http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58041
--- Comment #9 from Martin Jambor <jamborm at gcc dot gnu.org> ---
More specifically, if I am correct assuming that the MEM_REF
replace_ref builds always accesses exactly the same memory as the
previous access *expr does (and only the address is computed better)
and that *expr is how the function accessed that memory before, then I
think what you need is the following (untested, except that I know it
seems to fix the testcase, at least the assembly looks very different
:-)
*** /tmp/heQHTs_gimple-ssa-strength-reduction.c Thu Aug 1 18:43:45 2013
--- gcc/gimple-ssa-strength-reduction.c Thu Aug 1 18:38:31 2013
*************** dump_incr_vec (void)
*** 1728,1738 ****
static void
replace_ref (tree *expr, slsr_cand_t c)
{
! tree add_expr = fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (c->base_expr),
! c->base_expr, c->stride);
! tree mem_ref = fold_build2 (MEM_REF, TREE_TYPE (*expr), add_expr,
! double_int_to_tree (c->cand_type, c->index));
!
/* Gimplify the base addressing expression for the new MEM_REF tree. */
gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt);
TREE_OPERAND (mem_ref, 0)
--- 1728,1748 ----
static void
replace_ref (tree *expr, slsr_cand_t c)
{
! tree add_expr, mem_ref, acc_type = TREE_TYPE (*expr);
! unsigned HOST_WIDE_INT misalign;
! unsigned align;
!
! get_object_alignment_1 (*expr, &align, &misalign);
! if (misalign != 0)
! align = (misalign & -misalign);
! if (align < TYPE_ALIGN (acc_type))
! acc_type = build_aligned_type (acc_type, align);
!
! add_expr = fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (c->base_expr),
! c->base_expr, c->stride);
! mem_ref = fold_build2 (MEM_REF, acc_type, add_expr,
! double_int_to_tree (c->cand_type, c->index));
!
/* Gimplify the base addressing expression for the new MEM_REF tree. */
gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt);
TREE_OPERAND (mem_ref, 0)
