re PR tree-optimization/52406 (likely wrong code bug)

2012-03-02  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/52406
	* tree-data-ref.h: Update documentation about DR_BASE_OBJECT.
	(struct indices): Add unconstrained_base member.
	(struct dr_alias): Remove unused vops member.
	(DR_UNCONSTRAINED_BASE): New define.
	* tree-data-ref.c (dr_analyze_indices): For COMPONENT_REFs
	add indices to allow their disambiguation.  Make DR_BASE_OBJECT
	be an artificial access that covers the whole indexed object,
	or mark it with DR_UNCONSTRAINED_BASE if we cannot do so.  Canonicalize
	plain decl base-objects to their MEM_REF variant.
	(dr_may_alias_p): When the base-object of either data reference
	has unknown size use only points-to information.
	(compute_affine_dependence): Make dumps easier to read and
	more verbose.
	* tree-vect-data-ref.c (vector_alignment_reachable_p): Use
	DR_REF when looking for packed references.
	(vect_supportable_dr_alignment): Likewise.

	* gcc.dg/torture/pr52406.c: New testcase.

From-SVN: r184789

1 files changed, 16 insertions, 15 deletions

diff --git a/gcc/tree-data-ref.h b/gcc/tree-data-ref.h
index 15bae6b..d983c8c 100644
--- a/gcc/tree-data-ref.h
+++ b/gcc/tree-data-ref.h
@@ -60,16 +60,17 @@ struct innermost_loop_behavior
 };
 
 /* Describes the evolutions of indices of the memory reference.  The indices
-   are indices of the ARRAY_REFs and the operands of INDIRECT_REFs.
-   For ARRAY_REFs, BASE_OBJECT is the reference with zeroed indices
-   (note that this reference does not have to be valid, if zero does not
-   belong to the range of the array; hence it is not recommended to use
-   BASE_OBJECT in any code generation).  For INDIRECT_REFs, the address is
-   set to the loop-invariant part of the address of the object, except for
-   the constant offset.  For the examples above,
-
-   base_object:        a[0].b[0][0]                   *(p + x + 4B * j_0)
+   are indices of the ARRAY_REFs, indexes in artificial dimensions
+   added for member selection of records and the operands of MEM_REFs.
+   BASE_OBJECT is the part of the reference that is loop-invariant
+   (note that this reference does not have to cover the whole object
+   being accessed, in which case UNCONSTRAINED_BASE is set; hence it is
+   not recommended to use BASE_OBJECT in any code generation).
+   For the examples above,
+
+   base_object:        a                              *(p + x + 4B * j_0)
    indices:            {j_0, +, 1}_2                  {16, +, 4}_2
+		       4
 		       {i_0, +, 1}_1
 		       {j_0, +, 1}_2
 */
@@ -81,18 +82,17 @@ struct indices
 
   /* A list of chrecs.  Access functions of the indices.  */
   VEC(tree,heap) *access_fns;
+
+  /* Whether BASE_OBJECT is an access representing the whole object
+     or whether the access could not be constrained.  */
+  bool unconstrained_base;
 };
 
 struct dr_alias
 {
   /* The alias information that should be used for new pointers to this
-     location.  SYMBOL_TAG is either a DECL or a SYMBOL_MEMORY_TAG.  */
+     location.  */
   struct ptr_info_def *ptr_info;
-
-  /* The set of virtual operands corresponding to this memory reference,
-     serving as a description of the alias information for the memory
-     reference.  This could be eliminated if we had alias oracle.  */
-  bitmap vops;
 };
 
 /* An integer vector.  A vector formally consists of an element of a vector
@@ -201,6 +201,7 @@ struct data_reference
 #define DR_STMT(DR)                (DR)->stmt
 #define DR_REF(DR)                 (DR)->ref
 #define DR_BASE_OBJECT(DR)         (DR)->indices.base_object
+#define DR_UNCONSTRAINED_BASE(DR)  (DR)->indices.unconstrained_base
 #define DR_ACCESS_FNS(DR)	   (DR)->indices.access_fns
 #define DR_ACCESS_FN(DR, I)        VEC_index (tree, DR_ACCESS_FNS (DR), I)
 #define DR_NUM_DIMENSIONS(DR)      VEC_length (tree, DR_ACCESS_FNS (DR))