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a couple of compiler questions

Jon Peterson
Expert 1760 points

Maybe it's just me, but I find it confusing that --no_inlining is in the "Language Options" but the rest of the inlining options are in "Optimizations".

string.h uses __OPTIMIZE_FOR_SPACE but I can't find a reference in the ARM Compiler User's Guide (V4.6) nor can i figure out where it gets defined.

Thanks for considering my questions, Jon

  • 0
    Expert 1760 points

    whoops....that ought to be "_OPTIMIZE_FOR_SPACE".

  • 0 in reply to Jon Peterson
    TI__Guru**** 253390 points

    _OPTIMIZE_FOR_SPACE is a preprocessor symbol that is predefined by the compiler when no -mf option is specified, or when you use -mf0, -mf1, or -mf2.  It is not defined when you use -mf3, -mf4, or -mf5.  The option -mf is a short form for the longer alias --opt_for_speed.

    Thanks and regards,

    -George

     

     

  • 0 in reply to George Mock
    Expert 1760 points

    Hi George,

    This is great information to have and it should be in the compiler user's guide. It does, however, raise an interesting question. You say it is set if "...no -mf option is specified,...", when the compiler user's guide says: "The default setting is --opt_for_speed=4.". If the default is -mf4, then why is _OPTIMIZE_FOR_SPACE also defined by default? This appears somewhat inconsistent to me at least...

    Thanks, Jon

  • 0 in reply to Jon Peterson
    TI__Guru**** 253390 points

    I understand your confusion.  The documentation is not clear.  The default it is talking about here is what happens when you use --opt_for_speed without also specifying a value.  In that case, the value is 4.  If you don't mention --opt_for_speed at all, then the default value is 1.  Here is a (not so well formatted) summary:

    Command line         Equivalent --opt_for_speed level
------------         --------------------------------
EMPTY                     1
--opt_for_speed           4
--opt_for_speed=N         N

    Thanks and regards,

    -George