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* [Bug c++/59800] New: Compilation with g++ fails when -Ofast -flto is used to compile code using some <random> distribution
@ 2014-01-14 6:01 rionda at gmail dot com
2014-01-14 12:05 ` [Bug c++/59800] " rguenth at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: rionda at gmail dot com @ 2014-01-14 6:01 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59800
Bug ID: 59800
Summary: Compilation with g++ fails when -Ofast -flto is used
to compile code using some <random> distribution
Product: gcc
Version: 4.8.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: rionda at gmail dot com
Created attachment 31828
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31828&action=edit
Code that fails
The attached code compiles cleanly when using
g++ -Ofast -Wall -Wextra -Wno-unused-parameter test.cpp test.cpp
and when using
g++ -flto -Wall -Wextra -Wno-unused-parameter test.cpp
but fails when using "g++8 -std=c++11 -Ofast -flto -Wall -Wextra
-Wno-unused-parameter test.cpp" (i.e., when using both -Ofast and -flto).
The reported error is:
test.cpp: In function 'main':
/opt/local/include/gcc48/c++/bits/random.h:2404:60: warning: 'MEM[(struct
normal_distribution *)&my_lognormal + 16B]._M_saved' may be used uninitialized
in this function [-Wmaybe-uninitialized]
{ return std::exp(__p.s() * _M_nd(__urng) + __p.m()); }
^
test.cpp:11:33: note: 'MEM[(struct normal_distribution *)&my_lognormal +
16B]._M_saved' was declared here
lognormal_distribution<double> my_lognormal(0.0, 1.0);
^
I am running
g++-mp-4.8 (MacPorts gcc48 4.8.2_0) 4.8.2
Copyright (C) 2013 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
on Mac OS X 10.6.8
(uname -a : darwin xxxx.local 10.8.0 Darwin Kernel Version 10.8.0: Tue Jun 7
16:33:36 PDT 2011; root:xnu-1504.15.3~1/RELEASE_I386 i386)
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/59800] Compilation with g++ fails when -Ofast -flto is used to compile code using some <random> distribution
2014-01-14 6:01 [Bug c++/59800] New: Compilation with g++ fails when -Ofast -flto is used to compile code using some <random> distribution rionda at gmail dot com
@ 2014-01-14 12:05 ` rguenth at gcc dot gnu.org
2014-07-09 19:52 ` rionda at gmail dot com
2014-07-09 20:49 ` manu at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: rguenth at gcc dot gnu.org @ 2014-01-14 12:05 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59800
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |WAITING
Last reconfirmed| |2014-01-14
Ever confirmed|0 |1
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
That's not an error but a warning?! Anyway, it's triggered by
-Wmaybe-uninitialized.
Also happens on trunk.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/59800] Compilation with g++ fails when -Ofast -flto is used to compile code using some <random> distribution
2014-01-14 6:01 [Bug c++/59800] New: Compilation with g++ fails when -Ofast -flto is used to compile code using some <random> distribution rionda at gmail dot com
2014-01-14 12:05 ` [Bug c++/59800] " rguenth at gcc dot gnu.org
@ 2014-07-09 19:52 ` rionda at gmail dot com
2014-07-09 20:49 ` manu at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: rionda at gmail dot com @ 2014-07-09 19:52 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59800
--- Comment #3 from Matteo Riondato <rionda at gmail dot com> ---
What exactly does the "WAITING" status mean?
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/59800] Compilation with g++ fails when -Ofast -flto is used to compile code using some <random> distribution
2014-01-14 6:01 [Bug c++/59800] New: Compilation with g++ fails when -Ofast -flto is used to compile code using some <random> distribution rionda at gmail dot com
2014-01-14 12:05 ` [Bug c++/59800] " rguenth at gcc dot gnu.org
2014-07-09 19:52 ` rionda at gmail dot com
@ 2014-07-09 20:49 ` manu at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: manu at gcc dot gnu.org @ 2014-07-09 20:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59800
Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|WAITING |NEW
CC| |manu at gcc dot gnu.org
--- Comment #4 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
The meaning is explained here: https://gcc.gnu.org/bugs/management.html
but I think it was a slip in this case.
Probably the uninit pass is not powerful enough, but in this case the warning
should be suppressed for system-headers:
manuel@gcc10:~$ ~/test1/210581/install/bin/g++ -std=c++11 -O2 -Wsystem-headers
-Wmaybe-uninitialized test.cc
In file included from
/home/manuel/test1/210581/install/include/c++/4.10.0/random:51:0,
from test.cc:3:
/home/manuel/test1/210581/install/include/c++/4.10.0/bits/random.tcc: In
function ‘int main(int, char**)’:
/home/manuel/test1/210581/install/include/c++/4.10.0/bits/random.tcc:1964:2:
warning: ‘*((void*)(&
my_lognormal)+16).std::normal_distribution<double>::_M_saved’ may be used
uninitialized in this function [-Wmaybe-uninitialized]
__ret = __ret * __param.stddev() + __param.mean();
^
test.cc:11:33: note: ‘*((void*)(&
my_lognormal)+16).std::normal_distribution<double>::_M_saved’ was declared here
lognormal_distribution<double> my_lognormal(0.0, 1.0);
^
and -flto bypassed the system_header pragma somehow.
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From: "unmobile at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/46097] Switch to warn of global variables in a C++ shared object
Date: Wed, 09 Jul 2014 21:13:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idF097
Phil Miller <unmobile at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |unmobile at gmail dot com
--- Comment #32 from Phil Miller <unmobile at gmail dot com> ---
A switch to generate warnings about global variables would be useful to me and
my colleagues (http://ppl.cs.illinois.edu/) for a reason totally distinct from
ODR violations. We have a parallel programming system that includes a feature
for running application code in multiple, nominally independent, user-level
threads within a process. A mechanism to call attention to code that may fail
or misbehave in this setting would be helpful.
I would definitely agree that this doesn't belong in -Wall or -Wextra, as such.
So a -fnote-global-variables might be more appropriate.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2014-07-09 20:49 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-01-14 6:01 [Bug c++/59800] New: Compilation with g++ fails when -Ofast -flto is used to compile code using some <random> distribution rionda at gmail dot com
2014-01-14 12:05 ` [Bug c++/59800] " rguenth at gcc dot gnu.org
2014-07-09 19:52 ` rionda at gmail dot com
2014-07-09 20:49 ` manu at gcc dot gnu.org
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