Hello,
for RTEMS we use linker sets to initialize the system. The following
code worked up to GCC 6, but no longer in GCC 7:
typedef void ( *rtems_sysinit_handler )( void );
typedef struct {
rtems_sysinit_handler handler;
} rtems_sysinit_item;
rtems_sysinit_item volatile const _Linker_set__Sysinit_begin[0]
__attribute__((__section__(".rtemsroset." "_Sysinit" ".begin")))
__attribute__((__used__));
rtems_sysinit_item volatile const _Linker_set__Sysinit_end[0]
__attribute__((__section__(".rtemsroset." "_Sysinit" ".end")))
__attribute__((__used__));
void rtems_initialize_executive(void)
{
const volatile rtems_sysinit_item *cur = _Linker_set__Sysinit_begin;
const volatile rtems_sysinit_item *end = _Linker_set__Sysinit_end;
while ( cur != end ) {
( *cur->handler )();
++cur;
}
}
The corresponding GNU ld linker script section is:
.rtemsroset : ALIGN_WITH_INPUT {
KEEP (*(SORT(.rtemsroset.*)))
} > REGION_RODATA AT > REGION_RODATA_LOAD
In GCC 7, the compiler deduces that "cur != end" is always true and
generates an infinite loop.
Up to GCC 6 the "volatile const" seemed to prevent this optimization. I
know that this linker set stuff is quite non-standard, but is there a
way to get this to work again on GCC 7?
The nice thing with the "type volatile const X[0]..." construct is that
you can generate arbitrary linker sets via it without a need to edit the
linker command file and with no storage overhead.
--
Sebastian Huber, embedded brains GmbH
Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone : +49 89 189 47 41-16
Fax : +49 89 189 47 41-09
E-Mail : sebastian.hu...@embedded-brains.de
PGP : Public key available on request.
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