yggdrasil/gcc
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

tree-optimization/110381 - preserve SLP permutation with in-order reductions

Browse Source 
The following fixes a bug that manifests itself during fold-left
reduction transform in picking not the last scalar def to replace
and thus double-counting some elements.  But the underlying issue
is that we merge a load permutation into the in-order reduction
which is of course wrong.

Now, reduction analysis has not yet been performend when optimizing
permutations so we have to resort to check that ourselves.

	PR tree-optimization/110381
	* tree-vect-slp.cc (vect_optimize_slp_pass::start_choosing_layouts):
	Materialize permutes before fold-left reductions.

	* gcc.dg/vect/pr110381.c: New testcase.

(cherry picked from commit 53d6f57c1b20c6da52aefce737fb7d5263686ba3)
This commit is contained in:
Richard Biener 2023-06-26 12:51:37 +02:00
parent 857d763ed1
commit 32c7f05f8b
2 changed files with 61 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

45
gcc/testsuite/gcc.dg/vect/pr110381.c Normal file
View File

@ -0,0 +1,45 @@
/* { dg-do run } */
/* { dg-require-effective-target vect_float_strict } */
#include "tree-vect.h"
struct FOO {
double a;
double b;
double c;
};
double __attribute__((noipa))
sum_8_foos(const struct FOO* foos)
{
double sum = 0;
for (int i = 0; i < 8; ++i)
{
struct FOO foo = foos[i];
/* Need to use an in-order reduction here, preserving
the load permutation. */
sum += foo.a;
sum += foo.c;
sum += foo.b;
}
return sum;
}
int main()
{
struct FOO foos[8];
check_vect ();
__builtin_memset (foos, 0, sizeof (foos));
foos[0].a = __DBL_MAX__;
foos[0].b = 5;
foos[0].c = -__DBL_MAX__;
if (sum_8_foos (foos) != 5)
__builtin_abort ();
return 0;
}

18
gcc/tree-vect-slp.cc
View File

@ -4670,14 +4670,28 @@ vect_optimize_slp_pass::start_choosing_layouts ()
m_partition_layout_costs.safe_grow_cleared (m_partitions.length ()
* m_perms.length ());
/* We have to mark outgoing permutations facing non-reduction graph
entries that are not represented as to be materialized. */
/* We have to mark outgoing permutations facing non-associating-reduction
graph entries that are not represented as to be materialized.
slp_inst_kind_bb_reduc currently only covers associatable reductions. */
for (slp_instance instance : m_vinfo->slp_instances)
if (SLP_INSTANCE_KIND (instance) == slp_inst_kind_ctor)
{
unsigned int node_i = SLP_INSTANCE_TREE (instance)->vertex;
m_partitions[m_vertices[node_i].partition].layout = 0;
}
else if (SLP_INSTANCE_KIND (instance) == slp_inst_kind_reduc_chain)
{
stmt_vec_info stmt_info
= SLP_TREE_REPRESENTATIVE (SLP_INSTANCE_TREE (instance));
stmt_vec_info reduc_info = info_for_reduction (m_vinfo, stmt_info);
if (needs_fold_left_reduction_p (TREE_TYPE
(gimple_get_lhs (stmt_info->stmt)),
STMT_VINFO_REDUC_CODE (reduc_info)))
{
unsigned int node_i = SLP_INSTANCE_TREE (instance)->vertex;
m_partitions[m_vertices[node_i].partition].layout = 0;
}
}
/* Check which layouts each node and partition can handle. Calculate the
weights associated with inserting layout changes on edges. */