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tree-optimization/106498 - reduce SSA updates in autopar

Message ID 20220802064103.940663853575@sourceware.org
State New, archived
Headers
Series tree-optimization/106498 - reduce SSA updates in autopar |

Commit Message

Richard Biener Aug. 2, 2022, 6:40 a.m. UTC 
  The following reduces the number of SSA updates done during autopar
OMP expansion, specifically avoiding the cases that just add virtual
operands (where maybe none have been before) in dead regions of the CFG.

Instead virtual SSA update is delayed until after the pass.  There's
much more TLC needed here, but test coverage makes it really difficult.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

	PR tree-optimization/106498
	* omp-expand.cc (expand_omp_taskreg): Do not perform virtual
	SSA update here.
	(expand_omp_for): Or here.
	(execute_expand_omp): Instead schedule it here together
	with CFG cleanup via TODO.
---
 gcc/omp-expand.cc | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)
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Patch

diff --git a/gcc/omp-expand.cc b/gcc/omp-expand.cc
index 936adff7f45..64e6308fc7b 100644
--- a/gcc/omp-expand.cc
+++ b/gcc/omp-expand.cc
@@ -1530,8 +1530,6 @@  expand_omp_taskreg (struct omp_region *region)
     expand_teams_call (new_bb, as_a <gomp_teams *> (entry_stmt));
   else
     expand_task_call (region, new_bb, as_a <gomp_task *> (entry_stmt));
-  if (gimple_in_ssa_p (cfun))
-    update_ssa (TODO_update_ssa_only_virtuals);
 }
 
 /* Information about members of an OpenACC collapsed loop nest.  */
@@ -8191,9 +8189,6 @@  expand_omp_for (struct omp_region *region, gimple *inner_stmt)
 			      (enum built_in_function) next_ix, sched_arg,
 			      inner_stmt);
     }
-
-  if (gimple_in_ssa_p (cfun))
-    update_ssa (TODO_update_ssa_only_virtuals);
 }
 
 /* Expand code for an OpenMP sections directive.  In pseudo code, we generate
@@ -10591,13 +10586,10 @@  execute_expand_omp (void)
 
   expand_omp (root_omp_region);
 
-  if (flag_checking && !loops_state_satisfies_p (LOOPS_NEED_FIXUP))
-    verify_loop_structure ();
-  cleanup_tree_cfg ();
-
   omp_free_regions ();
 
-  return 0;
+  return (TODO_cleanup_cfg
+	  | (gimple_in_ssa_p (cfun) ? TODO_update_ssa_only_virtuals : 0));
 }
 
 /* OMP expansion -- the default pass, run before creation of SSA form.  */