCompilerUsedGlobal(Entry);
 
   // Use this protocol meta-data to build protocol list table in section
   // __DATA, __objc_protolist
@@ -6384,7 +6384,7 @@ llvm::Constant *CGObjCNonFragileABIMac::GetOrEmitProtocol(
     CGM.getDataLayout().getABITypeAlignment(ObjCTypes.ProtocolnfABIPtrTy));
   PTGV->setSection("__DATA, __objc_protolist, coalesced, no_dead_strip");
   PTGV->setVisibility(llvm::GlobalValue::HiddenVisibility);
-  CGM.AddUsedGlobal(PTGV);
+  CGM.addCompilerUsedGlobal(PTGV);
   return Entry;
 }
 
@@ -6437,7 +6437,7 @@ CGObjCNonFragileABIMac::EmitProtocolList(Twine Name,
   GV->setSection("__DATA, __objc_const");
   GV->setAlignment(
     CGM.getDataLayout().getABITypeAlignment(Init->getType()));
-  CGM.AddUsedGlobal(GV);
+  CGM.addCompilerUsedGlobal(GV);
   return llvm::ConstantExpr::getBitCast(GV,
                                         ObjCTypes.ProtocolListnfABIPtrTy);
 }
@@ -6683,7 +6683,7 @@ llvm::Value *CGObjCNonFragileABIMac::EmitClassRefFromId(CodeGenFunction &CGF,
                         CGM.getDataLayout().getABITypeAlignment(
                                                                 ObjCTypes.ClassnfABIPtrTy));
     Entry->setSection("__DATA, __objc_classrefs, regular, no_dead_strip");
-    CGM.AddUsedGlobal(Entry);
+    CGM.addCompilerUsedGlobal(Entry);
   }
   assertPrivateName(Entry);
   return CGF.Builder.CreateLoad(Entry);
@@ -6717,7 +6717,7 @@ CGObjCNonFragileABIMac::EmitSuperClassRef(CodeGenFunction &CGF,
       CGM.getDataLayout().getABITypeAlignment(
         ObjCTypes.ClassnfABIPtrTy));
     Entry->setSection("__DATA, __objc_superrefs, regular, no_dead_strip");
-    CGM.AddUsedGlobal(Entry);
+    CGM.addCompilerUsedGlobal(Entry);
   }
   assertPrivateName(Entry);
   return CGF.Builder.CreateLoad(Entry);
@@ -6742,7 +6742,7 @@ llvm::Value *CGObjCNonFragileABIMac::EmitMetaClassRef(CodeGenFunction &CGF,
         CGM.getDataLayout().getABITypeAlignment(ObjCTypes.ClassnfABIPtrTy));
 
     Entry->setSection("__DATA, __objc_superrefs, regular, no_dead_strip");
-    CGM.AddUsedGlobal(Entry);
+    CGM.addCompilerUsedGlobal(Entry);
   }
 
   assertPrivateName(Entry);
@@ -6827,7 +6827,7 @@ llvm::Value *CGObjCNonFragileABIMac::EmitSelector(CodeGenFunction &CGF,
                                Casted, "\01L_OBJC_SELECTOR_REFERENCES_");
     Entry->setExternallyInitialized(true);
     Entry->setSection("__DATA, __objc_selrefs, literal_pointers, no_dead_strip");
-    CGM.AddUsedGlobal(Entry);
+    CGM.addCompilerUsedGlobal(Entry);
   }
   assertPrivateName(Entry);
 

diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index f0265b33f5790149fcb5c9cf220d6709a1c7704b..9b3e32952e1f1405796270dd52258fd186364216 100644 (file)
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -258,7 +258,7 @@ void CodeGenModule::Release() {
   EmitCtorList(GlobalDtors, "llvm.global_dtors");
   EmitGlobalAnnotations();
   EmitStaticExternCAliases();
-  EmitLLVMUsed();
+  emitLLVMUsed();
 
   if (CodeGenOpts.Autolink &&
       (Context.getLangOpts().Modules || !LinkerOptionsMetadata.empty())) {
@@ -699,7 +699,7 @@ void CodeGenModule::SetCommonAttributes(const Decl *D,
     GV->setVisibility(llvm::GlobalValue::DefaultVisibility);
 
   if (D->hasAttr<UsedAttr>())
-    AddUsedGlobal(GV);
+    addUsedGlobal(GV);
 
   if (const SectionAttr *SA = D->getAttr<SectionAttr>())
     GV->setSection(SA->getName());
@@ -776,39 +776,51 @@ void CodeGenModule::SetFunctionAttributes(GlobalDecl GD,
                     llvm::Attribute::NoBuiltin);
 }
 
-void CodeGenModule::AddUsedGlobal(llvm::GlobalValue *GV) {
+void CodeGenModule::addUsedGlobal(llvm::GlobalValue *GV) {
   assert(!GV->isDeclaration() &&
          "Only globals with definition can force usage.");
   LLVMUsed.push_back(GV);
 }
 
-void CodeGenModule::EmitLLVMUsed() {
+void CodeGenModule::addCompilerUsedGlobal(llvm::GlobalValue *GV) {
+  assert(!GV->isDeclaration() &&
+         "Only globals with definition can force usage.");
+  LLVMCompilerUsed.push_back(GV);
+}
+
+static void emitUsed(CodeGenModule &CGM, StringRef Name,
+                     std::vector<llvm::WeakVH> &List) {
   // Don't create llvm.used if there is no need.
-  if (LLVMUsed.empty())
+  if (List.empty())
     return;
 
-  // Convert LLVMUsed to what ConstantArray needs.
+  // Convert List to what ConstantArray needs.
   SmallVector<llvm::Constant*, 8> UsedArray;
-  UsedArray.resize(LLVMUsed.size());
-  for (unsigned i = 0, e = LLVMUsed.size(); i != e; ++i) {
+  UsedArray.resize(List.size());
+  for (unsigned i = 0, e = List.size(); i != e; ++i) {
     UsedArray[i] =
-     llvm::ConstantExpr::getBitCast(cast<llvm::Constant>(&*LLVMUsed[i]),
-                                    Int8PtrTy);
+     llvm::ConstantExpr::getBitCast(cast<llvm::Constant>(&*List[i]),
+                                    CGM.Int8PtrTy);
   }
 
   if (UsedArray.empty())
     return;
-  llvm::ArrayType *ATy = llvm::ArrayType::get(Int8PtrTy, UsedArray.size());
+  llvm::ArrayType *ATy = llvm::ArrayType::get(CGM.Int8PtrTy, UsedArray.size());
 
   llvm::GlobalVariable *GV =
-    new llvm::GlobalVariable(getModule(), ATy, false,
+    new llvm::GlobalVariable(CGM.getModule(), ATy, false,
                              llvm::GlobalValue::AppendingLinkage,
                              llvm::ConstantArray::get(ATy, UsedArray),
-                             "llvm.used");
+                             Name);
 
   GV->setSection("llvm.metadata");
 }
 
+void CodeGenModule::emitLLVMUsed() {
+  emitUsed(*this, "llvm.used", LLVMUsed);
+  emitUsed(*this, "llvm.compiler.used", LLVMCompilerUsed);
+}
+
 void CodeGenModule::AppendLinkerOptions(StringRef Opts) {
   llvm::Value *MDOpts = llvm::MDString::get(getLLVMContext(), Opts);
   LinkerOptionsMetadata.push_back(llvm::MDNode::get(getLLVMContext(), MDOpts));
@@ -3054,7 +3066,7 @@ void CodeGenModule::EmitStaticExternCAliases() {
     IdentifierInfo *Name = I->first;
     llvm::GlobalValue *Val = I->second;
     if (Val && !getModule().getNamedValue(Name->getName()))
-      AddUsedGlobal(new llvm::GlobalAlias(Val->getType(), Val->getLinkage(),
+      addUsedGlobal(new llvm::GlobalAlias(Val->getType(), Val->getLinkage(),
                                           Name->getName(), Val, &getModule()));
   }
 }

diff --git a/lib/CodeGen/CodeGenModule.h b/lib/CodeGen/CodeGenModule.h
index 151cb33d67c088d7a13251376d82afa23fd864bc..11272fc2cae5eb66afefae8bae78010f7324288c 100644 (file)
--- a/lib/CodeGen/CodeGenModule.h
+++ b/lib/CodeGen/CodeGenModule.h
@@ -298,6 +298,7 @@ class CodeGenModule : public CodeGenTypeCache {
   /// forcing visibility of symbols which may otherwise be optimized
   /// out.
   std::vector<llvm::WeakVH> LLVMUsed;
+  std::vector<llvm::WeakVH> LLVMCompilerUsed;
 
   /// GlobalCtors - Store the list of global constructors and their respective
   /// priorities to be emitted when the translation unit is complete.
@@ -799,10 +800,11 @@ public:
   template<typename SomeDecl>
   void MaybeHandleStaticInExternC(const SomeDecl *D, llvm::GlobalValue *GV);
 
-  /// AddUsedGlobal - Add a global which should be forced to be
-  /// present in the object file; these are emitted to the llvm.used
-  /// metadata global.
-  void AddUsedGlobal(llvm::GlobalValue *GV);
+  /// Add a global to a list to be added to the llvm.used metadata.
+  void addUsedGlobal(llvm::GlobalValue *GV);
+
+  /// Add a global to a list to be added to the llvm.compiler.used metadata.
+  void addCompilerUsedGlobal(llvm::GlobalValue *GV);
 
   /// AddCXXDtorEntry - Add a destructor and object to add to the C++ global
   /// destructor function.
@@ -1104,9 +1106,8 @@ private:
   /// still have a use for.
   void EmitDeferredVTables();
 
-  /// EmitLLVMUsed - Emit the llvm.used metadata used to force
-  /// references to global which may otherwise be optimized out.
-  void EmitLLVMUsed();
+  /// Emit the llvm.used and llvm.compiler.used metadata.
+  void emitLLVMUsed();
 
   /// \brief Emit the link options introduced by imported modules.
   void EmitModuleLinkOptions();

diff --git a/test/CodeGenObjC/forward-protocol-metadata-symbols.m b/test/CodeGenObjC/forward-protocol-metadata-symbols.m
index c71cecbf5b6c95d739a95766efcc57354036e5d7..2b687d19f907e3c8b82655200cfcef225085f5b6 100644 (file)
--- a/test/CodeGenObjC/forward-protocol-metadata-symbols.m
+++ b/test/CodeGenObjC/forward-protocol-metadata-symbols.m
@@ -23,4 +23,4 @@ int main() {
 // CHECK: @"\01l_OBJC_LABEL_PROTOCOL_$_P0" = weak hidden global
 // CHECK: @"\01l_OBJC_PROTOCOL_REFERENCE_$_P0" = weak hidden global
 
-// CHECK: llvm.used = appending global [10 x i8*] {{[^"]*}}"\01L_OBJC_CLASS_NAME_"{{[^"]*}}"\01L_OBJC_METH_VAR_NAME_"{{[^"]*}}"\01L_OBJC_METH_VAR_TYPE_"{{[^"]*}}"\01l_OBJC_$_CLASS_METHODS_A"{{[^"]*}}"\01l_OBJC_CLASS_PROTOCOLS_$_A"{{[^"]*}}"\01L_OBJC_CLASS_NAME_1"{{[^"]*}}"\01l_OBJC_PROTOCOL_$_P0"{{[^"]*}}"\01l_OBJC_LABEL_PROTOCOL_$_P0"{{[^"]*}}"\01l_OBJC_PROTOCOL_REFERENCE_$_P0"{{[^"]*}}"\01L_OBJC_LABEL_CLASS_$"{{[^"]*}} section "llvm.metadata"
+// CHECK: llvm.compiler.used = appending global [10 x i8*] {{[^"]*}}"\01L_OBJC_CLASS_NAME_"{{[^"]*}}"\01L_OBJC_METH_VAR_NAME_"{{[^"]*}}"\01L_OBJC_METH_VAR_TYPE_"{{[^"]*}}"\01l_OBJC_$_CLASS_METHODS_A"{{[^"]*}}"\01l_OBJC_CLASS_PROTOCOLS_$_A"{{[^"]*}}"\01L_OBJC_CLASS_NAME_1"{{[^"]*}}"\01l_OBJC_PROTOCOL_$_P0"{{[^"]*}}"\01l_OBJC_LABEL_PROTOCOL_$_P0"{{[^"]*}}"\01l_OBJC_PROTOCOL_REFERENCE_$_P0"{{[^"]*}}"\01L_OBJC_LABEL_CLASS_$"{{[^"]*}} section "llvm.metadata"