On 02/28/2012 08:32 PM, ольга крыжановская wrote:
Michal, why are you comiling with -fno-strict-aliasing? Any problems
with C aliasing should IMO be reported as bugs and fixed quickly,
because it causes trouble with other platforms and portabilty.
Why? Because of this:
warning: dereferencing type-punned pointer will break strict-aliasing rules
If some optimization can't be used, it should be turned off.
Why do you think it's a bug?
"""
-fstrict-aliasing
Allow the compiler to assume the strictest aliasing rules
applicable to the language being compiled. For C (and C++), this
ctivates optimizations based on the type of expressions.
"""
The code is still valid and works as expected. Only some type of
optimization can't be used. Maybe it's an annoyance, but I won't call it
a bug.
The warnings in your mail, which gcc and ast-open version did you use?
I tested with Suse 12.1, gcc (SUSE Linux) 4.6.2, ast-open.2012-02-14
and only got this one warning
src/lib/libast/vmalloc/vmstat.c: In function 'vmstat':
src/lib/libast/vmalloc/vmstat.c:100:7: warning: dereferencing
type-punned pointer will break strict-aliasing rules
[-Wstrict-aliasing]
Olga
On Tue, Feb 28, 2012 at 3:59 PM, Michal Hlavinka<[email protected]> wrote:
On 02/26/2012 01:29 PM, ольга крыжановская wrote:
Glenn, I use a newer gcc version: gcc (SUSE Linux) 4.5.0 20100604
[gcc-4_5-branch revision 160292].
Can any one in the list confirm the warning with gcc>= 4.5?
We use -fno-strict-aliasing for ksh compilation. I've turned it off and got
this:
src/lib/libast/vmalloc/vmbest.c:202:5: warning: dereferencing type-punned
pointer will break strict-aliasing rules
src/lib/libast/vmalloc/vmbest.c:440:4: warning: dereferencing type-punned
pointer will break strict-aliasing rules
src/lib/libast/vmalloc/vmbest.c:571:3: warning: dereferencing type-punned
pointer will break strict-aliasing rules
src/lib/libast/vmalloc/vmbest.c:682:3: warning: dereferencing type-punned
pointer will break strict-aliasing rules
src/lib/libast/vmalloc/vmbest.c:693:5: warning: dereferencing type-punned
pointer will break strict-aliasing rules
src/lib/libast/vmalloc/vmbest.c:694:5: warning: dereferencing type-punned
pointer will break strict-aliasing rules
src/lib/libast/vmalloc/vmopen.c:145:2: warning: dereferencing type-punned
pointer will break strict-aliasing rules
src/lib/libast/vmalloc/vmopen.c:150:2: warning: dereferencing type-punned
pointer will break strict-aliasing rules
src/lib/libast/vmalloc/vmopen.c:151:2: warning: dereferencing type-punned
pointer will break strict-aliasing rules
src/lib/libast/vmalloc/vmprivate.c:169:2: warning: dereferencing type-punned
pointer will break strict-aliasing rules
src/lib/libast/vmalloc/vmstat.c:100:7: warning: dereferencing type-punned
pointer will break strict-aliasing rules
src/lib/libast/vmalloc/vmstat.c:102:7: warning: dereferencing type-punned
pointer will break strict-aliasing rules
src/lib/libsum/sum-sha2.c:743:2: warning: dereferencing type-punned pointer
will break strict-aliasing rules
src/lib/libsum/sum-sha2.c:1104:2: warning: dereferencing type-punned pointer
will break strict-aliasing rules
src/lib/libsum/sum-sha2.c:1105:2: warning: dereferencing type-punned pointer
will break strict-aliasing rules
src/cmd/ksh93/edit/emacs.c:1077:7: warning: dereferencing type-punned
pointer will break strict-aliasing rules
src/cmd/ksh93/edit/emacs.c:1079:7: warning: dereferencing type-punned
pointer will break strict-aliasing rules
Olga
On Sun, Feb 26, 2012 at 7:02 AM, Glenn Fowler<[email protected]>
wrote:
I don;t see this with
gcc version 4.3.4 [gcc-4_3-branch revision 152973] (SUSE Linux)
On Wed, 15 Feb 2012 23:32:38 +0100 =?KOI8-R?B?z8zYx8Egy9LZ1sHOz9fTy8HR?=
wrote:
Glenn, in libast's vmalloc I get this warning if I compile libast on
Suse Linux with gcc4 and CCFLAGS='-O3 -flto -fstrict-aliasing
-Wstrict-aliasing': src/lib/libast/vmalloc/vmstat.c:100:7: warning:
dereferencing type-punned pointer will break strict-aliasing rules
This appears to be the only aliasing related warning.
Olga
--
, _ _ ,
{ \/`o;====- Olga Kryzhanovska -====;o`\/ }
.----'-/`-/ [email protected] \-`\-'----.
`'-..-| / http://twitter.com/fleyta \ |-..-'`
/\/\ Solaris/BSD//C/C++ programmer /\/\
`--` `--`
_______________________________________________
ast-developers mailing list
[email protected]
https://mailman.research.att.com/mailman/listinfo/ast-developers
_______________________________________________
ast-developers mailing list
[email protected]
https://mailman.research.att.com/mailman/listinfo/ast-developers
_______________________________________________
ast-developers mailing list
[email protected]
https://mailman.research.att.com/mailman/listinfo/ast-developers
