[Flang] Rename libFortranRuntime.a to libflang_rt.runtime.a (#122341)

Following the conclusion of the
[RFC](https://discourse.llvm.org/t/rfc-names-for-flang-rt-libraries/84321),
rename Flang's runtime libraries as follows:

 * libFortranRuntime.(a|so) to libflang_rt.runtime.(a|so)
 * libFortranFloat128Math.a to libflang_rt.quadmath.a
* libCufRuntime_cuda_${CUDAToolkit_VERSION_MAJOR}.(a|so) to
libflang_rt.cuda_${CUDAToolkit_VERSION_MAJOR}.(a|so)

This follows the same naming scheme as Compiler-RT libraries
(`libclang_rt.${component}.(a|so)`). It provides some consistency
between Flang's runtime libraries for current and potential future
library components.

Author: Meinersbur

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
+  // Link flang_rt.runtime
   // 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.
@@ -1330,14 +1330,14 @@ void tools::addFortranRuntimeLibs(const ToolChain &TC, const ArgList &Args,
     F128LibName.consume_front_insensitive("lib");
     if (!F128LibName.empty()) {
       bool AsNeeded = !TC.getTriple().isOSAIX();
-      CmdArgs.push_back("-lFortranFloat128Math");
+      CmdArgs.push_back("-lflang_rt.quadmath");
       if (AsNeeded)
         addAsNeededOption(TC, Args, CmdArgs, /*as_needed=*/true);
       CmdArgs.push_back(Args.MakeArgString("-l" + F128LibName));
       if (AsNeeded)
         addAsNeededOption(TC, Args, CmdArgs, /*as_needed=*/false);
     }
-    CmdArgs.push_back("-lFortranRuntime");
+    CmdArgs.push_back("-lflang_rt.runtime");
     addArchSpecificRPath(TC, Args, CmdArgs);
 
     // needs libexecinfo for backtrace functions

clang/lib/Driver/ToolChains/Flang.cpp

@@ -346,11 +346,15 @@ static void processVSRuntimeLibrary(const ToolChain &TC, const ArgList &Args,
                                     ArgStringList &CmdArgs) {
   assert(TC.getTriple().isKnownWindowsMSVCEnvironment() &&
          "can only add VS runtime library on Windows!");
-  // if -fno-fortran-main has been passed, skip linking Fortran_main.a
-  if (TC.getTriple().isKnownWindowsMSVCEnvironment()) {
-    CmdArgs.push_back(Args.MakeArgString(
-        "--dependent-lib=" + TC.getCompilerRTBasename(Args, "builtins")));
-  }
+
+  // Flang/Clang (including clang-cl) -compiled programs targeting the MSVC ABI
+  // should only depend on msv(u)crt. LLVM still emits libgcc/compiler-rt
+  // functions in some cases like 128-bit integer math (__udivti3, __modti3,
+  // __fixsfti, __floattidf, ...) that msvc does not support. We are injecting a
+  // dependency to Compiler-RT's builtin library where these are implemented.
+  CmdArgs.push_back(Args.MakeArgString(
+      "--dependent-lib=" + TC.getCompilerRTBasename(Args, "builtins")));
+
   unsigned RTOptionID = options::OPT__SLASH_MT;
   if (auto *rtl = Args.getLastArg(options::OPT_fms_runtime_lib_EQ)) {
     RTOptionID = llvm::StringSwitch<unsigned>(rtl->getValue())
@@ -364,26 +368,26 @@ static void processVSRuntimeLibrary(const ToolChain &TC, const ArgList &Args,
   case options::OPT__SLASH_MT:
     CmdArgs.push_back("-D_MT");
     CmdArgs.push_back("--dependent-lib=libcmt");
-    CmdArgs.push_back("--dependent-lib=FortranRuntime.static.lib");
+    CmdArgs.push_back("--dependent-lib=flang_rt.runtime.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=flang_rt.runtime.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=flang_rt.runtime.dynamic.lib");
     break;
   case options::OPT__SLASH_MDd:
     CmdArgs.push_back("-D_MT");
     CmdArgs.push_back("-D_DEBUG");
     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=flang_rt.runtime.dynamic_dbg.lib");
     break;
   }
 }

flang/CMakeLists.txt

@@ -301,7 +301,7 @@ set(FLANG_DEFAULT_LINKER "" CACHE STRING
   "Default linker to use (linker name or absolute path, empty for platform default)")
 
 set(FLANG_DEFAULT_RTLIB "" CACHE STRING
-   "Default Fortran runtime library to use (\"libFortranRuntime\"), leave empty for platform default.")
+   "Default Fortran runtime library to use (\"libflang_rt.runtime\"), leave empty for platform default.")
 
 if (NOT(FLANG_DEFAULT_RTLIB STREQUAL ""))
   message(WARNING "Resetting Flang's default runtime library to use platform default.")

flang/cmake/modules/AddFlang.cmake

@@ -57,7 +57,7 @@ function(add_flang_library name)
     set(LIBTYPE SHARED)
   elseif(ARG_STATIC)
     # If BUILD_SHARED_LIBS and ARG_STATIC are both set, llvm_add_library prioritizes STATIC.
-    # This is required behavior for libFortranFloat128Math.
+    # This is required behavior for libflang_rt.quadmath.
     set(LIBTYPE STATIC)
   else()
     # Let llvm_add_library decide, taking BUILD_SHARED_LIBS into account.

flang/docs/FlangDriver.md

@@ -175,18 +175,18 @@ like this:
 
 ```
 $ flang -v -o example example.o
-"/usr/bin/ld" [...] example.o [...] "-lFortranRuntime" [...]
+"/usr/bin/ld" [...] example.o [...] "-lflang_rt.runtime" [...]
 ```
 
 The automatically added libraries are:
 
-* `FortranRuntime`: Provides most of the Flang runtime library.
+* `flang_rt.runtime`: Provides most of the Flang runtime library.
 
 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 library
-`FortranRuntime`.  An alternative is to use Flang to link.
+`flang_rt.runtime`.  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/docs/GettingStarted.md

@@ -216,7 +216,7 @@ cmake \
   -DCMAKE_CUDA_COMPILER=clang \
   -DCMAKE_CUDA_HOST_COMPILER=clang++ \
   ../runtime/
-make -j FortranRuntime
+make -j flang-rt
 ```
 
 Note that the used version of `clang` must [support](https://releases.llvm.org/16.0.0/tools/clang/docs/ReleaseNotes.html#cuda-support)
@@ -239,7 +239,7 @@ cmake \
   -DCMAKE_CUDA_HOST_COMPILER=clang++ \
   ../runtime/
 
-make -j FortranRuntime
+make -j flang-rt
 ```
 
 Note that `nvcc` might limit support to certain
@@ -294,7 +294,7 @@ cmake \
   -DFLANG_OMP_DEVICE_ARCHITECTURES="all" \
   ../runtime/
 
-make -j FortranRuntime
+make -j flang-rt
 ```
 
 The result of the build is a "device-only" library, i.e. the host
@@ -309,7 +309,7 @@ The same set of CMake variables works for Flang in-tree build.
 One may provide optional CMake variables to customize the build. Available options:
 
 * `-DFLANG_RUNTIME_F128_MATH_LIB=libquadmath`: enables build of
-  `FortranFloat128Math` library that provides `REAL(16)` math APIs
+  `flang_rt.quadmath` library that provides `REAL(16)` math APIs
   for intrinsics such as `SIN`, `COS`, etc. GCC `libquadmath`'s header file
   `quadmath.h` must be available to the build compiler.
   [More details](Real16MathSupport.md).

flang/docs/OpenACC-descriptor-management.md

@@ -427,7 +427,7 @@ The implementation's behavior may be described as (OpenACC 2.7.2):
 
 All the "is-present" checks and the data actions for the auxiliary pointers must be performed atomically with regards to the present counters bookkeeping.
 
-The API relies on the primitives provided by `liboffload`, so it is provided by a new F18 runtime library, e.g. `FortranOffloadRuntime`, that depends on `FortranRuntime` and `liboffload`.  The F18 driver adds `FortranOffloadRuntime` for linking under `-fopenacc`/`-fopenmp` (and maybe additional switches like `-fopenmp-targets`).
+The API relies on the primitives provided by `liboffload`, so it is provided by a new F18 runtime library, e.g. `FortranOffloadRuntime`, that depends on `flang_rt.runtime` and `liboffload`.  The F18 driver adds `FortranOffloadRuntime` for linking under `-fopenacc`/`-fopenmp` (and maybe additional switches like `-fopenmp-targets`).
 
 ## TODOs:
 

flang/docs/Real16MathSupport.md

@@ -12,9 +12,9 @@ To support most `REAL(16)` (i.e. 128-bit float) math intrinsics Flang relies
 on third-party libraries providing the implementation.
 
 `-DFLANG_RUNTIME_F128_MATH_LIB=libquadmath` CMake option can be used
-to build `FortranFloat128Math` library that has unresolved references
+to build `libflang_rt.quadmath` library that has unresolved references
 to GCC `libquadmath` library. A Flang driver built with this option
-will automatically link `FortranFloat128Math` and `libquadmath` libraries
+will automatically link `libflang_rt.quadmath` and `libquadmath` libraries
 to any Fortran program. This implies that `libquadmath` library
 has to be available in the standard library paths, so that linker
 can find it. The `libquadmath` library installation into Flang project

flang/docs/ReleaseNotes.md

@@ -36,6 +36,13 @@ page](https://llvm.org/releases/).
 
 ## Build System Changes
 
+ * The FortranRuntime library has been renamed to `flang_rt.runtime`.
+
+ * The FortranFloat128Math library has been renamed to `flang_rt.quadmath`.
+
+ * The CufRuntime_cuda_${version} library has been renamed to
+   `flang_rt.cuda_${version}`.
+
 ## New Issues Found
 
 

flang/examples/ExternalHelloWorld/CMakeLists.txt

@@ -5,5 +5,5 @@ add_llvm_example(external-hello-world
 
 target_link_libraries(external-hello-world
   PRIVATE
-  FortranRuntime
+  flang_rt.runtime
   )