Add @hidden UDA

dmd/id.d

@@ -553,6 +553,7 @@ immutable Msgtable[] msgtable =
     { "udaDynamicCompile", "_dynamicCompile" },
     { "udaDynamicCompileConst", "_dynamicCompileConst" },
     { "udaDynamicCompileEmit", "_dynamicCompileEmit" },
+    { "udaHidden", "_hidden" },
 
     // IN_LLVM: DCompute specific types and functionss
     { "dcompute" },

dmd/id.h

@@ -94,6 +94,7 @@ struct Id
     static Identifier *udaDynamicCompile;
     static Identifier *udaDynamicCompileConst;
     static Identifier *udaDynamicCompileEmit;
+    static Identifier *udaHidden;
     static Identifier *io;
 #endif
 };

gen/tollvm.cpp

@@ -274,21 +274,48 @@ void setLinkageAndVisibility(Dsymbol *sym, llvm::GlobalObject *obj) {
   setVisibility(sym, obj);
 }
 
+namespace {
+bool hasExportedLinkage(llvm::GlobalObject *obj) {
+  const auto l = obj->getLinkage();
+  return l == LLGlobalValue::ExternalLinkage ||
+         l == LLGlobalValue::WeakODRLinkage ||
+         l == LLGlobalValue::WeakAnyLinkage;
+}
+}
+
 void setVisibility(Dsymbol *sym, llvm::GlobalObject *obj) {
-  if (global.params.targetTriple->isOSWindows()) {
+  const auto &triple = *global.params.targetTriple;
+
+  const bool hasHiddenUDA = obj->hasHiddenVisibility();
+
+  if (triple.isOSWindows()) {
     bool isExported = sym->isExport();
-    if (!isExported && global.params.dllexport) {
-      const auto l = obj->getLinkage();
-      isExported = l == LLGlobalValue::ExternalLinkage ||
-                   l == LLGlobalValue::WeakODRLinkage ||
-                   l == LLGlobalValue::WeakAnyLinkage;
+    // also export with -fvisibility=public without @hidden
+    if (!isExported && global.params.dllexport && !hasHiddenUDA) {
+      isExported = hasExportedLinkage(obj);
+    }
+    // reset default visibility & DSO locality - on Windows, the DLL storage
+    // classes matter
+    if (hasHiddenUDA) {
+      obj->setVisibility(LLGlobalValue::DefaultVisibility);
+      obj->setDSOLocal(false);
     }
     obj->setDLLStorageClass(isExported ? LLGlobalValue::DLLExportStorageClass
                                        : LLGlobalValue::DefaultStorageClass);
   } else {
-    if (opts::symbolVisibility == opts::SymbolVisibility::hidden &&
-        !sym->isExport()) {
-      obj->setVisibility(LLGlobalValue::HiddenVisibility);
+    if (sym->isExport()) {
+      obj->setVisibility(LLGlobalValue::DefaultVisibility); // overrides @hidden
+    } else if (!hasHiddenUDA) {
+      // Hide with -fvisibility=hidden, or linkonce_odr etc.
+      // The Apple linker warns about hidden linkonce_odr symbols from object
+      // files compiled with -linkonce-templates being folded with *public*
+      // weak_odr symbols from non-linkonce-templates code (e.g., Phobos), so
+      // don't hide instantiated symbols for Mac.
+      if (opts::symbolVisibility == opts::SymbolVisibility::hidden ||
+          (!hasExportedLinkage(obj) &&
+           !(triple.isOSDarwin() && sym->isInstantiated()))) {
+        obj->setVisibility(LLGlobalValue::HiddenVisibility);
+      }
     }
   }
 }

gen/uda.cpp

@@ -376,6 +376,9 @@ void applyVarDeclUDAs(VarDeclaration *decl, llvm::GlobalVariable *gvar) {
     auto ident = sle->sd->ident;
     if (ident == Id::udaSection) {
       applyAttrSection(sle, gvar);
+    } else if (ident == Id::udaHidden) {
+      if (!decl->isExport()) // export visibility is stronger
+        gvar->setVisibility(LLGlobalValue::HiddenVisibility);
     } else if (ident == Id::udaOptStrategy || ident == Id::udaTarget) {
       sle->error(
           "Special attribute `ldc.attributes.%s` is only valid for functions",
@@ -423,6 +426,9 @@ void applyFuncDeclUDAs(FuncDeclaration *decl, IrFunction *irFunc) {
 #else
         func->addAttributes(LLAttributeList::FunctionIndex, attrs);
 #endif
+      } else if (ident == Id::udaHidden) {
+        if (!decl->isExport()) // export visibility is stronger
+          func->setVisibility(LLGlobalValue::HiddenVisibility);
       } else if (ident == Id::udaLLVMFastMathFlag) {
         applyAttrLLVMFastMathFlag(sle, irFunc);
       } else if (ident == Id::udaOptStrategy) {

tests/codegen/fvisibility_posix.d

@@ -0,0 +1,44 @@
+// Non-Windows: test generated IR for -fvisibility / `export` / @hidden combinations.
+
+// UNSUPPORTED: Windows
+
+// RUN: %ldc -fvisibility=public -output-ll -of=%t_public.ll %s
+// RUN: FileCheck %s --check-prefix=PUBLIC --check-prefix=COMMON < %t_public.ll
+
+// RUN: %ldc -fvisibility=hidden -output-ll -of=%t_hidden.ll %s
+// RUN: FileCheck %s --check-prefix=HIDDEN --check-prefix=COMMON < %t_hidden.ll
+
+import ldc.attributes : hidden;
+
+extern(C):
+
+export
+{
+    // COMMON-DAG: @exportedGlobal = global i32
+    __gshared int exportedGlobal;
+    // COMMON-DAG: define void @exportedFunc()
+    void exportedFunc() {}
+}
+
+// PUBLIC-DAG: @global = global i32
+// HIDDEN-DAG: @global = hidden global i32
+__gshared int global;
+// PUBLIC-DAG: define void @func()
+// HIDDEN-DAG: define hidden void @func()
+void func() {}
+
+@hidden
+{
+    // COMMON-DAG: @hiddenGlobal = hidden global i32
+    __gshared int hiddenGlobal;
+    // COMMON-DAG: define hidden void @hiddenFunc()
+    void hiddenFunc() {}
+
+    export
+    {
+        // COMMON-DAG: @exportedHiddenGlobal = global i32
+        __gshared int exportedHiddenGlobal;
+        // COMMON-DAG: define void @exportedHiddenFunc()
+        void exportedHiddenFunc() {}
+    }
+}

tests/codegen/fvisibility_windows.d

@@ -0,0 +1,44 @@
+// Windows: test generated IR for -fvisibility / `export` / @hidden combinations.
+
+// REQUIRES: Windows
+
+// RUN: %ldc -fvisibility=public -output-ll -of=%t_public.ll %s
+// RUN: FileCheck %s --check-prefix=PUBLIC --check-prefix=COMMON < %t_public.ll
+
+// RUN: %ldc -fvisibility=hidden -output-ll -of=%t_hidden.ll %s
+// RUN: FileCheck %s --check-prefix=HIDDEN --check-prefix=COMMON < %t_hidden.ll
+
+import ldc.attributes : hidden;
+
+extern(C):
+
+export
+{
+    // COMMON-DAG: @exportedGlobal = dllexport global i32
+    __gshared int exportedGlobal;
+    // COMMON-DAG: define dllexport void @exportedFunc()
+    void exportedFunc() {}
+}
+
+// PUBLIC-DAG: @global = dllexport global i32
+// HIDDEN-DAG: @global = global i32
+__gshared int global;
+// PUBLIC-DAG: define dllexport void @func()
+// HIDDEN-DAG: define void @func()
+void func() {}
+
+@hidden
+{
+    // COMMON-DAG: @hiddenGlobal = global i32
+    __gshared int hiddenGlobal;
+    // COMMON-DAG: define void @hiddenFunc()
+    void hiddenFunc() {}
+
+    export
+    {
+        // COMMON-DAG: @exportedHiddenGlobal = dllexport global i32
+        __gshared int exportedHiddenGlobal;
+        // COMMON-DAG: define dllexport void @exportedHiddenFunc()
+        void exportedHiddenFunc() {}
+    }
+}

tests/codegen/lambdas_gh3648.d

@@ -26,9 +26,9 @@ void foo()
 }
 
 // the global variables should be defined as linkonce_odr:
-// CHECK: _D14lambdas_gh36489__lambda5FZ10global_bari{{.*}} = linkonce_odr thread_local global
-// CHECK: _D14lambdas_gh36489__lambda6FZ18global_bar_inlinedOi{{.*}} = linkonce_odr global
-// CHECK: _D14lambdas_gh36483fooFZ__T9__lambda1TiZQnFiZ12lambda_templi{{.*}} = linkonce_odr global
+// CHECK: _D14lambdas_gh36489__lambda5FZ10global_bari{{.*}} = linkonce_odr {{(hidden )?}}thread_local global
+// CHECK: _D14lambdas_gh36489__lambda6FZ18global_bar_inlinedOi{{.*}} = linkonce_odr {{(hidden )?}}global
+// CHECK: _D14lambdas_gh36483fooFZ__T9__lambda1TiZQnFiZ12lambda_templi{{.*}} = linkonce_odr {{(hidden )?}}global
 
 // foo() should only call two lambdas:
 // CHECK: define {{.*}}_D14lambdas_gh36483fooFZv

tests/codegen/lambdas_gh3648b.d

@@ -11,8 +11,8 @@ void foo()
 }
 
 // the global variables should be defined as linkonce_odr:
-// CHECK: _D14lambdas_gh36489__lambda5FZ10global_bari{{.*}} = linkonce_odr thread_local global
-// CHECK: _D14lambdas_gh36489__lambda6FZ18global_bar_inlinedOi{{.*}} = linkonce_odr global
+// CHECK: _D14lambdas_gh36489__lambda5FZ10global_bari{{.*}} = linkonce_odr {{(hidden )?}}thread_local global
+// CHECK: _D14lambdas_gh36489__lambda6FZ18global_bar_inlinedOi{{.*}} = linkonce_odr {{(hidden )?}}global
 
 // foo() should only call one lambda:
 // CHECK: define {{.*}}_D15lambdas_gh3648b3fooFZv