2.17.4 Effect of --multifile on compilation build time
When compiling with
--multifile, the compiler might generate code with additional optimizations by compiling across several source files to produce a single object file. These additional cross-source optimizations can increase compilation time.
Conversely, if there is little additional optimization to
apply, and only small amounts of code to check for possible optimizations,
--multifile to generate a single object
file instead of several might reduce compilation time as a result
of time recovered from creating (opening and closing) multiple object
In RVCT 4.0, if you compile
--multifile is enabled
In ARM Compiler 4.1 and later,
disabled by default, regardless of the optimization level.