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release/22.x: [cmake] Restore exception flags in llvm-config --cxxflags (#176195) #176328

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Merged
c-rhodes merged 1 commit into from
Jan 19, 2026
Merged

release/22.x: [cmake] Restore exception flags in llvm-config --cxxflags (#176195) #176328

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36 changes: 21 additions & 15 deletions llvm/cmake/modules/AddLLVM.cmake
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,24 @@ elseif(CMAKE_CXX_COMPILER_ID MATCHES "XL")
set(LLVM_CXXFLAGS_RTTI_DISABLE "-qnortti")
endif()

# Determine required flags to enable/disable EH.
set(LLVM_CXXFLAGS_EH_DISABLE "")
set(LLVM_CXXFLAGS_EH_ENABLE "")
if(LLVM_COMPILER_IS_GCC_COMPATIBLE)
set(LLVM_CXXFLAGS_EH_DISABLE "-fno-exceptions")
if(LLVM_ENABLE_UNWIND_TABLES)
list(APPEND LLVM_CXXFLAGS_EH_DISABLE "-funwind-tables")
else()
list(APPEND LLVM_CXXFLAGS_EH_DISABLE "-fno-unwind-tables")
list(APPEND LLVM_CXXFLAGS_EH_DISABLE "-fno-asynchronous-unwind-tables")
endif()
elseif(MSVC)
set(LLVM_CXXFLAGS_EH_ENABLE "/EHsc")
set(LLVM_CXXFLAGS_EH_DISABLE "/EHs-c-")
elseif (CMAKE_CXX_COMPILER_ID MATCHES "XL")
set(LLVM_CXXFLAGS_EH_DISABLE "-qnoeh")
endif()

function(llvm_update_compile_flags name)
set(LLVM_COMPILE_CXXFLAGS "")

Expand All @@ -41,24 +59,12 @@ function(llvm_update_compile_flags name)
message(AUTHOR_WARNING "Exception handling requires RTTI. Enabling RTTI for ${name}")
set(LLVM_REQUIRES_RTTI ON)
endif()
if(MSVC)
list(APPEND LLVM_COMPILE_CXXFLAGS "/EHsc")
endif()
list(APPEND LLVM_COMPILE_CXXFLAGS ${LLVM_CXXFLAGS_EH_ENABLE})
else()
if(LLVM_COMPILER_IS_GCC_COMPATIBLE)
list(APPEND LLVM_COMPILE_CXXFLAGS "-fno-exceptions")
if(LLVM_ENABLE_UNWIND_TABLES)
list(APPEND LLVM_COMPILE_CXXFLAGS "-funwind-tables")
else()
list(APPEND LLVM_COMPILE_CXXFLAGS "-fno-unwind-tables")
list(APPEND LLVM_COMPILE_CXXFLAGS "-fno-asynchronous-unwind-tables")
endif()
elseif(MSVC)
if(MSVC)
list(APPEND LLVM_COMPILE_DEFINITIONS _HAS_EXCEPTIONS=0)
list(APPEND LLVM_COMPILE_CXXFLAGS "/EHs-c-")
elseif (CMAKE_CXX_COMPILER_ID MATCHES "XL")
list(APPEND LLVM_COMPILE_CXXFLAGS "-qnoeh")
endif()
list(APPEND LLVM_COMPILE_CXXFLAGS ${LLVM_CXXFLAGS_EH_DISABLE})
endif()

# LLVM_REQUIRES_RTTI is an internal flag that individual
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5 changes: 5 additions & 0 deletions llvm/tools/llvm-config/CMakeLists.txt
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Expand Up @@ -59,6 +59,11 @@ set(LLVM_CFLAGS "${LLVM_C_STD_FLAG} ${LLVM_DEFINITIONS}")
# The language standard potentially affects the ABI/API of LLVM, so we want
# to make sure it is reported by llvm-config.
set(LLVM_CXXFLAGS "${CMAKE_CXX${CMAKE_CXX_STANDARD}_STANDARD_COMPILE_OPTION} ${LLVM_CXX_STDLIB_FLAG} ${LLVM_DEFINITIONS}")
if(LLVM_ENABLE_EH)
append(${LLVM_CXXFLAGS_EH_ENABLE} LLVM_CXXFLAGS)
else()
append(${LLVM_CXXFLAGS_EH_DISABLE} LLVM_CXXFLAGS)
endif()
if(LLVM_ENABLE_RTTI)
append(${LLVM_CXXFLAGS_RTTI_ENABLE} LLVM_CXXFLAGS)
else()
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