Hi!
On Thu, Jan 10, 2019 at 04:36:35PM +0100, Eric Botcazou wrote:
> > If there are other spots that need this, wondering about:
> > else
> > copy = assign_temp (type, 1, 0);
> > in calls.c, either it can be done by using the variable-sized object
> > case in the then block, or could be done using assign_stack_local +
> > this short realignment too.
>
> The latter I'd say.
Will handle that tomorrow.
But, there is another thing, while assign_stack_local_1 lowers
alignment_in_bits to MAX_SUPPORTED_STACK_ALIGNMENT if it is higher than that
and records that in the MEM it creates, the caller,
assign_stack_temp_for_type will happily count with higher alignments and
on the MEMs it creates will happily set MEM_ALIGN to the higher value.
I think we shouldn't lie here, something in the optimizers could try to take
advantage of the higher MEM_ALIGN.
Bootstrapped/regtested on x86_64-linux and i686-linux, but that doesn't mean
much, because MAX_SUPPORTED_STACK_ALIGNMENT there is 1 << 28. Guess more
useful would be to test it on mingw where BIGGEST_ALIGNMENT is often higher
than MAX_SUPPORTED_STACK_ALIGNMENT.
Thoughts on this?
2019-01-10 Jakub Jelinek <ja...@redhat.com>
PR bootstrap/88450
* function.c (assign_stack_temp_for_type): Use alignment at most
MAX_SUPPORTED_STACK_ALIGNMENT. Adjust assert correspondingly.
--- gcc/function.c.jj 2019-01-10 00:13:47.593688442 +0100
+++ gcc/function.c 2019-01-10 00:17:42.464890435 +0100
@@ -792,6 +792,7 @@ assign_stack_temp_for_type (machine_mode
gcc_assert (known_size_p (size));
align = get_stack_local_alignment (type, mode);
+ align = MIN (align, MAX_SUPPORTED_STACK_ALIGNMENT);
/* Try to find an available, already-allocated temporary of the proper
mode which meets the size and alignment requirements. Choose the
@@ -872,8 +873,10 @@ assign_stack_temp_for_type (machine_mode
So for requests which depended on the rounding of SIZE, we go ahead
and round it now. We also make sure ALIGNMENT is at least
- BIGGEST_ALIGNMENT. */
- gcc_assert (mode != BLKmode || align == BIGGEST_ALIGNMENT);
+ minimum of BIGGEST_ALIGNMENT and MAX_SUPPORTED_STACK_ALIGNMENT. */
+ gcc_assert (mode != BLKmode
+ || align == MIN (BIGGEST_ALIGNMENT,
+ MAX_SUPPORTED_STACK_ALIGNMENT));
p->slot = assign_stack_local_1 (mode,
(mode == BLKmode
? aligned_upper_bound (size,
Jakub
