Use stringmap to deduplicate strings by their section name

Author: ellishg

lib/IRGen/GenDecl.cpp

@@ -6052,7 +6052,7 @@ IRGenModule::getAddrOfGlobalString(StringRef data, CStringSectionType type,
   }
 
   // Check whether this string already exists.
-  auto &entry = GlobalStrings[type][data];
+  auto &entry = GlobalStrings[sectionName][data];
 
   if (entry.second) {
     // FIXME: Clear unnamed_addr if the global will be relative referenced

lib/IRGen/IRGenModule.h

@@ -1339,8 +1339,8 @@ class IRGenModule {
   llvm::DenseMap<LinkEntity, llvm::Constant*> GlobalGOTEquivalents;
   llvm::DenseMap<LinkEntity, llvm::Function*> GlobalFuncs;
   llvm::DenseSet<const clang::Decl *> GlobalClangDecls;
-  llvm::DenseMap<
-      CStringSectionType,
+  // Maps sectionName -> string data -> constant
+  llvm::StringMap<
       llvm::StringMap<std::pair<llvm::GlobalVariable *, llvm::Constant *>>>
       GlobalStrings;
   llvm::StringMap<llvm::Constant*> GlobalUTF16Strings;

test/IRGen/objc_extensions.swift

@@ -13,7 +13,7 @@ import objc_extension_base
 // Check that metadata for nested enums added in extensions to imported classes
 // gets emitted concretely.
 
-// CHECK: [[CATEGORY_NAME:@.*]] = private constant [16 x i8] c"objc_extensions\00"
+// CHECK: [[CATEGORY_NAME:@.*]] = private unnamed_addr constant [16 x i8] c"objc_extensions\00"
 // CHECK: [[METHOD_TYPE:@.*]] = private unnamed_addr constant [8 x i8] c"v16@0:8\00"
 
 // CHECK-LABEL: @"_CATEGORY_PROTOCOLS_Gizmo_$_objc_extensions" = internal constant