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Fix PR46194: fix the computation of distance vectors.

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2011-02-04  Sebastian Pop  <sebastian.pop@amd.com>

	PR tree-optimization/46194
	* tree-data-ref.c (analyze_miv_subscript): Remove comment.
	(build_classic_dist_vector_1): Do not represent classic distance
	vectors when the access functions are variating in different loops.

	* gcc.dg/autopar/pr46194.c: New.

From-SVN: r169847
This commit is contained in:
Sebastian Pop 2011-02-05 01:39:20 +00:00 committed by Sebastian Pop
parent a44b6422a3
commit a130584a8a
4 changed files with 42 additions and 24 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2011-02-04 Sebastian Pop <sebastian.pop@amd.com>
PR tree-optimization/46194
* tree-data-ref.c (analyze_miv_subscript): Remove comment.
(build_classic_dist_vector_1): Do not represent classic distance
vectors when the access functions are variating in different loops.
2011-02-04 Joseph Myers <joseph@codesourcery.com>
* config/mips/iris6.opt: New.

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2011-02-04 Sebastian Pop <sebastian.pop@amd.com>
PR tree-optimization/46194
* gcc.dg/autopar/pr46194.c: New.
2011-02-04 H.J. Lu <hongjiu.lu@intel.com>
PR tree-optimization/43695

24
gcc/testsuite/gcc.dg/autopar/pr46194.c Normal file
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@ -0,0 +1,24 @@
/* PR tree-optimization/46194 */
/* { dg-do compile } */
/* { dg-options "-O -ftree-parallelize-loops=2 -fdump-tree-parloops-details" } */
#define N 1000
int a[N];
int foo (void)
{
int j;
int i;
/* This is not blocked as it is not profitable. */
for (i = 0; i < N; i++)
for (j = 0; j < N; j++)
a[j] = a[i] + 1;
return a[0];
}
/* This loop cannot be parallelized due to a dependence. */
/* { dg-final { scan-tree-dump-times "SUCCESS: may be parallelized" 0 "parloops" } } */
/* { dg-final { cleanup-tree-dump "parloops" } } */

30
gcc/tree-data-ref.c
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@ -2681,14 +2681,6 @@ analyze_miv_subscript (tree chrec_a,
tree *last_conflicts,
struct loop *loop_nest)
{
/* FIXME: This is a MIV subscript, not yet handled.
Example: (A[{1, +, 1}_1] vs. A[{1, +, 1}_2]) that comes from
(A[i] vs. A[j]).
In the SIV test we had to solve a Diophantine equation with two
variables. In the MIV case we have to solve a Diophantine
equation with 2*n variables (if the subscript uses n IVs).
*/
tree type, difference;
dependence_stats.num_miv++;
@ -2960,29 +2952,19 @@ build_classic_dist_vector_1 (struct data_dependence_relation *ddr,
&& TREE_CODE (access_fn_b) == POLYNOMIAL_CHREC)
{
int dist, index;
int index_a = index_in_loop_nest (CHREC_VARIABLE (access_fn_a),
DDR_LOOP_NEST (ddr));
int index_b = index_in_loop_nest (CHREC_VARIABLE (access_fn_b),
DDR_LOOP_NEST (ddr));
int var_a = CHREC_VARIABLE (access_fn_a);
int var_b = CHREC_VARIABLE (access_fn_b);
/* The dependence is carried by the outermost loop. Example:
| loop_1
| A[{4, +, 1}_1]
| loop_2
| A[{5, +, 1}_2]
| endloop_2
| endloop_1
In this case, the dependence is carried by loop_1. */
index = index_a < index_b ? index_a : index_b;
*index_carry = MIN (index, *index_carry);
if (chrec_contains_undetermined (SUB_DISTANCE (subscript)))
if (var_a != var_b
|| chrec_contains_undetermined (SUB_DISTANCE (subscript)))
{
non_affine_dependence_relation (ddr);
return false;
}
dist = int_cst_value (SUB_DISTANCE (subscript));
index = index_in_loop_nest (var_a, DDR_LOOP_NEST (ddr));
*index_carry = MIN (index, *index_carry);
/* This is the subscript coupling test. If we have already
recorded a distance for this loop (a distance coming from