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* [Bug middle-end/56526] New: [4.8 regression] false positive for maybe-uninitialized
@ 2013-03-04 19:00 matt at use dot net
2013-03-04 19:06 ` [Bug middle-end/56526] " matt at use dot net
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: matt at use dot net @ 2013-03-04 19:00 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56526
Bug #: 56526
Summary: [4.8 regression] false positive for
maybe-uninitialized
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: matt@use.net
I haven't tracked down when this started happening, but it's a regression from
fsf/4.7 and google/4.7, as well as trunk from some months ago.
/work/mhargett/gcc-trunk-lto-O3/./prev-gcc/xg++
-B/work/mhargett/gcc-trunk-lto-O3/./prev-gcc/
-B/u/mhargett/x86_64-unknown-linux-gnu/bin/ -nostdinc++
-B/work/mhargett/gcc-trunk-lto-O3/prev-x86_64-unknown-linux-gnu/libstdc++-v3/src/.libs
-B/work/mhargett/gcc-trunk-lto-O3/prev-x86_64-unknown-linux-gnu/libstdc++-v3/libsupc++/.libs
-I/work/mhargett/gcc-trunk-lto-O3/prev-x86_64-unknown-linux-gnu/libstdc++-v3/include/x86_64-unknown-linux-gnu
-I/work/mhargett/gcc-trunk-lto-O3/prev-x86_64-unknown-linux-gnu/libstdc++-v3/include
-I/work/mhargett/gcc-trunk/libstdc++-v3/libsupc++
-L/work/mhargett/gcc-trunk-lto-O3/prev-x86_64-unknown-linux-gnu/libstdc++-v3/src/.libs
-L/work/mhargett/gcc-trunk-lto-O3/prev-x86_64-unknown-linux-gnu/libstdc++-v3/libsupc++/.libs
-O3 -g -flto=jobserver -frandom-seed=1 -DIN_GCC -fno-exceptions -fno-rtti
-fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings
-Wcast-qual -Wmissing-format-attribute -pedantic -Wno-long-long
-Wno-variadic-macros -Wno-overlength-strings -Werror -fno-common
-DHAVE_CONFIG_H -static-libstdc++ -static-libgcc gcc-nm.o -o gcc-nm \
file-find.o libcommon.a ../libcpp/libcpp.a
../libbacktrace/.libs/libbacktrace.a ../libiberty/libiberty.a
../libdecnumber/libdecnumber.a
../../gcc-trunk/libiberty/simple-object-mach-o.c: In function
'simple_object_mach_o_find_sections':
../../gcc-trunk/libiberty/simple-object-mach-o.c:653:37: error:
'wrapper_sect_offset' may be used uninitialized in this function
[-Werror=maybe-uninitialized]
secoffset = wrapper_sect_offset + subsect_offset;
^
lto1: all warnings being treated as errors
make[4]: *** [/tmp/ccGVpjK3.ltrans21.ltrans.o] Error 1
../../gcc-trunk/libiberty/simple-object-mach-o.c: In function
'simple_object_mach_o_find_sections':
../../gcc-trunk/libiberty/simple-object-mach-o.c:653:37: error:
'wrapper_sect_offset' may be used uninitialized in this function
[-Werror=maybe-uninitialized]
secoffset = wrapper_sect_offset + subsect_offset;
^
lto1: all warnings being treated as errors
make[4]: *** [/tmp/ccGVpjK3.ltrans21.ltrans.o] Error 1
lto-wrapper: make returned 2 exit status
/u/mhargett/x86_64-unknown-linux-gnu/bin/ld: lto-wrapper failed
collect2: error: ld returned 1 exit status
make[3]: *** [lto-wrapper] Error 1
make[3]: *** Waiting for unfinished jobs....
mv -f Tcollect2 collect2
make[3]: Leaving directory `/work/mhargett/gcc-trunk-lto-O3/gcc'
make[2]: *** [all-stage2-gcc] Error 2
wrapper_sect_offset is initialized in the block predicated by
((gnu_sections_found & SOMO_WRAPPING) != 0), and is only accessed in a block
with the same (outer) predicate.
reproduced with bootstrap-lto on current trunk with -O3. save-temp outputs are
attached.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug middle-end/56526] [4.8 regression] false positive for maybe-uninitialized
2013-03-04 19:00 [Bug middle-end/56526] New: [4.8 regression] false positive for maybe-uninitialized matt at use dot net
@ 2013-03-04 19:06 ` matt at use dot net
2013-03-05 10:23 ` rguenth at gcc dot gnu.org
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: matt at use dot net @ 2013-03-04 19:06 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56526
--- Comment #1 from Matt Hargett <matt at use dot net> 2013-03-04 19:04:58 UTC ---
Created attachment 29580
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29580
save-temps output from same commandline/path
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug middle-end/56526] [4.8 regression] false positive for maybe-uninitialized
2013-03-04 19:00 [Bug middle-end/56526] New: [4.8 regression] false positive for maybe-uninitialized matt at use dot net
2013-03-04 19:06 ` [Bug middle-end/56526] " matt at use dot net
@ 2013-03-05 10:23 ` rguenth at gcc dot gnu.org
2013-03-05 15:17 ` jakub at gcc dot gnu.org
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu.org @ 2013-03-05 10:23 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56526
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |diagnostic
Target Milestone|--- |4.8.0
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug middle-end/56526] [4.8 regression] false positive for maybe-uninitialized
2013-03-04 19:00 [Bug middle-end/56526] New: [4.8 regression] false positive for maybe-uninitialized matt at use dot net
2013-03-04 19:06 ` [Bug middle-end/56526] " matt at use dot net
2013-03-05 10:23 ` rguenth at gcc dot gnu.org
@ 2013-03-05 15:17 ` jakub at gcc dot gnu.org
2013-03-05 15:23 ` jakub at gcc dot gnu.org
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: jakub at gcc dot gnu.org @ 2013-03-05 15:17 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56526
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-03-05 15:16:59 UTC ---
Author: jakub
Date: Tue Mar 5 15:16:49 2013
New Revision: 196466
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=196466
Log:
PR middle-end/56526
* simple-object-mach-o.c (simple_object_mach_o_segment): Initialize
wrapper_sect_offset to avoid a warning.
Modified:
trunk/libiberty/ChangeLog
trunk/libiberty/simple-object-mach-o.c
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug middle-end/56526] [4.8 regression] false positive for maybe-uninitialized
2013-03-04 19:00 [Bug middle-end/56526] New: [4.8 regression] false positive for maybe-uninitialized matt at use dot net
` (2 preceding siblings ...)
2013-03-05 15:17 ` jakub at gcc dot gnu.org
@ 2013-03-05 15:23 ` jakub at gcc dot gnu.org
2013-03-06 2:06 ` matt at use dot net
2013-03-06 7:03 ` jakub at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: jakub at gcc dot gnu.org @ 2013-03-05 15:23 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56526
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
CC| |jakub at gcc dot gnu.org
Resolution| |FIXED
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-03-05 15:22:39 UTC ---
Should be fixed hopefully.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug middle-end/56526] [4.8 regression] false positive for maybe-uninitialized
2013-03-04 19:00 [Bug middle-end/56526] New: [4.8 regression] false positive for maybe-uninitialized matt at use dot net
` (3 preceding siblings ...)
2013-03-05 15:23 ` jakub at gcc dot gnu.org
@ 2013-03-06 2:06 ` matt at use dot net
2013-03-06 7:03 ` jakub at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: matt at use dot net @ 2013-03-06 2:06 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56526
--- Comment #4 from Matt Hargett <matt at use dot net> 2013-03-06 02:06:03 UTC ---
It does fix that warning, but there's a bug in the analysis that makes it a
false positive. I've had difficulty reducing it to a self-contained example,
and I don't have the expertise to do more in-depth debugging.
This should stay open until the analysis is done to show that it's an accepted
limitation of the warning's capabilities, IMO.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug middle-end/56526] [4.8 regression] false positive for maybe-uninitialized
2013-03-04 19:00 [Bug middle-end/56526] New: [4.8 regression] false positive for maybe-uninitialized matt at use dot net
` (4 preceding siblings ...)
2013-03-06 2:06 ` matt at use dot net
@ 2013-03-06 7:03 ` jakub at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: jakub at gcc dot gnu.org @ 2013-03-06 7:03 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56526
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-03-06 07:03:23 UTC ---
Maybe-uninitialized warnings have tons of known false positives, while the
predicated analysis can handle the simplest cases, it can't handle anything
more complicated. As this isn't a usable testcase, requires LTO to reproduce,
I don't think it is worth keeping it open.
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2013-03-06 7:03 UTC | newest]
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2013-03-04 19:00 [Bug middle-end/56526] New: [4.8 regression] false positive for maybe-uninitialized matt at use dot net
2013-03-04 19:06 ` [Bug middle-end/56526] " matt at use dot net
2013-03-05 10:23 ` rguenth at gcc dot gnu.org
2013-03-05 15:17 ` jakub at gcc dot gnu.org
2013-03-05 15:23 ` jakub at gcc dot gnu.org
2013-03-06 2:06 ` matt at use dot net
2013-03-06 7:03 ` jakub at gcc dot gnu.org
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