From: Richard Biener <rguenther@suse.de>
To: Richard Sandiford <richard.sandiford@arm.com>
Cc: Richard Biener via Gcc-patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] tree-optimization/110742 - fix latent issue with permuting existing vectors
Date: Thu, 20 Jul 2023 16:57:50 +0200 [thread overview]
Message-ID: <B9C83843-20CB-4A77-8B08-7542ED4FBE2C@suse.de> (raw)
In-Reply-To: <mptzg3qisk4.fsf@arm.com>
> Am 20.07.2023 um 16:09 schrieb Richard Sandiford <richard.sandiford@arm.com>:
>
> Richard Biener via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
>> When we materialize a layout we push edge permutes to constant/external
>> defs without checking we can actually do so. For externals defined
>> by vector stmts rather than scalar components we can't.
>>
>> Bootstrapped and tested on x86_64-unknown-linux-gnu.
>>
>> OK?
>>
>> Thanks,
>> Richard.
>>
>> PR tree-optimization/110742
>> * tree-vect-slp.cc (vect_optimize_slp_pass::get_result_with_layout):
>> Do not materialize an edge permutation in an external node with
>> vector defs.
>> (vect_slp_analyze_node_operations_1): Guard purely internal
>> nodes better.
>>
>> * g++.dg/torture/pr110742.C: New testcase.
>> ---
>> gcc/testsuite/g++.dg/torture/pr110742.C | 47 +++++++++++++++++++++++++
>> gcc/tree-vect-slp.cc | 8 +++--
>> 2 files changed, 53 insertions(+), 2 deletions(-)
>> create mode 100644 gcc/testsuite/g++.dg/torture/pr110742.C
>>
>> diff --git a/gcc/testsuite/g++.dg/torture/pr110742.C b/gcc/testsuite/g++.dg/torture/pr110742.C
>> new file mode 100644
>> index 00000000000..d41ac0479d2
>> --- /dev/null
>> +++ b/gcc/testsuite/g++.dg/torture/pr110742.C
>> @@ -0,0 +1,47 @@
>> +// { dg-do compile }
>> +
>> +struct HARD_REG_SET {
>> + HARD_REG_SET operator~() const {
>> + HARD_REG_SET res;
>> + for (unsigned int i = 0; i < (sizeof(elts) / sizeof((elts)[0])); ++i)
>> + res.elts[i] = ~elts[i];
>> + return res;
>> + }
>> + HARD_REG_SET operator&(const HARD_REG_SET &other) const {
>> + HARD_REG_SET res;
>> + for (unsigned int i = 0; i < (sizeof(elts) / sizeof((elts)[0])); ++i)
>> + res.elts[i] = elts[i] & other.elts[i];
>> + return res;
>> + }
>> + unsigned long elts[4];
>> +};
>> +typedef const HARD_REG_SET &const_hard_reg_set;
>> +inline bool hard_reg_set_subset_p(const_hard_reg_set x, const_hard_reg_set y) {
>> + unsigned long bad = 0;
>> + for (unsigned int i = 0; i < (sizeof(x.elts) / sizeof((x.elts)[0])); ++i)
>> + bad |= (x.elts[i] & ~y.elts[i]);
>> + return bad == 0;
>> +}
>> +inline bool hard_reg_set_empty_p(const_hard_reg_set x) {
>> + unsigned long bad = 0;
>> + for (unsigned int i = 0; i < (sizeof(x.elts) / sizeof((x.elts)[0])); ++i)
>> + bad |= x.elts[i];
>> + return bad == 0;
>> +}
>> +extern HARD_REG_SET rr[2];
>> +extern int t[2];
>> +extern HARD_REG_SET nn;
>> +static HARD_REG_SET mm;
>> +void setup_reg_class_relations(void) {
>> + HARD_REG_SET intersection_set, union_set, temp_set2;
>> + for (int cl2 = 0; cl2 < 2; cl2++) {
>> + temp_set2 = rr[cl2] & ~nn;
>> + if (hard_reg_set_empty_p(mm) && hard_reg_set_empty_p(temp_set2)) {
>> + mm = rr[0] & nn;
>> + if (hard_reg_set_subset_p(mm, intersection_set))
>> + if (!hard_reg_set_subset_p(mm, temp_set2) ||
>> + hard_reg_set_subset_p(rr[0], rr[t[cl2]]))
>> + t[cl2] = 0;
>> + }
>> + }
>> +}
>> diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
>> index 693621ca990..1d79c77e8ce 100644
>> --- a/gcc/tree-vect-slp.cc
>> +++ b/gcc/tree-vect-slp.cc
>> @@ -5198,7 +5198,10 @@ vect_optimize_slp_pass::get_result_with_layout (slp_tree node,
>> return result;
>>
>> if (SLP_TREE_DEF_TYPE (node) == vect_constant_def
>> - || SLP_TREE_DEF_TYPE (node) == vect_external_def)
>> + || (SLP_TREE_DEF_TYPE (node) == vect_external_def
>> + && (to_layout_i == 0
>> + /* We can't permute vector defs. */
>> + || SLP_TREE_VEC_DEFS (node).is_empty ())))
>
> Guess it's personal preference, but IMO it's easier to follow without the
> to_layout_i condition, so that it ties directly to the create_partitions
> test.
I don’t understand- in the code guarding this we seem to expect to_layout_i == 0 and that’s the case we can handle as noop. I didn’t understand why the function doesn’t always just do nothing in this case though, so I must have missed something.
Richard
> (Would be nice to have a name for whatever a node matching the new
> condition is, but I don't have any good ideas.)
>
> LGTM otherwise FWIW.
>
> Thanks,
> Richard
>
>> {
>> /* If the vector is uniform or unchanged, there's nothing to do. */
>> if (to_layout_i == 0 || vect_slp_tree_uniform_p (node))
>> @@ -5944,7 +5947,8 @@ vect_slp_analyze_node_operations_1 (vec_info *vinfo, slp_tree node,
>> calculated by the recursive call). Otherwise it is the number of
>> scalar elements in one scalar iteration (DR_GROUP_SIZE) multiplied by
>> VF divided by the number of elements in a vector. */
>> - if (!STMT_VINFO_DATA_REF (stmt_info)
>> + if (SLP_TREE_CODE (node) != VEC_PERM_EXPR
>> + && !STMT_VINFO_DATA_REF (stmt_info)
>> && REDUC_GROUP_FIRST_ELEMENT (stmt_info))
>> {
>> for (unsigned i = 0; i < SLP_TREE_CHILDREN (node).length (); ++i)
next prev parent reply other threads:[~2023-07-20 14:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230720123855.334A4385AF91@sourceware.org>
2023-07-20 14:08 ` Richard Sandiford
2023-07-20 14:57 ` Richard Biener [this message]
2023-07-20 16:58 ` Richard Sandiford
2023-07-20 17:10 ` Richard Biener
2023-07-20 17:40 ` Richard Sandiford
2023-07-21 6:12 ` Richard Biener
[not found] <20230720123851.61BA33857711@sourceware.org>
2023-07-20 21:31 ` Jeff Law
2023-07-20 12:38 Richard Biener
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