Re: Use of option -fprofile-arcs is not compatible with -fprofile-use

[Edmar Wienskoski-RA8797 <edmar at freescale dot com>]

I said if you compile val-prof-1.c the same way bprob-1.c is compiled 
you get an warning.

gcc -g -fprofile-arcs val-prof-1.c -o val-prof-1.x1



Lijuan Hai wrote:
> seen in gcc-4.2, gcc.misc-tests/bprob-1.c is compiled with
> -fprofile-arcs and -fbranch-probabilities.
> gcc.dg/tree-prof/val-prof-1.c is compiled with -fprofile-generate and
> -fprofile-use. so there won't be any warnings.
>
> 2008/4/25 Edmar Wienskoski-RA8797 <edmar@freescale.com>:
>   
> > The test case gcc.misc/bprob-1.c is compiled with fprofile-arcs /
> > fprofile-use.
> >
> >  The option fprofile-arcs does not enable value profiling.
> >
> >  At the second stage compilation, the option fprofile-use enables value
> > profiling. Within tree_find_values_to_profile, if one of the value
> > optimizations algorithms sees an optimization opportunity, it will push an
> > histogram on stack. Later, compute_value_histograms will call
> > get_coverage_counts to load this histogram, but none where generated.
> >
> >  A warning is issued which means a FAIL under dejagnu.
> >
> >  I found this problem with bprob-1.c while debugging a new value profile
> > optimization. But it can be reproduced in any target, with non-modified gcc,
> > at any optimization level, using one of the value profile test cases and
> > compiler options fprofile-arcs / fprofile-use (same used with bprob-1.c).
> >
> >  Here is an example using gcc.dg/tree-prof/val-prof-1.c:
> >  ./gcc-trunk-reference/install_e600/bin/gcc -g -fprofile-arcs val-prof-1.c
> > -o val-prof-1.x1
> >  ./val-prof-1.x1
> >  ./gcc-trunk-reference/install_e600/bin/gcc -g -fprofile-use val-prof-1.c -o
> > val-prof-1.x2
> >  val-prof-1.c: In function 'main':
> >  val-prof-1.c:17: warning: no coverage for function 'main' found
> >
> >  IMHO there are 3 ways to go with this:
> >  1 - Require user behavior change (create new option -fprofile-arcs-use to
> > match -fprofile-arcs, mismatch of options is bad user behavior)
> >  2 - Record on the .gcda file how the first stage were done (fprofile-arcs /
> > fprofile-generate, etc) and use it to disable other optimizations under
> > fprofile-use (Does this already exists ?, I am not familiar with the .gcda
> > layout)
> >  3 - Let get_coverage_counts ignore inconsistencies when loading data.
> >
> >  Helps / comments are appreciated.
> >
> >  Edmar
> >
> >
> >
> >
> >     
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