正如我在评论中所说，这是我们如何做到的示例。

As I said in my comment, here is an example of how we did that.

if( CMAKE_SIZEOF_VOID_P EQUAL 8 )
    MESSAGE( "64 bits compiler detected" )
    SET( EX_PLATFORM 64 )
    SET( EX_PLATFORM_NAME "x64" )
else( CMAKE_SIZEOF_VOID_P EQUAL 8 ) 
    MESSAGE( "32 bits compiler detected" )
    SET( EX_PLATFORM 32 )
    SET( EX_PLATFORM_NAME "x86" )
endif( CMAKE_SIZEOF_VOID_P EQUAL 8 )

... 

IF( EX_PLATFORM EQUAL 64 )
MESSAGE( "Outputting to lib64 and bin64" )

# ---------- Setup output Directories -------------------------
SET (CMAKE_LIBRARY_OUTPUT_DIRECTORY
   ${YourSoftwarePath}/lib64
   CACHE PATH
   "Single Directory for all Libraries"
   )

# --------- Setup the Executable output Directory -------------
SET (CMAKE_RUNTIME_OUTPUT_DIRECTORY
   ${YourSoftwarePath}/bin64
   CACHE PATH
   "Single Directory for all Executables."
   )

# --------- Setup the Executable output Directory -------------
SET (CMAKE_ARCHIVE_OUTPUT_DIRECTORY
   ${YourSoftwarePath}/lib64
   CACHE PATH
   "Single Directory for all static libraries."
   )
ELSE( EX_PLATFORM EQUAL 64 )
# ---------- Setup output Directories -------------------------
SET (CMAKE_LIBRARY_OUTPUT_DIRECTORY
   ${YourSoftwarePath}/lib
   CACHE PATH
   "Single Directory for all Libraries"
   )

# --------- Setup the Executable output Directory -------------
SET (CMAKE_RUNTIME_OUTPUT_DIRECTORY
   ${YourSoftwarePath}/bin
   CACHE PATH
   "Single Directory for all Executables."
   )

# --------- Setup the Executable output Directory -------------
SET (CMAKE_ARCHIVE_OUTPUT_DIRECTORY
   ${YourSoftwarePath}/lib
   CACHE PATH
   "Single Directory for all static libraries."
   )
ENDIF( EX_PLATFORM EQUAL 64 )

...


add_library(YourSoftware SHARED
    ${INCLUDES}
    ${SRC}
)

即使在生产过程中，它也对我们很好。

It's working well for us, even in our production process.

它允许上面同时为两个做好准备：32和64位。之后，我们必须在两个平台中构建。

It permits top have our configuration ready for both : 32 and 64 bits. After that we have to build in both platform.