https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92860
Bug ID: 92860
Summary: [8,9,10 regression] Global flags affected by -O
settings are clobbered by optimize attribute
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: hubicka at gcc dot gnu.org
Target Milestone: ---
Hi,
the following testcase:
void linker_error();
__attribute__ ((optimize("-O0")))
int a ()
{
}
static int remove_me ()
{
linker_error ();
}
void
main()
{
}
builds with GCC6 but not with GCC8, GCC9 and GCC10:
hubicka@lomikamen-jh:/aux/hubicka/trunk4/gcc$ gcc -O2 t.c
hubicka@lomikamen-jh:/aux/hubicka/trunk4/gcc$
/aux/hubicka/trunk-install/bin/gcc -O2 t.c
/usr/local/bin/ld: /tmp/cckSFE5R.o: in function `remove_me':
t.c:(.text+0x17): undefined reference to `linker_error'
collect2: error: ld returned 1 exit status
The problem is that while processing the optimize attribute for a we overwritte
flag_toplevel_reorder that is affected by optimization flag but not marked as
Optimization. I suppose there are other cases like this.
