From 1baf2906ef9aa2870b7162b51f9e5b15c7251031 Mon Sep 17 00:00:00 2001
From: Sebastian Pop <sebastian.pop@inria.fr>
Date: Wed, 11 Apr 2007 19:10:23 +0200
Subject: [PATCH] tree-data-ref.c (affine_function_zero_p, [...]): New.
* tree-data-ref.c (affine_function_zero_p, constant_access_functions,
insert_innermost_unit_dist_vector, add_distance_for_zero_overlaps): New.
(build_classic_dist_vector): Call add_distance_for_zero_overlaps.
From-SVN: r123721
---
gcc/ChangeLog | 6 ++++++
gcc/tree-data-ref.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 81 insertions(+)
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 98d5bc7..6f75721 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2007-04-11 Sebastian Pop <sebastian.pop@inria.fr>
+
+ * tree-data-ref.c (affine_function_zero_p, constant_access_functions,
+ insert_innermost_unit_dist_vector, add_distance_for_zero_overlaps): New.
+ (build_classic_dist_vector): Call add_distance_for_zero_overlaps.
+
2007-04-10 Zdenek Dvorak <dvorakz@suse.cz>
* tree-data-ref.c (add_multivariate_self_dist): Force the distance
diff --git a/gcc/tree-data-ref.c b/gcc/tree-data-ref.c
index 7d80746..0340b9e 100644
--- a/gcc/tree-data-ref.c
+++ b/gcc/tree-data-ref.c
@@ -2124,6 +2124,15 @@ affine_function_constant_p (affine_fn fn)
return true;
}
+/* Returns true if FN is the zero constant function. */
+
+static bool
+affine_function_zero_p (affine_fn fn)
+{
+ return (integer_zerop (affine_function_base (fn))
+ && affine_function_constant_p (fn));
+}
+
/* Applies operation OP on affine functions FNA and FNB, and returns the
result. */
@@ -3847,6 +3856,22 @@ same_access_functions (struct data_dependence_relation *ddr)
return true;
}
+/* Return true when the DDR contains only constant access functions. */
+
+static bool
+constant_access_functions (struct data_dependence_relation *ddr)
+{
+ unsigned i;
+
+ for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++)
+ if (!evolution_function_is_constant_p (DR_ACCESS_FN (DDR_A (ddr), i))
+ || !evolution_function_is_constant_p (DR_ACCESS_FN (DDR_B (ddr), i)))
+ return false;
+
+ return true;
+}
+
+
/* Helper function for the case where DDR_A and DDR_B are the same
multivariate access function. */
@@ -3928,6 +3953,53 @@ add_other_self_distances (struct data_dependence_relation *ddr)
add_outer_distances (ddr, dist_v, index_carry);
}
+static void
+insert_innermost_unit_dist_vector (struct data_dependence_relation *ddr)
+{
+ lambda_vector dist_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
+
+ dist_v[DDR_INNER_LOOP (ddr)] = 1;
+ save_dist_v (ddr, dist_v);
+}
+
+/* Adds a unit distance vector to DDR when there is a 0 overlap. This
+ is the case for example when access functions are the same and
+ equal to a constant, as in:
+
+ | loop_1
+ | A[3] = ...
+ | ... = A[3]
+ | endloop_1
+
+ in which case the distance vectors are (0) and (1). */
+
+static void
+add_distance_for_zero_overlaps (struct data_dependence_relation *ddr)
+{
+ unsigned i, j;
+
+ for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++)
+ {
+ subscript_p sub = DDR_SUBSCRIPT (ddr, i);
+ conflict_function *ca = SUB_CONFLICTS_IN_A (sub);
+ conflict_function *cb = SUB_CONFLICTS_IN_B (sub);
+
+ for (j = 0; j < ca->n; j++)
+ if (affine_function_zero_p (ca->fns[j]))
+ {
+ insert_innermost_unit_dist_vector (ddr);
+ return;
+ }
+
+ for (j = 0; j < cb->n; j++)
+ if (affine_function_zero_p (cb->fns[j]))
+ {
+ insert_innermost_unit_dist_vector (ddr);
+ return;
+ }
+ }
+}
+
/* Compute the classic per loop distance vector. DDR is the data
dependence relation to build a vector from. Return false when fail
to represent the data dependence as a distance vector. */
@@ -3948,6 +4020,9 @@ build_classic_dist_vector (struct data_dependence_relation *ddr)
dist_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
save_dist_v (ddr, dist_v);
+ if (constant_access_functions (ddr))
+ add_distance_for_zero_overlaps (ddr);
+
if (DDR_NB_LOOPS (ddr) > 1)
add_other_self_distances (ddr);
--
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