On Wed, 20 Feb 2013, Richard Biener wrote:
>
> Hunting for the "we're getting slower" bits I noticed that
> TODO_remove_unused_locals is a big part of execute_function_todo
> (and accounts for 1% of compile-time of ac.f90).
> The following patch removes most of the remove_unused_locals
> calls based on the fact that with anonymous SSA names now available
> we should never create new locals (wishful thinking of course ...)
> and the important places to remove unused stuff are driven by
> 1) avoid creating yet another copy of the unused stuff, thus do
> it before inlining, on the callee; 2) avoid pinning unused memory
> while we operate on other function bodies, thus, do it at the end
> of non-IPA pass pipelines
>
> In the end this asks for more explicit placement and thus a
> real pass ... but the following should be enough as a RFC and
> be good enough for 4.8.
>
> We keep doing remove_unused_locals after going into SSA
> and now after releasing unused SSA names (that should suffice
> to achieve 1) for early and IPA inlining and for 2) pre-IPA.
> post-IPA we perform it after IPA inline transform and at right
> before expanding to RTL (avoid expanding unused stack vars).
>
> I'm scheduling a bootstrap & regtest.
>
> Ok for trunk?
As requested, here is some statistics. stage2 gcc/ compiled with
-fdump-statistics-stats, summed over all files with
Index: gcc/tree-ssa-live.c
===================================================================
--- gcc/tree-ssa-live.c (revision 196170)
+++ gcc/tree-ssa-live.c (working copy)
@@ -889,7 +889,10 @@ remove_unused_locals (void)
dstidx++;
}
if (dstidx != num)
- cfun->local_decls->truncate (dstidx);
+ {
+ statistics_counter_event (cfun, "unused VAR_DECLs removed", num -
dstidx);
+ cfun->local_decls->truncate (dstidx);
+ }
remove_unused_scope_block_p (DECL_INITIAL (current_function_decl));
clear_unused_block_pointer ();
gives us before the patch (first number is the static pass number,
last is the pass name, the number of removed vars is second):
20 323409 ssa
23 131864 einline
25 29311 copyrename
26 2178 ccp
27 9771 forwprop
30 29 fre
31 60212 copyprop
33 13849 cddce
35 10 tailr
39 355 local-pure-const
40 4347 fnsplit
-----
subtotal 575335
52 46056 inline
59 10834 copyrename
61 3721 ccp
62 83 forwprop
66 826 fre
67 4821 copyprop
69 5017 vrp
70 24764 dce
73 2 ifcombine
74 662 phiopt
76 137 ch
80 2909 copyrename
81 212 dom
82 1472 phicprop
85 1322 dce
86 51 forwprop
87 4 phiopt
90 48 ccp
91 19 copyprop
95 6 pre
101 5 lim
102 883 copyprop
103 3082 dceloop
125 2 loopdone
129 589 vrp
131 49 dom
132 145 phicprop
133 316 cddce
137 5 forwprop
138 1 phiopt
142 458 copyrename
168 2955 optimized
--------
total 686791
and after the patch, adjusted as below (eh, I failed to notice
we schedule remove_unused_locals if TODO_cleanup_cfg did sth...):
20 323396 ssa
23 107755 einline
41 135260 release_ssa
------
subtotal 566411
52 47513 inline
168 61713 optimized
--------
total 675637
as expected the most unused locals are removed before final inlining.
I suppose the difference in (sub-)total is because patched we copy
less unused locals due to the extra remove-unused locals at
release_ssa time. I can't explain the 13 difference for into-SSA.
I suppose I should also count the number of remaining locals ...
Scheduled for re-bootstrap / regtest.
Thanks,
Richard.
2013-02-20 Richard Biener <[email protected]>
* tree-call-cdce.c (tree_call_cdce): Do not remove unused locals.
* tree-ssa-forwprop.c (ssa_forward_propagate_and_combine): Likewise.
* tree-ssa-dce.c (perform_tree_ssa_dce): Likewise.
* tree-ssa-copyrename.c (copy_rename_partition_coalesce): Do
not return anything.
(rename_ssa_copies): Do not remove unused locals.
* tree-ssa-ccp.c (do_ssa_ccp): Likewise.
* tree-ssanames.c (pass_release_ssa_names): Remove unused
locals first.
* passes.c (execute_function_todo): Do not schedule unused locals
removal if cleanup_tree_cfg did something.
* tree-ssa-live.c (remove_unused_locals): Dump statistics
about the number of removed locals.
Index: gcc/tree-call-cdce.c
===================================================================
*** gcc/tree-call-cdce.c.orig 2013-02-20 12:49:24.000000000 +0100
--- gcc/tree-call-cdce.c 2013-02-20 12:51:00.528421709 +0100
*************** tree_call_cdce (void)
*** 898,908 ****
/* As we introduced new control-flow we need to insert PHI-nodes
for the call-clobbers of the remaining call. */
mark_virtual_operands_for_renaming (cfun);
! return (TODO_update_ssa | TODO_cleanup_cfg | TODO_ggc_collect
! | TODO_remove_unused_locals);
}
! else
! return 0;
}
static bool
--- 898,907 ----
/* As we introduced new control-flow we need to insert PHI-nodes
for the call-clobbers of the remaining call. */
mark_virtual_operands_for_renaming (cfun);
! return TODO_update_ssa;
}
!
! return 0;
}
static bool
Index: gcc/tree-ssa-forwprop.c
===================================================================
*** gcc/tree-ssa-forwprop.c.orig 2013-02-20 12:49:24.000000000 +0100
--- gcc/tree-ssa-forwprop.c 2013-02-20 12:51:00.556422021 +0100
*************** ssa_forward_propagate_and_combine (void)
*** 2936,2942 ****
&& forward_propagate_addr_expr (lhs, rhs))
{
release_defs (stmt);
- todoflags |= TODO_remove_unused_locals;
gsi_remove (&gsi, true);
}
else
--- 2936,2941 ----
*************** ssa_forward_propagate_and_combine (void)
*** 2961,2967 ****
off)))))
{
release_defs (stmt);
- todoflags |= TODO_remove_unused_locals;
gsi_remove (&gsi, true);
}
else if (is_gimple_min_invariant (rhs))
--- 2960,2965 ----
Index: gcc/tree-ssa-dce.c
===================================================================
*** gcc/tree-ssa-dce.c.orig 2013-02-20 12:49:24.000000000 +0100
--- gcc/tree-ssa-dce.c 2013-02-20 12:51:00.579422275 +0100
*************** perform_tree_ssa_dce (bool aggressive)
*** 1607,1616 ****
free_edge_list (el);
if (something_changed)
! return (TODO_update_ssa | TODO_cleanup_cfg | TODO_ggc_collect
! | TODO_remove_unused_locals);
! else
! return 0;
}
/* Pass entry points. */
--- 1607,1614 ----
free_edge_list (el);
if (something_changed)
! return TODO_update_ssa | TODO_cleanup_cfg;
! return 0;
}
/* Pass entry points. */
Index: gcc/tree-ssa-copyrename.c
===================================================================
*** gcc/tree-ssa-copyrename.c.orig 2013-02-20 12:49:24.000000000 +0100
--- gcc/tree-ssa-copyrename.c 2013-02-20 12:55:59.374738833 +0100
*************** static struct
*** 113,119 ****
/* Coalesce the partitions in MAP representing VAR1 and VAR2 if it is valid.
Choose a representative for the partition, and send debug info to DEBUG.
*/
! static bool
copy_rename_partition_coalesce (var_map map, tree var1, tree var2, FILE
*debug)
{
int p1, p2, p3;
--- 113,119 ----
/* Coalesce the partitions in MAP representing VAR1 and VAR2 if it is valid.
Choose a representative for the partition, and send debug info to DEBUG.
*/
! static void
copy_rename_partition_coalesce (var_map map, tree var1, tree var2, FILE
*debug)
{
int p1, p2, p3;
*************** copy_rename_partition_coalesce (var_map
*** 146,152 ****
{
if (debug)
fprintf (debug, " : Already coalesced.\n");
! return false;
}
rep1 = partition_to_var (map, p1);
--- 146,152 ----
{
if (debug)
fprintf (debug, " : Already coalesced.\n");
! return;
}
rep1 = partition_to_var (map, p1);
*************** copy_rename_partition_coalesce (var_map
*** 154,160 ****
root1 = SSA_NAME_VAR (rep1);
root2 = SSA_NAME_VAR (rep2);
if (!root1 && !root2)
! return false;
/* Don't coalesce if one of the variables occurs in an abnormal PHI. */
abnorm = (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rep1)
--- 154,160 ----
root1 = SSA_NAME_VAR (rep1);
root2 = SSA_NAME_VAR (rep2);
if (!root1 && !root2)
! return;
/* Don't coalesce if one of the variables occurs in an abnormal PHI. */
abnorm = (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rep1)
*************** copy_rename_partition_coalesce (var_map
*** 163,169 ****
{
if (debug)
fprintf (debug, " : Abnormal PHI barrier. No coalesce.\n");
! return false;
}
/* Partitions already have the same root, simply merge them. */
--- 163,169 ----
{
if (debug)
fprintf (debug, " : Abnormal PHI barrier. No coalesce.\n");
! return;
}
/* Partitions already have the same root, simply merge them. */
*************** copy_rename_partition_coalesce (var_map
*** 172,178 ****
p1 = partition_union (map->var_partition, p1, p2);
if (debug)
fprintf (debug, " : Same root, coalesced --> P%d.\n", p1);
! return false;
}
/* Never attempt to coalesce 2 different parameters. */
--- 172,178 ----
p1 = partition_union (map->var_partition, p1, p2);
if (debug)
fprintf (debug, " : Same root, coalesced --> P%d.\n", p1);
! return;
}
/* Never attempt to coalesce 2 different parameters. */
*************** copy_rename_partition_coalesce (var_map
*** 181,187 ****
{
if (debug)
fprintf (debug, " : 2 different PARM_DECLS. No coalesce.\n");
! return false;
}
if ((root1 && TREE_CODE (root1) == RESULT_DECL)
--- 181,187 ----
{
if (debug)
fprintf (debug, " : 2 different PARM_DECLS. No coalesce.\n");
! return;
}
if ((root1 && TREE_CODE (root1) == RESULT_DECL)
*************** copy_rename_partition_coalesce (var_map
*** 189,195 ****
{
if (debug)
fprintf (debug, " : One root a RESULT_DECL. No coalesce.\n");
! return false;
}
ign1 = !root1 || (TREE_CODE (root1) == VAR_DECL && DECL_IGNORED_P (root1));
--- 189,195 ----
{
if (debug)
fprintf (debug, " : One root a RESULT_DECL. No coalesce.\n");
! return;
}
ign1 = !root1 || (TREE_CODE (root1) == VAR_DECL && DECL_IGNORED_P (root1));
*************** copy_rename_partition_coalesce (var_map
*** 206,212 ****
{
if (debug)
fprintf (debug, " : 2 different USER vars. No coalesce.\n");
! return false;
}
else
ign2 = true;
--- 206,212 ----
{
if (debug)
fprintf (debug, " : 2 different USER vars. No coalesce.\n");
! return;
}
else
ign2 = true;
*************** copy_rename_partition_coalesce (var_map
*** 220,226 ****
{
if (debug)
fprintf (debug, " : 2 default defs. No coalesce.\n");
! return false;
}
else
{
--- 220,226 ----
{
if (debug)
fprintf (debug, " : 2 default defs. No coalesce.\n");
! return;
}
else
{
*************** copy_rename_partition_coalesce (var_map
*** 240,246 ****
{
if (debug)
fprintf (debug, " : Choosen variable has no root. No coalesce.\n");
! return false;
}
/* Don't coalesce if the new chosen root variable would be read-only.
--- 240,246 ----
{
if (debug)
fprintf (debug, " : Choosen variable has no root. No coalesce.\n");
! return;
}
/* Don't coalesce if the new chosen root variable would be read-only.
*************** copy_rename_partition_coalesce (var_map
*** 253,259 ****
{
if (debug)
fprintf (debug, " : Readonly variable. No coalesce.\n");
! return false;
}
/* Don't coalesce if the two variables aren't type compatible . */
--- 253,259 ----
{
if (debug)
fprintf (debug, " : Readonly variable. No coalesce.\n");
! return;
}
/* Don't coalesce if the two variables aren't type compatible . */
*************** copy_rename_partition_coalesce (var_map
*** 266,272 ****
{
if (debug)
fprintf (debug, " : Incompatible types. No coalesce.\n");
! return false;
}
/* Merge the two partitions. */
--- 266,272 ----
{
if (debug)
fprintf (debug, " : Incompatible types. No coalesce.\n");
! return;
}
/* Merge the two partitions. */
*************** copy_rename_partition_coalesce (var_map
*** 288,294 ****
TDF_SLIM);
fprintf (debug, "\n");
}
- return true;
}
--- 288,293 ----
*************** rename_ssa_copies (void)
*** 308,314 ****
gimple stmt, phi;
unsigned x;
FILE *debug;
- bool updated = false;
memset (&stats, 0, sizeof (stats));
--- 307,312 ----
*************** rename_ssa_copies (void)
*** 330,336 ****
tree lhs = gimple_assign_lhs (stmt);
tree rhs = gimple_assign_rhs1 (stmt);
! updated |= copy_rename_partition_coalesce (map, lhs, rhs, debug);
}
}
}
--- 328,334 ----
tree lhs = gimple_assign_lhs (stmt);
tree rhs = gimple_assign_rhs1 (stmt);
! copy_rename_partition_coalesce (map, lhs, rhs, debug);
}
}
}
*************** rename_ssa_copies (void)
*** 358,365 ****
{
tree arg = PHI_ARG_DEF (phi, i);
if (TREE_CODE (arg) == SSA_NAME)
! updated |= copy_rename_partition_coalesce (map, res, arg,
! debug);
}
/* Else if all arguments are in the same partition try to merge
it with the result. */
--- 356,363 ----
{
tree arg = PHI_ARG_DEF (phi, i);
if (TREE_CODE (arg) == SSA_NAME)
! copy_rename_partition_coalesce (map, res, arg,
! debug);
}
/* Else if all arguments are in the same partition try to merge
it with the result. */
*************** rename_ssa_copies (void)
*** 390,398 ****
}
}
if (all_p_same == 1)
! updated |= copy_rename_partition_coalesce (map, res,
! PHI_ARG_DEF (phi, 0),
! debug);
}
}
}
--- 388,396 ----
}
}
if (all_p_same == 1)
! copy_rename_partition_coalesce (map, res,
! PHI_ARG_DEF (phi, 0),
! debug);
}
}
}
*************** rename_ssa_copies (void)
*** 426,432 ****
statistics_counter_event (cfun, "copies coalesced",
stats.coalesced);
delete_var_map (map);
! return updated ? TODO_remove_unused_locals : 0;
}
/* Return true if copy rename is to be performed. */
--- 424,430 ----
statistics_counter_event (cfun, "copies coalesced",
stats.coalesced);
delete_var_map (map);
! return 0;
}
/* Return true if copy rename is to be performed. */
Index: gcc/tree-ssa-ccp.c
===================================================================
*** gcc/tree-ssa-ccp.c.orig 2013-02-20 12:49:24.000000000 +0100
--- gcc/tree-ssa-ccp.c 2013-02-20 12:51:00.580422285 +0100
*************** do_ssa_ccp (void)
*** 2108,2114 ****
ccp_initialize ();
ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node);
if (ccp_finalize ())
! todo = (TODO_cleanup_cfg | TODO_update_ssa | TODO_remove_unused_locals);
free_dominance_info (CDI_DOMINATORS);
return todo;
}
--- 2108,2114 ----
ccp_initialize ();
ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node);
if (ccp_finalize ())
! todo = (TODO_cleanup_cfg | TODO_update_ssa);
free_dominance_info (CDI_DOMINATORS);
return todo;
}
Index: gcc/tree-ssanames.c
===================================================================
*** gcc/tree-ssanames.c.orig 2013-02-20 12:49:24.000000000 +0100
--- gcc/tree-ssanames.c 2013-02-20 12:51:29.583743873 +0100
*************** struct gimple_opt_pass pass_release_ssa_
*** 455,461 ****
PROP_ssa, /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
! 0, /* todo_flags_start */
! 0 /* todo_flags_finish */
}
};
--- 455,461 ----
PROP_ssa, /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
! TODO_remove_unused_locals, /* todo_flags_start */
! 0 /* todo_flags_finish */
}
};
Index: gcc/passes.c
===================================================================
*** gcc/passes.c.orig 2013-02-11 11:41:01.000000000 +0100
--- gcc/passes.c 2013-02-20 12:54:45.700917657 +0100
*************** execute_function_todo (void *data)
*** 1918,1927 ****
/* Always cleanup the CFG before trying to update SSA. */
if (flags & TODO_cleanup_cfg)
{
! bool cleanup = cleanup_tree_cfg ();
!
! if (cleanup && (cfun->curr_properties & PROP_ssa))
! flags |= TODO_remove_unused_locals;
/* When cleanup_tree_cfg merges consecutive blocks, it may
perform some simplistic propagation when removing single
--- 1918,1924 ----
/* Always cleanup the CFG before trying to update SSA. */
if (flags & TODO_cleanup_cfg)
{
! cleanup_tree_cfg ();
/* When cleanup_tree_cfg merges consecutive blocks, it may
perform some simplistic propagation when removing single
Index: gcc/tree-ssa-live.c
===================================================================
*** gcc/tree-ssa-live.c.orig 2013-01-11 10:54:52.000000000 +0100
--- gcc/tree-ssa-live.c 2013-02-20 12:55:30.066411897 +0100
*************** remove_unused_locals (void)
*** 889,895 ****
dstidx++;
}
if (dstidx != num)
! cfun->local_decls->truncate (dstidx);
remove_unused_scope_block_p (DECL_INITIAL (current_function_decl));
clear_unused_block_pointer ();
--- 889,898 ----
dstidx++;
}
if (dstidx != num)
! {
! statistics_counter_event (cfun, "unused VAR_DECLs removed", num -
dstidx);
! cfun->local_decls->truncate (dstidx);
! }
remove_unused_scope_block_p (DECL_INITIAL (current_function_decl));
clear_unused_block_pointer ();
