| Message ID | 13967188.4S6WqxrUkn@polaris |
|---|---|
| State | New |
| Headers | show |
| Series | Relax IVOPTs restriction on auto-increment | expand |
On Tue, Oct 17, 2017 at 9:45 AM, Eric Botcazou <ebotcazou@adacore.com> wrote: > Hi, > > add_autoinc_candidates begins with this test: > > /* If we insert the increment in any position other than the standard > ones, we must ensure that it is incremented once per iteration. > It must not be in an inner nested loop, or one side of an if > statement. */ > if (use_bb->loop_father != data->current_loop > || !dominated_by_p (CDI_DOMINATORS, data->current_loop->latch, use_bb) > || stmt_could_throw_p (use->stmt) > || !cst_and_fits_in_hwi (step)) > return; > > This means that, for languages supporting non-call exceptions like Ada, no > auto-inc candidates will be added for a simple iteration over an array in most > cases since stmt_could_throw_p returns true. I don't think that's necessary, > or else it would also be necessary to test gimple_could_trap_p, which would > have the same effect for all languages. Note that add_autoinc_candidates is > only invoked for USE_ADDRESS use types: > > /* At last, add auto-incremental candidates. Make such variables > important since other iv uses with same base object may be based > on it. */ > if (use != NULL && use->type == USE_ADDRESS) > add_autoinc_candidates (data, iv->base, iv->step, true, use); > > So the attached patch replaces it with stmt_can_throw_internal (which is the > predicate used to compute the flow of control) as e.g. in the vectorizer. > > Bootstrapped/regtested on PowerPC64/Linux, OK for the mainline? Ok. Richard. > > 2017-10-17 Eric Botcazou <ebotcazou@adacore.com> > > * tree-ssa-loop-ivopts.c (add_autoinc_candidates): Bail out only if > the use statement can throw internally. > > -- > Eric Botcazou
Index: tree-ssa-loop-ivopts.c =================================================================== --- tree-ssa-loop-ivopts.c (revision 253767) +++ tree-ssa-loop-ivopts.c (working copy) @@ -3140,7 +3140,7 @@ add_autoinc_candidates (struct ivopts_da statement. */ if (use_bb->loop_father != data->current_loop || !dominated_by_p (CDI_DOMINATORS, data->current_loop->latch, use_bb) - || stmt_could_throw_p (use->stmt) + || stmt_can_throw_internal (use->stmt) || !cst_and_fits_in_hwi (step)) return;
Hi, add_autoinc_candidates begins with this test: /* If we insert the increment in any position other than the standard ones, we must ensure that it is incremented once per iteration. It must not be in an inner nested loop, or one side of an if statement. */ if (use_bb->loop_father != data->current_loop || !dominated_by_p (CDI_DOMINATORS, data->current_loop->latch, use_bb) || stmt_could_throw_p (use->stmt) || !cst_and_fits_in_hwi (step)) return; This means that, for languages supporting non-call exceptions like Ada, no auto-inc candidates will be added for a simple iteration over an array in most cases since stmt_could_throw_p returns true. I don't think that's necessary, or else it would also be necessary to test gimple_could_trap_p, which would have the same effect for all languages. Note that add_autoinc_candidates is only invoked for USE_ADDRESS use types: /* At last, add auto-incremental candidates. Make such variables important since other iv uses with same base object may be based on it. */ if (use != NULL && use->type == USE_ADDRESS) add_autoinc_candidates (data, iv->base, iv->step, true, use); So the attached patch replaces it with stmt_can_throw_internal (which is the predicate used to compute the flow of control) as e.g. in the vectorizer. Bootstrapped/regtested on PowerPC64/Linux, OK for the mainline? 2017-10-17 Eric Botcazou <ebotcazou@adacore.com> * tree-ssa-loop-ivopts.c (add_autoinc_candidates): Bail out only if the use statement can throw internally.