https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104414
Bug ID: 104414
Summary: [AArch64] About the condition of calls_alloca in
aarch64_layout_frame
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: ashimida at linux dot alibaba.com
Target Milestone: ---
There is the following code in aarch64_layout_frame:
else if (crtl->outgoing_args_size.is_constant (&const_outgoing_args_size)
&& frame.saved_regs_size.is_constant (&const_saved_regs_size)
&& const_outgoing_args_size + const_saved_regs_size < 512
&& (!saves_below_hard_fp_p || const_outgoing_args_size == 0)
// 1)
&& !(cfun->calls_alloca
&& frame.hard_fp_offset.is_constant (&const_fp_offset)
&& const_fp_offset < max_push_offset))
{
/* Frame with small outgoing arguments:
sub sp, sp, frame_size
stp reg1, reg2, [sp, outgoing_args_size]
stp reg3, reg4, [sp, outgoing_args_size + 16] */
frame.initial_adjust = frame.frame_size;
frame.callee_offset = const_outgoing_args_size;
}
......
else if (frame.hard_fp_offset.is_constant (&const_fp_offset)
&& const_fp_offset < max_push_offset)
{
// 2)
/* Frame with large outgoing arguments or SVE saves, but with
a small local area:
stp reg1, reg2, [sp, -hard_fp_offset]!
stp reg3, reg4, [sp, 16]
[sub sp, sp, below_hard_fp_saved_regs_size]
[save SVE registers relative to SP]
sub sp, sp, outgoing_args_size */
As described in 2), "Frame with large outgoing arguments or SVE saves,
but with a small local area".
But due to the condition at 1), the following code (small outgoing with
a small local area) also uses the insns in 2), which is slightly different
from the description:
#include <stdio.h>
#include <alloca.h>
#define REP9(X) X,X,X,X,X,X,X,X,X
int alloc_size;
void outgoing_1 (int x, ...)
{
return 0;
}
int main(void)
{
outgoing1 (REP9(1));
char * y = alloca(alloc_size);
return 0;
}
Could the condition in 1) be removed, or am I missing something?
Thanks,
Dan.
