[gcc r12-1381] middle-end/101009 - fix distance vector recording

[gcc r12-1381] middle-end/101009 - fix distance vector recording

[Richard Biener]

https://gcc.gnu.org/g:336c41dbcb21740f8964021e157bc69ca547059b

commit r12-1381-g336c41dbcb21740f8964021e157bc69ca547059b
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.

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 b1f64684840..b37c234aea8 100644
--- a/gcc/tree-data-ref.c
+++ b/gcc/tree-data-ref.c
@@ -5121,6 +5121,8 @@ build_classic_dist_vector_1 (struct data_dependence_relation *ddr,
 	  non_affine_dependence_relation (ddr);
 	  return false;
 	}
+      else
+	*init_b = true;
     }
 
   return true;
@@ -5616,9 +5618,13 @@ 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);
     }