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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