Re: xlc for RS6000 -0 flag

jpennell@axion.bt.co.uk (John Pennell) writes:


>Can anyone help?


>Are there any known bugs with the optimisation feature on xlc (AIX 3.2).
>When compiling on one particular file, the compiler appears to "hang" for
>10 minutes. When I inspect memory usage, it shows that AVM is being used
>at a very high rate, during the last few minutes, the process is only
>slowed by the pagin in and out of memory!


>The compilation eventually fails with the message "compilation failed -
>out of space" (or something like that). ...


There is a bug with the ibm rs6000 xlc compiler goes to infinite loop
trying to optimize code with unused variable. This occurs when you when
you use the compiler as xlc or c89 because the default setting enable the
`-qansialias' flag in /etc/xlc.cfg.


You can work around it by removing the `-qansialias' from the default
flags in the config file /et/xlc.cfg. This is will make it hang less. Or
remove any unused variable from your functions.


I have already reported that problem to ibm support. Also if you haven't
got the latest version of the xlc compiler (1.2.0.12 at least) you should
call up ibm support and ask for it because it fixes a bunch of bugs.
(Except the one we are talking about). The newer version of the xlc
compiler still hangs while trying to do certain optimization but it does
not run out of paging space anymore.


Minh Tran-Le.
--

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