[ClassicFlang][Driver] Coexist with LLVM Flang

Make TableGen respect the ENABLE_CLASSIC_FLANG macro and better separate the
driver options that are mutually exclusive. When the macro is defined, do not
build LLVM Flang at all.

Author: bryanpkc

clang/include/clang/Driver/CMakeLists.txt

@@ -1,3 +1,7 @@
 set(LLVM_TARGET_DEFINITIONS Options.td)
-tablegen(LLVM Options.inc -gen-opt-parser-defs)
+if(LLVM_ENABLE_CLASSIC_FLANG)
+  tablegen(LLVM Options.inc -DENABLE_CLASSIC_FLANG -gen-opt-parser-defs)
+else()
+  tablegen(LLVM Options.inc -gen-opt-parser-defs)
+endif()
 add_public_tablegen_target(ClangDriverOptions)

clang/include/clang/Driver/Options.td

@@ -6718,18 +6718,19 @@ def fconvert_EQ : Joined<["-"], "fconvert=">, Group<f_Group>,
   HelpText<"Set endian conversion of data for unformatted files">;
 def fdefault_double_8 : Flag<["-"],"fdefault-double-8">, Group<f_Group>,
   HelpText<"Set the default double precision kind to an 8 byte wide type">;
+def fdefault_integer_8 : Flag<["-"],"fdefault-integer-8">, Group<f_Group>,
+  HelpText<"Set the default integer and logical kind to an 8 byte wide type">;
 #ifdef ENABLE_CLASSIC_FLANG
 def fno_default_integer_8 : Flag<["-"], "fno-default-integer-8">, Group<f_Group>;
 #endif
-def fdefault_integer_8 : Flag<["-"],"fdefault-integer-8">, Group<f_Group>,
-  HelpText<"Set the default integer and logical kind to an 8 byte wide type">;
 def fdefault_real_8 : Flag<["-"],"fdefault-real-8">, Group<f_Group>,
   HelpText<"Set the default real kind to an 8 byte wide type">;
 #ifdef ENABLE_CLASSIC_FLANG
 def fno_default_real_8 : Flag<["-"], "fno-default-real-8">, Group<f_Group>;
 #endif
 def flarge_sizes : Flag<["-"],"flarge-sizes">, Group<f_Group>,
   HelpText<"Use INTEGER(KIND=8) for the result type in size-related intrinsics">;
+
 def falternative_parameter_statement : Flag<["-"], "falternative-parameter-statement">, Group<f_Group>,
   HelpText<"Enable the old style PARAMETER statement">;
 def fintrinsic_modules_path : Separate<["-"], "fintrinsic-modules-path">,  Group<f_Group>, MetaVarName<"<dir>">,
@@ -8861,8 +8862,8 @@ def enable_16bit_types : DXCFlag<"enable-16bit-types">, Alias<fnative_half_type>
            "Available in HLSL 2018 and shader model 6.2.">;
 
 #ifdef ENABLE_CLASSIC_FLANG
-// gfortran options that we recognize in the driver and pass along when
-// invoking GCC to compile Fortran code.
+// Classic Flang options that we recognize in the driver and pass along when
+// invoking flang1/flang2 to compile Fortran code.
 def flang_rt_Group : OptionGroup<"Flang runtime library Group">;
 def pgi_fortran_Group : OptionGroup<"PGI Fortran compatibility Group">,
   Flags<[HelpHidden]>;

clang/include/clang/Driver/ToolChain.h

@@ -676,13 +676,15 @@ class ToolChain {
   AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
                             llvm::opt::ArgStringList &CC1Args) const;
 
+#ifdef ENABLE_CLASSIC_FLANG
   /// \brief Add the flang arguments for system include paths.
   ///
   /// This routine is responsible for adding the -stdinc argument to
   /// include headers and module files from standard system header directories.
   virtual void
   AddFlangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
                             llvm::opt::ArgStringList &Flang1Args) const { }
+#endif
 
   /// Add options that need to be passed to cc1 for this target.
   virtual void addClangTargetOptions(const llvm::opt::ArgList &DriverArgs,
@@ -790,10 +792,12 @@ class ToolChain {
   virtual void AddHIPRuntimeLibArgs(const llvm::opt::ArgList &Args,
                                     llvm::opt::ArgStringList &CmdArgs) const {}
 
+#ifdef ENABLE_CLASSIC_FLANG
   /// AddFortranStdlibLibArgs - Add the system specific linker arguments to use
   /// for the given Fortran runtime library type.
   virtual void AddFortranStdlibLibArgs(const llvm::opt::ArgList &Args,
                                        llvm::opt::ArgStringList &CmdArgs) const;
+#endif
 
   /// Return sanitizers which are available in this toolchain.
   virtual SanitizerMask getSupportedSanitizers() const;

clang/lib/Driver/CMakeLists.txt

@@ -15,7 +15,9 @@ if(WIN32)
 endif()
 
 if(LLVM_ENABLE_CLASSIC_FLANG)
-  set(CLASSIC_FLANG_FILES ToolChains/ClassicFlang.cpp)
+  set(TOOLCHAINS_FLANG_CPP ToolChains/ClassicFlang.cpp)
+else()
+  set(TOOLCHAINS_FLANG_CPP ToolChains/Flang.cpp)
 endif()
 
 add_clang_library(clangDriver
@@ -57,7 +59,7 @@ add_clang_library(clangDriver
   ToolChains/Cuda.cpp
   ToolChains/Darwin.cpp
   ToolChains/DragonFly.cpp
-  ToolChains/Flang.cpp
+  ${TOOLCHAINS_FLANG_CPP}
   ToolChains/FreeBSD.cpp
   ToolChains/Fuchsia.cpp
   ToolChains/Gnu.cpp
@@ -91,7 +93,6 @@ add_clang_library(clangDriver
   ToolChains/ZOS.cpp
   Types.cpp
   XRayArgs.cpp
-  ${CLASSIC_FLANG_FILES}
 
   DEPENDS
   ClangDriverOptions

clang/lib/Driver/ToolChain.cpp

@@ -467,9 +467,13 @@ Tool *ToolChain::getClang() const {
 }
 
 Tool *ToolChain::getFlang() const {
+#ifndef ENABLE_CLASSIC_FLANG
   if (!Flang)
     Flang.reset(new tools::Flang(*this));
   return Flang.get();
+#else
+  llvm_unreachable("Flang is not supported by this toolchain");
+#endif
 }
 
 Tool *ToolChain::buildAssembler() const {
@@ -1332,6 +1336,7 @@ void ToolChain::AddCCKextLibArgs(const ArgList &Args,
   CmdArgs.push_back("-lcc_kext");
 }
 
+#ifdef ENABLE_CLASSIC_FLANG
 void ToolChain::AddFortranStdlibLibArgs(const ArgList &Args,
                                     ArgStringList &CmdArgs) const {
  bool staticFlangLibs = false;
@@ -1370,6 +1375,7 @@ void ToolChain::AddFortranStdlibLibArgs(const ArgList &Args,
   // Allways link Fortran executables with Pthreads
   CmdArgs.push_back("-lpthread");
 }
+#endif
 
 bool ToolChain::isFastMathRuntimeAvailable(const ArgList &Args,
                                            std::string &Path) const {

clang/lib/Driver/ToolChains/ClassicFlang.cpp

@@ -366,18 +366,18 @@ void ClassicFlang::ConstructJob(Compilation &C, const JobAction &JA,
   // Handle -fdefault-real-8 (and its alias, -r8) and -fno-default-real-8
   if (Arg *A = Args.getLastArg(options::OPT_r8,
                                options::OPT_fdefault_real_8,
-                               options::OPT_default_real_8_fno)) {
+                               options::OPT_fno_default_real_8)) {
     const char * fl;
     // For -f version add -x flag, for -fno add -y
-    if (A->getOption().matches(options::OPT_default_real_8_fno)) {
+    if (A->getOption().matches(options::OPT_fno_default_real_8)) {
       fl = "-y";
     } else {
       fl = "-x";
     }
 
     for (Arg *A : Args.filtered(options::OPT_r8,
                                 options::OPT_fdefault_real_8,
-                                options::OPT_default_real_8_fno)) {
+                                options::OPT_fno_default_real_8)) {
       A->claim();
     }
 
@@ -392,18 +392,18 @@ void ClassicFlang::ConstructJob(Compilation &C, const JobAction &JA,
   // Process and claim -i8/-fdefault-integer-8/-fno-default-integer-8 argument
   if (Arg *A = Args.getLastArg(options::OPT_i8,
                                options::OPT_fdefault_integer_8,
-                               options::OPT_default_integer_8_fno)) {
+                               options::OPT_fno_default_integer_8)) {
     const char * fl;
 
-    if (A->getOption().matches(options::OPT_default_integer_8_fno)) {
+    if (A->getOption().matches(options::OPT_fno_default_integer_8)) {
       fl = "-y";
     } else {
       fl = "-x";
     }
 
     for (Arg *A : Args.filtered(options::OPT_i8,
                                 options::OPT_fdefault_integer_8,
-                                options::OPT_default_integer_8_fno)) {
+                                options::OPT_fno_default_integer_8)) {
       A->claim();
     }
 
@@ -730,14 +730,14 @@ void ClassicFlang::ConstructJob(Compilation &C, const JobAction &JA,
         default:
           llvm_unreachable("missed a case");
          case options::OPT_ffixed_form:
-         case options::OPT_free_form_off:
+         case options::OPT_fno_free_form:
          case options::OPT_Mfixed:
          case options::OPT_Mfree_off:
          case options::OPT_Mfreeform_off:
            UpperCmdArgs.push_back("-nofreeform");
            break;
          case options::OPT_ffree_form:
-         case options::OPT_fixed_form_off:
+         case options::OPT_fno_fixed_form:
          case options::OPT_Mfree_on:
          case options::OPT_Mfreeform_on:
            UpperCmdArgs.push_back("-freeform");

clang/lib/Driver/ToolChains/CommonArgs.cpp

@@ -337,6 +337,7 @@ static bool shouldIgnoreUnsupportedTargetFeature(const Arg &TargetFeatureArg,
   return TargetFeatureArg.getOption().matches(options::OPT_mno_cumode);
 }
 
+#ifdef ENABLE_CLASSIC_FLANG
 /// \brief Determine if Fortran "main" object is needed
 static bool needFortranMain(const Driver &D, const ArgList &Args) {
   return (needFortranLibs(D, Args)
@@ -353,6 +354,7 @@ bool tools::needFortranLibs(const Driver &D, const ArgList &Args) {
 
   return false;
 }
+#endif
 
 void tools::addPathIfExists(const Driver &D, const Twine &Path,
                             ToolChain::path_list &Paths) {
@@ -462,7 +464,9 @@ void tools::AddLinkerInputs(const ToolChain &TC, const InputInfoList &Inputs,
                             const ArgList &Args, ArgStringList &CmdArgs,
                             const JobAction &JA) {
   const Driver &D = TC.getDriver();
+#ifdef ENABLE_CLASSIC_FLANG
   bool SeenFirstLinkerInput = false;
+#endif
 
   // Add extra linker input arguments which are not treated as inputs
   // (constructed via -Xarch_).
@@ -496,14 +500,15 @@ void tools::AddLinkerInputs(const ToolChain &TC, const InputInfoList &Inputs,
     if (II.isNothing())
       continue;
 
+#ifdef ENABLE_CLASSIC_FLANG
     // Add Fortan "main" before the first linker input
     if (!SeenFirstLinkerInput) {
       if (needFortranMain(D, Args)) {
         CmdArgs.push_back("-lflangmain");
       }
       SeenFirstLinkerInput = true;
     }
-
+#endif
     // Otherwise, this is a linker input argument.
     const Arg &A = II.getInputArg();
 
@@ -515,7 +520,7 @@ void tools::AddLinkerInputs(const ToolChain &TC, const InputInfoList &Inputs,
     else
       A.renderAsInput(Args, CmdArgs);
   }
-
+#ifdef ENABLE_CLASSIC_FLANG
   if (!SeenFirstLinkerInput && needFortranMain(D, Args)) {
     CmdArgs.push_back("-lflangmain");
   }
@@ -524,6 +529,7 @@ void tools::AddLinkerInputs(const ToolChain &TC, const InputInfoList &Inputs,
   for (auto Arg : Args.filtered(options::OPT_no_fortran_main, options::OPT_Mnomain)) {
     Arg->claim();
   }
+#endif
 }
 
 void tools::addLinkerCompressDebugSectionsOption(

clang/lib/Driver/ToolChains/CommonArgs.h

@@ -24,7 +24,9 @@ namespace clang {
 namespace driver {
 namespace tools {
 
+#ifdef ENABLE_CLASSIC_FLANG
 bool needFortranLibs(const Driver &D, const llvm::opt::ArgList &Args);
+#endif
 
 void addPathIfExists(const Driver &D, const Twine &Path,
                      ToolChain::path_list &Paths);

clang/lib/Driver/ToolChains/Cuda.cpp

@@ -1036,6 +1036,7 @@ VersionTuple CudaToolChain::computeMSVCVersion(const Driver *D,
   return HostTC.computeMSVCVersion(D, Args);
 }
 
+#ifdef ENABLE_CLASSIC_FLANG
 static void AddFlangSysIncludeArg(const ArgList &DriverArgs,
                                   ArgStringList &Flang1Args,
                                   ToolChain::path_list IncludePathList) {
@@ -1068,3 +1069,4 @@ void CudaToolChain::AddFlangSystemIncludeArgs(const llvm::opt::ArgList &DriverAr
   IncludePathList.push_back(P.c_str());
   AddFlangSysIncludeArg(DriverArgs, Flang1Args, IncludePathList);
 }
+#endif

clang/lib/Driver/ToolChains/Cuda.h

@@ -222,6 +222,11 @@ class LLVM_LIBRARY_VISIBILITY CudaToolChain : public NVPTXToolChain {
       llvm::opt::ArgStringList &CC1Args) const override;
   void AddIAMCUIncludeArgs(const llvm::opt::ArgList &DriverArgs,
                            llvm::opt::ArgStringList &CC1Args) const override;
+#ifdef ENABLE_CLASSIC_FLANG
+  void
+  AddFlangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
+                            llvm::opt::ArgStringList &Flang1Args) const override;
+#endif
 
   SanitizerMask getSupportedSanitizers() const override;
 
@@ -231,12 +236,6 @@ class LLVM_LIBRARY_VISIBILITY CudaToolChain : public NVPTXToolChain {
 
   const ToolChain &HostTC;
 
-#ifdef ENABLE_CLASSIC_FLANG
-  void
-  AddFlangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
-                            llvm::opt::ArgStringList &Flang1Args) const override;
-#endif
-
 protected:
   Tool *buildAssembler() const override; // ptxas
   Tool *buildLinker() const override;    // fatbinary (ok, not really a linker)