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* [Bug tree-optimization/110289] New: Phiprop may be good idea in early opts
@ 2023-06-16 14:50 hubicka at gcc dot gnu.org
2023-06-16 14:59 ` [Bug tree-optimization/110289] " hubicka at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: hubicka at gcc dot gnu.org @ 2023-06-16 14:50 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110289
Bug ID: 110289
Summary: Phiprop may be good idea in early opts
Product: gcc
Version: 13.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: hubicka at gcc dot gnu.org
Target Milestone: ---
libstdc++ in push_back operation does equivalent of the following:
int max(int a, int b)
{
int *ptr;
if (a > b)
ptr = &a;
else
ptr = &b;
return *ptr;
}
this is a sily implementation of max operation that sadly is not optimized
until late phiprop pass and confuses inlining heuristics: memory load is
considered to be expensive.
I think this is win-win pass and not very expensive, so perhaps adding it to
early opts is possible?
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/110289] Phiprop may be good idea in early opts
2023-06-16 14:50 [Bug tree-optimization/110289] New: Phiprop may be good idea in early opts hubicka at gcc dot gnu.org
@ 2023-06-16 14:59 ` hubicka at gcc dot gnu.org
2023-06-16 15:32 ` hubicka at gcc dot gnu.org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: hubicka at gcc dot gnu.org @ 2023-06-16 14:59 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110289
--- Comment #1 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
This is caused by the way libstdc++ defines max:
constexpr
inline const _Tp&
max(const _Tp& __a, const _Tp& __b)
{
if (__a < __b)
return __b;
return __a;
}
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/110289] Phiprop may be good idea in early opts
2023-06-16 14:50 [Bug tree-optimization/110289] New: Phiprop may be good idea in early opts hubicka at gcc dot gnu.org
2023-06-16 14:59 ` [Bug tree-optimization/110289] " hubicka at gcc dot gnu.org
@ 2023-06-16 15:32 ` hubicka at gcc dot gnu.org
2023-06-16 18:01 ` pinskia at gcc dot gnu.org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: hubicka at gcc dot gnu.org @ 2023-06-16 15:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110289
--- Comment #2 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
This patch fixes the problem
diff --git a/gcc/passes.def b/gcc/passes.def
index c9a8f19747b..faa5208b26b 100644
--- a/gcc/passes.def
+++ b/gcc/passes.def
@@ -88,6 +88,8 @@ along with GCC; see the file COPYING3. If not see
/* pass_build_ealias is a dummy pass that ensures that we
execute TODO_rebuild_alias at this point. */
NEXT_PASS (pass_build_ealias);
+ /* Do phiprop before FRE so we optimize std::min and std::max well.
*/
+ NEXT_PASS (pass_phiprop);
NEXT_PASS (pass_fre, true /* may_iterate */);
NEXT_PASS (pass_early_vrp);
NEXT_PASS (pass_merge_phi);
diff --git a/gcc/tree-ssa-phiprop.cc b/gcc/tree-ssa-phiprop.cc
index 3cb4900b6be..5dc505df420 100644
--- a/gcc/tree-ssa-phiprop.cc
+++ b/gcc/tree-ssa-phiprop.cc
@@ -476,6 +476,7 @@ public:
{}
/* opt_pass methods: */
+ opt_pass * clone () final override { return new pass_phiprop (m_ctxt); }
bool gate (function *) final override { return flag_tree_phiprop; }
unsigned int execute (function *) final override;
and helps PR110287
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/110289] Phiprop may be good idea in early opts
2023-06-16 14:50 [Bug tree-optimization/110289] New: Phiprop may be good idea in early opts hubicka at gcc dot gnu.org
2023-06-16 14:59 ` [Bug tree-optimization/110289] " hubicka at gcc dot gnu.org
2023-06-16 15:32 ` hubicka at gcc dot gnu.org
@ 2023-06-16 18:01 ` pinskia at gcc dot gnu.org
2023-06-19 6:52 ` rguenth at gcc dot gnu.org
2023-06-23 16:09 ` hubicka at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-06-16 18:01 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110289
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Keywords| |missed-optimization
Last reconfirmed| |2023-06-16
Status|UNCONFIRMED |NEW
Severity|normal |enhancement
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Yes this should definitely run after early inline in the early optimizations
because of C++ code.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/110289] Phiprop may be good idea in early opts
2023-06-16 14:50 [Bug tree-optimization/110289] New: Phiprop may be good idea in early opts hubicka at gcc dot gnu.org
` (2 preceding siblings ...)
2023-06-16 18:01 ` pinskia at gcc dot gnu.org
@ 2023-06-19 6:52 ` rguenth at gcc dot gnu.org
2023-06-23 16:09 ` hubicka at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2023-06-19 6:52 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110289
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
probably makes sense, yes.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/110289] Phiprop may be good idea in early opts
2023-06-16 14:50 [Bug tree-optimization/110289] New: Phiprop may be good idea in early opts hubicka at gcc dot gnu.org
` (3 preceding siblings ...)
2023-06-19 6:52 ` rguenth at gcc dot gnu.org
@ 2023-06-23 16:09 ` hubicka at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: hubicka at gcc dot gnu.org @ 2023-06-23 16:09 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110289
Jan Hubicka <hubicka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|NEW |RESOLVED
--- Comment #5 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
Phiprop was enabled in g:7b34cacc5735385e7e2855d7c0a6fad60ef4a99b
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-06-23 16:09 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2023-06-16 14:50 [Bug tree-optimization/110289] New: Phiprop may be good idea in early opts hubicka at gcc dot gnu.org
2023-06-16 14:59 ` [Bug tree-optimization/110289] " hubicka at gcc dot gnu.org
2023-06-16 15:32 ` hubicka at gcc dot gnu.org
2023-06-16 18:01 ` pinskia at gcc dot gnu.org
2023-06-19 6:52 ` rguenth at gcc dot gnu.org
2023-06-23 16:09 ` hubicka at gcc dot gnu.org
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