* [Bug c++/32132] bogus warning at -O3 ( 'r' may be used uninitialized in this function ).
2007-05-28 20:08 [Bug c++/32132] New: bogus warning at -O3 ( 'r' may be used uninitialized in this function ) pluto at agmk dot net
@ 2007-05-28 20:09 ` pluto at agmk dot net
2007-05-28 20:13 ` pinskia at gcc dot gnu dot org
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From: pluto at agmk dot net @ 2007-05-28 20:09 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from pluto at agmk dot net 2007-05-28 20:08 -------
Created an attachment (id=13623)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=13623&action=view)
testcase
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32132
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug c++/32132] bogus warning at -O3 ( 'r' may be used uninitialized in this function ).
2007-05-28 20:08 [Bug c++/32132] New: bogus warning at -O3 ( 'r' may be used uninitialized in this function ) pluto at agmk dot net
2007-05-28 20:09 ` [Bug c++/32132] " pluto at agmk dot net
@ 2007-05-28 20:13 ` pinskia at gcc dot gnu dot org
2007-05-28 20:16 ` pluto at agmk dot net
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From: pinskia at gcc dot gnu dot org @ 2007-05-28 20:13 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from pinskia at gcc dot gnu dot org 2007-05-28 20:13 -------
This might not be a bug ....
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32132
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug c++/32132] bogus warning at -O3 ( 'r' may be used uninitialized in this function ).
2007-05-28 20:08 [Bug c++/32132] New: bogus warning at -O3 ( 'r' may be used uninitialized in this function ) pluto at agmk dot net
2007-05-28 20:09 ` [Bug c++/32132] " pluto at agmk dot net
2007-05-28 20:13 ` pinskia at gcc dot gnu dot org
@ 2007-05-28 20:16 ` pluto at agmk dot net
2007-05-28 20:26 ` pinskia at gcc dot gnu dot org
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From: pluto at agmk dot net @ 2007-05-28 20:16 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from pluto at agmk dot net 2007-05-28 20:16 -------
(In reply to comment #2)
> This might not be a bug ....
>
so, how 'r' can be used uninitialized in this case?
template <typename R>
R hex_cast ( const std::string & s )
{
if ( s.empty () )
throw bad_hex_cast ();
R r;
std::istringstream str ( s );
str >> std::hex >> r;
return r;
}
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32132
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug c++/32132] bogus warning at -O3 ( 'r' may be used uninitialized in this function ).
2007-05-28 20:08 [Bug c++/32132] New: bogus warning at -O3 ( 'r' may be used uninitialized in this function ) pluto at agmk dot net
` (2 preceding siblings ...)
2007-05-28 20:16 ` pluto at agmk dot net
@ 2007-05-28 20:26 ` pinskia at gcc dot gnu dot org
2007-05-28 21:48 ` pinskia at gcc dot gnu dot org
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From: pinskia at gcc dot gnu dot org @ 2007-05-28 20:26 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from pinskia at gcc dot gnu dot org 2007-05-28 20:26 -------
so, how 'r' can be used uninitialized in this case?
Because istringstream >> r could have caused an error. so you need to check if
there is an error.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32132
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug c++/32132] bogus warning at -O3 ( 'r' may be used uninitialized in this function ).
2007-05-28 20:08 [Bug c++/32132] New: bogus warning at -O3 ( 'r' may be used uninitialized in this function ) pluto at agmk dot net
` (3 preceding siblings ...)
2007-05-28 20:26 ` pinskia at gcc dot gnu dot org
@ 2007-05-28 21:48 ` pinskia at gcc dot gnu dot org
2007-05-29 8:51 ` pluto at agmk dot net
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From: pinskia at gcc dot gnu dot org @ 2007-05-28 21:48 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from pinskia at gcc dot gnu dot org 2007-05-28 21:48 -------
The warning is correct you need to check if str had an error after reading the
integer. This is not a GCC bug.
The IR looks like:
<bb 7>:
__comp_ctor (&str, s, 8);
this.104 = (struct ios_base *) &str.D.25711;
__s = this.104 + *(int *) (str.D.25711._vptr.basic_istream + -12);
D.40158 = __s->_M_fmtflags;
__s->_M_fmtflags = D.40158 & -57 | 16;
_M_get_num (&str.D.25711, &__lval);
<bb 8>:
if (((this.104 + *(int *) (str.D.25711._vptr.basic_istream +
-12))->_M_iostate & 5) != 0)
goto <bb 10>;
else
goto <bb 9>;
<bb 9>:
__lval.107 = __lval;
r = __lval.107;
<bb 10>:
__comp_dtor (&str);
return r;
Which shows for sure r may be used unitialized.
Note using libstdc++ does not warn about this because we made >> out of line
only which means you will not see the warning (even though the warning is
correct).
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution| |INVALID
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32132
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug c++/32132] bogus warning at -O3 ( 'r' may be used uninitialized in this function ).
2007-05-28 20:08 [Bug c++/32132] New: bogus warning at -O3 ( 'r' may be used uninitialized in this function ) pluto at agmk dot net
` (4 preceding siblings ...)
2007-05-28 21:48 ` pinskia at gcc dot gnu dot org
@ 2007-05-29 8:51 ` pluto at agmk dot net
2007-05-29 10:18 ` pluto at agmk dot net
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From: pluto at agmk dot net @ 2007-05-29 8:51 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from pluto at agmk dot net 2007-05-29 08:50 -------
(In reply to comment #5)
> Which shows for sure r may be used unitialized.
yes, but even if i catch possible i/o failure, gcc still produces warning.
--- auHexCastTest.ii.orig
+++ auHexCastTest.ii
@@ -18958,7 +18958,12 @@
R r;
stlp_std::istringstream str ( s );
- str >> stlp_std::hex >> r;
+ str.exceptions ( stlp_std::istringstream::eofbit ||
stlp_std::istringstream::badbit || stlp_std::istringstream::failbit );
+ try {
+ str >> stlp_std::hex >> r;
+ } catch ( stlp_std::istringstream::failure ) {
+ throw;
+ }
return r;
}
so, is it still an invalid testcase?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32132
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug c++/32132] bogus warning at -O3 ( 'r' may be used uninitialized in this function ).
2007-05-28 20:08 [Bug c++/32132] New: bogus warning at -O3 ( 'r' may be used uninitialized in this function ) pluto at agmk dot net
` (5 preceding siblings ...)
2007-05-29 8:51 ` pluto at agmk dot net
@ 2007-05-29 10:18 ` pluto at agmk dot net
2007-05-29 12:31 ` manu at gcc dot gnu dot org
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From: pluto at agmk dot net @ 2007-05-29 10:18 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from pluto at agmk dot net 2007-05-29 10:17 -------
(In reply to comment #6)
> + str.exceptions ( stlp_std::istringstream::eofbit ||
> stlp_std::istringstream::badbit || stlp_std::istringstream::failbit );
^^^^^^^^^^^^ of course it should be '|' instead of '||' (shame on me)
but the warning is still presents. it is also presents when i use
the fail() method instead of exceptions machinery.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32132
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug c++/32132] bogus warning at -O3 ( 'r' may be used uninitialized in this function ).
2007-05-28 20:08 [Bug c++/32132] New: bogus warning at -O3 ( 'r' may be used uninitialized in this function ) pluto at agmk dot net
` (6 preceding siblings ...)
2007-05-29 10:18 ` pluto at agmk dot net
@ 2007-05-29 12:31 ` manu at gcc dot gnu dot org
2007-05-29 12:35 ` pluto at agmk dot net
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From: manu at gcc dot gnu dot org @ 2007-05-29 12:31 UTC (permalink / raw)
To: gcc-bugs
------- Comment #8 from manu at gcc dot gnu dot org 2007-05-29 12:31 -------
(In reply to comment #6)
>
> so, is it still an invalid testcase?
Does the warning show up with -O1 and -O2 ?
--
manu at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |manu at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32132
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug c++/32132] bogus warning at -O3 ( 'r' may be used uninitialized in this function ).
2007-05-28 20:08 [Bug c++/32132] New: bogus warning at -O3 ( 'r' may be used uninitialized in this function ) pluto at agmk dot net
` (7 preceding siblings ...)
2007-05-29 12:31 ` manu at gcc dot gnu dot org
@ 2007-05-29 12:35 ` pluto at agmk dot net
2007-05-29 12:42 ` pluto at agmk dot net
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From: pluto at agmk dot net @ 2007-05-29 12:35 UTC (permalink / raw)
To: gcc-bugs
------- Comment #9 from pluto at agmk dot net 2007-05-29 12:35 -------
(In reply to comment #8)
> (In reply to comment #6)
> >
> > so, is it still an invalid testcase?
>
> Does the warning show up with -O1 and -O2 ?
>
only with -O3.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32132
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug c++/32132] bogus warning at -O3 ( 'r' may be used uninitialized in this function ).
2007-05-28 20:08 [Bug c++/32132] New: bogus warning at -O3 ( 'r' may be used uninitialized in this function ) pluto at agmk dot net
` (8 preceding siblings ...)
2007-05-29 12:35 ` pluto at agmk dot net
@ 2007-05-29 12:42 ` pluto at agmk dot net
2007-05-29 12:57 ` manu at gcc dot gnu dot org
2007-06-10 3:19 ` pinskia at gcc dot gnu dot org
11 siblings, 0 replies; 13+ messages in thread
From: pluto at agmk dot net @ 2007-05-29 12:42 UTC (permalink / raw)
To: gcc-bugs
------- Comment #10 from pluto at agmk dot net 2007-05-29 12:42 -------
Created an attachment (id=13627)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=13627&action=view)
update for the testcase.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32132
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug c++/32132] bogus warning at -O3 ( 'r' may be used uninitialized in this function ).
2007-05-28 20:08 [Bug c++/32132] New: bogus warning at -O3 ( 'r' may be used uninitialized in this function ) pluto at agmk dot net
` (9 preceding siblings ...)
2007-05-29 12:42 ` pluto at agmk dot net
@ 2007-05-29 12:57 ` manu at gcc dot gnu dot org
2007-06-10 3:19 ` pinskia at gcc dot gnu dot org
11 siblings, 0 replies; 13+ messages in thread
From: manu at gcc dot gnu dot org @ 2007-05-29 12:57 UTC (permalink / raw)
To: gcc-bugs
------- Comment #11 from manu at gcc dot gnu dot org 2007-05-29 12:57 -------
(In reply to comment #9)
> (In reply to comment #8)
> > (In reply to comment #6)
> > >
> > > so, is it still an invalid testcase?
> >
> > Does the warning show up with -O1 and -O2 ?
> >
>
> only with -O3.
>
That is a bug by itself. Using more optimisations could result in some cases
clearing out (and thus, less warnings). It should never result in more
warnings.
--
manu at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |UNCONFIRMED
Resolution|INVALID |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32132
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug c++/32132] bogus warning at -O3 ( 'r' may be used uninitialized in this function ).
2007-05-28 20:08 [Bug c++/32132] New: bogus warning at -O3 ( 'r' may be used uninitialized in this function ) pluto at agmk dot net
` (10 preceding siblings ...)
2007-05-29 12:57 ` manu at gcc dot gnu dot org
@ 2007-06-10 3:19 ` pinskia at gcc dot gnu dot org
11 siblings, 0 replies; 13+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2007-06-10 3:19 UTC (permalink / raw)
To: gcc-bugs
------- Comment #12 from pinskia at gcc dot gnu dot org 2007-06-10 03:18 -------
> It should never result in more warnings.
More inlining :)
Anyways the use is still uninitialized if you look at the IR, GCC itself cannot
tell if r is initialized by looking at the IR.
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution| |INVALID
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32132
^ permalink raw reply [flat|nested] 13+ messages in thread