http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60221
Bug ID: 60221
Summary: gcc -fexceptions generates unnecessary cleanup code
Product: gcc
Version: 4.8.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: redlizard at redlizard dot nl
> gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/tmp/gcc-4.8.2/libexec/gcc/x86_64-unknown-linux-gnu/4.8.2/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-4.8.2/configure --prefix=/tmp/gcc-4.8.2
--enable-languages=c,c++
Thread model: posix
gcc version 4.8.2 (GCC)
> cat test.c
void bar(void);
void foo(void)
{
struct { int x; } y;
bar();
}
When compiled with `gcc -fexceptions -O0 -c test.c`, the above code generates
cleanup code for stack unwinding purposes, referencing __gcc_personality_v0;
this necessitates linking with shared-libgcc.
I am not sure this is really a bug, but versions of gcc older than 4.7 do not
generate cleanup code for this example; neither does gcc 4.8 when the local
variable is replaced by `int y;`. Moreover, according to the gcc documentation,
there are "several situations" (I have been unable to find more a detailed
specification) in which linking with shared-libgcc is necessary, which includes
code throwing or catching exceptions, but should -- as far as I can see --
*not* include c code just passing through exceptions.
Tested on x86_64-unknown-linux-gnu, x86_64-unknown-linux-gnu -m32, and
i386-pc-solaris2.11, using gcc 4.7.1, 4.7.3, and 4.8.2. gcc 4.6.4 and earlier
tested versions are not affected. I have been unable to test gcc 4.7.0.
