Check array indices in object_address_invariant_in_loop_p (PR 84357)

Message ID 87eflnc3dh.fsf@linaro.org
State New
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  • Check array indices in object_address_invariant_in_loop_p (PR 84357)
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Commit Message

Richard Sandiford Feb. 14, 2018, 9:44 a.m.
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.

Tested on aarch64-linux-gnu, x86_64-linux-gnu and powerpc64le-linux-gnu.
OK to install?

Richard


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.

Comments

Richard Biener Feb. 14, 2018, 12:50 p.m. | #1
On Wed, Feb 14, 2018 at 10:44 AM, Richard Sandiford
<richard.sandiford@linaro.org> wrote:
> 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.


GCC 4.7!

>  We were therefore

> treating "two->arr[i]" and "three->arr[i]" as loop invariant.

>

> Tested on aarch64-linux-gnu, x86_64-linux-gnu and powerpc64le-linux-gnu.

> OK to install?


Ok.

Thanks,
Richard.

> Richard

>

>

> 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.

>

> Index: gcc/tree-data-ref.c

> ===================================================================

> --- gcc/tree-data-ref.c 2018-02-08 15:16:21.784407397 +0000

> +++ gcc/tree-data-ref.c 2018-02-14 09:42:14.801095011 +0000

> @@ -2200,13 +2200,10 @@ object_address_invariant_in_loop_p (cons

>      {

>        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)

>         {

> Index: gcc/testsuite/gcc.dg/vect/pr84357.c

> ===================================================================

> --- /dev/null   2018-02-10 09:05:46.714416790 +0000

> +++ gcc/testsuite/gcc.dg/vect/pr84357.c 2018-02-14 09:42:14.800095067 +0000

> @@ -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;

> +    }

> +}

Patch

Index: gcc/tree-data-ref.c
===================================================================
--- gcc/tree-data-ref.c	2018-02-08 15:16:21.784407397 +0000
+++ gcc/tree-data-ref.c	2018-02-14 09:42:14.801095011 +0000
@@ -2200,13 +2200,10 @@  object_address_invariant_in_loop_p (cons
     {
       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)
 	{
Index: gcc/testsuite/gcc.dg/vect/pr84357.c
===================================================================
--- /dev/null	2018-02-10 09:05:46.714416790 +0000
+++ gcc/testsuite/gcc.dg/vect/pr84357.c	2018-02-14 09:42:14.800095067 +0000
@@ -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;
+    }
+}