https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69981
Bug ID: 69981
Summary: -f[no]keep-static-consts has no effect
Product: gcc
Version: 5.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: equinox-gccbugs at diac24 dot net
Target Milestone: ---
This bug is an extension of #20319; the -fkeep-static-consts option seems to
have no effect in either direction. (#20319 was focused on the "-fkeep"
variant; my issue is with -O0 -fno-keep-static-consts.)
My application code is
extern struct foo ref;
static struct foo * const myconst = &ref;
Where ref is defined in a library that is not always linked in, which works on
-O1 -Og -Os -O2 -O3 but not on "-O0 -fno-keep-static-consts". I think it
should.
Trying older versions, gcc-4.2.4 already behaves the same.
$ ./test.sh
gcc-4.9.3 -O0
0000000000000000 l O .rodata 0000000000000004 intval
0000000000000000 l O .data.rel.ro 0000000000000008 ptrval
gcc-4.9.3 -O0 -fkeep-static-consts
0000000000000000 l O .rodata 0000000000000004 intval
0000000000000000 l O .data.rel.ro 0000000000000008 ptrval
gcc-4.9.3 -O0 -fno-keep-static-consts
0000000000000000 l O .rodata 0000000000000004 intval
0000000000000000 l O .data.rel.ro 0000000000000008 ptrval
gcc-4.9.3 -O1
gcc-4.9.3 -O1 -fkeep-static-consts
gcc-4.9.3 -O1 -fno-keep-static-consts
gcc-5.3.0 -O0
0000000000000000 l O .rodata 0000000000000004 intval
0000000000000000 l O .data.rel.ro 0000000000000008 ptrval
gcc-5.3.0 -O0 -fkeep-static-consts
0000000000000000 l O .rodata 0000000000000004 intval
0000000000000000 l O .data.rel.ro 0000000000000008 ptrval
gcc-5.3.0 -O0 -fno-keep-static-consts
0000000000000000 l O .rodata 0000000000000004 intval
0000000000000000 l O .data.rel.ro 0000000000000008 ptrval
gcc-5.3.0 -O1
gcc-5.3.0 -O1 -fkeep-static-consts
gcc-5.3.0 -O1 -fno-keep-static-consts
$ cat test.sh
#!/bin/sh
cat >const.c <<EOF
static const int intval = 1234;
extern int dst;
static int * const ptrval = &dst;
EOF
for CC in gcc-4.9.3 gcc-5.3.0; do
for OPT in -O0 -O1; do
for ARG in "" "-fkeep-static-consts" "-fno-keep-static-consts";
do
echo $CC $OPT $ARG
$CC $OPT $ARG -o const.o -c const.c
objdump -t const.o | grep val
done
done
done
