Driver: Handle /GR- in a compatible way with MSVC

There are slight differences between /GR- and -fno-rtti which made
mapping one to the other inappropriate.

-fno-rtti disables dynamic_cast, typeid, and does not emit RTTI related
information for the v-table.

/GR- does not generate complete object locators and thus will not
reference them in vftables.  However, constructs like dynamic_cast and
typeid are permitted.

This should bring our implementation of RTTI up to semantic parity with
MSVC modulo bugs.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@212138 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/LangOptions.def

@@ -84,6 +84,7 @@ LANGOPT(CXXExceptions     , 1, 0, "C++ exceptions")
 LANGOPT(SjLjExceptions    , 1, 0, "setjmp-longjump exception handling")
 LANGOPT(TraditionalCPP    , 1, 0, "traditional CPP emulation")
 LANGOPT(RTTI              , 1, 1, "run-time type information")
+LANGOPT(RTTIData          , 1, 1, "emit run-time type information data")
 LANGOPT(MSBitfields       , 1, 0, "Microsoft-compatible structure layout")
 LANGOPT(Freestanding, 1, 0, "freestanding implementation")
 LANGOPT(NoBuiltin         , 1, 0, "disable builtin functions")

include/clang/Driver/CC1Options.td

@@ -484,6 +484,8 @@ def fobjc_subscripting_legacy_runtime : Flag<["-"], "fobjc-subscripting-legacy-r
   HelpText<"Allow Objective-C array and dictionary subscripting in legacy runtime">;
 def vtordisp_mode_EQ : Joined<["-"], "vtordisp-mode=">,
   HelpText<"Control vtordisp placement on win32 targets">;
+def fno_rtti_data : Flag<["-"], "fno-rtti-data">,
+  HelpText<"Control emission of RTTI data">;
 
 //===----------------------------------------------------------------------===//
 // Header Search Options

include/clang/Driver/CLCompatOptions.td

@@ -58,8 +58,8 @@ def _SLASH_c : CLFlag<"c">, HelpText<"Compile only">, Alias<c>;
 def _SLASH_D : CLJoinedOrSeparate<"D">, HelpText<"Define macro">,
   MetaVarName<"<macro[=value]>">, Alias<D>;
 def _SLASH_E : CLFlag<"E">, HelpText<"Preprocess to stdout">, Alias<E>;
-def _SLASH_GR : CLFlag<"GR">, HelpText<"Enable RTTI">, Alias<frtti>;
-def _SLASH_GR_ : CLFlag<"GR-">, HelpText<"Disable RTTI">, Alias<fno_rtti>;
+def _SLASH_GR : CLFlag<"GR">, HelpText<"Enable emission of RTTI data">;
+def _SLASH_GR_ : CLFlag<"GR-">, HelpText<"Disable emission of RTTI data">;
 def _SLASH_GF_ : CLFlag<"GF-">, HelpText<"Disable string pooling">,
   Alias<fwritable_strings>;
 def _SLASH_Gy : CLFlag<"Gy">, HelpText<"Put each function in its own section">,

lib/AST/VTableBuilder.cpp

@@ -2579,7 +2579,7 @@ public:
         Overriders(MostDerivedClass, CharUnits(), MostDerivedClass) {
     // Only include the RTTI component if we know that we will provide a
     // definition of the vftable.
-    HasRTTIComponent = Context.getLangOpts().RTTI &&
+    HasRTTIComponent = Context.getLangOpts().RTTIData &&
                        !MostDerivedClass->hasAttr<DLLImportAttr>();
     if (HasRTTIComponent)
       Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass));

lib/Basic/Targets.cpp

@@ -572,7 +572,7 @@ protected:
   void getVisualStudioDefines(const LangOptions &Opts,
                               MacroBuilder &Builder) const {
     if (Opts.CPlusPlus) {
-      if (Opts.RTTI)
+      if (Opts.RTTIData)
         Builder.defineMacro("_CPPRTTI");
 
       if (Opts.Exceptions)

lib/CodeGen/MicrosoftCXXABI.cpp

@@ -1152,7 +1152,7 @@ llvm::GlobalVariable *MicrosoftCXXABI::getAddrOfVTable(const CXXRecordDecl *RD,
         llvm::GlobalValue::ExternalLinkage;
     llvm::ArrayType *VTableType =
         llvm::ArrayType::get(CGM.Int8PtrTy, NumVTableSlots);
-    if (getContext().getLangOpts().RTTI) {
+    if (getContext().getLangOpts().RTTIData) {
       VTableLinkage = llvm::GlobalValue::PrivateLinkage;
       VTableName = "";
     }
@@ -1163,7 +1163,8 @@ llvm::GlobalVariable *MicrosoftCXXABI::getAddrOfVTable(const CXXRecordDecl *RD,
           CGM.getModule(), VTableType, /*isConstant=*/true, VTableLinkage,
           /*Initializer=*/nullptr, VTableName);
       VTable->setUnnamedAddr(true);
-      if (getContext().getLangOpts().RTTI && !RD->hasAttr<DLLImportAttr>()) {
+      if (getContext().getLangOpts().RTTIData &&
+          !RD->hasAttr<DLLImportAttr>()) {
         llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.IntTy, 0),
                                      llvm::ConstantInt::get(CGM.IntTy, 1)};
         llvm::Constant *VTableGEP =

lib/CodeGen/MicrosoftRTTI.cpp

@@ -508,7 +508,7 @@ llvm::Constant *CodeGenModule::getMSTypeDescriptor(QualType Type) {
 llvm::Constant *
 CodeGenModule::getMSCompleteObjectLocator(const CXXRecordDecl *RD,
                                           const VPtrInfo *Info) {
-  if (!getLangOpts().RTTI)
+  if (!getLangOpts().RTTIData)
     return llvm::Constant::getNullValue(Int8PtrTy);
   return MSRTTIBuilder(*this, RD).getCompleteObjectLocator(Info);
 }

lib/Driver/Tools.cpp

@@ -4193,15 +4193,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
       (InputType == types::TY_C || InputType == types::TY_CXX)) {
     Command *CLCommand = getCLFallback()->GetCommand(C, JA, Output, Inputs,
                                                      Args, LinkingOutput);
-    // RTTI support in clang-cl is a work in progress.  Fall back to MSVC early
-    // if we are using 'clang-cl /fallback /GR'.
-    // FIXME: Remove this when RTTI is finished.
-    if (Args.hasFlag(options::OPT_frtti, options::OPT_fno_rtti, false)) {
-      D.Diag(diag::warn_drv_rtti_fallback) << CLCommand->getExecutable();
-      C.addCommand(CLCommand);
-    } else {
-      C.addCommand(new FallbackCommand(JA, *this, Exec, CmdArgs, CLCommand));
-    }
+    C.addCommand(new FallbackCommand(JA, *this, Exec, CmdArgs, CLCommand));
   } else {
     C.addCommand(new Command(JA, *this, Exec, CmdArgs));
   }
@@ -4446,9 +4438,10 @@ void Clang::AddClangCLArgs(const ArgList &Args, ArgStringList &CmdArgs) const {
   if (Arg *A = Args.getLastArg(options::OPT_show_includes))
     A->render(Args, CmdArgs);
 
-  // RTTI is currently not supported, so disable it by default.
-  if (!Args.hasArg(options::OPT_frtti, options::OPT_fno_rtti))
-    CmdArgs.push_back("-fno-rtti");
+  // This controls whether or not we emit RTTI data for polymorphic types.
+  if (Args.hasFlag(options::OPT__SLASH_GR_, options::OPT__SLASH_GR,
+                   /*default=*/false))
+    CmdArgs.push_back("-fno-rtti-data");
 
   const Driver &D = getToolChain().getDriver();
   EHFlags EH = parseClangCLEHFlags(D, Args);
@@ -7709,9 +7702,9 @@ Command *visualstudio::Compile::GetCommand(Compilation &C, const JobAction &JA,
   // Flags for which clang-cl have an alias.
   // FIXME: How can we ensure this stays in sync with relevant clang-cl options?
 
-  if (Arg *A = Args.getLastArg(options::OPT_frtti, options::OPT_fno_rtti))
-    CmdArgs.push_back(A->getOption().getID() == options::OPT_frtti ? "/GR"
-                                                                   : "/GR-");
+  if (Args.hasFlag(options::OPT__SLASH_GR_, options::OPT__SLASH_GR,
+                   /*default=*/false))
+    CmdArgs.push_back("/GR-");
   if (Arg *A = Args.getLastArg(options::OPT_ffunction_sections,
                                options::OPT_fno_function_sections))
     CmdArgs.push_back(A->getOption().getID() == options::OPT_ffunction_sections

lib/Frontend/CompilerInvocation.cpp

@@ -1447,6 +1447,7 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
   Opts.TraditionalCPP = Args.hasArg(OPT_traditional_cpp);
 
   Opts.RTTI = !Args.hasArg(OPT_fno_rtti);
+  Opts.RTTIData = Opts.RTTI && !Args.hasArg(OPT_fno_rtti_data);
   Opts.Blocks = Args.hasArg(OPT_fblocks);
   Opts.BlocksRuntimeOptional = Args.hasArg(OPT_fblocks_runtime_optional);
   Opts.Modules = Args.hasArg(OPT_fmodules);

test/CodeGenCXX/microsoft-no-rtti-data.cpp

@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 %s -fno-rtti-data -triple=i386-pc-win32 -o - -emit-llvm | FileCheck %s
+
+// vftable shouldn't have RTTI data in it.
+// CHECK: @"\01??_7S@@6B@" = linkonce_odr unnamed_addr constant [1 x i8*] [i8* bitcast ({{.*}} @"\01??_GS@@UAEPAXI@Z" to i8*)]
+
+struct type_info;
+namespace std { using ::type_info; }
+
+struct S {
+  virtual ~S();
+} s;
+
+struct U : S {
+  virtual ~U();
+};
+
+extern S *getS();
+
+const std::type_info &ti = typeid(*getS());
+const U &u = dynamic_cast<U &>(*getS());
+// CHECK: call i8* @__RTDynamicCast(i8* %0, i32 0, i8* bitcast ({{.*}} @"\01??_R0?AUS@@@8" to i8*), i8* bitcast ({{.*}} @"\01??_R0?AUU@@@8" to i8*), i32 1)

test/Driver/cl-fallback.c

@@ -31,6 +31,10 @@
 // CHECK: "/Tc" "{{.*cl-fallback.c}}"
 // CHECK: "/Fo{{.*cl-fallback.*.obj}}"
 
+// RUN: %clang_cl /fallback /GR- -### -- %s 2>&1 | FileCheck -check-prefix=GR %s
+// GR: cl.exe
+// GR: "/GR-"
+
 // RUN: %clang_cl /fallback /Od -### -- %s 2>&1 | FileCheck -check-prefix=O0 %s
 // O0: cl.exe
 // O0: "/Od"
@@ -56,15 +60,12 @@
 // RUN:     FileCheck -check-prefix=ErrWarn %s
 // ErrWarn: warning: falling back to {{.*}}cl.exe
 
-// Don't attempt to run clang -cc1 with /fallback and /GR.  It isn't ready yet.
-// RUN: %clang_cl /fallback /c /GR -### -- %s 2>&1 | \
-// RUN:     FileCheck -check-prefix=RTTI %s
-// RTTI: warning: cannot compile RTTI yet, falling back to {{.*}}cl.exe
 // RUN: %clang_cl /fallback /c /GR /GR- -### -- %s 2>&1 | \
 // RUN:     FileCheck -check-prefix=NO_RTTI %s
 // NO_RTTI: "-cc1"
 // NO_RTTI: ||
 // NO_RTTI: cl.exe
+// NO_RTTI: "/GR-"
 
 // Don't fall back on non-C or C++ files.
 // RUN: %clang_cl /fallback -### -- %S/Inputs/file.ll 2>&1 | FileCheck -check-prefix=LL %s

test/Driver/cl-options.c

@@ -289,10 +289,12 @@
 // RUN: %clang_cl /Zs /WX -m32 -m64 -### -- 2>&1 %s | FileCheck -check-prefix=MFLAGS %s
 // MFLAGS-NOT: argument unused during compilation
 
-// Use -fno-rtti by default.
-// RUN: %clang_cl /c -### -- %s 2>&1 | FileCheck -check-prefix=NoRTTI %s
-// NoRTTI: "-fno-rtti"
+// RTTI is on by default. /GR- controls -fno-rtti-data.
+// RUN: %clang_cl /c /GR- -### -- %s 2>&1 | FileCheck -check-prefix=NoRTTI %s
+// NoRTTI: "-fno-rtti-data"
+// NoRTTI-NOT: "-fno-rtti"
 // RUN: %clang_cl /c /GR -### -- %s 2>&1 | FileCheck -check-prefix=RTTI %s
+// RTTI-NOT: "-fno-rtti-data"
 // RTTI-NOT: "-fno-rtti"