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* [Bug c++/52699] New: infinite loop generated with -O0
@ 2012-03-24 7:54 jarrydb at cse dot unsw.edu.au
2012-03-24 7:55 ` [Bug c++/52699] " jarrydb at cse dot unsw.edu.au
` (9 more replies)
0 siblings, 10 replies; 11+ messages in thread
From: jarrydb at cse dot unsw.edu.au @ 2012-03-24 7:54 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52699
Bug #: 52699
Summary: infinite loop generated with -O0
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: jarrydb@cse.unsw.edu.au
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/52699] infinite loop generated with -O0
2012-03-24 7:54 [Bug c++/52699] New: infinite loop generated with -O0 jarrydb at cse dot unsw.edu.au
@ 2012-03-24 7:55 ` jarrydb at cse dot unsw.edu.au
2012-03-24 7:56 ` jarrydb at cse dot unsw.edu.au
` (8 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: jarrydb at cse dot unsw.edu.au @ 2012-03-24 7:55 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52699
Jarryd Beck <jarrydb at cse dot unsw.edu.au> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target| |i686-pc-linux-gnu
Host| |i686-pc-linux-gnu
Build| |i686-pc-linux-gnu
--- Comment #1 from Jarryd Beck <jarrydb at cse dot unsw.edu.au> 2012-03-24 07:54:23 UTC ---
When the attached file is compiled with no optimisation, the resulting program
never terminates.
g++ -std=gnu++11 random.cpp
If I compile it with:
g++ -std=gnu++11 random.cpp -O1
then it works.
The program is as follows, fully preprocessed sources are attached.
#include <random>
typedef std::mt19937::result_type unit_type;
typedef std::independent_bits_engine
<
std::mt19937,
sizeof(unit_type)*8,
unit_type
> full_bits_generator;
int main()
{
full_bits_generator gen;
gen();
return 0;
}
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/home/jarryd/local/gcc-4.8/libexec/gcc/i686-pc-linux-gnu/4.8.0/lto-wrapper
Target: i686-pc-linux-gnu
Configured with: /home/jarryd/git/gcc-git/configure
--prefix=/home/jarryd/local/gcc-4.8 --disable-multilib --enable-languages=c,c++
Thread model: posix
gcc version 4.8.0 20120323 (experimental) (GCC)
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/52699] infinite loop generated with -O0
2012-03-24 7:54 [Bug c++/52699] New: infinite loop generated with -O0 jarrydb at cse dot unsw.edu.au
2012-03-24 7:55 ` [Bug c++/52699] " jarrydb at cse dot unsw.edu.au
@ 2012-03-24 7:56 ` jarrydb at cse dot unsw.edu.au
2012-03-24 7:57 ` jarrydb at cse dot unsw.edu.au
` (7 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: jarrydb at cse dot unsw.edu.au @ 2012-03-24 7:56 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52699
--- Comment #2 from Jarryd Beck <jarrydb at cse dot unsw.edu.au> 2012-03-24 07:55:16 UTC ---
Created attachment 26972
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26972
this file never terminates with -O0
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/52699] infinite loop generated with -O0
2012-03-24 7:54 [Bug c++/52699] New: infinite loop generated with -O0 jarrydb at cse dot unsw.edu.au
2012-03-24 7:55 ` [Bug c++/52699] " jarrydb at cse dot unsw.edu.au
2012-03-24 7:56 ` jarrydb at cse dot unsw.edu.au
@ 2012-03-24 7:57 ` jarrydb at cse dot unsw.edu.au
2012-03-24 8:07 ` jarrydb at cse dot unsw.edu.au
` (6 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: jarrydb at cse dot unsw.edu.au @ 2012-03-24 7:57 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52699
--- Comment #3 from Jarryd Beck <jarrydb at cse dot unsw.edu.au> 2012-03-24 07:56:15 UTC ---
Created attachment 26973
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26973
The preprocessed version
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug c++/52699] infinite loop generated with -O0
2012-03-24 7:54 [Bug c++/52699] New: infinite loop generated with -O0 jarrydb at cse dot unsw.edu.au
` (2 preceding siblings ...)
2012-03-24 7:57 ` jarrydb at cse dot unsw.edu.au
@ 2012-03-24 8:07 ` jarrydb at cse dot unsw.edu.au
2012-03-24 8:42 ` [Bug libstdc++/52699] " pinskia at gcc dot gnu.org
` (5 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: jarrydb at cse dot unsw.edu.au @ 2012-03-24 8:07 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52699
--- Comment #4 from Jarryd Beck <jarrydb at cse dot unsw.edu.au> 2012-03-24 07:57:20 UTC ---
Note that this appears to happen only on 32 bit.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug libstdc++/52699] infinite loop generated with -O0
2012-03-24 7:54 [Bug c++/52699] New: infinite loop generated with -O0 jarrydb at cse dot unsw.edu.au
` (3 preceding siblings ...)
2012-03-24 8:07 ` jarrydb at cse dot unsw.edu.au
@ 2012-03-24 8:42 ` pinskia at gcc dot gnu.org
2012-04-12 12:53 ` paolo.carlini at oracle dot com
` (4 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: pinskia at gcc dot gnu.org @ 2012-03-24 8:42 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52699
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|target |libstdc++
--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-03-24 08:06:58 UTC ---
>From the looks of it, it looks more like a source (library) issue rather than a
compiler one. Though I don't know enough of this code to say that.
We are stuck in the following loop:
754 result_type __u;
755 do
756 __u = _M_b() - _M_b.min();
757 while (__u >= __y0);
__y0 is 0 which means the loop is always true.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug libstdc++/52699] infinite loop generated with -O0
2012-03-24 7:54 [Bug c++/52699] New: infinite loop generated with -O0 jarrydb at cse dot unsw.edu.au
` (4 preceding siblings ...)
2012-03-24 8:42 ` [Bug libstdc++/52699] " pinskia at gcc dot gnu.org
@ 2012-04-12 12:53 ` paolo.carlini at oracle dot com
2012-04-12 13:10 ` paolo.carlini at oracle dot com
` (3 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: paolo.carlini at oracle dot com @ 2012-04-12 12:53 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52699
Paolo Carlini <paolo.carlini at oracle dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2012-04-12
AssignedTo|unassigned at gcc dot |paolo.carlini at oracle dot
|gnu.org |com
Target Milestone|--- |4.7.1
Ever Confirmed|0 |1
--- Comment #6 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-04-12 12:52:50 UTC ---
Looks like something is wrong in the operator()() code vs 26.5.4.3.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug libstdc++/52699] infinite loop generated with -O0
2012-03-24 7:54 [Bug c++/52699] New: infinite loop generated with -O0 jarrydb at cse dot unsw.edu.au
` (5 preceding siblings ...)
2012-04-12 12:53 ` paolo.carlini at oracle dot com
@ 2012-04-12 13:10 ` paolo.carlini at oracle dot com
2012-04-14 22:34 ` paolo at gcc dot gnu.org
` (2 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: paolo.carlini at oracle dot com @ 2012-04-12 13:10 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52699
--- Comment #7 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-04-12 13:09:39 UTC ---
And the problem seems pretty clear: we have computations like:
__s0 = result_type(1) << __w0;
with __w0 which can be 32, result_type 32 bits, thus definitely we aren't
handling a mathematical 2^32, as we should per 26.5.4.3. A fix should be
relatively easy.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug libstdc++/52699] infinite loop generated with -O0
2012-03-24 7:54 [Bug c++/52699] New: infinite loop generated with -O0 jarrydb at cse dot unsw.edu.au
` (6 preceding siblings ...)
2012-04-12 13:10 ` paolo.carlini at oracle dot com
@ 2012-04-14 22:34 ` paolo at gcc dot gnu.org
2012-04-15 2:15 ` paolo at gcc dot gnu.org
2012-04-15 2:15 ` paolo.carlini at oracle dot com
9 siblings, 0 replies; 11+ messages in thread
From: paolo at gcc dot gnu.org @ 2012-04-14 22:34 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52699
--- Comment #8 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> 2012-04-14 22:33:27 UTC ---
Author: paolo
Date: Sat Apr 14 22:33:22 2012
New Revision: 186456
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=186456
Log:
2012-04-14 Paolo Carlini <paolo.carlini@oracle.com>
PR libstdc++/52699
* include/bits/random.tcc (independent_bits_engine<>::operator()())
Avoid various overflows; use common_type on result_type and
_RandomNumberEngine::result_type; avoid floating point computations;
other smaller tweaks.
* include/bits/random.tcc (uniform_int_distribution<>::operator())
Use common_type; assume _UniformRandomNumberGenerator::result_type
unsigned; tidy.
* include/bits/stl_algobase.h (__lg(unsigned), __lg(unsigned long),
__lg(unsigned long long)): Add.
Modified:
trunk/libstdc++-v3/ChangeLog
trunk/libstdc++-v3/include/bits/random.tcc
trunk/libstdc++-v3/include/bits/stl_algobase.h
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug libstdc++/52699] infinite loop generated with -O0
2012-03-24 7:54 [Bug c++/52699] New: infinite loop generated with -O0 jarrydb at cse dot unsw.edu.au
` (7 preceding siblings ...)
2012-04-14 22:34 ` paolo at gcc dot gnu.org
@ 2012-04-15 2:15 ` paolo at gcc dot gnu.org
2012-04-15 2:15 ` paolo.carlini at oracle dot com
9 siblings, 0 replies; 11+ messages in thread
From: paolo at gcc dot gnu.org @ 2012-04-15 2:15 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52699
--- Comment #9 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> 2012-04-15 02:14:45 UTC ---
Author: paolo
Date: Sun Apr 15 02:14:39 2012
New Revision: 186461
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=186461
Log:
2012-04-14 Paolo Carlini <paolo.carlini@oracle.com>
PR libstdc++/52699
* include/bits/random.tcc (independent_bits_engine<>::operator()())
Avoid various overflows; use common_type on result_type and
_RandomNumberEngine::result_type; avoid floating point computations;
other smaller tweaks.
* include/bits/random.tcc (uniform_int_distribution<>::operator())
Use common_type; assume _UniformRandomNumberGenerator::result_type
unsigned; tidy.
* include/bits/stl_algobase.h (__lg(unsigned), __lg(unsigned long),
__lg(unsigned long long)): Add.
Modified:
branches/gcc-4_7-branch/libstdc++-v3/ChangeLog
branches/gcc-4_7-branch/libstdc++-v3/include/bits/random.tcc
branches/gcc-4_7-branch/libstdc++-v3/include/bits/stl_algobase.h
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug libstdc++/52699] infinite loop generated with -O0
2012-03-24 7:54 [Bug c++/52699] New: infinite loop generated with -O0 jarrydb at cse dot unsw.edu.au
` (8 preceding siblings ...)
2012-04-15 2:15 ` paolo at gcc dot gnu.org
@ 2012-04-15 2:15 ` paolo.carlini at oracle dot com
9 siblings, 0 replies; 11+ messages in thread
From: paolo.carlini at oracle dot com @ 2012-04-15 2:15 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52699
Paolo Carlini <paolo.carlini at oracle dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
--- Comment #10 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-04-15 02:15:17 UTC ---
Fixed 4.7.1 and mainline.
^ permalink raw reply [flat|nested] 11+ messages in thread
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2012-03-24 7:54 [Bug c++/52699] New: infinite loop generated with -O0 jarrydb at cse dot unsw.edu.au
2012-03-24 7:55 ` [Bug c++/52699] " jarrydb at cse dot unsw.edu.au
2012-03-24 7:56 ` jarrydb at cse dot unsw.edu.au
2012-03-24 7:57 ` jarrydb at cse dot unsw.edu.au
2012-03-24 8:07 ` jarrydb at cse dot unsw.edu.au
2012-03-24 8:42 ` [Bug libstdc++/52699] " pinskia at gcc dot gnu.org
2012-04-12 12:53 ` paolo.carlini at oracle dot com
2012-04-12 13:10 ` paolo.carlini at oracle dot com
2012-04-14 22:34 ` paolo at gcc dot gnu.org
2012-04-15 2:15 ` paolo at gcc dot gnu.org
2012-04-15 2:15 ` paolo.carlini at oracle dot com
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