# Returns the host triple.
# Invokes config.guess

function( get_host_triple var )
  if( MSVC OR CMAKE_CXX_SIMULATE_ID STREQUAL "MSVC")
    if( CMAKE_C_COMPILER_ARCHITECTURE_ID MATCHES "ARM64.*" )
      set( value "aarch64-pc-windows-msvc" )
    elseif( CMAKE_C_COMPILER_ARCHITECTURE_ID MATCHES "ARM.*" )
      set( value "armv7-pc-windows-msvc" )
    elseif( CMAKE_C_COMPILER_ARCHITECTURE_ID STREQUAL "x64" )
      set( value "x86_64-pc-windows-msvc" )
    elseif( CMAKE_C_COMPILER_ARCHITECTURE_ID STREQUAL "X86" )
      set( value "i686-pc-windows-msvc" )
    elseif( CMAKE_SIZEOF_VOID_P EQUAL 8 )
      set( value "x86_64-pc-windows-msvc" )
    else()
      set( value "i686-pc-windows-msvc" )
    endif()
  elseif( MINGW AND NOT MSYS )
    # CMake doesn't provide COMPILER_ARCHITECTURE_ID for Clang/GCC,
    # but it does for MSVC.
    if( CMAKE_HOST_SYSTEM_PROCESSOR MATCHES "ARM.*" )
      if( CMAKE_SIZEOF_VOID_P EQUAL 8 )
        set( value "aarch64-w64-windows-gnu" )
      else()
        set( value "armv7-w64-windows-gnu" )
      endif()
    else()
      if( CMAKE_SIZEOF_VOID_P EQUAL 8 )
        set( value "x86_64-w64-windows-gnu" )
      else()
        set( value "i686-w64-windows-gnu" )
      endif()
    endif()
  elseif( CMAKE_SYSTEM_NAME MATCHES "OS390" )
    set( value "s390x-ibm-zos" )
  elseif( CMAKE_SYSTEM_NAME STREQUAL "AIX" )
    # We defer to dynamic detection of the host AIX version.
    if( CMAKE_SIZEOF_VOID_P EQUAL 8 )
      set( value "powerpc64-ibm-aix" )
    else()
      set( value "powerpc-ibm-aix" )
    endif()
  else()
    if(CMAKE_HOST_SYSTEM_NAME STREQUAL Windows AND NOT MSYS)
      message(WARNING "unable to determine host target triple")
    else()
      set(config_guess ${LLVM_MAIN_SRC_DIR}/cmake/config.guess)
      execute_process(COMMAND sh ${config_guess}
        RESULT_VARIABLE TT_RV
        OUTPUT_VARIABLE TT_OUT
        OUTPUT_STRIP_TRAILING_WHITESPACE)
      if( NOT TT_RV EQUAL 0 )
        message(FATAL_ERROR "Failed to execute ${config_guess}")
      endif( NOT TT_RV EQUAL 0 )
      set( value ${TT_OUT} )
    endif()
  endif()
  set( ${var} ${value} PARENT_SCOPE )
endfunction( get_host_triple var )