Re: [PATCH GCC8][32/33]Save niter check for vect peeling if loop versioning is required

[Richard Sandiford <richard dot sandiford at linaro dot org>]

Another one sorry, but:

Bin Cheng <Bin.Cheng@arm.com> writes:
> diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
> index af874e7..98caa5e 100644
> --- a/gcc/tree-vect-loop.c
> +++ b/gcc/tree-vect-loop.c
> @@ -2214,6 +2214,36 @@ start_over:
>          }
>      }
>  
> +  /* During peeling, we need to check if number of loop iterations is
> +     enough for both peeled prolog loop and vector loop.  This check
> +     can be merged along with threshold check of loop versioning, so
> +     increase threshold for this case if necessary.  */
> +  if (LOOP_REQUIRES_VERSIONING (loop_vinfo)
> +      && (LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo)
> +	  || LOOP_VINFO_PEELING_FOR_NITER (loop_vinfo)))
> +    {
> +      unsigned niters_th;
> +
> +      /* Niters for peeled prolog loop.  */
> +      if (LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo) < 0)
> +	{
> +	  struct data_reference *dr = LOOP_VINFO_UNALIGNED_DR (loop_vinfo);
> +	  tree vectype = STMT_VINFO_VECTYPE (vinfo_for_stmt (DR_STMT (dr)));
> +
> +	  niters_th = TYPE_VECTOR_SUBPARTS (vectype) - 1;
> +	}
> +      else
> +	niters_th = LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo);
> +
> +      /* Niters for at least one iteration of vectorized loop.  */
> +      niters_th += LOOP_VINFO_VECT_FACTOR (loop_vinfo);
> +      /* One additional iteration because of peeling for gap.  */
> +      if (!LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo))
> +	niters_th++;

is the ! intentional here?  It looks like it should adding 1 when
peeling for gaps _is_ needed.

> +      if (LOOP_VINFO_COST_MODEL_THRESHOLD (loop_vinfo) < niters_th)
> +	LOOP_VINFO_COST_MODEL_THRESHOLD (loop_vinfo) = niters_th;
> +    }
> +
>    gcc_assert (vectorization_factor
>  	      == (unsigned)LOOP_VINFO_VECT_FACTOR (loop_vinfo));