Sorry for the slow reponse.
"Kewen.Lin" <li...@linux.ibm.com> writes:
> diff --git a/gcc/vec-perm-indices.c b/gcc/vec-perm-indices.c
> index ede590dc5c9..57dd11d723c 100644
> --- a/gcc/vec-perm-indices.c
> +++ b/gcc/vec-perm-indices.c
> @@ -101,6 +101,70 @@ vec_perm_indices::new_expanded_vector (const
> vec_perm_indices &orig,
> m_encoding.finalize ();
> }
>
> +/* Check whether we can switch to a new permutation vector that
> + selects the same input elements as ORIG, but with each element
> + built up from FACTOR pieces. Return true if yes, otherwise
> + return false. Every FACTOR permutation indexes should be
> + continuous separately and the first one of each batch should
> + be able to exactly modulo FACTOR. For example, if ORIG is
> + { 2, 3, 4, 5, 0, 1, 6, 7 } and FACTOR is 2, the new permutation
> + is { 1, 2, 0, 3 }. */
> +
> +bool
> +vec_perm_indices::new_shrunk_vector (const vec_perm_indices &orig,
> + unsigned int factor)
> +{
> + gcc_assert (factor > 0);
> +
> + if (maybe_lt (orig.m_nelts_per_input, factor))
> + return false;
> +
> + poly_uint64 nelts;
> + /* Invalid if vector units number isn't multiple of factor. */
> + if (!multiple_p (orig.m_nelts_per_input, factor, &nelts))
> + return false;
> +
> + /* Only handle the case that npatterns is multiple of factor.
> + FIXME: Try to see whether we can reshape it by factor npatterns. */
> + if (orig.m_encoding.npatterns () % factor != 0)
> + return false;
> +
> + unsigned int encoded_nelts = orig.m_encoding.encoded_nelts ();
> + auto_vec<element_type> encodings (encoded_nelts);
auto_vec<element_type, 32> would avoid memory allocations in the
same cases that m_encoding can. “encoding” might be better than
“encodings” since there's only really one encoding here.
> + /* Separate all encoded elements into batches by size factor,
> + then ensure the first element of each batch is multiple of
> + factor and all elements in each batch is consecutive from
> + the first one. */
> + for (unsigned int i = 0; i < encoded_nelts; i += factor)
> + {
> + element_type first = orig.m_encoding[i];
> + element_type new_index;
> + if (!multiple_p (first, factor, &new_index))
> + return false;
> + for (unsigned int j = 1; j < factor; ++j)
> + {
> + if (maybe_ne (first + j, orig.m_encoding[i + j]))
> + return false;
> + }
Formatting nit: unnecessary braces around if.
> + encodings.quick_push (new_index);
> + }
> +
> + m_ninputs = orig.m_ninputs;
> + m_nelts_per_input = nelts;
> + poly_uint64 full_nelts = exact_div (orig.m_encoding.full_nelts (), factor);
> + unsigned int npatterns = orig.m_encoding.npatterns () / factor;
> +
> + m_encoding.new_vector (full_nelts, npatterns,
> + orig.m_encoding.nelts_per_pattern ());
> +
> + for (unsigned int i = 0; i < encodings.length (); i++)
> + m_encoding.quick_push (encodings[i]);
I think this can be:
m_encoding.splice (encodings);
OK with those changes, thanks. Thanks also for doing it in a
variable-length-friendly way.
Richard
> +
> + m_encoding.finalize ();
> +
> + return true;
> +}
> +
> /* Rotate the inputs of the permutation right by DELTA inputs. This changes
> the values of the permutation vector but it doesn't change the way that
> the elements are encoded. */
> diff --git a/gcc/vec-perm-indices.h b/gcc/vec-perm-indices.h
> index bc70ecd8a1d..98d27f0ec42 100644
> --- a/gcc/vec-perm-indices.h
> +++ b/gcc/vec-perm-indices.h
> @@ -57,6 +57,7 @@ public:
>
> void new_vector (const vec_perm_builder &, unsigned int, poly_uint64);
> void new_expanded_vector (const vec_perm_indices &, unsigned int);
> + bool new_shrunk_vector (const vec_perm_indices &, unsigned int);
> void rotate_inputs (int delta);
>
> /* Return the underlying vector encoding. */
