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* [Bug tree-optimization/21829] New: [4.1 Regression] missed jump threading after unroller
@ 2005-05-30 19:06 pinskia at gcc dot gnu dot org
2005-05-30 19:21 ` [Bug tree-optimization/21829] " pinskia at gcc dot gnu dot org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-05-30 19:06 UTC (permalink / raw)
To: gcc-bugs
Take the following code:
int test(int v)
{
int x = 0;
for (int u=0;u<2;u++)
{
if (u>v) // v is input-arg the compiler can't deside at compiletime
{
if (u%2==1) // can only happen for u==1 (so loops for 0 and 2 does not do
x++; // anything. Hoped gcc would notice when unrolling.
}
}
return x;
}
We get:
<bb 0>:
if (v_8 < 0) goto <L1>; else goto <L15>;
<L15>:;
if (v_8 <= 0) goto <L1>; else goto <L3>;
<L1>:;
# x_1 = PHI <0(3), 1(1)>;
<L3>:;
return x_1;
}
Notice that the if in L15 is always true.
The 4.0 branch gets this correct.
--
Summary: [4.1 Regression] missed jump threading after unroller
Product: gcc
Version: 4.0.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: minor
Priority: P2
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: pinskia at gcc dot gnu dot org
CC: gcc-bugs at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21829
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/21829] [4.1 Regression] missed jump threading after unroller
2005-05-30 19:06 [Bug tree-optimization/21829] New: [4.1 Regression] missed jump threading after unroller pinskia at gcc dot gnu dot org
@ 2005-05-30 19:21 ` pinskia at gcc dot gnu dot org
2005-06-12 3:44 ` pinskia at gcc dot gnu dot org
2005-09-10 5:56 ` pinskia at gcc dot gnu dot org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-05-30 19:21 UTC (permalink / raw)
To: gcc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |4.1.0
Version|4.0.0 |4.1.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21829
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/21829] [4.1 Regression] missed jump threading after unroller
2005-05-30 19:06 [Bug tree-optimization/21829] New: [4.1 Regression] missed jump threading after unroller pinskia at gcc dot gnu dot org
2005-05-30 19:21 ` [Bug tree-optimization/21829] " pinskia at gcc dot gnu dot org
@ 2005-06-12 3:44 ` pinskia at gcc dot gnu dot org
2005-09-10 5:56 ` pinskia at gcc dot gnu dot org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-06-12 3:44 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-06-12 03:44 -------
Confirmed.
--
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed| |1
Last reconfirmed|0000-00-00 00:00:00 |2005-06-12 03:44:19
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21829
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/21829] [4.1 Regression] missed jump threading after unroller
2005-05-30 19:06 [Bug tree-optimization/21829] New: [4.1 Regression] missed jump threading after unroller pinskia at gcc dot gnu dot org
2005-05-30 19:21 ` [Bug tree-optimization/21829] " pinskia at gcc dot gnu dot org
2005-06-12 3:44 ` pinskia at gcc dot gnu dot org
@ 2005-09-10 5:56 ` pinskia at gcc dot gnu dot org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-09-10 5:56 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-09-10 05:56 -------
We now get:
<bb 0>:
if (v_8 < 0) goto <L1>; else goto <L14>;
Invalid sum of incoming frequencies 2500, should be 1775
<L14>:;
if (v_8 <= 0) goto <L1>; else goto <L3>;
<L1>:;
Invalid sum of incoming frequencies 4275, should be 5000
# x_1 = PHI <0(1), 1(2)>;
<L3>:;
return x_1;
Which means jump threading is also messing up the frequencies :(.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21829
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2005-09-10 5:56 UTC | newest]
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2005-05-30 19:06 [Bug tree-optimization/21829] New: [4.1 Regression] missed jump threading after unroller pinskia at gcc dot gnu dot org
2005-05-30 19:21 ` [Bug tree-optimization/21829] " pinskia at gcc dot gnu dot org
2005-06-12 3:44 ` pinskia at gcc dot gnu dot org
2005-09-10 5:56 ` pinskia at gcc dot gnu dot org
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