[ImportVerilog] Update to Slang 4

Bump the Slang dependency to version 4. This version supports builds
with exceptions and RTTI fully disabled, which allows us to get rid of
the ugly glue code that tried to bridge the gap between the RTTI/EH
world of Slang and the non-RTTI/non-EH world of LLVM.

.github/workflows/unifiedBuildTestAndInstall.yml

@@ -177,7 +177,33 @@ 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_ENABLE_TERMINFO=OFF -DLLVM_PARALLEL_LINK_JOBS=1 -DLLVM_TARGETS_TO_BUILD="host" -DLLVM_FORCE_ENABLE_STATS=${{ inputs.llvm_force_enable_stats }} -DLLVM_ENABLE_ZSTD=OFF -DVERILATOR_DISABLE=ON -DLLVM_PARALLEL_LINK_JOBS=1 -DCIRCT_RELEASE_TAG_ENABLED=ON -DCIRCT_RELEASE_TAG=firtool -DCMAKE_EXPORT_COMPILE_COMMANDS=OFF -DCMAKE_C_COMPILER=${{ 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_ENABLE_TERMINFO=OFF \
+            -DLLVM_PARALLEL_LINK_JOBS=1 \
+            -DLLVM_TARGETS_TO_BUILD="host" \
+            -DLLVM_FORCE_ENABLE_STATS=${{ inputs.llvm_force_enable_stats }} \
+            -DLLVM_ENABLE_ZSTD=OFF \
+            -DVERILATOR_DISABLE=ON \
+            -DLLVM_PARALLEL_LINK_JOBS=1 \
+            -DCIRCT_RELEASE_TAG_ENABLED=ON \
+            -DCIRCT_RELEASE_TAG=firtool \
+            -DCMAKE_EXPORT_COMPILE_COMMANDS=OFF \
+            -DCMAKE_C_COMPILER=${{ 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.runTests

CMakeLists.txt

@@ -546,8 +546,8 @@ if(CIRCT_SLANG_FRONTEND_ENABLED)
     include(FetchContent)
     FetchContent_Declare(
       slang
-      URL https://github.com/MikePopoloski/slang/archive/refs/tags/v3.0.tar.gz
-      URL_HASH SHA256=02d184133525f6330a32bef492761b8ff52d0a33caed08eb51733f63cddb08e3
+      URL https://github.com/MikePopoloski/slang/archive/refs/tags/v4.0.tar.gz
+      URL_HASH SHA256=4f58535220e9d2bed9942d60fa2330d9e4efb14b5c02bedaabb8d0cc60d39f2f
     )
     set(FETCHCONTENT_TRY_FIND_PACKAGE_MODE "NEVER")
 
@@ -558,11 +558,12 @@ if(CIRCT_SLANG_FRONTEND_ENABLED)
     set(ORIGINAL_BUILD_SHARED_LIBS ${BUILD_SHARED_LIBS})
 
     if (MSVC)
-      set(CMAKE_CXX_FLAGS "/EHsc")
+      # MSVC seems to build without exception support by default anyway.
     else ()
-      set(CMAKE_CXX_FLAGS "")
+      set(CMAKE_CXX_FLAGS "-fno-exceptions -fno-rtti")
     endif ()
     set(BUILD_SHARED_LIBS OFF)
+    set(SLANG_USE_MIMALLOC OFF)
     FetchContent_MakeAvailable(slang)
 
     set(CMAKE_CXX_FLAGS ${ORIGINAL_CMAKE_CXX_FLAGS})
@@ -571,7 +572,6 @@ if(CIRCT_SLANG_FRONTEND_ENABLED)
     if(BUILD_SHARED_LIBS)
       set_target_properties(slang_slang PROPERTIES POSITION_INDEPENDENT_CODE ON)
       set_target_properties(fmt PROPERTIES POSITION_INDEPENDENT_CODE ON)
-      set_target_properties(unordered_dense PROPERTIES POSITION_INDEPENDENT_CODE ON)
     endif()
 
     # The following feels *very* hacky, but CMake complains about the
@@ -580,10 +580,10 @@ if(CIRCT_SLANG_FRONTEND_ENABLED)
     # statically link slang into the CIRCTImportVerilog library, but seems to be
     # harder than it ought to be.
     set_property(
-      GLOBAL APPEND PROPERTY CIRCT_EXPORTS slang_slang unordered_dense fmt)
-    install(TARGETS slang_slang unordered_dense fmt EXPORT CIRCTTargets)
+      GLOBAL APPEND PROPERTY CIRCT_EXPORTS slang_slang fmt)
+    install(TARGETS slang_slang fmt EXPORT CIRCTTargets)
   else()
-    find_package(slang 3.0 REQUIRED)
+    find_package(slang 4.0 REQUIRED)
   endif()
 endif()
 

lib/Conversion/ImportVerilog/CMakeLists.txt

@@ -1,7 +1,3 @@
-# slang uses exceptions
-set(LLVM_REQUIRES_EH ON)
-set(LLVM_REQUIRES_RTTI ON)
-
 # For ABI compatibility, define the DEBUG macro in debug builds. Slang sets this
 # internally. If we don't set this here as well, header-defined things like the
 # destructor of `Driver`, which is generated in ImportVerilog's compilation
@@ -15,9 +11,6 @@ add_compile_definitions($<$<CONFIG:Debug>:DEBUG>)
 if (MSVC)
   # No idea what to put here
 else ()
-  # slang uses exceptions; we intercept these in ImportVerilog
-  add_compile_options(-fexceptions)
-  add_compile_options(-frtti)
   # slang has some classes with virtual funcs but non-virtual destructor.
   add_compile_options(-Wno-non-virtual-dtor)
   # some other warnings we've seen

test/circt-verilog/commandline.sv

@@ -3,4 +3,4 @@
 // REQUIRES: slang
 
 // CHECK-HELP: OVERVIEW: Verilog and SystemVerilog frontend
-// CHECK-VERSION: slang version 3.
+// CHECK-VERSION: slang version 4.