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* [Bug optimization/15352] New: [tree-ssa]
@ 2004-05-09 19:59 kazu at cs dot umass dot edu
2004-05-09 20:00 ` [Bug optimization/15352] [tree-ssa] missed jump threading opportunity due to lack of short circuit kazu at cs dot umass dot edu
` (8 more replies)
0 siblings, 9 replies; 11+ messages in thread
From: kazu at cs dot umass dot edu @ 2004-05-09 19:59 UTC (permalink / raw)
To: gcc-bugs
int
foo (int a, int b, int c)
{
if (a == 1 || b == 2)
{
if (a == 1 || c == 3)
f1 ();
else
f2 ();
}
}
I get:
foo (a, b, c)
{
_Bool T.4;
_Bool T.3;
_Bool T.2;
_Bool T.1;
_Bool T.0;
<bb 0>:
T.0_2 = a_1 == 1;
T.1_4 = b_3 == 2;
T.2_5 = T.0_2 || T.1_4;
if (T.2_5) goto <L0>; else goto <L3>;
<L0>:;
T.3_8 = c_7 == 3;
T.4_9 = T.0_2 || T.3_8;
if (T.4_9) goto <L1>; else goto <L2>;
<L1>:;
f1 () [tail call];
goto <bb 4> (<L3>);
<L2>:;
f2 () [tail call];
<L3>:;
return;
}
Note that a jump threading opportunity of T.0_2 is missed.
Ideally, we should get something like:
bar (a, b, c)
{
<bb 0>:
if (a_1 != 1) goto <L0>; else goto <L6>;
<L0>:;
if (b_3 != 2) goto <L1>; else goto <L4>;
<L1>:;
return;
<L4>:;
if (c_2 != 3) goto <L5>; else goto <L6>;
<L5>:;
f2 () [tail call];
return;
<L6>:;
f1 () [tail call];
return;
}
We should probably prefer short circuit to reduce the number of temporaries
during SSA optimizations to get full exposure to jump threading.
We "un-short-circuit" later as needed.
--
Summary: [tree-ssa]
Product: gcc
Version: tree-ssa
Status: UNCONFIRMED
Keywords: pessimizes-code
Severity: enhancement
Priority: P2
Component: optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: kazu at cs dot umass dot edu
CC: gcc-bugs at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15352
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug optimization/15352] [tree-ssa] missed jump threading opportunity due to lack of short circuit
2004-05-09 19:59 [Bug optimization/15352] New: [tree-ssa] kazu at cs dot umass dot edu
@ 2004-05-09 20:00 ` kazu at cs dot umass dot edu
2004-05-09 20:51 ` pinskia at gcc dot gnu dot org
` (7 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: kazu at cs dot umass dot edu @ 2004-05-09 20:00 UTC (permalink / raw)
To: gcc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
Summary|[tree-ssa] |[tree-ssa] missed jump
| |threading opportunity due to
| |lack of short circuit
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15352
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug optimization/15352] [tree-ssa] missed jump threading opportunity due to lack of short circuit
2004-05-09 19:59 [Bug optimization/15352] New: [tree-ssa] kazu at cs dot umass dot edu
2004-05-09 20:00 ` [Bug optimization/15352] [tree-ssa] missed jump threading opportunity due to lack of short circuit kazu at cs dot umass dot edu
@ 2004-05-09 20:51 ` pinskia at gcc dot gnu dot org
2004-05-09 22:11 ` pinskia at gcc dot gnu dot org
` (6 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2004-05-09 20:51 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2004-05-09 20:51 -------
Confirmed. I am going try to do some of this, at least the combining back.
--
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed| |1
Last reconfirmed|0000-00-00 00:00:00 |2004-05-09 20:51:01
date| |
Target Milestone|--- |tree-ssa
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15352
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug optimization/15352] [tree-ssa] missed jump threading opportunity due to lack of short circuit
2004-05-09 19:59 [Bug optimization/15352] New: [tree-ssa] kazu at cs dot umass dot edu
2004-05-09 20:00 ` [Bug optimization/15352] [tree-ssa] missed jump threading opportunity due to lack of short circuit kazu at cs dot umass dot edu
2004-05-09 20:51 ` pinskia at gcc dot gnu dot org
@ 2004-05-09 22:11 ` pinskia at gcc dot gnu dot org
2004-05-13 23:50 ` [Bug tree-optimization/15352] " pinskia at gcc dot gnu dot org
` (5 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2004-05-09 22:11 UTC (permalink / raw)
To: gcc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
BugsThisDependsOn| |15357
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15352
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/15352] [tree-ssa] missed jump threading opportunity due to lack of short circuit
2004-05-09 19:59 [Bug optimization/15352] New: [tree-ssa] kazu at cs dot umass dot edu
` (2 preceding siblings ...)
2004-05-09 22:11 ` pinskia at gcc dot gnu dot org
@ 2004-05-13 23:50 ` pinskia at gcc dot gnu dot org
2004-05-24 22:23 ` pinskia at gcc dot gnu dot org
` (4 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2004-05-13 23:50 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2004-05-13 13:34 -------
Mine.
--
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |pinskia at gcc dot gnu dot
|dot org |org
Status|NEW |ASSIGNED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15352
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/15352] [tree-ssa] missed jump threading opportunity due to lack of short circuit
2004-05-09 19:59 [Bug optimization/15352] New: [tree-ssa] kazu at cs dot umass dot edu
` (3 preceding siblings ...)
2004-05-13 23:50 ` [Bug tree-optimization/15352] " pinskia at gcc dot gnu dot org
@ 2004-05-24 22:23 ` pinskia at gcc dot gnu dot org
2005-02-14 22:38 ` law at redhat dot com
` (3 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2004-05-24 22:23 UTC (permalink / raw)
To: gcc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|3.5.0 |---
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15352
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/15352] [tree-ssa] missed jump threading opportunity due to lack of short circuit
2004-05-09 19:59 [Bug optimization/15352] New: [tree-ssa] kazu at cs dot umass dot edu
` (4 preceding siblings ...)
2004-05-24 22:23 ` pinskia at gcc dot gnu dot org
@ 2005-02-14 22:38 ` law at redhat dot com
2005-02-15 0:32 ` pinskia at gcc dot gnu dot org
` (2 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: law at redhat dot com @ 2005-02-14 22:38 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From law at redhat dot com 2005-02-14 20:01 -------
The new jump thread selection code handles this properly.
I will note that your comments about the code we ought to be able to generate
are wrong. The correctly optimized code should look like this: (note the
difference in where we test c == 3.
foo (a, b, c)
{
# BLOCK 0
# PRED: ENTRY [100.0%] (fallthru,exec)
if (a_1 == 1) goto <L3>; else goto <L0>;
# SUCC: 3 [14.9%] (true,exec) 1 [85.1%] (false,exec)
# BLOCK 1
# PRED: 0 [85.1%] (false,exec)
<L0>:;
if (b_3 == 2) goto <L2>; else goto <L5>;
# SUCC: 2 [45.3%] (true,exec) 5 [54.7%] (false,exec)
# BLOCK 2
# PRED: 1 [45.3%] (true,exec)
<L2>:;
if (c_2 == 3) goto <L3>; else goto <L4>;
# SUCC: 3 [48.8%] (true,exec) 4 [51.2%] (false,exec)
# BLOCK 3
# PRED: 0 [14.9%] (true,exec) 2 [48.8%] (true,exec)
<L3>:;
f1 ();
goto <bb 5> (<L5>);
# SUCC: 5 [100.0%] (fallthru,exec)
# BLOCK 4
# PRED: 2 [51.2%] (false,exec)
<L4>:;
f2 ();
# SUCC: 5 [100.0%] (fallthru,exec)
# BLOCK 5
# PRED: 1 [54.7%] (false,exec) 3 [100.0%] (fallthru,exec) 4 [100.0%]
(fallthru,exec)
<L5>:;
return;
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15352
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/15352] [tree-ssa] missed jump threading opportunity due to lack of short circuit
2004-05-09 19:59 [Bug optimization/15352] New: [tree-ssa] kazu at cs dot umass dot edu
` (5 preceding siblings ...)
2005-02-14 22:38 ` law at redhat dot com
@ 2005-02-15 0:32 ` pinskia at gcc dot gnu dot org
2005-04-23 0:56 ` law at redhat dot com
2005-04-25 4:58 ` law at redhat dot com
8 siblings, 0 replies; 11+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-02-15 0:32 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-02-14 20:14 -------
This is very closely related to PR 18832.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15352
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/15352] [tree-ssa] missed jump threading opportunity due to lack of short circuit
2004-05-09 19:59 [Bug optimization/15352] New: [tree-ssa] kazu at cs dot umass dot edu
` (6 preceding siblings ...)
2005-02-15 0:32 ` pinskia at gcc dot gnu dot org
@ 2005-04-23 0:56 ` law at redhat dot com
2005-04-25 4:58 ` law at redhat dot com
8 siblings, 0 replies; 11+ messages in thread
From: law at redhat dot com @ 2005-04-23 0:56 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From law at redhat dot com 2005-04-23 00:55 -------
Should be fixed with today's checkin -- with the caveat that Kazu's
desired code is incorrect. We thread everything fully in this code now.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15352
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/15352] [tree-ssa] missed jump threading opportunity due to lack of short circuit
2004-05-09 19:59 [Bug optimization/15352] New: [tree-ssa] kazu at cs dot umass dot edu
` (7 preceding siblings ...)
2005-04-23 0:56 ` law at redhat dot com
@ 2005-04-25 4:58 ` law at redhat dot com
8 siblings, 0 replies; 11+ messages in thread
From: law at redhat dot com @ 2005-04-25 4:58 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From law at redhat dot com 2005-04-25 04:58 -------
Fixed by:
http://gcc.gnu.org/ml/gcc-patches/2005-04/msg02426.html
--
What |Removed |Added
----------------------------------------------------------------------------
URL| |http://gcc.gnu.org/ml/gcc-
| |patches/2005-
| |04/msg02426.html
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
Target Milestone|--- |4.1.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15352
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/15352] [tree-ssa] missed jump threading opportunity due to lack of short circuit
[not found] <bug-15352-4@http.gcc.gnu.org/bugzilla/>
@ 2013-11-09 20:40 ` pinskia at gcc dot gnu.org
0 siblings, 0 replies; 11+ messages in thread
From: pinskia at gcc dot gnu.org @ 2013-11-09 20:40 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15352
Bug 15352 depends on bug 15357, which changed state.
Bug 15357 Summary: [tree-ssa] combing if statements
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15357
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution|--- |FIXED
^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2013-11-09 20:39 UTC | newest]
Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
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2004-05-09 19:59 [Bug optimization/15352] New: [tree-ssa] kazu at cs dot umass dot edu
2004-05-09 20:00 ` [Bug optimization/15352] [tree-ssa] missed jump threading opportunity due to lack of short circuit kazu at cs dot umass dot edu
2004-05-09 20:51 ` pinskia at gcc dot gnu dot org
2004-05-09 22:11 ` pinskia at gcc dot gnu dot org
2004-05-13 23:50 ` [Bug tree-optimization/15352] " pinskia at gcc dot gnu dot org
2004-05-24 22:23 ` pinskia at gcc dot gnu dot org
2005-02-14 22:38 ` law at redhat dot com
2005-02-15 0:32 ` pinskia at gcc dot gnu dot org
2005-04-23 0:56 ` law at redhat dot com
2005-04-25 4:58 ` law at redhat dot com
[not found] <bug-15352-4@http.gcc.gnu.org/bugzilla/>
2013-11-09 20:40 ` pinskia at gcc dot gnu.org
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