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tree-optimization/97334 - improve BB SLP discovery

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We're running into a multiplication with one unvectorizable
operand we expect to build from scalars but SLP discovery
fatally fails the build of both since one stmt is commutated:

  _60 = _58 * _59;
  _63 = _59 * _62;
  _66 = _59 * _65;
...

where _59 is the "bad" operand.  The following patch makes the
case work where the first stmt has a good operand by not fatally
failing the SLP build for the operand but communicating upwards
how to commutate.

2020-10-09  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/97334
	* tree-vect-slp.c (vect_build_slp_tree_1): Do not fatally
	fail lanes other than zero when BB vectorizing.

	* gcc.dg/vect/bb-slp-pr65935.c: Amend.
This commit is contained in:
Richard Biener 2020-10-09 12:24:46 +02:00
parent afcbeb35e0
commit 16760e5bf7
2 changed files with 25 additions and 0 deletions
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3
gcc/testsuite/gcc.dg/vect/bb-slp-pr65935.c
View file

@ -60,3 +60,6 @@ int main()
/* We should also be able to use 2-lane SLP to initialize the real and
imaginary components in the first loop of main. */
/* { dg-final { scan-tree-dump-times "optimized: basic block" 10 "slp1" } } */
/* We should see the s->phase[dir] operand and only that operand built
from scalars. See PR97334. */
/* { dg-final { scan-tree-dump-times "Building vector operands from scalars" 1 "slp1" } } */

22
gcc/tree-vect-slp.c
View file

@ -773,6 +773,12 @@ vect_build_slp_tree_1 (vec_info *vinfo, unsigned char *swap,
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
"Build SLP failed: unvectorizable statement %G",
stmt);
/* ??? For BB vectorization we want to commutate operands in a way
to shuffle all unvectorizable defs into one operand and have
the other still vectorized. The following doesn't reliably
work for this though but it's the easiest we can do here. */
if (is_a <bb_vec_info> (vinfo) && i != 0)
continue;
/* Fatal mismatch. */
matches[0] = false;
return false;
@ -785,6 +791,8 @@ vect_build_slp_tree_1 (vec_info *vinfo, unsigned char *swap,
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
"Build SLP failed: not GIMPLE_ASSIGN nor "
"GIMPLE_CALL %G", stmt);
if (is_a <bb_vec_info> (vinfo) && i != 0)
continue;
/* Fatal mismatch. */
matches[0] = false;
return false;
@ -797,6 +805,8 @@ vect_build_slp_tree_1 (vec_info *vinfo, unsigned char *swap,
&& !vect_record_max_nunits (vinfo, stmt_info, group_size,
nunits_vectype, max_nunits)))
{
if (is_a <bb_vec_info> (vinfo) && i != 0)
continue;
/* Fatal mismatch. */
matches[0] = false;
return false;
@ -823,6 +833,8 @@ vect_build_slp_tree_1 (vec_info *vinfo, unsigned char *swap,
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
"Build SLP failed: unsupported call type %G",
call_stmt);
if (is_a <bb_vec_info> (vinfo) && i != 0)
continue;
/* Fatal mismatch. */
matches[0] = false;
return false;
@ -865,6 +877,8 @@ vect_build_slp_tree_1 (vec_info *vinfo, unsigned char *swap,
if (dump_enabled_p ())
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
"Build SLP failed: no optab.\n");
if (is_a <bb_vec_info> (vinfo) && i != 0)
continue;
/* Fatal mismatch. */
matches[0] = false;
return false;
@ -876,6 +890,8 @@ vect_build_slp_tree_1 (vec_info *vinfo, unsigned char *swap,
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
"Build SLP failed: "
"op not supported by target.\n");
if (is_a <bb_vec_info> (vinfo) && i != 0)
continue;
/* Fatal mismatch. */
matches[0] = false;
return false;
@ -900,6 +916,8 @@ vect_build_slp_tree_1 (vec_info *vinfo, unsigned char *swap,
if (TREE_CODE (vec) != SSA_NAME
|| !types_compatible_p (vectype, TREE_TYPE (vec)))
{
if (is_a <bb_vec_info> (vinfo) && i != 0)
continue;
if (dump_enabled_p ())
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
"Build SLP failed: "
@ -1048,6 +1066,8 @@ vect_build_slp_tree_1 (vec_info *vinfo, unsigned char *swap,
"Build SLP failed: not grouped load %G", stmt);
/* FORNOW: Not grouped loads are not supported. */
if (is_a <bb_vec_info> (vinfo) && i != 0)
continue;
/* Fatal mismatch. */
matches[0] = false;
return false;
@ -1066,6 +1086,8 @@ vect_build_slp_tree_1 (vec_info *vinfo, unsigned char *swap,
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
"Build SLP failed: operation unsupported %G",
stmt);
if (is_a <bb_vec_info> (vinfo) && i != 0)
continue;
/* Fatal mismatch. */
matches[0] = false;
return false;