Check array indices in object_address_invariant_in_loop_p (PR 84357)

object_address_invariant_in_loop_p ignored ARRAY_REF indices on
the basis that:

	  /* Index of the ARRAY_REF was zeroed in analyze_indices, thus we only
	     need to check the stride and the lower bound of the reference.  */

That was true back in 2007 when the code was added:

static void
dr_analyze_indices (struct data_reference *dr, struct loop *nest)
{
  [...]
  while (handled_component_p (aref))
    {
      if (TREE_CODE (aref) == ARRAY_REF)
        {
          op = TREE_OPERAND (aref, 1);
          access_fn = analyze_scalar_evolution (loop, op);
          access_fn = resolve_mixers (nest, access_fn);
          VEC_safe_push (tree, heap, access_fns, access_fn);

          TREE_OPERAND (aref, 1) = build_int_cst (TREE_TYPE (op), 0);
        }

      aref = TREE_OPERAND (aref, 0);
    }

but the assignment was removed a few years ago.  We were therefore
treating "two->arr[i]" and "three->arr[i]" as loop invariant.

2018-02-14  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	PR tree-optimization/84357
	* tree-data-ref.c (object_address_invariant_in_loop_p): Check
	operand 1 of an ARRAY_REF too.

gcc/testsuite/
	PR tree-optimization/84357
	* gcc.dg/vect/pr84357.c: New test.

From-SVN: r257657

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 22589babaa6a3dd29dca8136176998af114f1458..cc294407691ba2feb7d823e4a64a52dcdfab50f6 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2018-02-14  Richard Sandiford  <richard.sandiford@linaro.org>
+
+       PR tree-optimization/84357
+       * tree-data-ref.c (object_address_invariant_in_loop_p): Check
+       operand 1 of an ARRAY_REF too.
+
 2018-02-14  Oleg Endo  <olegendo@gcc.gnu.org>
 
        PR target/83831

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 776542aa5fa0e41c68e1409ee093c6c949eeecd1..473a2723012b298c207ac94fc5229e1359815b3c 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-02-14  Richard Sandiford  <richard.sandiford@linaro.org>
+
+       PR tree-optimization/84357
+       * gcc.dg/vect/pr84357.c: New test.
+
 2018-02-14  Oleg Endo  <olegendo@gcc.gnu.org>
 
        PR target/83831

diff --git a/gcc/testsuite/gcc.dg/vect/pr84357.c b/gcc/testsuite/gcc.dg/vect/pr84357.c
new file mode 100644 (file)
index 0000000..cd3cc4a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr84357.c
@@ -0,0 +1,31 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-Wall" } */
+
+#define COUNT 32
+
+typedef struct s1 {
+    unsigned char c;
+} s1;
+
+typedef struct s2
+{
+    char pad;
+    s1 arr[COUNT];
+} s2;
+
+typedef struct s3 {
+    s1 arr[COUNT];
+} s3;
+
+s2 * get_s2();
+s3 * gActiveS3;
+void foo()
+{
+    s3 * three = gActiveS3;
+    s2 * two = get_s2();
+
+    for (int i = 0; i < COUNT; i++)
+    {
+        two->arr[i].c = three->arr[i].c;
+    }
+}

diff --git a/gcc/tree-data-ref.c b/gcc/tree-data-ref.c
index fdb2ac1b8454e4a013b83547b1fd9ab27dfc5668..a886329966cb89361c187afebbe1870c6f06e62e 100644 (file)
--- a/gcc/tree-data-ref.c
+++ b/gcc/tree-data-ref.c
@@ -2200,13 +2200,10 @@ object_address_invariant_in_loop_p (const struct loop *loop, const_tree obj)
     {
       if (TREE_CODE (obj) == ARRAY_REF)
        {
-         /* Index of the ARRAY_REF was zeroed in analyze_indices, thus we only
-            need to check the stride and the lower bound of the reference.  */
-         if (chrec_contains_symbols_defined_in_loop (TREE_OPERAND (obj, 2),
-                                                     loop->num)
-             || chrec_contains_symbols_defined_in_loop (TREE_OPERAND (obj, 3),
-                                                        loop->num))
-           return false;
+         for (int i = 1; i < 4; ++i)
+           if (chrec_contains_symbols_defined_in_loop (TREE_OPERAND (obj, i),
+                                                       loop->num))
+             return false;
        }
       else if (TREE_CODE (obj) == COMPONENT_REF)
        {