Redundant store removal in FRE was restricted for correctness reasons.
The following extends correctness fixes required to memcpy/aggregate
copy translation. The main change is that we no longer insert
references rewritten to cover such aggregate copies into the hashtable
but the original one.
2020-02-04 Richard Biener <rguenther@suse.de>
PR tree-optimization/91123
* tree-ssa-sccvn.c (vn_walk_cb_data::finish): New method.
(vn_walk_cb_data::last_vuse): New member.
(vn_walk_cb_data::saved_operands): Likewsie.
(vn_walk_cb_data::~vn_walk_cb_data): Release saved_operands.
(vn_walk_cb_data::push_partial_def): Use finish.
(vn_reference_lookup_2): Update last_vuse and use finish if
we've saved operands.
(vn_reference_lookup_3): Use finish and update calls to
push_partial_defs everywhere. When translating through
memcpy or aggregate copies save off operands and alias-set.
(eliminate_dom_walker::eliminate_stmt): Restore VN_WALKREWRITE
operation for redundant store removal.
* gcc.dg/tree-ssa/ssa-fre-85.c: New testcase.
