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From: "regehr at cs dot utah.edu" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c/52979] New: likely wrong code bug w/packed bitfields Date: Fri, 13 Apr 2012 16:35:00 -0000 [thread overview] Message-ID: <bug-52979-4@http.gcc.gnu.org/bugzilla/> (raw) http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52979 Bug #: 52979 Summary: likely wrong code bug w/packed bitfields Classification: Unclassified Product: gcc Version: 4.8.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassigned@gcc.gnu.org ReportedBy: regehr@cs.utah.edu CC: chenyang@cs.utah.edu [regehr@dyson r30]$ current-gcc -O2 small.c ; ./a.out 0 [regehr@dyson r30]$ current-gcc -O3 small.c ; ./a.out 1 [regehr@dyson r30]$ cat small.c int printf (const char *, ...); int c, d, e; void fn1 () { } #pragma pack(1) struct S1 { int f0:31; int f1:6; } a = { 1 }; static struct S1 b = { 1 }; void fn2 () { for (;;) { a.f1 = 1; struct S1 f = { }; b = f; e = 0; if (d) c = a.f0; break; } } void fn3 () { fn2 (); a = b; } int main (void) { fn3 (); printf ("%d\n", a.f0); return 0; } [regehr@dyson r30]$ current-gcc -v Using built-in specs. COLLECT_GCC=current-gcc COLLECT_LTO_WRAPPER=/uusoc/exports/scratch/regehr/z/compiler-install/gcc-r186403-install/bin/../libexec/gcc/x86_64-unknown-linux-gnu/4.8.0/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: ../configure --with-libelf=/usr/local --enable-lto --prefix=/home/regehr/z/compiler-install/gcc-r186403-install --program-prefix=r186403- --enable-languages=c,c++ Thread model: posix gcc version 4.8.0 20120413 (experimental) (GCC)
next reply other threads:[~2012-04-13 16:35 UTC|newest] Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-04-13 16:35 regehr at cs dot utah.edu [this message] 2012-04-16 9:46 ` [Bug tree-optimization/52979] [4.7/4.8 Regression] " rguenth at gcc dot gnu.org 2012-04-23 17:39 ` jakub at gcc dot gnu.org 2012-04-23 17:48 ` regehr at cs dot utah.edu 2012-04-24 10:48 ` jakub at gcc dot gnu.org 2012-04-24 11:42 ` jakub at gcc dot gnu.org 2012-04-24 12:00 ` rguenth at gcc dot gnu.org 2012-04-24 12:29 ` rguenth at gcc dot gnu.org 2012-04-24 15:34 ` jakub at gcc dot gnu.org 2012-04-25 14:27 ` jakub at gcc dot gnu.org 2012-04-25 18:37 ` [Bug tree-optimization/52979] [4.7 " jakub at gcc dot gnu.org 2012-04-26 14:16 ` rguenth at gcc dot gnu.org 2012-06-04 10:20 ` rguenth at gcc dot gnu.org 2012-06-04 10:24 ` rguenth at gcc dot gnu.org
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