Re: [committed] Fix -fstack-check with really big frames on aarch64

[Christophe Lyon <christophe.lyon@linaro.org>]

On 22 June 2017 at 19:21, Jeff Law <law@redhat.com> wrote:
>
> This time with the test.  Just #includes 20031023-1.c with a suitable dg
> directive to ensure we compile with -fstack-check.
>
> I won't be surprised if other targets fail this test.  It's a really big
> stack frame :-)
>
> Anyways, committed to the trunk.
>
>
>
> Jeff
>
> diff --git a/gcc/ChangeLog b/gcc/ChangeLog
> index 0a3426eef3e..03a824f6b3f 100644
> --- a/gcc/ChangeLog
> +++ b/gcc/ChangeLog
> @@ -1,3 +1,8 @@
> +2017-06-22  Jeff Law  <law@redhat.com>
> +
> +       * config/aarch64/aarch64.c (aarch64_emit_probe_stack_range): Handle
> +       frame sizes that do not satisfy aarch64_uimm12_shift.
> +
>  2017-06-22  Jan Hubicka <hubicka@ucw.cz>
>
>         * profile-count.h (apply_probability,
> diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
> index 3364a02e89c..95592f9fa17 100644
> --- a/gcc/config/aarch64/aarch64.c
> +++ b/gcc/config/aarch64/aarch64.c
> @@ -2766,11 +2766,19 @@ aarch64_emit_probe_stack_range (HOST_WIDE_INT first, HOST_WIDE_INT size)
>                      plus_constant (Pmode, stack_pointer_rtx, -first));
>
>        /* LAST_ADDR = SP + FIRST + ROUNDED_SIZE.  */
> -      emit_set_insn (reg2,
> -                    plus_constant (Pmode, stack_pointer_rtx,
> -                                   -(first + rounded_size)));
> -
> -
> +      HOST_WIDE_INT adjustment = - (first + rounded_size);
> +      if (! aarch64_uimm12_shift (adjustment))
> +       {
> +         aarch64_internal_mov_immediate (reg2, GEN_INT (adjustment),
> +                                         true, Pmode);
> +         emit_set_insn (reg2, gen_rtx_PLUS (Pmode, stack_pointer_rtx, reg2));
> +       }
> +      else
> +       {
> +         emit_set_insn (reg2,
> +                        plus_constant (Pmode, stack_pointer_rtx, adjustment));
> +       }
> +
>        /* Step 3: the loop
>
>          do
> diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
> index 641e4124e37..e162386fb68 100644
> --- a/gcc/testsuite/ChangeLog
> +++ b/gcc/testsuite/ChangeLog
> @@ -1,3 +1,7 @@
> +2017-06-22  Jeff Law  <law@redhat.com>
> +
> +       * gcc.c-torture/compile/stack-check-1.c: New test.
> +
>  2016-06-22  Richard Biener  <rguenther@suse.de>
>
>         * gcc.dg/vect/pr65947-1.c: Remove xfail.
> diff --git a/gcc/testsuite/gcc.c-torture/compile/stack-check-1.c b/gcc/testsuite/gcc.c-torture/compile/stack-check-1.c
> new file mode 100644
> index 00000000000..4058eb58709
> --- /dev/null
> +++ b/gcc/testsuite/gcc.c-torture/compile/stack-check-1.c
> @@ -0,0 +1,2 @@
> +/* { dg-additional-options "-fstack-check" } */
> +#include "20031023-1.c"
>

Hi,

A minor comment at this stage: this new test fails to compile for
thumb-1 targets:
testsuite/gcc.c-torture/compile/20031023-1.c:27:1: sorry,
unimplemented: -fstack-check=specific for Thumb-1

for instance on arm-none-linux-gnueabi --with-mode=thumb --with-cpu=cortex-a9
and forcing -march=armv5t in runtest flags.

Is there a clean way to make it unsupported?

Thanks,

Christophe