------- Comment #3 from rguenth at gcc dot gnu dot org 2010-09-17 15:39 -------
Index: tree-ssa-dom.c
===================================================================
--- tree-ssa-dom.c (revision 164371)
+++ tree-ssa-dom.c (working copy)
@@ -1804,6 +1804,37 @@ eliminate_redundant_computations (gimple
tree def = gimple_get_lhs (stmt);
+ if (gimple_assign_single_p (stmt)
+ && TREE_CODE (def) != SSA_NAME)
+ {
+ tree rhs = gimple_assign_rhs1 (stmt);
+ gimple new_stmt;
+ /* Build a new statement with the RHS and LHS exchanged. */
+ if (TREE_CODE (rhs) == SSA_NAME)
+ {
+ gimple defstmt = SSA_NAME_DEF_STMT (rhs);
+ new_stmt = gimple_build_assign (rhs, def);
+ SSA_NAME_DEF_STMT (rhs) = defstmt;
+ }
+ else
+ new_stmt = gimple_build_assign (rhs, def);
+ gimple_set_vuse (new_stmt, gimple_vuse (stmt));
+ cached_lhs = lookup_avail_expr (new_stmt, false);
+ if (cached_lhs
+ && (rhs == cached_lhs
+ || (TREE_CODE (rhs) == SSA_NAME
+ && SSA_NAME_VALUE (rhs) == cached_lhs)))
+ {
+ gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
+ basic_block bb = gimple_bb (stmt);
+ unlink_stmt_vdef (stmt);
+ gsi_remove (&gsi, true);
+ if (gimple_purge_dead_eh_edges (bb))
+ ;
+ return;
+ }
+ }
+
/* Certain expressions on the RHS can be optimized away, but can not
themselves be entered into the hash tables. */
if (! def
works for both constants and SSA names. Need to clean the patch up
(removing stmts at that point is probably going to wreck dom, removing
EH edges for sure I guess).
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |rguenth at gcc dot gnu dot
|dot org |org
Status|NEW |ASSIGNED
Keywords|missed-optimization |
Last reconfirmed|2010-09-17 15:18:08 |2010-09-17 15:39:14
date| |
Target Milestone|4.3.6 |---
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45705
