[Bug tree-optimization/90488] OpenACC Profiling Interface: callbacks from the OpenACC implementation into user code

[tschwinge at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90488

--- Comment #1 from Thomas Schwinge <tschwinge at gcc dot gnu.org> ---
I filed <https://github.com/OpenACC/openacc-spec/issues/186> "OpenACC Profiling
Interface: callbacks branching out of an OpenACC construct/executable
directive", hoping to get some aspects of this clarified/restricted.


(In reply to my comment #0)
> I suppose this is due to the 'GOACC_parallel_keyed' function (implementing
> the OpenACC 'parallel' construct) being tagged as some kind of "leaf"
> function?  It's not in 'gcc/omp-builtins.def', however.  But indeed, if in
> 'gcc/tree-ssa-structalias.c' I disable the special handling for
> 'BUILT_IN_GOACC_PARALLEL' in function 'find_func_aliases_for_builtin_call'
> or 'ipa_pta_execute', then this example behaves as expected.  (Tom added
> this IPA-PTA handling in late 2015; CCed, in case you have any input.)

What this is doing, per my superficial understanding, is "look through" the
'BUILT_IN_GOACC_PARALLEL' internal-function call, into the attached region. 
Thus it doesn't notice that callbacks now may by triggered by the
'GOACC_parallel_keyed' function, before and after the attached region executes.