[1/3] tree-ssa-sink: do not sink to in front of setjmp

  gcc/ChangeLog:

	* tree-ssa-sink.c (select_best_block): Punt if selected block
	has incoming abnormal edges.

gcc/testsuite/ChangeLog:

	* gcc.dg/setjmp-7.c: New test.
---
 gcc/testsuite/gcc.dg/setjmp-7.c | 13 +++++++++++++
 gcc/tree-ssa-sink.c             |  6 ++++++
 2 files changed, 19 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/setjmp-7.c
  

On Fri, Jan 14, 2022 at 7:21 PM Alexander Monakov <amonakov@ispras.ru> wrote:
>
> gcc/ChangeLog:
>
>         * tree-ssa-sink.c (select_best_block): Punt if selected block
>         has incoming abnormal edges.

OK.

> gcc/testsuite/ChangeLog:
>
>         * gcc.dg/setjmp-7.c: New test.
> ---
>  gcc/testsuite/gcc.dg/setjmp-7.c | 13 +++++++++++++
>  gcc/tree-ssa-sink.c             |  6 ++++++
>  2 files changed, 19 insertions(+)
>  create mode 100644 gcc/testsuite/gcc.dg/setjmp-7.c
>
> diff --git a/gcc/testsuite/gcc.dg/setjmp-7.c b/gcc/testsuite/gcc.dg/setjmp-7.c
> new file mode 100644
> index 000000000..44b5bcbfa
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/setjmp-7.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fno-guess-branch-probability -w" } */
> +/* { dg-require-effective-target indirect_jumps } */
> +
> +struct __jmp_buf_tag { };
> +typedef struct __jmp_buf_tag jmp_buf[1];
> +struct globals { jmp_buf listingbuf; };
> +extern struct globals *const ptr_to_globals;
> +void foo()
> +{
> +    if ( _setjmp ( ((*ptr_to_globals).listingbuf )))
> +       ;
> +}
> diff --git a/gcc/tree-ssa-sink.c b/gcc/tree-ssa-sink.c
> index 66d7ae89e..016ecbaec 100644
> --- a/gcc/tree-ssa-sink.c
> +++ b/gcc/tree-ssa-sink.c
> @@ -208,6 +208,12 @@ select_best_block (basic_block early_bb,
>        temp_bb = get_immediate_dominator (CDI_DOMINATORS, temp_bb);
>      }
>
> +  /* Placing a statement before a setjmp-like function would be invalid
> +     (it cannot be reevaluated when execution follows an abnormal edge).
> +     If we selected a block with abnormal predecessors, just punt.  */
> +  if (bb_has_abnormal_pred (best_bb))
> +    return early_bb;
> +
>    /* If we found a shallower loop nest, then we always consider that
>       a win.  This will always give us the most control dependent block
>       within that loop nest.  */
> --
> 2.33.1
>
  

* Alexander Monakov via Gcc-patches:

> diff --git a/gcc/testsuite/gcc.dg/setjmp-7.c b/gcc/testsuite/gcc.dg/setjmp-7.c
> new file mode 100644
> index 000000000..44b5bcbfa
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/setjmp-7.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fno-guess-branch-probability -w" } */
> +/* { dg-require-effective-target indirect_jumps } */
> +
> +struct __jmp_buf_tag { };
> +typedef struct __jmp_buf_tag jmp_buf[1];
> +struct globals { jmp_buf listingbuf; };
> +extern struct globals *const ptr_to_globals;
> +void foo()
> +{
> +    if ( _setjmp ( ((*ptr_to_globals).listingbuf )))
> +	;
> +}

Is the implicit declaration of _setjmp important to this test?
Could we declare it explicitly instead?

Thanks,
Florian
  

> Am 08.11.2023 um 10:04 schrieb Florian Weimer <fweimer@redhat.com>:
> 
> * Alexander Monakov via Gcc-patches:
> 
>> diff --git a/gcc/testsuite/gcc.dg/setjmp-7.c b/gcc/testsuite/gcc.dg/setjmp-7.c
>> new file mode 100644
>> index 000000000..44b5bcbfa
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/setjmp-7.c
>> @@ -0,0 +1,13 @@
>> +/* { dg-do compile } */
>> +/* { dg-options "-O2 -fno-guess-branch-probability -w" } */
>> +/* { dg-require-effective-target indirect_jumps } */
>> +
>> +struct __jmp_buf_tag { };
>> +typedef struct __jmp_buf_tag jmp_buf[1];
>> +struct globals { jmp_buf listingbuf; };
>> +extern struct globals *const ptr_to_globals;
>> +void foo()
>> +{
>> +    if ( _setjmp ( ((*ptr_to_globals).listingbuf )))
>> +    ;
>> +}
> 
> Is the implicit declaration of _setjmp important to this test?
> Could we declare it explicitly instead?

It shouldn’t be important.

> Thanks,
> Florian
>
  

On Wed, 8 Nov 2023, Richard Biener wrote:

> >> --- /dev/null
> >> +++ b/gcc/testsuite/gcc.dg/setjmp-7.c
> >> @@ -0,0 +1,13 @@
> >> +/* { dg-do compile } */
> >> +/* { dg-options "-O2 -fno-guess-branch-probability -w" } */
> >> +/* { dg-require-effective-target indirect_jumps } */
> >> +
> >> +struct __jmp_buf_tag { };
> >> +typedef struct __jmp_buf_tag jmp_buf[1];
> >> +struct globals { jmp_buf listingbuf; };
> >> +extern struct globals *const ptr_to_globals;
> >> +void foo()
> >> +{
> >> +    if ( _setjmp ( ((*ptr_to_globals).listingbuf )))
> >> +    ;
> >> +}
> > 
> > Is the implicit declaration of _setjmp important to this test?
> > Could we declare it explicitly instead?
> 
> It shouldn’t be important.

Yes, it's an artifact from testcase minimization, sorry about that.

Florian, I see you've sent a patch to fix this up — thank you!

Alexander