diff options
Diffstat (limited to 'gcc/tree-ssa-loop-niter.c')
| -rw-r--r-- | gcc/tree-ssa-loop-niter.c | 33 |
1 files changed, 20 insertions, 13 deletions
diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c index 78040364a97..32fe2f91edd 100644 --- a/gcc/tree-ssa-loop-niter.c +++ b/gcc/tree-ssa-loop-niter.c @@ -3721,8 +3721,26 @@ estimate_numbers_of_iterations_loop (struct loop *loop) return; loop->estimate_state = EST_AVAILABLE; - /* Force estimate compuation but leave any existing upper bound in place. */ - loop->any_estimate = false; + + /* If we have a measured profile, use it to estimate the number of + iterations. Normally this is recorded by branch_prob right after + reading the profile. In case we however found a new loop, record the + information here. + + Explicitly check for profile status so we do not report + wrong prediction hitrates for guessed loop iterations heuristics. + Do not recompute already recorded bounds - we ought to be better on + updating iteration bounds than updating profile in general and thus + recomputing iteration bounds later in the compilation process will just + introduce random roundoff errors. */ + if (!loop->any_estimate + && loop->header->count != 0 + && profile_status_for_fn (cfun) >= PROFILE_READ) + { + gcov_type nit = expected_loop_iterations_unbounded (loop); + bound = gcov_type_to_wide_int (nit); + record_niter_bound (loop, bound, true, false); + } /* Ensure that loop->nb_iterations is computed if possible. If it turns out to be constant, we avoid undefined behavior implied bounds and instead @@ -3756,17 +3774,6 @@ estimate_numbers_of_iterations_loop (struct loop *loop) maybe_lower_iteration_bound (loop); - /* If we have a measured profile, use it to estimate the number of - iterations. Explicitly check for profile status so we do not report - wrong prediction hitrates for guessed loop iterations heuristics. */ - if (loop->header->count != 0 - && profile_status_for_fn (cfun) >= PROFILE_READ) - { - gcov_type nit = expected_loop_iterations_unbounded (loop); - bound = gcov_type_to_wide_int (nit); - record_niter_bound (loop, bound, true, false); - } - /* If we know the exact number of iterations of this loop, try to not break code with undefined behavior by not recording smaller maximum number of iterations. */ |