ldc-developers · kinke · Jun 18, 2021 · Jun 14, 2021 · Jun 14, 2021 · Jun 15, 2021
diff --git a/dmd/globals.d b/dmd/globals.d
@@ -109,6 +109,14 @@ enum FeatureState : byte
     enabled = 1    /// Specified as `-preview=`
 }
 
+version (IN_LLVM)
+enum DLLImport : byte
+{
+    none,
+    defaultLibsOnly, // only symbols from druntime/Phobos
+    all
+}
+
 // Put command line switches in here
 extern (C++) struct Param
 {
@@ -304,8 +312,8 @@ version (IN_LLVM)
     bool linkonceTemplates; // -linkonce-templates
 
     // Windows-specific:
-    bool dllexport; // dllexport ~all defined symbols?
-    bool dllimport; // dllimport data symbols not defined in any root module?
+    bool dllexport;      // dllexport ~all defined symbols?
+    DLLImport dllimport; // dllimport data symbols not defined in any root module?
 } // IN_LLVM
 }
 

diff --git a/dmd/globals.h b/dmd/globals.h
@@ -98,6 +98,15 @@ enum class FeatureState : signed char
     enabled = 1    /// Specified as `-preview=`
 };
 
+#if IN_LLVM
+enum class DLLImport : char
+{
+    none,
+    defaultLibsOnly, // only symbols from druntime/Phobos
+    all
+};
+#endif
+
 // Put command line switches in here
 struct Param
 {
@@ -279,8 +288,8 @@ struct Param
     bool linkonceTemplates; // -linkonce-templates
 
     // Windows-specific:
-    bool dllexport; // dllexport ~all defined symbols?
-    bool dllimport; // dllimport data symbols not defined in any root module?
+    bool dllexport;      // dllexport ~all defined symbols?
+    DLLImport dllimport; // dllimport data symbols not defined in any root module?
 #endif
 };
 

diff --git a/dmd/id.d b/dmd/id.d
@@ -544,6 +544,9 @@ immutable Msgtable[] msgtable =
     { "dcPointer", "Pointer" },
     { "dcReflect", "__dcompute_reflect" },
     { "RTInfoImpl" },
+
+    // IN_LLVM
+    { "io" },
 ];
 
 

diff --git a/dmd/id.h b/dmd/id.h
@@ -44,6 +44,9 @@ struct Id
     static Identifier *dcompute;
     static Identifier *dcPointer;
     static Identifier *object;
+    static Identifier *core;
+    static Identifier *etc;
+    static Identifier *std;
     static Identifier *ensure;
     static Identifier *require;
     static Identifier *xopEquals;
@@ -90,5 +93,6 @@ struct Id
     static Identifier *udaDynamicCompile;
     static Identifier *udaDynamicCompileConst;
     static Identifier *udaDynamicCompileEmit;
+    static Identifier *io;
 #endif
 };
diff --git a/driver/cl_options.cpp b/driver/cl_options.cpp
@@ -71,6 +71,22 @@ cl::opt<SymbolVisibility> symbolVisibility(
                    "Only export symbols marked with 'export'"),
         clEnumValN(SymbolVisibility::public_, "public", "Export all symbols")));
 
+cl::opt<DLLImport, true> dllimport(
+    "dllimport", cl::ZeroOrMore, cl::location(global.params.dllimport),
+    cl::desc("Windows only: which extern(D) global variables to dllimport "
+             "implicitly if not defined in a root module"),
+    cl::values(
+        clEnumValN(DLLImport::none, "none",
+                   "None (default with -link-defaultlib-shared=false)"),
+        clEnumValN(DLLImport::defaultLibsOnly, "defaultLibsOnly",
+                   "Only druntime/Phobos symbols (default with "
+                   "-link-defaultlib-shared and -fvisibility=hidden). May "
+                   "likely need to be coupled with -linkonce-templates to "
+                   "overcome linker errors wrt. instantiated symbols."),
+        clEnumValN(DLLImport::all, "all",
+                   "All (default with -link-defaultlib-shared and "
+                   "-fvisibility=public)")));
+
 static cl::opt<bool, true> verbose("v", cl::desc("Verbose"), cl::ZeroOrMore,
                                    cl::location(global.params.verbose));
 

diff --git a/driver/cl_options.h b/driver/cl_options.h
@@ -85,6 +85,7 @@ extern FloatABI::Type floatABI;
 extern cl::opt<bool> disableLinkerStripDead;
 enum class SymbolVisibility { default_, hidden, public_ };
 extern cl::opt<SymbolVisibility> symbolVisibility;
+extern cl::opt<DLLImport, true> dllimport;
 extern cl::opt<bool> noPLT;
 extern cl::opt<bool> useDIP25;
 

diff --git a/driver/main.cpp b/driver/main.cpp
@@ -1090,10 +1090,15 @@ int cppmain() {
         v == opts::SymbolVisibility::public_ ||
         // default with -shared
         (v == opts::SymbolVisibility::default_ && global.params.dll);
-    global.params.dllimport =
-        v == opts::SymbolVisibility::public_ ||
-        // enforced when linking against shared default libs
-        linkAgainstSharedDefaultLibs();
+    if (opts::dllimport.getNumOccurrences() == 0) {
+      global.params.dllimport =
+          !linkAgainstSharedDefaultLibs() ? DLLImport::none
+          : global.params.dllexport       ? DLLImport::all
+                                          : DLLImport::defaultLibsOnly;
+    }
+  } else {
+    global.params.dllexport = false;
+    global.params.dllimport = DLLImport::none;
   }
 
   // allocate the target abi

diff --git a/gen/llvmhelpers.cpp b/gen/llvmhelpers.cpp
@@ -1670,6 +1670,38 @@ std::string llvmTypeToString(llvm::Type *type) {
   return result;
 }
 
+// Is the specified symbol defined in the druntime/Phobos libs?
+// Note: fuzzy semantics for instantiated symbols, except with
+// -linkonce-templates.
+static bool isDefaultLibSymbol(Dsymbol *sym) {
+  if (defineOnDeclare(sym))
+    return false;
+
+  auto mod = sym->getModule();
+  if (!mod)
+    return false;
+
+  auto md = mod->md;
+  if (!md)
+    return false;
+
+  if (md->packages.length == 0)
+    return md->id == Id::object || md->id == Id::std;
+
+  auto p = md->packages.ptr[0];
+  return p == Id::core || p == Id::etc || p == Id::ldc ||
+         (p == Id::std &&
+          // 3rd-party package: std.io (https://github.com/MartinNowak/io/)
+          !((md->packages.length == 1 && md->id == Id::io) ||
+            (md->packages.length > 1 && md->packages.ptr[1] == Id::io)));
+}
+
+bool dllimportSymbol(Dsymbol *sym) {
+  return sym->isExport() || global.params.dllimport == DLLImport::all ||
+         (global.params.dllimport == DLLImport::defaultLibsOnly &&
+          isDefaultLibSymbol(sym));
+}
+
 llvm::GlobalVariable *declareGlobal(const Loc &loc, llvm::Module &module,
                                     llvm::Type *type,
                                     llvm::StringRef mangledName,

diff --git a/gen/llvmhelpers.h b/gen/llvmhelpers.h
@@ -245,6 +245,9 @@ LLConstant *toConstantArray(LLType *ct, LLArrayType *at, T *str, size_t len,
 
 llvm::Constant *buildStringLiteralConstant(StringExp *se, bool zeroTerm);
 
+/// Indicates whether the specified symbol is a general dllimport candidate.
+bool dllimportSymbol(Dsymbol *sym);
+
 /// Tries to declare an LLVM global. If a variable with the same mangled name
 /// already exists, checks if the types match and returns it instead.
 ///

diff --git a/gen/modules.cpp b/gen/modules.cpp
@@ -190,8 +190,9 @@ LLFunction *build_module_reference_and_ctor(const char *moduleMangle,
   LLConstant *mref = gIR->module.getNamedGlobal(mrefIRMangle);
   LLType *modulerefPtrTy = getPtrToType(modulerefTy);
   if (!mref) {
-    mref = declareGlobal(Loc(), gIR->module, modulerefPtrTy, mrefIRMangle,
-                         false, false, global.params.dllimport);
+    mref =
+        declareGlobal(Loc(), gIR->module, modulerefPtrTy, mrefIRMangle, false,
+                      false, global.params.dllimport != DLLImport::none);
   }
   mref = DtoBitCast(mref, getPtrToType(modulerefPtrTy));
 

diff --git a/gen/optimizer.cpp b/gen/optimizer.cpp
@@ -423,7 +423,7 @@ bool ldc_optimize_module(llvm::Module *M) {
 
   addOptimizationPasses(mpm, fpm, optLevel(), sizeLevel());
 
-  if (global.params.dllimport) {
+  if (global.params.dllimport != DLLImport::none) {
     mpm.add(createDLLImportRelocationPass());
   }
 

diff --git a/gen/typinf.cpp b/gen/typinf.cpp
@@ -439,8 +439,7 @@ void buildTypeInfo(TypeInfoDeclaration *decl) {
     // immutable on the D side, and e.g. synchronized() can be used on the
     // implicit monitor.
     const bool isConstant = false;
-    // TODO: no dllimport when compiling druntime itself
-    const bool useDLLImport = isBuiltin && global.params.dllimport;
+    bool useDLLImport = isBuiltin && global.params.dllimport != DLLImport::none;
     gvar = declareGlobal(decl->loc, gIR->module, type, irMangle, isConstant,
                          false, useDLLImport);
   }

diff --git a/ir/iraggr.cpp b/ir/iraggr.cpp
@@ -56,7 +56,7 @@ bool IrAggr::useDLLImport() const {
   if (!global.params.targetTriple->isOSWindows())
     return false;
 
-  if (global.params.dllimport || aggrdecl->isExport()) {
+  if (dllimportSymbol(aggrdecl)) {
     // dllimport, unless defined in a root module (=> no extra indirection for
     // other root modules, assuming *all* root modules will be linked together
     // to one or more binaries).

diff --git a/ir/irmodule.cpp b/ir/irmodule.cpp
@@ -27,7 +27,7 @@ llvm::GlobalVariable *IrModule::moduleInfoSymbol() {
 
   const auto irMangle = getIRMangledModuleInfoSymbolName(M);
 
-  const bool useDLLImport = global.params.dllimport && !M->isRoot();
+  const bool useDLLImport = !M->isRoot() && dllimportSymbol(M);
 
   moduleInfoVar = declareGlobal(Loc(), gIR->module,
                                 llvm::StructType::create(gIR->context()),

diff --git a/ir/irvar.cpp b/ir/irvar.cpp
@@ -85,9 +85,8 @@ void IrGlobal::declare() {
   if (global.params.targetTriple->isOSWindows()) {
     // dllimport isn't supported for thread-local globals (MSVC++ neither)
     if (!V->isThreadlocal()) {
-      // with -fvisibility=public / -link-defaultlib-shared, also include all
-      // extern(D) globals
-      if (V->isExport() || (global.params.dllimport && V->linkage == LINK::d)) {
+      // implicitly include extern(D) globals with -dllimport
+      if (V->isExport() || (V->linkage == LINK::d && dllimportSymbol(V))) {
         const bool isDefinedInRootModule =
             !(V->storage_class & STCextern) && !V->inNonRoot();
         if (!isDefinedInRootModule)

diff --git a/runtime/CMakeLists.txt b/runtime/CMakeLists.txt
@@ -708,7 +708,7 @@ macro(build_runtime_variant d_flags c_flags ld_flags lib_suffix path_suffix emit
        AND NOT ${all_d_files_at_once})
         set(phobos2_o "")
         set(phobos2_bc "")
-        compile_phobos2("${phobos2_d_flags};-relocation-model=pic;-fvisibility=public"
+        compile_phobos2("${phobos2_d_flags};-relocation-model=pic;-fvisibility=public;-dllimport=all"
                         "${lib_suffix}${SHARED_LIB_SUFFIX}" "${path_suffix}"
                         "${emit_bc}" "${all_d_files_at_once}" "OFF" phobos2_o phobos2_bc)
 
@@ -753,15 +753,15 @@ macro(build_runtime_variant d_flags c_flags ld_flags lib_suffix path_suffix emit
         # compile druntime with public visibility and extra `version (Shared)`
         set(druntime_o "")
         set(druntime_bc "")
-        compile_druntime("${druntime_d_flags};-relocation-model=pic;-fvisibility=public;-d-version=Shared"
+        compile_druntime("${druntime_d_flags};-relocation-model=pic;-fvisibility=public;-dllimport=none;-d-version=Shared"
                          "${lib_suffix}${SHARED_LIB_SUFFIX}" "${path_suffix}"
                          "OFF" "${all_d_files_at_once}" "OFF" druntime_o druntime_bc)
 
         # compile Phobos with public visibility (and preferably to a single object file)
         if(phobos2_common STREQUAL "")
             set(phobos2_o "")
             set(phobos2_bc "")
-            compile_phobos2("${phobos2_d_flags};-relocation-model=pic;-fvisibility=public"
+            compile_phobos2("${phobos2_d_flags};-relocation-model=pic;-fvisibility=public;-dllimport=all"
                             "${lib_suffix}${SHARED_LIB_SUFFIX}" "${path_suffix}"
                             "OFF" "${all_d_files_at_once}" "${all_d_files_at_once}" phobos2_o phobos2_bc)
         endif()

diff --git a/runtime/druntime b/runtime/druntime
diff --git a/runtime/phobos b/runtime/phobos
diff --git a/tests/codegen/fvisibility_dll.d b/tests/codegen/fvisibility_dll.d
@@ -4,11 +4,11 @@
 
 // REQUIRES: Windows
 
-// generate DLL and import lib
+// generate DLL and import lib (public visibility by default)
 // RUN: %ldc %S/inputs/fvisibility_dll_lib.d -betterC -shared -of=%t_lib.dll
 
-// compile, link and run the app; -link-defaultlib-shared for importing data symbols as dllimport
-// RUN: %ldc %s -I%S/inputs -betterC -link-defaultlib-shared %t_lib.lib -of=%t.exe
+// compile, link and run the app; `-dllimport=all` for dllimporting data symbols
+// RUN: %ldc %s -I%S/inputs -betterC -dllimport=all %t_lib.lib -of=%t.exe
 // RUN: %t.exe
 
 import fvisibility_dll_lib;