https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84292
Bug ID: 84292
Summary: __sync_add_and_fetch returns the old value instead of
the new value
Product: gcc
Version: 5.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libgcc
Assignee: unassigned at gcc dot gnu.org
Reporter: maryse.levavasseur at stormshield dot eu
Target Milestone: ---
Created attachment 43378
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43378&action=edit
proposed patch
I am using gcc5.4.0 on ARMv5 and FreeBSD 10.3
and __sync_add_and_fetch returns the old value of the first argument while I
expect the new value.
#include <stdio.h>
int main(void)
{
unsigned int var = 1;
printf("%u\n", __sync_add_and_fetch(&var, 1));
return 0;
}
==> This displays 1 on ARMv5 and 2 on the other platforms (still on FreeBSD
10.3)
In the source file libgcc/config/arm/freebsd-atomic.c,
the source code of __sync_##NAME##_and_fetch_##N is exactly the same as
__sync_fetch_and_##NAME##_##N
You can find attached a proposed patch for this problem.
$ gcc5 -v
Using built-in specs.
COLLECT_GCC=gcc5
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc5/gcc/arm-portbld-freebsd10.3/5.4.0/lto-wrapper
Target: arm-portbld-freebsd10.3
Configured with: ../gcc-5.4.0/configure --disable-multilib
--with-build-config=bootstrap-debug --disable-nls
--enable-gnu-indirect-function --libdir=/usr/local/lib/gcc5
--libexecdir=/usr/local/libexec/gcc5 --program-suffix=5 --with-gmp=/usr/local
--with-gxx-include-dir=/usr/local/lib/gcc5/include/c++/
--with-pkgversion='FreeBSD Ports Collection' --with-system-zlib
--disable-libgcj --enable-languages=c,c++ --prefix=/usr/local
--localstatedir=/var --mandir=/usr/local/man --infodir=/usr/local/info/gcc5
--target=arm-portbld-freebsd10.3 --disable-lto
Thread model: posix
gcc version 5.4.0 (FreeBSD Ports Collection)
