IRGen: add a constant for common linkages

Swift uses LinkOnceODR with Internal linkage and normal Internal linkage quite
frequently.  Define a constant for this.

Author: compnerd

include/swift/IRGen/Linking.h

@@ -1012,6 +1012,9 @@ struct IRLinkage {
   llvm::GlobalValue::LinkageTypes Linkage;
   llvm::GlobalValue::VisibilityTypes Visibility;
   llvm::GlobalValue::DLLStorageClassTypes DLLStorage;
+
+  static const IRLinkage InternalLinkOnceODR;
+  static const IRLinkage Internal;
 };
 
 class ApplyIRLinkage {

lib/IRGen/GenDecl.cpp

@@ -3914,6 +3914,8 @@ IRGenModule::getAddrOfWitnessTableLazyAccessFunction(
   Signature signature(fnType, llvm::AttributeList(), DefaultCC);
   LinkInfo link = LinkInfo::get(*this, entity, forDefinition);
   entry = createFunction(*this, link, signature);
+  ApplyIRLinkage({link.getLinkage(), link.getVisibility(), link.getDLLStorage()})
+      .to(entry);
   return entry;
 }
 
@@ -4026,10 +4028,7 @@ static llvm::Function *shouldDefineHelper(IRGenModule &IGM,
   if (!def) return nullptr;
   if (!def->empty()) return nullptr;
 
-  ApplyIRLinkage({llvm::GlobalValue::LinkOnceODRLinkage,
-                 llvm::GlobalValue::HiddenVisibility,
-                 llvm::GlobalValue::DefaultStorageClass})
-      .to(def);
+  ApplyIRLinkage(IRLinkage::InternalLinkOnceODR).to(def);
   def->setDoesNotThrow();
   def->setCallingConv(IGM.DefaultCC);
   if (setIsNoInline)

lib/IRGen/GenEnum.cpp

@@ -1473,10 +1473,7 @@ namespace {
     auto func =
         llvm::Function::Create(consumeTy, llvm::GlobalValue::LinkOnceODRLinkage,
                                llvm::StringRef(name), IGM.getModule());
-    ApplyIRLinkage({llvm::GlobalValue::LinkOnceODRLinkage,
-                    llvm::GlobalValue::HiddenVisibility,
-                    llvm::GlobalValue::DefaultStorageClass})
-        .to(func);
+    ApplyIRLinkage(IRLinkage::InternalLinkOnceODR).to(func);
     func->setAttributes(IGM.constructInitialAttributes());
     func->setDoesNotThrow();
     func->setCallingConv(IGM.DefaultCC);

lib/IRGen/GenObjC.cpp

@@ -931,10 +931,7 @@ static llvm::Constant *findSwiftAsObjCThunk(IRGenModule &IGM, SILDeclRef ref,
   SILFn = IGM.getSILModule().lookUpFunction(ref);
   assert(SILFn && "no IR function for swift-as-objc thunk");
   auto fn = IGM.getAddrOfSILFunction(SILFn, NotForDefinition);
-  ApplyIRLinkage({llvm::GlobalValue::InternalLinkage,
-                  llvm::GlobalValue::DefaultVisibility,
-                  llvm::GlobalValue::DefaultStorageClass})
-      .to(fn);
+  ApplyIRLinkage(IRLinkage::Internal).to(fn);
   fn->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
 
   return llvm::ConstantExpr::getBitCast(fn, IGM.Int8PtrTy);

lib/IRGen/GenReflection.cpp

@@ -980,10 +980,7 @@ void IRGenModule::emitReflectionMetadataVersion() {
                                           llvm::GlobalValue::LinkOnceODRLinkage,
                                           Init,
                                           "__swift_reflection_version");
-  ApplyIRLinkage({llvm::GlobalValue::LinkOnceODRLinkage,
-                  llvm::GlobalValue::HiddenVisibility,
-                  llvm::GlobalValue::DefaultStorageClass})
-      .to(Version);
+  ApplyIRLinkage(IRLinkage::InternalLinkOnceODR).to(Version);
   addUsedGlobal(Version);
 }
 

lib/IRGen/Linking.cpp

@@ -31,6 +31,18 @@ using namespace swift;
 using namespace irgen;
 using namespace Mangle;
 
+const IRLinkage IRLinkage::InternalLinkOnceODR = {
+  llvm::GlobalValue::LinkOnceODRLinkage,
+  llvm::GlobalValue::HiddenVisibility,
+  llvm::GlobalValue::DefaultStorageClass,
+};
+
+const IRLinkage IRLinkage::Internal = {
+  llvm::GlobalValue::InternalLinkage,
+  llvm::GlobalValue::DefaultVisibility,
+  llvm::GlobalValue::DefaultStorageClass,
+};
+
 bool swift::irgen::useDllStorage(const llvm::Triple &triple) {
   return triple.isOSBinFormatCOFF() && !triple.isOSCygMing();
 }

lib/IRGen/MetadataRequest.cpp

@@ -317,10 +317,7 @@ llvm::Constant *IRGenModule::getAddrOfStringForTypeRef(
                                       llvm::GlobalValue::LinkOnceODRLinkage,
                                       nullptr,
                                       symbolName);
-  ApplyIRLinkage({llvm::GlobalValue::LinkOnceODRLinkage,
-                  llvm::GlobalValue::HiddenVisibility,
-                  llvm::GlobalValue::DefaultStorageClass})
-      .to(var);
+  ApplyIRLinkage(IRLinkage::InternalLinkOnceODR).to(var);
   var->setAlignment(2);
   setTrueConstGlobal(var);
   var->setSection(getReflectionTypeRefSectionName());