[Flang] Don't use FortranDecimal for runtime (#121997)

Avoid using the same library for runtime and compiler. `FortranDecimal`
was used in two ways:

1. As an auxiliary library needed for `libFortranRuntime.a`. This patch
adds the two source files of FortranDecimal directly into
FortranRuntime, so `FortranRuntime` is not used anymore.
 
2. As a library used by the Flang compiler. As the only remaining use of
the library, extra CMake code to make it compatible with the runtime can
be removed.

Before this PR, `enable_cuda_compilation` is applied to `FortranDecimal`
which causes everything that links to it, including flang (the
compiler), to depend on libcudart when CUDA support is enabled.

Having two runtime library just makes everything more complicated while
the user ideally should not be concerned with how the runtime is
structured internally. Some logic was copied for FortranDecimal because
of this, such as the ability to be compiled out-of tree
(b75a3c9f31c1ffdc9856aee32991d8129b372ee7) which is undocumented, the
logic to link against the various versions of Microsofts runtime library
(#70833), and avoiding dependency on the C++ runtime
(7783bba22c7add678d796741d30669c73159b3d8).

clang/lib/Driver/ToolChains/CommonArgs.cpp

@@ -1321,7 +1321,7 @@ void tools::addOpenMPHostOffloadingArgs(const Compilation &C,
 /// Add Fortran runtime libs
 void tools::addFortranRuntimeLibs(const ToolChain &TC, const ArgList &Args,
                                   llvm::opt::ArgStringList &CmdArgs) {
-  // Link FortranRuntime and FortranDecimal
+  // Link FortranRuntime
   // These are handled earlier on Windows by telling the frontend driver to
   // add the correct libraries to link against as dependents in the object
   // file.
@@ -1338,7 +1338,6 @@ void tools::addFortranRuntimeLibs(const ToolChain &TC, const ArgList &Args,
         addAsNeededOption(TC, Args, CmdArgs, /*as_needed=*/false);
     }
     CmdArgs.push_back("-lFortranRuntime");
-    CmdArgs.push_back("-lFortranDecimal");
     addArchSpecificRPath(TC, Args, CmdArgs);
 
     // needs libexecinfo for backtrace functions

clang/lib/Driver/ToolChains/Flang.cpp

@@ -365,21 +365,18 @@ static void processVSRuntimeLibrary(const ToolChain &TC, const ArgList &Args,
     CmdArgs.push_back("-D_MT");
     CmdArgs.push_back("--dependent-lib=libcmt");
     CmdArgs.push_back("--dependent-lib=FortranRuntime.static.lib");
-    CmdArgs.push_back("--dependent-lib=FortranDecimal.static.lib");
     break;
   case options::OPT__SLASH_MTd:
     CmdArgs.push_back("-D_MT");
     CmdArgs.push_back("-D_DEBUG");
     CmdArgs.push_back("--dependent-lib=libcmtd");
     CmdArgs.push_back("--dependent-lib=FortranRuntime.static_dbg.lib");
-    CmdArgs.push_back("--dependent-lib=FortranDecimal.static_dbg.lib");
     break;
   case options::OPT__SLASH_MD:
     CmdArgs.push_back("-D_MT");
     CmdArgs.push_back("-D_DLL");
     CmdArgs.push_back("--dependent-lib=msvcrt");
     CmdArgs.push_back("--dependent-lib=FortranRuntime.dynamic.lib");
-    CmdArgs.push_back("--dependent-lib=FortranDecimal.dynamic.lib");
     break;
   case options::OPT__SLASH_MDd:
     CmdArgs.push_back("-D_MT");
@@ -387,7 +384,6 @@ static void processVSRuntimeLibrary(const ToolChain &TC, const ArgList &Args,
     CmdArgs.push_back("-D_DLL");
     CmdArgs.push_back("--dependent-lib=msvcrtd");
     CmdArgs.push_back("--dependent-lib=FortranRuntime.dynamic_dbg.lib");
-    CmdArgs.push_back("--dependent-lib=FortranDecimal.dynamic_dbg.lib");
     break;
   }
 }

flang/docs/FlangDriver.md

@@ -175,19 +175,18 @@ like this:
 
 ```
 $ flang -v -o example example.o
-"/usr/bin/ld" [...] example.o [...] "-lFortranRuntime" "-lFortranDecimal" [...]
+"/usr/bin/ld" [...] example.o [...] "-lFortranRuntime" [...]
 ```
 
 The automatically added libraries are:
 
 * `FortranRuntime`: Provides most of the Flang runtime library.
-* `FortranDecimal`: Provides operations for decimal numbers.
 
 If the code is C/C++ based and invokes Fortran routines, one can either use Clang
 or Flang as the linker driver.  If Clang is used, it will automatically all
 required runtime libraries needed by C++ (e.g., for STL) to the linker invocation.
-In this case, one has to explicitly provide the Fortran runtime libraries
-`FortranRuntime` and/or `FortranDecimal`.  An alternative is to use Flang to link.
+In this case, one has to explicitly provide the Fortran runtime library
+`FortranRuntime`.  An alternative is to use Flang to link.
 In this case, it may be required to explicitly supply C++ runtime libraries.
 
 On Darwin, the logical root where the system libraries are located (sysroot)

flang/lib/Decimal/CMakeLists.txt

@@ -6,89 +6,7 @@
 #
 #===------------------------------------------------------------------------===#
 
-if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
-  cmake_minimum_required(VERSION 3.20.0)
-
-  project(FortranDecimal C CXX)
-
-  set(CMAKE_CXX_STANDARD 17)
-  set(CMAKE_CXX_STANDARD_REQUIRED TRUE)
-  set(CMAKE_CXX_EXTENSIONS OFF)
-
-  set(FLANG_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../..")
-
-  set(LLVM_COMMON_CMAKE_UTILS "${FLANG_SOURCE_DIR}/../cmake")
-  set(LLVM_CMAKE_UTILS "${FLANG_SOURCE_DIR}/../llvm/cmake")
-  set(CLANG_CMAKE_UTILS "${FLANG_SOURCE_DIR}/../clang/cmake")
-
-  # Add path for custom modules
-  list(INSERT CMAKE_MODULE_PATH 0
-    "${FLANG_SOURCE_DIR}/cmake"
-    "${FLANG_SOURCE_DIR}/cmake/modules"
-    "${LLVM_COMMON_CMAKE_UTILS}"
-    "${LLVM_COMMON_CMAKE_UTILS}/Modules"
-    "${LLVM_CMAKE_UTILS}"
-    "${LLVM_CMAKE_UTILS}/modules"
-    "${CLANG_CMAKE_UTILS}/modules"
-    )
-
-  include(AddClang)
-  include(AddLLVM)
-  include(AddFlang)
-  include(HandleLLVMOptions)
-
-  include(TestBigEndian)
-  test_big_endian(IS_BIGENDIAN)
-  if (IS_BIGENDIAN)
-    add_compile_definitions(FLANG_BIG_ENDIAN=1)
-  else ()
-    add_compile_definitions(FLANG_LITTLE_ENDIAN=1)
-  endif ()
-  include_directories(BEFORE
-    ${FLANG_SOURCE_DIR}/include)
-endif()
-
-check_cxx_compiler_flag(-fno-lto FLANG_RUNTIME_HAS_FNO_LTO_FLAG)
-if (FLANG_RUNTIME_HAS_FNO_LTO_FLAG)
-  append("-fno-lto" CMAKE_CXX_FLAGS)
-endif()
-
-# Disable libstdc++ assertions, even in an LLVM_ENABLE_ASSERTIONS build, to
-# avoid an unwanted dependency on libstdc++.so.
-add_definitions(-U_GLIBCXX_ASSERTIONS)
-
-set(sources
+add_flang_library(FortranDecimal
   binary-to-decimal.cpp
   decimal-to-binary.cpp
 )
-
-include(AddFlangOffloadRuntime)
-enable_cuda_compilation(FortranDecimal "${sources}")
-enable_omp_offload_compilation("${sources}")
-
-add_flang_library(FortranDecimal INSTALL_WITH_TOOLCHAIN ${sources})
-
-if (DEFINED MSVC)
-  set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreaded)
-  add_flang_library(FortranDecimal.static INSTALL_WITH_TOOLCHAIN
-          binary-to-decimal.cpp
-          decimal-to-binary.cpp
-  )
-  set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreadedDLL)
-  add_flang_library(FortranDecimal.dynamic INSTALL_WITH_TOOLCHAIN
-    binary-to-decimal.cpp
-    decimal-to-binary.cpp
-  )
-  set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreadedDebug)
-  add_flang_library(FortranDecimal.static_dbg INSTALL_WITH_TOOLCHAIN
-          binary-to-decimal.cpp
-          decimal-to-binary.cpp
-  )
-  set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreadedDebugDLL)
-  add_flang_library(FortranDecimal.dynamic_dbg INSTALL_WITH_TOOLCHAIN
-    binary-to-decimal.cpp
-    decimal-to-binary.cpp
-  )
-  add_dependencies(FortranDecimal FortranDecimal.static FortranDecimal.dynamic
-    FortranDecimal.static_dbg FortranDecimal.dynamic_dbg)
-endif()

flang/runtime/CMakeLists.txt

@@ -59,7 +59,7 @@ if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
     )
 endif()
 
-set(linked_libraries FortranDecimal)
+set(linked_libraries "")
 
 # function checks
 find_package(Backtrace)
@@ -116,6 +116,8 @@ add_definitions(-U_LIBCPP_ENABLE_ASSERTIONS)
 add_subdirectory(Float128Math)
 
 set(sources
+  ${FLANG_SOURCE_DIR}/lib/Decimal/binary-to-decimal.cpp
+  ${FLANG_SOURCE_DIR}/lib/Decimal/decimal-to-binary.cpp
   ISO_Fortran_binding.cpp
   allocator-registry.cpp
   allocatable.cpp
@@ -288,26 +290,18 @@ else()
   )
   set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreaded)
   add_flang_library(FortranRuntime.static ${sources}
-    LINK_LIBS
-    FortranDecimal.static
     INSTALL_WITH_TOOLCHAIN)
   set_target_properties(FortranRuntime.static PROPERTIES FOLDER "Flang/Runtime Libraries")
   set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreadedDLL)
   add_flang_library(FortranRuntime.dynamic ${sources}
-    LINK_LIBS
-    FortranDecimal.dynamic
     INSTALL_WITH_TOOLCHAIN)
   set_target_properties(FortranRuntime.dynamic PROPERTIES FOLDER "Flang/Runtime Libraries")
   set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreadedDebug)
   add_flang_library(FortranRuntime.static_dbg ${sources}
-    LINK_LIBS
-    FortranDecimal.static_dbg
     INSTALL_WITH_TOOLCHAIN)
   set_target_properties(FortranRuntime.static_dbg PROPERTIES FOLDER "Flang/Runtime Libraries")
   set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreadedDebugDLL)
   add_flang_library(FortranRuntime.dynamic_dbg ${sources}
-    LINK_LIBS
-    FortranDecimal.dynamic_dbg
     INSTALL_WITH_TOOLCHAIN)
   set_target_properties(FortranRuntime.dynamic_dbg PROPERTIES FOLDER "Flang/Runtime Libraries")
   add_dependencies(FortranRuntime FortranRuntime.static FortranRuntime.dynamic

flang/test/Driver/linker-flags.f90

@@ -33,7 +33,7 @@
 ! SOLARIS-F128NONE-NOT: FortranFloat128Math
 ! UNIX-F128LIBQUADMATH-SAME: "-lFortranFloat128Math" "--as-needed" "-lquadmath" "--no-as-needed"
 ! SOLARIS-F128LIBQUADMATH-SAME: "-lFortranFloat128Math" "-z" "ignore" "-lquadmath" "-z" "record"
-! UNIX-SAME: "-lFortranRuntime" "-lFortranDecimal" "-lm"
+! UNIX-SAME: "-lFortranRuntime" "-lm"
 ! COMPILER-RT: "{{.*}}{{\\|/}}libclang_rt.builtins.a"
 
 ! BSD-LABEL:  "{{.*}}ld{{(\.exe)?}}"
@@ -41,7 +41,6 @@
 ! BSD-F128NONE-NOT: FortranFloat128Math
 ! BSD-F128LIBQUADMATH-SAME: "-lFortranFloat128Math" "--as-needed" "-lquadmath" "--no-as-needed"
 ! BSD-SAME: -lFortranRuntime
-! BSD-SAME: -lFortranDecimal
 ! BSD-SAME: -lexecinfo
 
 ! DARWIN-LABEL:  "{{.*}}ld{{(\.exe)?}}"
@@ -49,20 +48,18 @@
 ! DARWIN-F128NONE-NOT: FortranFloat128Math
 ! DARWIN-F128LIBQUADMATH-SAME: "-lFortranFloat128Math" "--as-needed" "-lquadmath" "--no-as-needed"
 ! DARWIN-SAME: -lFortranRuntime
-! DARWIN-SAME: -lFortranDecimal
 
 ! HAIKU-LABEL:  "{{.*}}ld{{(\.exe)?}}"
 ! HAIKU-SAME: "[[object_file]]"
 ! HAIKU-F128NONE-NOT: FortranFloat128Math
 ! HAIKU-F128LIBQUADMATH-SAME: "-lFortranFloat128Math" "--as-needed" "-lquadmath" "--no-as-needed"
-! HAIKU-SAME: "-lFortranRuntime" "-lFortranDecimal"
+! HAIKU-SAME: "-lFortranRuntime"
 
 ! MINGW-LABEL:  "{{.*}}ld{{(\.exe)?}}"
 ! MINGW-SAME: "[[object_file]]"
 ! MINGW-F128NONE-NOT: FortranFloat128Math
 ! MINGW-F128LIBQUADMATH-SAME: "-lFortranFloat128Math" "--as-needed" "-lquadmath" "--no-as-needed"
 ! MINGW-SAME: -lFortranRuntime
-! MINGW-SAME: -lFortranDecimal
 
 ! NOTE: This also matches lld-link (when CLANG_DEFAULT_LINKER=lld) and
 !       any .exe suffix that is added when resolving to the full path of

flang/test/Driver/msvc-dependent-lib-flags.f90

@@ -8,7 +8,6 @@
 ! MSVC-SAME: -D_MT
 ! MSVC-SAME: --dependent-lib=libcmt
 ! MSVC-SAME: --dependent-lib=FortranRuntime.static.lib
-! MSVC-SAME: --dependent-lib=FortranDecimal.static.lib
 
 ! MSVC-DEBUG: -fc1
 ! MSVC-DEBUG-SAME: --dependent-lib=clang_rt.builtins.lib
@@ -16,7 +15,6 @@
 ! MSVC-DEBUG-SAME: -D_DEBUG
 ! MSVC-DEBUG-SAME: --dependent-lib=libcmtd
 ! MSVC-DEBUG-SAME: --dependent-lib=FortranRuntime.static_dbg.lib
-! MSVC-DEBUG-SAME: --dependent-lib=FortranDecimal.static_dbg.lib
 
 ! MSVC-DLL: -fc1
 ! MSVC-DLL-SAME: --dependent-lib=clang_rt.builtins.lib
@@ -24,7 +22,6 @@
 ! MSVC-DLL-SAME: -D_DLL
 ! MSVC-DLL-SAME: --dependent-lib=msvcrt
 ! MSVC-DLL-SAME: --dependent-lib=FortranRuntime.dynamic.lib
-! MSVC-DLL-SAME: --dependent-lib=FortranDecimal.dynamic.lib
 
 ! MSVC-DLL-DEBUG: -fc1
 ! MSVC-DLL-DEBUG-SAME: --dependent-lib=clang_rt.builtins.lib
@@ -33,4 +30,3 @@
 ! MSVC-DLL-DEBUG-SAME: -D_DLL
 ! MSVC-DLL-DEBUG-SAME: --dependent-lib=msvcrtd
 ! MSVC-DLL-DEBUG-SAME: --dependent-lib=FortranRuntime.dynamic_dbg.lib
-! MSVC-DLL-DEBUG-SAME: --dependent-lib=FortranDecimal.dynamic_dbg.lib

flang/test/Driver/nostdlib.f90

@@ -25,5 +25,4 @@
 ! platform individually.
 
 ! CHECK-NOT: "-lFortranRuntime"
-! CHECK-NOT: "-lFortranDecimal"
 ! CHECK-NOT: "-lgcc"

flang/test/Runtime/no-cpp-dep.c

@@ -6,7 +6,7 @@ a C compiler.
 REQUIRES: c-compiler
 
 RUN: %if system-aix %{ export OBJECT_MODE=64 %}
-RUN: %cc -std=c99 %s -I%include %libruntime %libdecimal -lm  \
+RUN: %cc -std=c99 %s -I%include %libruntime -lm  \
 RUN: %if system-aix %{-lpthread %}
 RUN: rm a.out
 */

flang/test/lit.cfg.py

@@ -168,12 +168,10 @@ else:
 # we don't have one, we can just disable the test.
 if config.cc:
     libruntime = os.path.join(config.flang_lib_dir, "libFortranRuntime.a")
-    libdecimal = os.path.join(config.flang_lib_dir, "libFortranDecimal.a")
     include = os.path.join(config.flang_src_dir, "include")
 
     if (
         os.path.isfile(libruntime)
-        and os.path.isfile(libdecimal)
         and os.path.isdir(include)
     ):
         config.available_features.add("c-compiler")
@@ -183,7 +181,6 @@ if config.cc:
             )
         )
         tools.append(ToolSubst("%libruntime", command=libruntime, unresolved="fatal"))
-        tools.append(ToolSubst("%libdecimal", command=libdecimal, unresolved="fatal"))
         tools.append(ToolSubst("%include", command=include, unresolved="fatal"))
 
 # Add all the tools and their substitutions (if applicable). Use the search paths provided for

lld/COFF/MinGW.cpp

@@ -50,7 +50,6 @@ AutoExporter::AutoExporter(
       "libc++",
       "libc++abi",
       "libFortranRuntime",
-      "libFortranDecimal",
       "libunwind",
       "libmsvcrt",
       "libucrtbase",