Re: [PATCH]middle-end: inspect all exits for additional annotations for loop.

[Richard Biener <rguenther@suse.de>]

> Am 14.02.2024 um 16:16 schrieb Tamar Christina <tamar.christina@arm.com>:
> 
> 
>> 
>> 
>> I think this isn't entirely good.  For simple cases for
>> do {} while the condition ends up in the latch while for while () {}
>> loops it ends up in the header.  In your case the latch isn't empty
>> so it doesn't end up with the conditional.
>> 
>> I think your patch is OK to the point of looking at all loop exit
>> sources but you should elide the special-casing of header and
>> latch since it's really only exit conditionals that matter.
>> 
> 
> That makes sense, since in both cases the edges are in the respective
> blocks.  Should have thought about it more.
> 
> So how about this one.
> 
> Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
> 
> Ok for master?

Ok

Richard 

> Thanks,
> Tamar
> 
> gcc/ChangeLog:
> 
>    * tree-cfg.cc (replace_loop_annotate): Inspect loop edges for annotations.
> 
> gcc/testsuite/ChangeLog:
> 
>    * gcc.dg/vect/vect-novect_gcond.c: New test.
> 
> --- inline copy of patch ---
> 
> diff --git a/gcc/testsuite/gcc.dg/vect/vect-novect_gcond.c b/gcc/testsuite/gcc.dg/vect/vect-novect_gcond.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..01e69cbef9d51b234c08a400c78dc078d53252f1
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/vect/vect-novect_gcond.c
> @@ -0,0 +1,39 @@
> +/* { dg-add-options vect_early_break } */
> +/* { dg-require-effective-target vect_early_break_hw } */
> +/* { dg-require-effective-target vect_int } */
> +/* { dg-additional-options "-O3" } */
> +
> +/* { dg-final { scan-tree-dump-not "LOOP VECTORIZED" "vect" } } */
> +
> +#include "tree-vect.h"
> +
> +#define N 306
> +#define NEEDLE 136
> +
> +int table[N];
> +
> +__attribute__ ((noipa))
> +int foo (int i, unsigned short parse_tables_n)
> +{
> +  parse_tables_n >>= 9;
> +  parse_tables_n += 11;
> +#pragma GCC novector
> +  while (i < N && parse_tables_n--)
> +    table[i++] = 0;
> +
> +  return table[NEEDLE];
> +}
> +
> +int main ()
> +{
> +  check_vect ();
> +
> +#pragma GCC novector
> +  for (int j = 0; j < N; j++)
> +    table[j] = -1;
> +
> +  if (foo (0, 0xFFFF) != 0)
> +    __builtin_abort ();
> +
> +  return 0;
> +}
> diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
> index cdd439fe7506e7bc33654ffa027b493f23d278ac..bdffc3b4ed277724e81b7dd67fe7966e8ece0c13 100644
> --- a/gcc/tree-cfg.cc
> +++ b/gcc/tree-cfg.cc
> @@ -320,12 +320,9 @@ replace_loop_annotate (void)
> 
>   for (auto loop : loops_list (cfun, 0))
>     {
> -      /* First look into the header.  */
> -      replace_loop_annotate_in_block (loop->header, loop);
> -
> -      /* Then look into the latch, if any.  */
> -      if (loop->latch)
> -    replace_loop_annotate_in_block (loop->latch, loop);
> +      /* Check all exit source blocks for annotations.  */
> +      for (auto e : get_loop_exit_edges (loop))
> +    replace_loop_annotate_in_block (e->src, loop);
> 
>       /* Push the global flag_finite_loops state down to individual loops.  */
>       loop->finite_p = flag_finite_loops;
> <rb18267.patch>