# During cross-compilation in our CI we have to use llvm-tblgen and other building tools
# tools to be build for host architecture and everything else for target architecture (e.g. AArch64)
# Possible workaround is to use llvm-tblgen from some package...
# But lets just enable LLVM for native builds
if (CMAKE_CROSSCOMPILING OR SANITIZE STREQUAL "undefined")
    set (ENABLE_EMBEDDED_COMPILER_DEFAULT OFF)
else()
    set (ENABLE_EMBEDDED_COMPILER_DEFAULT ON)
endif()
option (ENABLE_EMBEDDED_COMPILER "Enable support for 'compile_expressions' option for query execution" ${ENABLE_EMBEDDED_COMPILER_DEFAULT})

if (NOT ENABLE_EMBEDDED_COMPILER)
    message(STATUS "Not using LLVM")
    return()
endif()

set (LLVM_FOUND 1)
set (LLVM_VERSION "12.0.0bundled")
set (LLVM_INCLUDE_DIRS
    "${ClickHouse_SOURCE_DIR}/contrib/llvm/llvm/include"
    "${ClickHouse_BINARY_DIR}/contrib/llvm/llvm/include"
)
set (LLVM_LIBRARY_DIRS "${ClickHouse_BINARY_DIR}/contrib/llvm/llvm")

# This list was generated by listing all LLVM libraries, compiling the binary and removing all libraries while it still compiles.
set (REQUIRED_LLVM_LIBRARIES
    LLVMExecutionEngine
    LLVMRuntimeDyld
    LLVMAsmPrinter
    LLVMDebugInfoDWARF
    LLVMGlobalISel
    LLVMSelectionDAG
    LLVMMCDisassembler
    LLVMPasses
    LLVMCodeGen
    LLVMipo
    LLVMBitWriter
    LLVMInstrumentation
    LLVMScalarOpts
    LLVMAggressiveInstCombine
    LLVMInstCombine
    LLVMVectorize
    LLVMTransformUtils
    LLVMTarget
    LLVMAnalysis
    LLVMProfileData
    LLVMObject
    LLVMBitReader
    LLVMCore
    LLVMRemarks
    LLVMBitstreamReader
    LLVMMCParser
    LLVMMC
    LLVMBinaryFormat
    LLVMDebugInfoCodeView
    LLVMSupport
    LLVMDemangle
)

if (ARCH_AMD64)
    list(APPEND REQUIRED_LLVM_LIBRARIES LLVMX86Info LLVMX86Desc LLVMX86CodeGen)
elseif (ARCH_AARCH64)
    list(APPEND REQUIRED_LLVM_LIBRARIES LLVMAArch64Info LLVMAArch64Desc LLVMAArch64CodeGen)
endif ()

#function(llvm_libs_all REQUIRED_LLVM_LIBRARIES)
#    llvm_map_components_to_libnames (result all)
#    if (USE_STATIC_LIBRARIES OR NOT "LLVM" IN_LIST result)
#        list (REMOVE_ITEM result "LTO" "LLVM")
#    else()
#        set (result "LLVM")
#    endif ()
#    list (APPEND result ${CMAKE_DL_LIBS} ch_contrib::zlib)
#    set (${REQUIRED_LLVM_LIBRARIES} ${result} PARENT_SCOPE)
#endfunction()

message (STATUS "LLVM include Directory: ${LLVM_INCLUDE_DIRS}")
message (STATUS "LLVM library Directory: ${LLVM_LIBRARY_DIRS}")
message (STATUS "LLVM C++ compiler flags: ${LLVM_CXXFLAGS}")

# ld: unknown option: --color-diagnostics
if (APPLE)
    set (LINKER_SUPPORTS_COLOR_DIAGNOSTICS 0 CACHE INTERNAL "")
endif ()

# Do not adjust RPATH in llvm, since then it will not be able to find libcxx/libcxxabi/libunwind
set (CMAKE_INSTALL_RPATH "ON")
set (LLVM_COMPILER_CHECKED 1 CACHE INTERNAL "")
set (LLVM_ENABLE_EH 1 CACHE INTERNAL "")
set (LLVM_ENABLE_RTTI 1 CACHE INTERNAL "")
set (LLVM_ENABLE_PIC 0 CACHE INTERNAL "")
set (LLVM_TARGETS_TO_BUILD "X86;AArch64" CACHE STRING "")

# Need to use C++17 since the compilation is not possible with C++20 currently, due to ambiguous operator != etc.
# LLVM project will set its default value for the -std=... but our global setting from CMake will override it.
set (CMAKE_CXX_STANDARD 17)

set (LLVM_SOURCE_DIR "${ClickHouse_SOURCE_DIR}/contrib/llvm/llvm")
set (LLVM_BINARY_DIR "${ClickHouse_BINARY_DIR}/contrib/llvm/llvm")
add_subdirectory ("${LLVM_SOURCE_DIR}" "${LLVM_BINARY_DIR}")

add_library (_llvm INTERFACE)
target_link_libraries (_llvm INTERFACE ${REQUIRED_LLVM_LIBRARIES})
target_include_directories (_llvm SYSTEM BEFORE INTERFACE ${LLVM_INCLUDE_DIRS})
add_library(ch_contrib::llvm ALIAS _llvm)