[gcc r10-10095] middle-end/101009 - fix distance vector recording

[gcc r10-10095] middle-end/101009 - fix distance vector recording

[Richard Biener]

https://gcc.gnu.org/g:917a675ad57f21f575c86192b22b1cc6d3bfc23d

commit r10-10095-g917a675ad57f21f575c86192b22b1cc6d3bfc23d
Author: Richard Biener <rguenther@suse.de>
Date:   Fri Jun 11 09:33:58 2021 +0200

    middle-end/101009 - fix distance vector recording
    
    This fixes recording of distance vectors in case the DDR has just
    constant equal indexes.  In that case we expect distance vectors
    with zero distances to be recorded which is what was done when
    any distance was computed for affine indexes.
    
    2021-06-11  Richard Biener  <rguenther@suse.de>
    
            PR middle-end/101009
            * tree-data-ref.c (build_classic_dist_vector_1): Make sure
            to set *init_b to true when we encounter a constant equal
            index pair.
            (compute_affine_dependence): Also dump the actual DR_REF.
    
            * gcc.dg/torture/pr101009.c: New testcase.
    
    (cherry picked from commit 336c41dbcb21740f8964021e157bc69ca547059b)

Diff:
---
 gcc/testsuite/gcc.dg/torture/pr101009.c | 17 +++++++++++++++++
 gcc/tree-data-ref.c                     | 10 ++++++++--
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/torture/pr101009.c b/gcc/testsuite/gcc.dg/torture/pr101009.c
new file mode 100644
index 00000000000..2bbed1dfc2c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr101009.c
@@ -0,0 +1,17 @@
+/* { dg-do run } */
+/* { dg-additional-options "-fno-tree-sra -fno-tree-pre -ftree-loop-distribution" } */
+
+struct a {
+  unsigned b;
+  unsigned c;
+} e, *f = &e;
+int d = 1;
+int main() {
+  for (; d; d--) {
+    struct a g[] = {{2, 1}, {2, 1}};
+    *f = g[1];
+  }
+  if (e.c != 1)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/tree-data-ref.c b/gcc/tree-data-ref.c
index 2a4da7a7a18..a0613ed83eb 100644
--- a/gcc/tree-data-ref.c
+++ b/gcc/tree-data-ref.c
@@ -4827,6 +4827,8 @@ build_classic_dist_vector_1 (struct data_dependence_relation *ddr,
 	  non_affine_dependence_relation (ddr);
 	  return false;
 	}
+      else
+	*init_b = true;
     }
 
   return true;
@@ -5322,9 +5324,13 @@ compute_affine_dependence (struct data_dependence_relation *ddr,
   if (dump_file && (dump_flags & TDF_DETAILS))
     {
       fprintf (dump_file, "(compute_affine_dependence\n");
-      fprintf (dump_file, "  stmt_a: ");
+      fprintf (dump_file, "  ref_a: ");
+      print_generic_expr (dump_file, DR_REF (dra));
+      fprintf (dump_file, ", stmt_a: ");
       print_gimple_stmt (dump_file, DR_STMT (dra), 0, TDF_SLIM);
-      fprintf (dump_file, "  stmt_b: ");
+      fprintf (dump_file, "  ref_b: ");
+      print_generic_expr (dump_file, DR_REF (drb));
+      fprintf (dump_file, ", stmt_b: ");
       print_gimple_stmt (dump_file, DR_STMT (drb), 0, TDF_SLIM);
     }