This fixes PR54132 where loop distribution pattern matching thinks
that every loop that copies contiguous memory regions and has
a dependence between input and output can be representet by a memmove.
Not. Obviously.
Thus, fixed by doing proper dependence checks.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
Richard.
2012-09-19 Richard Guenther <rguent...@suse.de>
PR tree-optimization/54132
* tree-loop-distribution.c (classify_partition): Properly
check dependences for memmove.
* tree-data-ref.h (compute_affine_dependence): Declare.
* tree-data-ref.c (compute_affine_dependence): Export.
* gcc.dg/tree-ssa/ldist-21.c: New testcase.
* gcc.dg/torture/pr54132.c: Likewise.
Index: gcc/tree-loop-distribution.c
===================================================================
*** gcc/tree-loop-distribution.c (revision 191415)
--- gcc/tree-loop-distribution.c (working copy)
*************** classify_partition (loop_p loop, struct
*** 1011,1016 ****
--- 1011,1049 ----
|| !operand_equal_p (DR_STEP (single_store),
DR_STEP (single_load), 0))
return;
+ /* Now check that if there is a dependence this dependence is
+ of a suitable form for memmove. */
+ VEC(loop_p, heap) *loops = NULL;
+ ddr_p ddr;
+ VEC_safe_push (loop_p, heap, loops, loop);
+ ddr = initialize_data_dependence_relation (single_load, single_store,
+ loops);
+ compute_affine_dependence (ddr, loop);
+ VEC_free (loop_p, heap, loops);
+ if (DDR_ARE_DEPENDENT (ddr) == chrec_dont_know)
+ {
+ free_dependence_relation (ddr);
+ return;
+ }
+ if (DDR_ARE_DEPENDENT (ddr) != chrec_known)
+ {
+ if (DDR_NUM_DIST_VECTS (ddr) == 0)
+ {
+ free_dependence_relation (ddr);
+ return;
+ }
+ lambda_vector dist_v;
+ FOR_EACH_VEC_ELT (lambda_vector, DDR_DIST_VECTS (ddr), i, dist_v)
+ {
+ int dist = dist_v[index_in_loop_nest (loop->num,
+ DDR_LOOP_NEST (ddr))];
+ if (dist > 0 && !DDR_REVERSED_P (ddr))
+ {
+ free_dependence_relation (ddr);
+ return;
+ }
+ }
+ }
partition->kind = PKIND_MEMCPY;
partition->main_dr = single_store;
partition->secondary_dr = single_load;
Index: gcc/testsuite/gcc.dg/tree-ssa/ldist-21.c
===================================================================
*** gcc/testsuite/gcc.dg/tree-ssa/ldist-21.c (revision 0)
--- gcc/testsuite/gcc.dg/tree-ssa/ldist-21.c (working copy)
***************
*** 0 ****
--- 1,11 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O3 -fdump-tree-ldist-details" } */
+
+ void bar(char *p, int n)
+ {
+ int i;
+ for (i = 1; i < n; i++)
+ p[i-1] = p[i];
+ }
+
+ /* { dg-final { scan-tree-dump "generated memmove" "ldist" } } */
Index: gcc/testsuite/gcc.dg/torture/pr54132.c
===================================================================
*** gcc/testsuite/gcc.dg/torture/pr54132.c (revision 0)
--- gcc/testsuite/gcc.dg/torture/pr54132.c (working copy)
***************
*** 0 ****
--- 1,18 ----
+ /* { dg-do run } */
+
+ extern void abort (void);
+ void foo(char *p, int n)
+ {
+ int i;
+ for (i = 1; i < n; i++)
+ p[i] = p[i - 1];
+ }
+ int main()
+ {
+ char a[1024];
+ a[0] = 1;
+ foo (a, 1024);
+ if (a[1023] != 1)
+ abort ();
+ return 0;
+ }
Index: gcc/tree-data-ref.c
===================================================================
*** gcc/tree-data-ref.c (revision 191415)
--- gcc/tree-data-ref.c (working copy)
*************** ddr_consistent_p (FILE *file,
*** 4130,4136 ****
relation the first time we detect a CHREC_KNOWN element for a given
subscript. */
! static void
compute_affine_dependence (struct data_dependence_relation *ddr,
struct loop *loop_nest)
{
--- 4130,4136 ----
relation the first time we detect a CHREC_KNOWN element for a given
subscript. */
! void
compute_affine_dependence (struct data_dependence_relation *ddr,
struct loop *loop_nest)
{
Index: gcc/tree-data-ref.h
===================================================================
*** gcc/tree-data-ref.h (revision 191415)
--- gcc/tree-data-ref.h (working copy)
*************** struct data_reference *create_data_ref (
*** 396,401 ****
--- 396,403 ----
extern bool find_loop_nest (struct loop *, VEC (loop_p, heap) **);
extern struct data_dependence_relation *initialize_data_dependence_relation
(struct data_reference *, struct data_reference *, VEC (loop_p, heap)
*);
+ extern void compute_affine_dependence (struct data_dependence_relation *,
+ loop_p);
extern void compute_self_dependence (struct data_dependence_relation *);
extern bool compute_all_dependences (VEC (data_reference_p, heap) *,
VEC (ddr_p, heap) **, VEC (loop_p, heap) *,
