Add missing unit dependence vector in data dependence analysis

Current data dependence analysis misses unit distant vector if DRs in
DDR have the same invariant access functions.  This adds the vector as
the constant access function case.

Also fix typo in testcase.

Backport from master commit: 287552950d56be47adb6b6bf2eae2d612233eaec
and f6e1a4cd83190746b6544917f7526fa480ca5f18

2020-06-20  Bin Cheng  <bin.cheng@linux.alibaba.com>

gcc/
	PR tree-optimization/94969
	* tree-data-ref.c (constant_access_functions): Rename to...
	(invariant_access_functions): ...this.  Add parameter.  Check for
	invariant access function, rather than constant.
	(build_classic_dist_vector): Call above function.
	* tree-loop-distribution.c (pg_add_dependence_edges): Add comment.

gcc/testsuite/
	PR tree-optimization/94969
	* gcc.dg/tree-ssa/pr94969.c: New test.

2020-06-20  Jakub Jelinek  <jakub@redhat.com>

gcc/testsuite/
	PR tree-optimization/95110
	* gcc.dg/tree-ssa/pr94969.c: Swap scan-tree-dump-not arguments.

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr94969.c b/gcc/testsuite/gcc.dg/tree-ssa/pr94969.c
new file mode 100644 (file)
index 0000000..f150461
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr94969.c
@@ -0,0 +1,28 @@
+/* PR tree-optimization/52267 */
+/* { dg-do run } */
+/* { dg-options "-O3 -fdump-tree-ldist-details" } */
+
+int a = 0, b = 0, c = 0;
+struct S {
+  signed m : 7;
+  signed e : 2;
+};
+struct S f[2] = {{0, 0}, {0, 0}};
+struct S g = {0, 0};
+
+void __attribute__((noinline))
+k()
+{
+  for (; c <= 1; c++) {
+    f[b] = g;
+    f[b].e ^= 1;
+  }
+}
+int main()
+{
+  k();
+  if (f[b].e != 1)
+    __builtin_abort ();
+}
+
+/* { dg-final { scan-tree-dump-not "Loop 1 distributed: split to 3 loops" "ldist" } } */

diff --git a/gcc/tree-data-ref.c b/gcc/tree-data-ref.c
index fc86bc2595113c43ef9bc0f625a138a90756f489..c90e862fb16289de24046971d01a80c007475787 100644 (file)
--- a/gcc/tree-data-ref.c
+++ b/gcc/tree-data-ref.c
@@ -4342,17 +4342,19 @@ build_classic_dist_vector_1 (struct data_dependence_relation *ddr,
   return true;
 }
 
-/* Return true when the DDR contains only constant access functions.  */
+/* Return true when the DDR contains only invariant access functions wrto. loop
+   number LNUM.  */
 
 static bool
-constant_access_functions (const struct data_dependence_relation *ddr)
+invariant_access_functions (const struct data_dependence_relation *ddr,
+                           int lnum)
 {
   unsigned i;
   subscript *sub;
 
   FOR_EACH_VEC_ELT (DDR_SUBSCRIPTS (ddr), i, sub)
-    if (!evolution_function_is_constant_p (SUB_ACCESS_FN (sub, 0))
-       || !evolution_function_is_constant_p (SUB_ACCESS_FN (sub, 1)))
+    if (!evolution_function_is_invariant_p (SUB_ACCESS_FN (sub, 0), lnum)
+       || !evolution_function_is_invariant_p (SUB_ACCESS_FN (sub, 1), lnum))
       return false;
 
   return true;
@@ -4551,7 +4553,7 @@ 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))
+      if (invariant_access_functions (ddr, loop_nest->num))
        add_distance_for_zero_overlaps (ddr);
 
       if (DDR_NB_LOOPS (ddr) > 1)

diff --git a/gcc/tree-loop-distribution.c b/gcc/tree-loop-distribution.c
index 769523ba21454e3477facae81be8a5b7a42f0e6d..05766c7300dfb110d8e9ca25b4f5a16d2ae120e8 100644 (file)
--- a/gcc/tree-loop-distribution.c
+++ b/gcc/tree-loop-distribution.c
@@ -1919,7 +1919,8 @@ pg_add_dependence_edges (struct graph *rdg, int dir,
                this_dir = -this_dir;
 
              /* Known dependences can still be unordered througout the
-                iteration space, see gcc.dg/tree-ssa/ldist-16.c.  */
+                iteration space, see gcc.dg/tree-ssa/ldist-16.c and
+                gcc.dg/tree-ssa/pr94969.c.  */
              if (DDR_NUM_DIST_VECTS (ddr) != 1)
                this_dir = 2;
              /* If the overlap is exact preserve stmt order.  */