On 09/17/16 22:29, Jan-Benedict Glaw wrote:
> On Fri, 2016-09-09 21:40:38 +0000, Bernd Edlinger <bernd.edlin...@hotmail.de>
> wrote:
>> Hi,
>>
>> I think it is time to remove support for INITIAL_FRAME_POINTER_OFFSET, which
>> is no longer
>> used by any target today. This removes a bunch of conditional code, and
>> fixes a few bits
>> in the documentation. I'd say that part of the documentation is quite out
>> of sync, but I just
>> have to stop somewhere.
>>
>>
>> Bootstrapped and reg-tested on x86_64-pc-linux.gnu
>
> The vax backend doesn't yet define ELIMINABLE_REGS.
>
Oh, yes. I see. What a hack.
Then we should define it.
But simply returning zero for the fp to sp offset is not ok,
and even if the offset is not used for register eliminations
it should still be correct for rtx_addr_can_trap_p
to know the safe stack frame offset ranges.
I would assume a small performance improvement, when
rtx_addr_can_trap_p has correct data available.
How about this patch, it should at least fix the bootstrap.
Is it OK for trunk?
Thanks
Bernd.
2016-09-17 Bernd Edlinger <bernd.edlin...@hotmail.de>
* config/var/vax.h (ELIMINABLE_REGS): Define.
(INITIAL_ELIMINATION_OFFSET): Define.
Index: gcc/config/vax/vax.h
===================================================================
--- gcc/config/vax/vax.h (revision 240215)
+++ gcc/config/vax/vax.h (working copy)
@@ -333,6 +333,16 @@
} \
while (0)
+/* This macro specifies a table of register pairs used to eliminate
+ unneeded registers that point into the stack frame. */
+#define ELIMINABLE_REGS {{FRAME_POINTER_REGNUM, STACK_POINTER_REGNUM}}
+
+/* On the VAX, FRAME_POINTER_REQUIRED is always 1, so the definition of this
+ macro doesn't matter for register eliminations, but it should still
+ give realistic data for rtx_addr_can_trap_p. */
+#define INITIAL_ELIMINATION_OFFSET(FROM, TO, OFFSET) \
+ ((OFFSET) = -get_frame_size ())
+
/* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
the stack pointer does not matter. The value is tested only in
functions that have frame pointers.
