http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50317
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-11-28 13:11:49 UTC --- Created attachment 25933 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25933 gcc47-pr50317-1.patch One way to fix this regression is schedule another update_addresses_taken before cddce. Already in *copyprop1 the var has address taken only solely in debug stmts, and by dropping TREE_ADDRESSABLE on it the right thing happens (except that {CLOBBER} stuff messes it up, see patch I'm going to attach momentarily). I've tried: --- gcc/tree-ssa-dce.c.jj 2011-11-08 23:35:12.000000000 +0100 +++ gcc/tree-ssa-dce.c 2011-11-28 12:35:55.745657320 +0100 @@ -1215,6 +1215,25 @@ remove_dead_stmt (gimple_stmt_iterator * ei_next (&ei); } + /* If this is a store into a variable that is being optimized away, + add a debug bind stmt if possible. */ + if (MAY_HAVE_DEBUG_STMTS + && gimple_assign_single_p (stmt) + && is_gimple_val (gimple_assign_rhs1 (stmt))) + { + tree lhs = gimple_assign_lhs (stmt); + if ((TREE_CODE (lhs) == VAR_DECL || TREE_CODE (lhs) == PARM_DECL) + && !DECL_IGNORED_P (lhs) + && is_gimple_reg_type (TREE_TYPE (lhs)) + && !DECL_HAS_VALUE_EXPR_P (lhs)) + { + tree rhs = gimple_assign_rhs1 (stmt); + gimple note + = gimple_build_debug_bind (lhs, unshare_expr (rhs), stmt); + gsi_insert_after (i, note, GSI_SAME_STMT); + } + } + unlink_stmt_vdef (stmt); gsi_remove (i, true); release_defs (stmt); as an alternative, but leads to ICEs, at some later point we'd need to somewhere determine if the var mentioned in the debug stmts on the RHS which is still TREE_ADDRESSABLE is ever referenced in non-debug stmts or not. If not, we'd want to drop TREE_ADDRESSABLE bit from it, otherwise e.g. at expansion time we could just ignore the debug stmt, because it is not target_for_debug_bind when it is TREE_ADDRESSABLE.
