I am testing the following patch to fix PR52406. We cannot simply
feed DR_BASE_OBJECT to the alias-oracle as it does not reflect
a real memory access. Only if we query two 'structurally compatible'
references we may do this. So the following patch reverts to
using DR_REF instead and improves data-ref index disambiguation
by handling COMPONENT_REFs as extra access dimension (similar to how
we handle REALPART/IMAGPART_EXPR).
Bootstrap / regtest pending on x86_64-unknown-linux-gnu.
Richard.
2012-02-28 Richard Guenther <rguent...@suse.de>
PR tree-optimization/52406
* tree-data-ref.c (dr_analyze_indices): For outer COMPONENT_REFs
add indices to allow their disambiguation.
(dr_may_alias_p): Use DR_REF for querying the alias oracle.
(compute_affine_dependence): Make dumps easier to read and
more verbose.
* gcc.dg/torture/pr52406.c: New testcase.
Index: gcc/tree-data-ref.c
===================================================================
*** gcc/tree-data-ref.c (revision 184622)
--- gcc/tree-data-ref.c (working copy)
*************** dr_analyze_indices (struct data_referenc
*** 886,891 ****
--- 886,908 ----
VEC_safe_push (tree, heap, access_fns, integer_one_node);
}
+ /* For outermost COMPONENT_REFs of records (but not unions!) use the
+ FIELD_DECL offset as constant access function so we can
+ disambiguate a[i].f1 and a[i].f2. */
+ while (TREE_CODE (ref) == COMPONENT_REF
+ && TREE_CODE (TREE_TYPE (TREE_OPERAND (ref, 0))) == RECORD_TYPE)
+ {
+ tree off = component_ref_field_offset (ref);
+ off = size_binop (PLUS_EXPR,
+ size_binop (MULT_EXPR,
+ fold_convert (bitsizetype, off),
+ bitsize_int (BITS_PER_UNIT)),
+ DECL_FIELD_BIT_OFFSET (TREE_OPERAND (ref, 1)));
+ ref = TREE_OPERAND (ref, 0);
+ VEC_safe_push (tree, heap, access_fns, off);
+ continue;
+ }
+
/* Analyze access functions of dimensions we know to be independent. */
aref = &ref;
while (handled_component_p (*aref))
*************** bool
*** 1325,1332 ****
dr_may_alias_p (const struct data_reference *a, const struct data_reference
*b,
bool loop_nest)
{
! tree addr_a = DR_BASE_OBJECT (a);
! tree addr_b = DR_BASE_OBJECT (b);
/* If we are not processing a loop nest but scalar code we
do not need to care about possible cross-iteration dependences
--- 1342,1349 ----
dr_may_alias_p (const struct data_reference *a, const struct data_reference
*b,
bool loop_nest)
{
! tree addr_a = DR_REF (a);
! tree addr_b = DR_REF (b);
/* If we are not processing a loop nest but scalar code we
do not need to care about possible cross-iteration dependences
*************** compute_affine_dependence (struct data_d
*** 4049,4059 ****
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "(compute_affine_dependence\n");
! fprintf (dump_file, " (stmt_a = \n");
! print_gimple_stmt (dump_file, DR_STMT (dra), 0, 0);
! fprintf (dump_file, ")\n (stmt_b = \n");
! print_gimple_stmt (dump_file, DR_STMT (drb), 0, 0);
! fprintf (dump_file, ")\n");
}
/* Analyze only when the dependence relation is not yet known. */
--- 4066,4075 ----
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "(compute_affine_dependence\n");
! fprintf (dump_file, " stmt_a: ");
! print_gimple_stmt (dump_file, DR_STMT (dra), 0, TDF_SLIM);
! fprintf (dump_file, " stmt_b: ");
! print_gimple_stmt (dump_file, DR_STMT (drb), 0, TDF_SLIM);
}
/* Analyze only when the dependence relation is not yet known. */
*************** compute_affine_dependence (struct data_d
*** 4129,4135 ****
}
if (dump_file && (dump_flags & TDF_DETAILS))
! fprintf (dump_file, ")\n");
}
/* Compute in DEPENDENCE_RELATIONS the data dependence graph for all
--- 4145,4158 ----
}
if (dump_file && (dump_flags & TDF_DETAILS))
! {
! if (DDR_ARE_DEPENDENT (ddr) == chrec_known)
! fprintf (dump_file, ") -> no dependence\n");
! else if (DDR_ARE_DEPENDENT (ddr) == chrec_dont_know)
! fprintf (dump_file, ") -> dependence analysis failed\n");
! else
! fprintf (dump_file, ")\n");
! }
}
/* Compute in DEPENDENCE_RELATIONS the data dependence graph for all
Index: gcc/testsuite/gcc.dg/torture/pr52406.c
===================================================================
*** gcc/testsuite/gcc.dg/torture/pr52406.c (revision 0)
--- gcc/testsuite/gcc.dg/torture/pr52406.c (revision 0)
***************
*** 0 ****
--- 1,29 ----
+ /* { dg-do run } */
+
+ extern void abort (void);
+ struct { int f1; } a[2];
+
+ int *b, *const k = &a[1].f1;
+ static int **c = &b;
+
+ int e, f, d;
+
+ int
+ main ()
+ {
+ int **l = &b;
+ *l = k;
+ for (; d <= 0; d++)
+ {
+ int *j = &e;
+ **c = 1;
+ *l = k;
+ *k ^= 0;
+ f = **l;
+ *j = f;
+ }
+ if (e != 1)
+ abort ();
+ return 0;
+ }
+
