public inbox for gcc-cvs@sourceware.org
help / color / mirror / Atom feed
* [gcc r12-5159] Fix some side cases of side effects discovery
@ 2021-11-11 15:08 Jan Hubicka
0 siblings, 0 replies; only message in thread
From: Jan Hubicka @ 2021-11-11 15:08 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:8d3abf42d5c2ccd5c5e879088fdf6e071c3d1b9e
commit r12-5159-g8d3abf42d5c2ccd5c5e879088fdf6e071c3d1b9e
Author: Jan Hubicka <jh@suse.cz>
Date: Thu Nov 11 16:06:48 2021 +0100
Fix some side cases of side effects discovery
I wrote script comparing modref pure/const discovery with ipa-pure-const
and found mistakes on both ends. This plugs the modref differences in handling
looping pure consts which were previously missed due to early exits on
ECF_CONST | ECF_PURE. Those early exists are bit anoying and I think as
a cleanup I may just drop some of them as premature optimizations coming from
time modref was very simplistic on what it propagates.
gcc/ChangeLog:
2021-11-11 Jan Hubicka <hubicka@ucw.cz>
* ipa-modref.c (modref_summary::useful_p): Check also for side-effects
with looping const/pure.
(modref_summary_lto::useful_p): Likewise.
(merge_call_side_effects): Merge side effects before early exit
for pure/const.
(process_fnspec): Also handle pure functions.
(analyze_call): Do not early exit on looping pure const.
(propagate_unknown_call): Also handle nontrivial SCC as side-effect.
(modref_propagate_in_scc): Update.
Diff:
---
gcc/ipa-modref.c | 100 +++++++++++++++++++++++++++++++++----------------------
1 file changed, 61 insertions(+), 39 deletions(-)
diff --git a/gcc/ipa-modref.c b/gcc/ipa-modref.c
index f8b7b900527..45b391a565e 100644
--- a/gcc/ipa-modref.c
+++ b/gcc/ipa-modref.c
@@ -331,11 +331,11 @@ modref_summary::useful_p (int ecf_flags, bool check_flags)
&& remove_useless_eaf_flags (static_chain_flags, ecf_flags, false))
return true;
if (ecf_flags & (ECF_CONST | ECF_NOVOPS))
- return false;
+ return (!side_effects && (ecf_flags & ECF_LOOPING_CONST_OR_PURE));
if (loads && !loads->every_base)
return true;
if (ecf_flags & ECF_PURE)
- return false;
+ return (!side_effects && (ecf_flags & ECF_LOOPING_CONST_OR_PURE));
return stores && !stores->every_base;
}
@@ -416,11 +416,11 @@ modref_summary_lto::useful_p (int ecf_flags, bool check_flags)
&& remove_useless_eaf_flags (static_chain_flags, ecf_flags, false))
return true;
if (ecf_flags & (ECF_CONST | ECF_NOVOPS))
- return false;
+ return (!side_effects && (ecf_flags & ECF_LOOPING_CONST_OR_PURE));
if (loads && !loads->every_base)
return true;
if (ecf_flags & ECF_PURE)
- return false;
+ return (!side_effects && (ecf_flags & ECF_LOOPING_CONST_OR_PURE));
return stores && !stores->every_base;
}
@@ -925,6 +925,18 @@ merge_call_side_effects (modref_summary *cur_summary,
auto_vec <modref_parm_map, 32> parm_map;
modref_parm_map chain_map;
bool changed = false;
+ int flags = gimple_call_flags (stmt);
+
+ if (!cur_summary->side_effects && callee_summary->side_effects)
+ {
+ if (dump_file)
+ fprintf (dump_file, " - merging side effects.\n");
+ cur_summary->side_effects = true;
+ changed = true;
+ }
+
+ if (flags & (ECF_CONST | ECF_NOVOPS))
+ return changed;
/* We can not safely optimize based on summary of callee if it does
not always bind to current def: it is possible that memory load
@@ -988,12 +1000,6 @@ merge_call_side_effects (modref_summary *cur_summary,
changed = true;
}
}
- if (!cur_summary->side_effects
- && callee_summary->side_effects)
- {
- cur_summary->side_effects = true;
- changed = true;
- }
return changed;
}
@@ -1091,7 +1097,7 @@ process_fnspec (modref_summary *cur_summary,
attr_fnspec fnspec = gimple_call_fnspec (call);
int flags = gimple_call_flags (call);
- if (!(flags & (ECF_CONST | ECF_NOVOPS))
+ if (!(flags & (ECF_CONST | ECF_NOVOPS | ECF_PURE))
|| (flags & ECF_LOOPING_CONST_OR_PURE)
|| (cfun->can_throw_non_call_exceptions
&& stmt_could_throw_p (cfun, call)))
@@ -1101,6 +1107,8 @@ process_fnspec (modref_summary *cur_summary,
if (cur_summary_lto)
cur_summary_lto->side_effects = true;
}
+ if (flags & (ECF_CONST | ECF_NOVOPS))
+ return true;
if (!fnspec.known_p ())
{
if (dump_file && gimple_call_builtin_p (call, BUILT_IN_NORMAL))
@@ -1203,7 +1211,8 @@ analyze_call (modref_summary *cur_summary, modref_summary_lto *cur_summary_lto,
/* Check flags on the function call. In certain cases, analysis can be
simplified. */
int flags = gimple_call_flags (stmt);
- if (flags & (ECF_CONST | ECF_NOVOPS))
+ if ((flags & (ECF_CONST | ECF_NOVOPS))
+ && !(flags & ECF_LOOPING_CONST_OR_PURE))
{
if (dump_file)
fprintf (dump_file,
@@ -3963,7 +3972,8 @@ static bool
propagate_unknown_call (cgraph_node *node,
cgraph_edge *e, int ecf_flags,
modref_summary *cur_summary,
- modref_summary_lto *cur_summary_lto)
+ modref_summary_lto *cur_summary_lto,
+ bool nontrivial_scc)
{
bool changed = false;
class fnspec_summary *fnspec_sum = fnspec_summaries->get (e);
@@ -3973,12 +3983,12 @@ propagate_unknown_call (cgraph_node *node,
if (e->callee
&& builtin_safe_for_const_function_p (&looping, e->callee->decl))
{
- if (cur_summary && !cur_summary->side_effects)
+ if (looping && cur_summary && !cur_summary->side_effects)
{
cur_summary->side_effects = true;
changed = true;
}
- if (cur_summary_lto && !cur_summary_lto->side_effects)
+ if (looping && cur_summary_lto && !cur_summary_lto->side_effects)
{
cur_summary_lto->side_effects = true;
changed = true;
@@ -3986,8 +3996,9 @@ propagate_unknown_call (cgraph_node *node,
return changed;
}
- if (!(ecf_flags & (ECF_CONST | ECF_NOVOPS))
- || (ecf_flags & ECF_LOOPING_CONST_OR_PURE))
+ if (!(ecf_flags & (ECF_CONST | ECF_NOVOPS | ECF_PURE))
+ || (ecf_flags & ECF_LOOPING_CONST_OR_PURE)
+ || nontrivial_scc)
{
if (cur_summary && !cur_summary->side_effects)
{
@@ -4000,6 +4011,8 @@ propagate_unknown_call (cgraph_node *node,
changed = true;
}
}
+ if (ecf_flags & (ECF_CONST | ECF_NOVOPS))
+ return changed;
if (fnspec_sum
&& compute_parm_map (e, &parm_map))
@@ -4126,6 +4139,8 @@ modref_propagate_in_scc (cgraph_node *component_node)
while (changed)
{
+ bool nontrivial_scc
+ = ((struct ipa_dfs_info *) component_node->aux)->next_cycle;
changed = false;
for (struct cgraph_node *cur = component_node; cur;
cur = ((struct ipa_dfs_info *) cur->aux)->next_cycle)
@@ -4151,14 +4166,12 @@ modref_propagate_in_scc (cgraph_node *component_node)
for (cgraph_edge *e = cur->indirect_calls; e; e = e->next_callee)
{
- if (e->indirect_info->ecf_flags & (ECF_CONST | ECF_NOVOPS))
- continue;
if (dump_file)
- fprintf (dump_file, " Indirect call"
- "collapsing loads\n");
+ fprintf (dump_file, " Indirect call\n");
if (propagate_unknown_call
(node, e, e->indirect_info->ecf_flags,
- cur_summary, cur_summary_lto))
+ cur_summary, cur_summary_lto,
+ nontrivial_scc))
{
changed = true;
remove_useless_summaries (node, &cur_summary,
@@ -4180,8 +4193,9 @@ modref_propagate_in_scc (cgraph_node *component_node)
modref_summary_lto *callee_summary_lto = NULL;
struct cgraph_node *callee;
- if (flags & (ECF_CONST | ECF_NOVOPS)
- || !callee_edge->inline_failed)
+ if (!callee_edge->inline_failed
+ || ((flags & (ECF_CONST | ECF_NOVOPS))
+ && !(flags & ECF_LOOPING_CONST_OR_PURE)))
continue;
/* Get the callee and its summary. */
@@ -4210,7 +4224,8 @@ modref_propagate_in_scc (cgraph_node *component_node)
" or not available\n");
changed |= propagate_unknown_call
(node, callee_edge, flags,
- cur_summary, cur_summary_lto);
+ cur_summary, cur_summary_lto,
+ nontrivial_scc);
if (!cur_summary && !cur_summary_lto)
break;
continue;
@@ -4226,7 +4241,8 @@ modref_propagate_in_scc (cgraph_node *component_node)
fprintf (dump_file, " No call target summary\n");
changed |= propagate_unknown_call
(node, callee_edge, flags,
- cur_summary, NULL);
+ cur_summary, NULL,
+ nontrivial_scc);
}
if (cur_summary_lto
&& !(callee_summary_lto = summaries_lto->get (callee)))
@@ -4235,9 +4251,27 @@ modref_propagate_in_scc (cgraph_node *component_node)
fprintf (dump_file, " No call target summary\n");
changed |= propagate_unknown_call
(node, callee_edge, flags,
- NULL, cur_summary_lto);
+ NULL, cur_summary_lto,
+ nontrivial_scc);
}
+ if (callee_summary && !cur_summary->side_effects
+ && (callee_summary->side_effects
+ || callee_edge->recursive_p ()))
+ {
+ cur_summary->side_effects = true;
+ changed = true;
+ }
+ if (callee_summary_lto && !cur_summary_lto->side_effects
+ && (callee_summary_lto->side_effects
+ || callee_edge->recursive_p ()))
+ {
+ cur_summary_lto->side_effects = true;
+ changed = true;
+ }
+ if (flags & (ECF_CONST | ECF_NOVOPS))
+ continue;
+
/* We can not safely optimize based on summary of callee if it
does not always bind to current def: it is possible that
memory load was optimized out earlier which may not happen in
@@ -4265,12 +4299,6 @@ modref_propagate_in_scc (cgraph_node *component_node)
changed |= cur_summary->loads->merge
(callee_summary->loads, &parm_map,
&chain_map, !first);
- if (!cur_summary->side_effects
- && callee_summary->side_effects)
- {
- cur_summary->side_effects = true;
- changed = true;
- }
if (!ignore_stores)
{
changed |= cur_summary->stores->merge
@@ -4289,12 +4317,6 @@ modref_propagate_in_scc (cgraph_node *component_node)
changed |= cur_summary_lto->loads->merge
(callee_summary_lto->loads, &parm_map,
&chain_map, !first);
- if (!cur_summary_lto->side_effects
- && callee_summary_lto->side_effects)
- {
- cur_summary_lto->side_effects = true;
- changed = true;
- }
if (!ignore_stores)
{
changed |= cur_summary_lto->stores->merge
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2021-11-11 15:08 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-11-11 15:08 [gcc r12-5159] Fix some side cases of side effects discovery Jan Hubicka
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).