* -fprofile-generate and multiple runs
@ 2011-09-24 15:11 Martin Mitáš
2011-09-26 8:22 ` Andi Hellmund
0 siblings, 1 reply; 2+ messages in thread
From: Martin Mitáš @ 2011-09-24 15:11 UTC (permalink / raw)
To: gcc-help
Hi.
I'm working on a shared lib which I would like to optimize
with profile guided optimization. I would prefer to have
multiple small programs (one for typical use case), each
examining a single module of the lib rather then one big
program covering complete lib's API, and to generate the
profile by running all those use cases.
When built with -fprofile-generate, and the resulted binary
is executed multiple times, are the .gcda files (re)written
from scratch every time, or are they updated so they contain
a combined profile data from multiple runs?
Any other gotchas this approach might bring?
gcc manual does not provide any details about this...
Thanks in advance,
Mity
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: -fprofile-generate and multiple runs
2011-09-24 15:11 -fprofile-generate and multiple runs Martin Mitáš
@ 2011-09-26 8:22 ` Andi Hellmund
0 siblings, 0 replies; 2+ messages in thread
From: Andi Hellmund @ 2011-09-26 8:22 UTC (permalink / raw)
To: Martin Mitáš; +Cc: gcc-help
Hi Mity
>
> When built with -fprofile-generate, and the resulted binary
> is executed multiple times, are the .gcda files (re)written
> from scratch every time, or are they updated so they contain
> a combined profile data from multiple runs?
The files are updated, so it is permitted to run the program mutiple times.
>
> Any other gotchas this approach might bring?
No, it shouldn't ...
Best regards,
Andi
^ permalink raw reply [flat|nested] 2+ messages in thread
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2011-09-24 15:11 -fprofile-generate and multiple runs Martin Mitáš
2011-09-26 8:22 ` Andi Hellmund
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