https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65090
Bug ID: 65090
Summary: GCC produces instruction with bad alignment on SPARC
when using -O
Product: gcc
Version: 4.7.4
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: dirk.bo...@inform-ac.com
Created attachment 34789
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34789&action=edit
Complete source code
$ uname -a
SunOS uxs450 5.10 Generic_150400-17 sun4v sparc sun4v Solaris
$ g++-4.7 -v
Using built-in specs.
COLLECT_GCC=g++-4.7
COLLECT_LTO_WRAPPER=/opt/its/runtime/gcc/4.7/libexec/gcc/sparc-sun-solaris2.10/4.7.4/lto-wrapper
Target: sparc-sun-solaris2.10
Configured with:
/SSD/compile/toolsexternal/packages/gcc-4.7/work/gcc-4.7.4/configure
--prefix=/opt/its/runtime/gcc/4.7 --program-suffix=-4.7
--enable-languages=c,c++ --disable-multilib --disable-nls
--enable-threads=posix --enable-__cxa_atexit --enable-libstdcxx-debug
--with-gnu-as --with-gnu-ld
Thread model: posix
gcc version 4.7.4 (GCC)
I got it down to two small files (see attachment). Reproduce it like this:
$ g++-4.7 -O -std=gnu++11 -c t.cc
$ g++-4.7 -O -std=gnu++11 -c t2.cc
$ g++-4.7 -O -std=gnu++11 -c t.cc
$ g++-4.7 -O -std=gnu++11 -c t2.cc
$ g++-4.7 -o t t.o t2.o
$ ./t
Bus Error (core dumped)
The code generated for "somefunction" is broken:
00010a68 <_Z12somefunctionv>:
10a68: 9d e3 bf 80 save %sp, -128, %sp
10a6c: c0 27 bf e4 clr [ %fp + -28 ]
10a70: c0 27 bf e8 clr [ %fp + -24 ]
10a74: c0 27 bf ec clr [ %fp + -20 ]
10a78: c0 27 bf f0 clr [ %fp + -16 ]
10a7c: c0 27 bf fb clr [ %fp + -5 ]
...
"%fp - 5" is not 4 bytes aligned and causes the bus error.
The function somefunction is in t.cc (attached), the relevant part is:
struct X {
size_t a = 0;
std::vector vec_;
X() {
vec_.emplace_back(nullptr);
}
};
void somefunction()
{
X cv;
f2(string());
}
