On Thu, 10 May 2018, Jakub Jelinek wrote:
> On Wed, May 09, 2018 at 04:53:19PM +0200, Allan Sandfeld Jensen wrote:
> > > > @@ -2022,8 +2022,9 @@ simplify_vector_constructor (gimple_stmt_iterator
> > > > *gsi)>
> > > >elem_type = TREE_TYPE (type);
> > > >elem_size = TREE_INT_CST_LOW (TYPE_SIZE (elem_type));
> > > >
> > > > - vec_perm_builder sel (nelts, nelts, 1);
> > > > - orig = NULL;
> > > > + vec_perm_builder sel (nelts, 2, nelts);
> > >
> > > Why this change? I admit the vec_parm_builder arguments are confusing,
> > > but
> > > I think the second times third is the number of how many indices are being
> > > pushed into the vector, so I think (nelts, nelts, 1) is right.
> > >
> > I had the impression it was what was selected from. In any case, I changed
> > it
> > because without I get crash when vec_perm_indices is created later with a
> > possible nparms of 2.
>
> The documentation is apparently in vector-builder.h:
>This class is a wrapper around auto_vec for building vectors of T.
>It aims to encode each vector as npatterns interleaved patterns,
>where each pattern represents a sequence:
>
> { BASE0, BASE1, BASE1 + STEP, BASE1 + STEP*2, BASE1 + STEP*3, ... }
>
>The first three elements in each pattern provide enough information
>to derive the other elements. If all patterns have a STEP of zero,
>we only need to encode the first two elements in each pattern.
>If BASE1 is also equal to BASE0 for all patterns, we only need to
>encode the first element in each pattern. The number of encoded
>elements per pattern is given by nelts_per_pattern.
>
>The class can be used in two ways:
>
>1. It can be used to build a full image of the vector, which is then
> canonicalized by finalize (). In this case npatterns is initially
> the number of elements in the vector and nelts_per_pattern is
> initially 1.
>
>2. It can be used to build a vector that already has a known encoding.
> This is preferred since it is more efficient and copes with
> variable-length vectors. finalize () then canonicalizes the encoding
> to a simpler form if possible.
>
> As the vector is constant width and we are building the full image of the
> vector, the right arguments are (nelts, nelts, 1) as per 1. above, and the
> finalization can perhaps change it to something more compact.
>
> > > (and sorry for missing your patch first, the PR wasn't ASSIGNED and there
> > > was no link to gcc-patches for it).
> > >
> > It is okay. You are welcome to take it over. I am not a regular gcc
> > contributor and thus not well-versed in the details, only the basic logic
> > of
> > how things work.
>
> Ok, here is my version of the patch. Bootstrapped/regtested on x86_64-linux
> and i686-linux, ok for trunk?
OK.
Thanks,
Richard.
> 2018-05-10 Allan Sandfeld Jensen
> Jakub Jelinek
>
> PR tree-optimization/85692
> * tree-ssa-forwprop.c (simplify_vector_constructor): Try two
> source permute as well.
>
> * gcc.target/i386/pr85692.c: New test.
>
> --- gcc/tree-ssa-forwprop.c.jj2018-05-08 18:16:36.866614130 +0200
> +++ gcc/tree-ssa-forwprop.c 2018-05-09 20:44:32.621900540 +0200
> @@ -2004,7 +2004,7 @@ simplify_vector_constructor (gimple_stmt
> {
>gimple *stmt = gsi_stmt (*gsi);
>gimple *def_stmt;
> - tree op, op2, orig, type, elem_type;
> + tree op, op2, orig[2], type, elem_type;
>unsigned elem_size, i;
>unsigned HOST_WIDE_INT nelts;
>enum tree_code code, conv_code;
> @@ -2023,7 +2023,8 @@ simplify_vector_constructor (gimple_stmt
>elem_size = TREE_INT_CST_LOW (TYPE_SIZE (elem_type));
>
>vec_perm_builder sel (nelts, nelts, 1);
> - orig = NULL;
> + orig[0] = NULL;
> + orig[1] = NULL;
>conv_code = ERROR_MARK;
>maybe_ident = true;
>FOR_EACH_VEC_SAFE_ELT (CONSTRUCTOR_ELTS (op), i, elt)
> @@ -2063,25 +2064,35 @@ simplify_vector_constructor (gimple_stmt
> return false;
>op1 = gimple_assign_rhs1 (def_stmt);
>ref = TREE_OPERAND (op1, 0);
> - if (orig)
> + unsigned int j;
> + for (j = 0; j < 2; ++j)
> {
> - if (ref != orig)
> - return false;
> - }
> - else
> - {
> - if (TREE_CODE (ref) != SSA_NAME)
> - return false;
> - if (! VECTOR_TYPE_P (TREE_TYPE (ref))
> - || ! useless_type_conversion_p (TREE_TYPE (op1),
> - TREE_TYPE (TREE_TYPE (ref
> - return false;
> - orig = ref;
> + if (!orig[j])
> + {
> + if (TREE_CODE (ref) != SSA_NAME)
> + return false;
> + if (! VECTOR_TYPE_P (TREE_TYPE (ref))
> + || ! useless_type_conversion_p (TREE_TYPE (op1),
> + TREE_TYPE (TREE_TYPE (ref
> + return false;
> + if (j && !useless_type_conversion_p (TREE_TYPE (orig[0]),
> +
