[Bug fortran/79165] [7 Regression] 100% compile-time increase for polyhedron aermod by r244581

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79165

Jakub Jelinek  changed:

   What|Removed |Added

 CC||jakub at gcc dot gnu.org

--- Comment #9 from Jakub Jelinek  ---
The tree.c hunk has been reverted, so can we close this PR (the other PR has
been reopened)?

[Bug fortran/79165] [7 Regression] 100% compile-time increase for polyhedron aermod by r244581

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79165

--- Comment #8 from David Malcolm  ---
https://gcc.opensuse.org/c++bench-czerny/pb11/ has this link:

 
http://www.polyhedron.com/fortran-compiler-comparisons/polyhedron-benchmark-suite

which is a 404.

An updated link seems to be:
 
http://www.fortran.uk/fortran-compiler-comparisons-2015/the-polyhedron-solutions-benchmark-suite/

from which a zipfile containing aermod.f90 can be seen (am looking at it now).

[Bug fortran/79165] [7 Regression] 100% compile-time increase for polyhedron aermod by r244581

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79165

--- Comment #7 from Richard Biener  ---
Ok, so the reason for the slowness is that the Fortran frontend emits full
diagnostics to a temporary buffer for gfc_match_rvalue:

/* Match a function reference.  */
function0:
  m = gfc_match_actual_arglist (0, _arglist);
  if (m == MATCH_NO)
{
  if (sym->attr.proc == PROC_ST_FUNCTION)
gfc_error ("Statement function %qs requires argument list at %C",
   sym->name);
  else
gfc_error ("Function %qs requires an argument list at %C",
   sym->name);

  m = MATCH_ERROR;
  break;
}

for aermod that's 18748 times.  And what slows down with the linemap mangling
is showing of the caret location (location_get_source_line/get_next_line
and thus the fcache I suppose).

Tentatively remembering an error like above is of course quite broken (read:
expensive).

So somehow with the tree.c hunk of the patch location_get_source_line
(inclusive callees) gets 90 times more expensive (when using callgrind on
aermod).