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re PR tree-optimization/81740 (wrong code at -O3 in both 32-bit and 64-bit modes on x86_64-linux-gnu)

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2019-03-26  Bin Cheng  <bin.cheng@linux.alibaba.com>

	PR tree-optimization/81740
	* tree-vect-data-refs.c (vect_analyze_data_ref_dependence):
	In case of outer loop vectorization, check for backward dependence
	at the inner loop if outer loop dependence is reversed.

	* gcc.dg/vect/pr81740-1.c: New testcase.
	* gcc.dg/vect/pr81740-2.c: Likewise.

From-SVN: r269938
This commit is contained in:
Bin Cheng 2019-03-26 11:12:37 +00:00 • committed by Richard Biener
parent a235c72e64
commit f30d4934a9
5 changed files with 75 additions and 2 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2019-03-26 Bin Cheng <bin.cheng@linux.alibaba.com>
PR tree-optimization/81740
* tree-vect-data-refs.c (vect_analyze_data_ref_dependence):
In case of outer loop vectorization, check for backward dependence
at the inner loop if outer loop dependence is reversed.
2019-03-26 Alan Modra <amodra@gmail.com>
* config/rs6000/rs6000.c (rs6000_init_hard_regno_mode_ok): Correct

6
gcc/testsuite/ChangeLog
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@ -1,3 +1,9 @@
2019-03-26 Bin Cheng <bin.cheng@linux.alibaba.com>
PR tree-optimization/81740
* gcc.dg/vect/pr81740-1.c: New testcase.
* gcc.dg/vect/pr81740-2.c: Likewise.
2019-03-26 Iain Buclaw <ibuclaw@gdcproject.org>
* gdc.test/gdc-test.exp (gdc-do-test): Sort and remove duplicate

22
gcc/testsuite/gcc.dg/vect/pr81740-1.c Normal file
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@ -0,0 +1,22 @@
/* { dg-do run } */
/* { dg-require-effective-target vect_int } */
#include "tree-vect.h"
int a[8][10] = { [2][5] = 4 }, c;
int
main ()
{
short b;
int i, d;
check_vect ();
for (b = 4; b >= 0; b--)
for (c = 0; c <= 6; c++)
a[c + 1][b + 2] = a[c][b + 1];
for (i = 0; i < 8; i++)
for (d = 0; d < 10; d++)
if (a[i][d] != (i == 3 && d == 6) * 4)
__builtin_abort ();
return 0;
}

24
gcc/testsuite/gcc.dg/vect/pr81740-2.c Normal file
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@ -0,0 +1,24 @@
/* { dg-do run } */
/* { dg-require-effective-target vect_int } */
#include "tree-vect.h"
int a[8][10] = { [2][5] = 4 }, c;
int
main ()
{
short b;
int i, d;
check_vect ();
for (b = 4; b >= 0; b--)
for (c = 6; c >= 0; c--)
a[c + 1][b + 2] = a[c][b + 1];
for (i = 0; i < 8; i++)
for (d = 0; d < 10; d++)
if (a[i][d] != (i == 3 && d == 6) * 4)
__builtin_abort ();
return 0;
}
/* { dg-final { scan-tree-dump "OUTER LOOP VECTORIZED" "vect" } } */

18
gcc/tree-vect-data-refs.c
View file

@ -473,8 +473,22 @@ vect_analyze_data_ref_dependence (struct data_dependence_relation *ddr,
reversed (to make distance vector positive), and the actual
distance is negative. */
if (dump_enabled_p ())
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
dump_printf_loc (MSG_NOTE, vect_location,
"dependence distance negative.\n");
/* When doing outer loop vectorization, we need to check if there is
a backward dependence at the inner loop level if the dependence
at the outer loop is reversed. See PR81740. */
if (nested_in_vect_loop_p (loop, stmtinfo_a)
|| nested_in_vect_loop_p (loop, stmtinfo_b))
{
unsigned inner_depth = index_in_loop_nest (loop->inner->num,
DDR_LOOP_NEST (ddr));
if (dist_v[inner_depth] < 0)
return opt_result::failure_at (stmtinfo_a->stmt,
"not vectorized, dependence "
"between data-refs %T and %T\n",
DR_REF (dra), DR_REF (drb));
}
/* Record a negative dependence distance to later limit the
amount of stmt copying / unrolling we can perform.
Only need to handle read-after-write dependence. */
@ -490,7 +504,7 @@ vect_analyze_data_ref_dependence (struct data_dependence_relation *ddr,
{
/* The dependence distance requires reduction of the maximal
vectorization factor. */
*max_vf = abs (dist);
*max_vf = abs_dist;
if (dump_enabled_p ())
dump_printf_loc (MSG_NOTE, vect_location,
"adjusting maximal vectorization factor to %i\n",