https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72488
Bug ID: 72488
Summary: wrong code (SIGFPE) at -Os and above on
x86_64-linux-gnu (in the 64-bit mode)
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: su at cs dot ucdavis.edu
Target Milestone: ---
Created attachment 39012
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39012&action=edit
test program
The current gcc trunk miscompiles the attached code (small.c) on
x86_64-linux-gnu at -Os and above in the 64-bit mode (but not in the 32-bit
mode).
This is a regression from 6.1.x.
The code is extremely difficult to reduce, so the reported test is still rather
large (21709 bytes). I am not certain, but fairly confident that it doesn't
have undefined behaviors as it passes UBSan, CompCert's reference interpreter,
the tis-interpreter, etc.
$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-source-trunk/configure --enable-languages=c,c++,lto
--prefix=/usr/local/gcc-trunk --disable-bootstrap
Thread model: posix
gcc version 7.0.0 20160725 (experimental) [trunk revision 238706] (GCC)
$
$ gcc-trunk -O1 small.c; ./a.out
507518-1357826554294967259-187769889781-5
$ gcc-6.1 -O2 small.c; ./a.out
507518-1357826554294967259-187769889781-5
$
$ gcc-trunk -Os small.c
$ ./a.out
Floating point exception (core dumped)
$
