On Wed, Aug 17, 2016 at 12:52 PM, Alan Hayward <[email protected]> wrote:
>
>
> On 16/08/2016 10:01, "Alan Hayward" <[email protected]> wrote:
>
>>
>>
>>On 16/08/2016 09:33, "Richard Biener" <[email protected]> wrote:
>>
>>>On Mon, Aug 15, 2016 at 4:16 PM, Alan Hayward <[email protected]>
>>>wrote:
>>>>
>>>>
>>>> On 15/08/2016 12:17, "Richard Biener" <[email protected]>
>>>>wrote:
>>>>
>>>>>On Mon, Aug 15, 2016 at 11:48 AM, Alan Hayward <[email protected]>
>>>>>wrote:
>>>>>> The testcase pr71752.c was failing because the SLP code was
>>>>>>generating
>>>>>>an
>>>>>> SLP
>>>>>> vector using arguments from the SLP scalar stmts, but was using the
>>>>>>wrong
>>>>>> argument number.
>>>>>>
>>>>>> vect_get_slp_defs() is given a vector of operands. When calling down
>>>>>>to
>>>>>> vect_get_constant_vectors it uses i as op_num - making the assumption
>>>>>>that
>>>>>> the
>>>>>> first op in the vector refers to the first argument in the SLP scalar
>>>>>> statement, the second op refers to the second arg and so on.
>>>>>>
>>>>>> However, previously in vectorizable_reduction, the call to
>>>>>> vect_get_vec_defs
>>>>>> destroyed this ordering by potentially only passing op1.
>>>>>>
>>>>>> The solution is in vectorizable_reduction to create a vector of
>>>>>>operands
>>>>>> equal
>>>>>> in size to the number of arguments in the SLP statements. We maintain
>>>>>>the
>>>>>> argument ordering and if we don't require defs for that argument we
>>>>>>instead
>>>>>> push NULL into the vector. In vect_get_slp_defs we need to handle
>>>>>>cases
>>>>>> where
>>>>>> an op might be NULL.
>>>>>>
>>>>>> Tested with a check run on X86 and AArch64.
>>>>>> Ok to commit?
>>>>>>
>>>>>
>>>>>Ugh. Note the logic in vect_get_slp_defs is incredibly fragile - I
>>>>>think you can't
>>>>>simply "skip" ops the way you do as you need to still increment
>>>>>child_index
>>>>>accordingly for ignored ops.
>>>>
>>>> Agreed, I should be maintaining the child_index.
>>>> Looking at the code, I need a valid oprnd for that code to work.
>>>>
>>>> Given that the size of the ops vector is never more than 3, it probably
>>>> makes
>>>> sense to reset child_index each time and do a quick for loop through
>>>>all
>>>> the
>>>> children.
>>>
>>>Hmm, yes - that should work. It should also remove the need to keep
>>>operand order in sync? So it might no longer require the
>>>vectorizable_reduction change.
>>
>>We still need to pass the correct index down to
>>vect_get_constant_vectors(),
>>which requires the operands in the original order for i to be correct.
>>(We can’t use child_index for that).
>>
>>Another option would be to pass down an additional vector containing the
>>indexes
>>of the operands. But I think that’d be an even worse option.
>>
>
> Updated with a loop for calculating child_index.
> Tested with a check run for x86 and aarch64.
LGTM.
Thanks,
Richard.
>
> diff --git a/gcc/testsuite/gcc.dg/vect/pr71752.c
> b/gcc/testsuite/gcc.dg/vect/pr71752.c
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..8d26754b4fedf8b104caae8742a445dff
> bf23f0a
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/vect/pr71752.c
> @@ -0,0 +1,19 @@
> +/* { dg-do compile } */
> +
> +unsigned int q4, yg;
> +
> +unsigned int
> +w6 (unsigned int z5, unsigned int jv)
> +{
> + unsigned int *f2 = &jv;
> +
> + while (*f2 < 21)
> + {
> + q4 -= jv;
> + z5 -= jv;
> + f2 = &yg;
> + ++(*f2);
> + }
> + return z5;
> +}
> +
> diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
> index
> 2a7e0c6661bc1ba82c9f03720e550749f2252a7c..826481af3d1d8b29bcdbd7d81c0fd5a85
> 9ecd9b0 100644
> --- a/gcc/tree-vect-loop.c
> +++ b/gcc/tree-vect-loop.c
> @@ -5364,7 +5364,7 @@ vectorizable_reduction (gimple *stmt,
> gimple_stmt_iterator *gsi,
> auto_vec<tree> vect_defs;
> auto_vec<gimple *> phis;
> int vec_num;
> - tree def0, def1, tem, op0, op1 = NULL_TREE;
> + tree def0, def1, tem, op1 = NULL_TREE;
> bool first_p = true;
> tree cr_index_scalar_type = NULL_TREE, cr_index_vector_type = NULL_TREE;
> gimple *cond_expr_induction_def_stmt = NULL;
> @@ -5964,29 +5964,36 @@ vectorizable_reduction (gimple *stmt,
> gimple_stmt_iterator *gsi,
> /* Handle uses. */
> if (j == 0)
> {
> - op0 = ops[!reduc_index];
> - if (op_type == ternary_op)
> - {
> - if (reduc_index == 0)
> - op1 = ops[2];
> - else
> - op1 = ops[1];
> - }
> + if (slp_node)
> + {
> + /* Get vec defs for all the operands except the reduction index,
> + ensuring the ordering of the ops in the vector is kept. */
> + auto_vec<tree, 3> slp_ops;
> + auto_vec<vec<tree>, 3> vec_defs;
>
> - if (slp_node)
> - vect_get_vec_defs (op0, op1, stmt, &vec_oprnds0, &vec_oprnds1,
> - slp_node, -1);
> + slp_ops.quick_push ((reduc_index == 0) ? NULL : ops[0]);
> + slp_ops.quick_push ((reduc_index == 1) ? NULL : ops[1]);
> + if (op_type == ternary_op)
> + slp_ops.quick_push ((reduc_index == 2) ? NULL : ops[2]);
> +
> + vect_get_slp_defs (slp_ops, slp_node, &vec_defs, -1);
> +
> + vec_oprnds0.safe_splice (vec_defs[(reduc_index == 0) ? 1 : 0]);
> + if (op_type == ternary_op)
> + vec_oprnds1.safe_splice (vec_defs[(reduc_index == 2) ? 1 :
> 2]);
> + }
> else
> - {
> + {
> loop_vec_def0 = vect_get_vec_def_for_operand
> (ops[!reduc_index],
> stmt);
> vec_oprnds0.quick_push (loop_vec_def0);
> if (op_type == ternary_op)
> {
> + op1 = (reduc_index == 0) ? ops[2] : ops[1];
> loop_vec_def1 = vect_get_vec_def_for_operand (op1, stmt);
> vec_oprnds1.quick_push (loop_vec_def1);
> }
> - }
> + }
> }
> else
> {
> diff --git a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
> index
> fb325d54f1084461d44cd54a98e5b7f99541a188..5a611e42556e0931a372a6c626cc24846
> f11029d 100644
> --- a/gcc/tree-vect-slp.c
> +++ b/gcc/tree-vect-slp.c
> @@ -3194,24 +3194,32 @@ vect_get_slp_defs (vec<tree> ops, slp_tree
> slp_node,
> {
> gimple *first_stmt;
> int number_of_vects = 0, i;
> - unsigned int child_index = 0;
> HOST_WIDE_INT lhs_size_unit, rhs_size_unit;
> slp_tree child = NULL;
> vec<tree> vec_defs;
> tree oprnd;
> - bool vectorized_defs;
> + bool first_iteration = true;
>
> first_stmt = SLP_TREE_SCALAR_STMTS (slp_node)[0];
> FOR_EACH_VEC_ELT (ops, i, oprnd)
> {
> + bool vectorized_defs = false;
> +
> + if (oprnd == NULL)
> + {
> + vec_defs = vNULL;
> + vec_defs.create (0);
> + vec_oprnds->quick_push (vec_defs);
> + continue;
> + }
> +
> /* For each operand we check if it has vectorized definitions in a
> child
> node or we need to create them (for invariants and constants). We
> check if the LHS of the first stmt of the next child matches OPRND.
> If it does, we found the correct child. Otherwise, we call
> - vect_get_constant_vectors (), and not advance CHILD_INDEX in order
> - to check this child node for the next operand. */
> - vectorized_defs = false;
> - if (SLP_TREE_CHILDREN (slp_node).length () > child_index)
> + vect_get_constant_vectors (). */
> + for (unsigned int child_index = 0;
> + child_index < SLP_TREE_CHILDREN (slp_node).length ();
> child_index++)
> {
> child = SLP_TREE_CHILDREN (slp_node)[child_index];
>
> @@ -3231,30 +3239,25 @@ vect_get_slp_defs (vec<tree> ops, slp_tree
> slp_node,
> statements. */
> number_of_vects = SLP_TREE_NUMBER_OF_VEC_STMTS (child);
> vectorized_defs = true;
> - child_index++;
> + break;
> }
> }
> - else
> - child_index++;
> }
>
> - if (!vectorized_defs)
> - {
> - if (i == 0)
> - {
> - number_of_vects = SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node);
> - /* Number of vector stmts was calculated according to LHS in
> - vect_schedule_slp_instance (), fix it by replacing LHS
> with
> - RHS, if necessary. See vect_get_smallest_scalar_type ()
> for
> - details. */
> - vect_get_smallest_scalar_type (first_stmt, &lhs_size_unit,
> - &rhs_size_unit);
> - if (rhs_size_unit != lhs_size_unit)
> - {
> - number_of_vects *= rhs_size_unit;
> - number_of_vects /= lhs_size_unit;
> - }
> - }
> + if (!vectorized_defs && first_iteration)
> + {
> + number_of_vects = SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node);
> + /* Number of vector stmts was calculated according to LHS in
> + vect_schedule_slp_instance (), fix it by replacing LHS with
> + RHS, if necessary. See vect_get_smallest_scalar_type () for
> + details. */
> + vect_get_smallest_scalar_type (first_stmt, &lhs_size_unit,
> + &rhs_size_unit);
> + if (rhs_size_unit != lhs_size_unit)
> + {
> + number_of_vects *= rhs_size_unit;
> + number_of_vects /= lhs_size_unit;
> + }
> }
>
> /* Allocate memory for vectorized defs. */
> @@ -3276,6 +3279,8 @@ vect_get_slp_defs (vec<tree> ops, slp_tree slp_node,
> /* For reductions, we only need initial values. */
> if (reduc_index != -1)
> return;
> +
> + first_iteration = false;
> }
> }
>
>
>
