[patch][IRA] Really record loop exits
Steven Bosscher
stevenb.gcc@gmail.com
Thu Oct 11 20:21:00 GMT 2012
Hello,
IRA uses record_loop_exits() to cache the loop exit edges, but due to
a code ordering bug the edges are not actually recorded.
record_loop_exits() starts with:
if (!current_loops)
return;
So ira.c should set current_loops before calling record_loop_exits.
With the current order, the exists are not actually recorded. Also,
ira.c should release recorded exits and loops, this releases a
considerable amount of GC memory that can be re-used in the next IRA
iteration.
It's not clear to me why IRA has to re-compute the cfgloop tree from
scratch, though, so I've added a "???" comment for that.
Bootstrapped&tested (with and without checking) on
powerpc64-unknown-linux-gnu. OK for trunk?
Ciao!
Steven
* ira.c (ira): Set current_loops to &ira_loops before recording
loop exits. Release recorded exits and loops early.
Index: ira.c
===================================================================
--- ira.c (revision 192377)
+++ ira.c (working copy)
@@ -4233,8 +4233,8 @@ ira (FILE *f)
if (flag_ira_region == IRA_REGION_ALL || flag_ira_region == IRA_REGION_MIXED)
{
flow_loops_find (&ira_loops);
+ current_loops = &ira_loops;
record_loop_exits ();
- current_loops = &ira_loops;
}
if (internal_flag_ira_verbose > 0 && ira_dump_file != NULL)
@@ -4277,9 +4277,14 @@ ira (FILE *f)
info. */
df_analyze ();
+ /* ??? Rebuild the loop tree, but why? Does the loop tree
+ change if new insns were generated? Can that be handled
+ by updating the loop tree incrementally? */
+ release_recorded_exits ();
+ flow_loops_free (&ira_loops);
flow_loops_find (&ira_loops);
+ current_loops = &ira_loops;
record_loop_exits ();
- current_loops = &ira_loops;
setup_allocno_assignment_flags ();
ira_initiate_assign ();
@@ -4363,6 +4368,7 @@ do_reload (void)
if (current_loops != NULL)
{
+ release_recorded_exits ();
flow_loops_free (&ira_loops);
free_dominance_info (CDI_DOMINATORS);
}
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