The following fixes PR63916 teaching SCCVN (when not used by PRE) to
aggressively forward-propagate addresses (even with variable indexes)
into its memory reference representation.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
Richard.
2015-06-03 Richard Biener <rguent...@suse.de>
PR tree-optimization/63916
* tree-ssa-sccvn.c (vn_reference_maybe_forwprop_address):
Forward-propagate non-invariant addresses by splicing their
reference ops if the result isn't going to be used by PRE.
(vn_reference_lookup_3): Remove pointless assert.
* gcc.dg/tree-ssa/ssa-fre-45.c: New testcase.
Index: gcc/tree-ssa-sccvn.c
===================================================================
*** gcc/tree-ssa-sccvn.c (revision 223979)
--- gcc/tree-ssa-sccvn.c (working copy)
*************** along with GCC; see the file COPYING3.
*** 144,149 ****
--- 144,153 ----
*/
+ static tree *last_vuse_ptr;
+ static vn_lookup_kind vn_walk_kind;
+ static vn_lookup_kind default_vn_walk_kind;
+
/* vn_nary_op hashtable helpers. */
struct vn_nary_op_hasher : typed_noop_remove <vn_nary_op_s>
*************** vn_reference_maybe_forwprop_address (vec
*** 1259,1264 ****
--- 1263,1287 ----
addr = gimple_assign_rhs1 (def_stmt);
addr_base = get_addr_base_and_unit_offset (TREE_OPERAND (addr, 0),
&addr_offset);
+ /* If that didn't work because the address isn't invariant propagate
+ the reference tree from the address operation in case the current
+ dereference isn't offsetted. */
+ if (!addr_base
+ && *i_p == ops->length () - 1
+ && off == 0
+ /* This makes us disable this transform for PRE where the
+ reference ops might be also used for code insertion which
+ is invalid. */
+ && default_vn_walk_kind == VN_WALKREWRITE)
+ {
+ auto_vec<vn_reference_op_s, 32> tem;
+ copy_reference_ops_from_ref (TREE_OPERAND (addr, 0), &tem);
+ ops->pop ();
+ ops->pop ();
+ ops->safe_splice (tem);
+ --*i_p;
+ return;
+ }
if (!addr_base
|| TREE_CODE (addr_base) != MEM_REF)
return;
*************** vn_reference_lookup_1 (vn_reference_t vr
*** 1557,1566 ****
return NULL_TREE;
}
- static tree *last_vuse_ptr;
- static vn_lookup_kind vn_walk_kind;
- static vn_lookup_kind default_vn_walk_kind;
-
/* Callback for walk_non_aliased_vuses. Adjusts the vn_reference_t VR_
with the current VUSE and performs the expression lookup. */
--- 1580,1585 ----
*************** vn_reference_lookup_3 (ao_ref *ref, tree
*** 1649,1663 ****
/* First try to disambiguate after value-replacing in the definitions LHS.
*/
if (is_gimple_assign (def_stmt))
{
- vec<vn_reference_op_s> tem;
tree lhs = gimple_assign_lhs (def_stmt);
bool valueized_anything = false;
/* Avoid re-allocation overhead. */
lhs_ops.truncate (0);
copy_reference_ops_from_ref (lhs, &lhs_ops);
- tem = lhs_ops;
lhs_ops = valueize_refs_1 (lhs_ops, &valueized_anything);
- gcc_assert (lhs_ops == tem);
if (valueized_anything)
{
lhs_ref_ok = ao_ref_init_from_vn_reference (&lhs_ref,
--- 1668,1679 ----
Index: gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-45.c
===================================================================
*** gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-45.c (revision 0)
--- gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-45.c (working copy)
***************
*** 0 ****
--- 1,16 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O -fdump-tree-fre1" } */
+
+ struct S { float a, b; };
+
+ float
+ foo (int x, float y)
+ {
+ struct S z[1024];
+ z[x].a = y;
+ struct S *p = &z[x];
+ float *q = (float *) p;
+ return *q;
+ }
+
+ /* { dg-final { scan-tree-dump "return y_\\d\+\\(D\\);" "fre1" } } */
