[Build] Set /utf-8 flag specifically for slang targets (#9027)

* Set utf-8 flag specifically for slang targets.
* Enable Slang in UBTI flow

Author: fzi-hielscher

.github/workflows/unifiedBuildTestAndInstall.yml

@@ -208,7 +208,7 @@ jobs:
           ${{ steps.setup-windows.outputs.setup }}
           mkdir build
           cd build
-          cmake -G Ninja -S "$(pwd)/../llvm/llvm" $EXTRA_CMAKE_ARGS -DCMAKE_BUILD_TYPE=${{ inputs.cmake_build_type }} -DBUILD_SHARED_LIBS=${{ inputs.build_shared_libs }} -DLLVM_BUILD_TOOLS=ON -DLLVM_BUILD_EXAMPLES=OFF -DLLVM_ENABLE_ASSERTIONS=${{ inputs.llvm_enable_assertions }} -DLLVM_ENABLE_PROJECTS=mlir -DLLVM_EXTERNAL_PROJECTS=circt -DLLVM_EXTERNAL_CIRCT_SOURCE_DIR=".." -DLLVM_STATIC_LINK_CXX_STDLIB=ON -DLLVM_PARALLEL_LINK_JOBS=1 -DLLVM_TARGETS_TO_BUILD="host" -DLLVM_FORCE_ENABLE_STATS=${{ inputs.llvm_force_enable_stats }} -DLLVM_ENABLE_ZSTD=OFF -DVERILATOR_DISABLE=ON -DCIRCT_RELEASE_TAG_ENABLED=ON -DCIRCT_RELEASE_TAG=firtool -DCMAKE_EXPORT_COMPILE_COMMANDS=OFF -DCMAKE_C_COMPILER=${{ inputs.cmake_c_compiler }} -DCMAKE_CXX_COMPILER=${{ inputs.cmake_cxx_compiler }} ${{ steps.configure-sccache.outputs.enable_sccache }} -DCMAKE_INSTALL_PREFIX="$(pwd)/../install" -DLLVM_INSTALL_UTILS=ON
+          cmake -G Ninja -S "$(pwd)/../llvm/llvm" $EXTRA_CMAKE_ARGS -DCMAKE_BUILD_TYPE=${{ inputs.cmake_build_type }} -DBUILD_SHARED_LIBS=${{ inputs.build_shared_libs }} -DLLVM_BUILD_TOOLS=ON -DLLVM_BUILD_EXAMPLES=OFF -DLLVM_ENABLE_ASSERTIONS=${{ inputs.llvm_enable_assertions }} -DLLVM_ENABLE_PROJECTS=mlir -DLLVM_EXTERNAL_PROJECTS=circt -DLLVM_EXTERNAL_CIRCT_SOURCE_DIR=".." -DLLVM_STATIC_LINK_CXX_STDLIB=ON -DLLVM_PARALLEL_LINK_JOBS=1 -DLLVM_TARGETS_TO_BUILD="host" -DLLVM_FORCE_ENABLE_STATS=${{ inputs.llvm_force_enable_stats }} -DLLVM_ENABLE_ZSTD=OFF -DVERILATOR_DISABLE=ON -DCIRCT_RELEASE_TAG_ENABLED=ON -DCIRCT_RELEASE_TAG=firtool -DCMAKE_EXPORT_COMPILE_COMMANDS=OFF -DCMAKE_C_COMPILER=${{ inputs.cmake_c_compiler }} -DCMAKE_CXX_COMPILER=${{ inputs.cmake_cxx_compiler }} ${{ steps.configure-sccache.outputs.enable_sccache }} -DCMAKE_INSTALL_PREFIX="$(pwd)/../install" -DLLVM_INSTALL_UTILS=ON -DCIRCT_SLANG_FRONTEND_ENABLED=ON
 # Optionally test
       - name: Test CIRCT
         if: inputs.run_tests

.github/workflows/unifiedBuildTestAndInstallStatic.yml

@@ -129,7 +129,7 @@ jobs:
         run: |
           mkdir -p build
           cd build
-          cmake -G Ninja -S "$(pwd)/../llvm/llvm" $EXTRA_CMAKE_ARGS -DCMAKE_BUILD_TYPE=${{ inputs.cmake_build_type }} -DLLVM_BUILD_TOOLS=ON -DLLVM_BUILD_EXAMPLES=OFF -DLLVM_ENABLE_ASSERTIONS=${{ inputs.llvm_enable_assertions }} -DLLVM_ENABLE_PROJECTS=mlir -DLLVM_EXTERNAL_PROJECTS=circt -DLLVM_EXTERNAL_CIRCT_SOURCE_DIR=".." -DLLVM_STATIC_LINK_CXX_STDLIB=ON -DLLVM_BUILD_STATIC=ON -DLLVM_LINK_LLVM_DYLIB=OFF -DLLVM_ENABLE_PIC=OFF -DLLVM_PARALLEL_LINK_JOBS=1 -DLLVM_TARGETS_TO_BUILD="host" -DLLVM_FORCE_ENABLE_STATS=${{ inputs.llvm_force_enable_stats }} -DLLVM_ENABLE_ZSTD=OFF -DVERILATOR_DISABLE=ON -DCIRCT_RELEASE_TAG_ENABLED=ON -DCIRCT_RELEASE_TAG=firtool -DCMAKE_EXPORT_COMPILE_COMMANDS=OFF -DCMAKE_C_COMPILER=clang-19 -DCMAKE_CXX_COMPILER=clang++-19 ${{ steps.configure-sccache.outputs.enable_sccache }} -DCMAKE_INSTALL_PREFIX="$(pwd)/../install" -DLLVM_INSTALL_UTILS=ON -DCMAKE_EXE_LINKER_FLAGS_INIT="-Wl,-z,stack-size=8388608 -Wl,--whole-archive $(pwd)/../build/mimalloc/build/libmimalloc.a -Wl,--no-whole-archive"
+          cmake -G Ninja -S "$(pwd)/../llvm/llvm" $EXTRA_CMAKE_ARGS -DCMAKE_BUILD_TYPE=${{ inputs.cmake_build_type }} -DLLVM_BUILD_TOOLS=ON -DLLVM_BUILD_EXAMPLES=OFF -DLLVM_ENABLE_ASSERTIONS=${{ inputs.llvm_enable_assertions }} -DLLVM_ENABLE_PROJECTS=mlir -DLLVM_EXTERNAL_PROJECTS=circt -DLLVM_EXTERNAL_CIRCT_SOURCE_DIR=".." -DLLVM_STATIC_LINK_CXX_STDLIB=ON -DLLVM_BUILD_STATIC=ON -DLLVM_LINK_LLVM_DYLIB=OFF -DLLVM_ENABLE_PIC=OFF -DLLVM_PARALLEL_LINK_JOBS=1 -DLLVM_TARGETS_TO_BUILD="host" -DLLVM_FORCE_ENABLE_STATS=${{ inputs.llvm_force_enable_stats }} -DLLVM_ENABLE_ZSTD=OFF -DVERILATOR_DISABLE=ON -DCIRCT_RELEASE_TAG_ENABLED=ON -DCIRCT_RELEASE_TAG=firtool -DCMAKE_EXPORT_COMPILE_COMMANDS=OFF -DCMAKE_C_COMPILER=clang-19 -DCMAKE_CXX_COMPILER=clang++-19 ${{ steps.configure-sccache.outputs.enable_sccache }} -DCMAKE_INSTALL_PREFIX="$(pwd)/../install" -DLLVM_INSTALL_UTILS=ON -DCIRCT_SLANG_FRONTEND_ENABLED=ON -DCMAKE_EXE_LINKER_FLAGS_INIT="-Wl,-z,stack-size=8388608 -Wl,--whole-archive $(pwd)/../build/mimalloc/build/libmimalloc.a -Wl,--no-whole-archive"
 # Optionally test
       - name: Test CIRCT
         if: inputs.run_tests

CMakeLists.txt

@@ -38,10 +38,6 @@ if( CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR )
   # MSVC-specific compiler configuration
   if (MSVC)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /EHs-c- /GR-")
-    # Enable UTF-8 support for source files and string literals.  This is
-    # required by dependencies like fmt library.
-    string(APPEND CMAKE_CXX_FLAGS " /utf-8")
-    string(APPEND CMAKE_C_FLAGS " /utf-8")
   else ()
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-exceptions -fno-rtti")
   endif ()

cmake/modules/SlangCompilerOptions.cmake

@@ -16,3 +16,8 @@ if(TARGET Boost::headers)
   add_compile_definitions(
     $<TARGET_PROPERTY:Boost::headers,INTERFACE_COMPILE_DEFINITIONS>)
 endif()
+
+# UTF-8 flag is required for MSVC when including the "fmt" library headers
+# which can get pulled in by the slang headers.
+add_compile_options("$<$<C_COMPILER_ID:MSVC>:/utf-8>")
+add_compile_options("$<$<CXX_COMPILER_ID:MSVC>:/utf-8>")