From 129b5668f18f6d4bc40a21566f75bdc280c594ea Mon Sep 17 00:00:00 2001 From: Jeff Law Date: Mon, 18 Dec 2017 21:35:59 -0700 Subject: Revert 2017-11-19 Jeff Law * tree-ssa-dom.c (record_equivalences_from_phis): Fix handling of degenerates resulting from ignoring an edge. From-SVN: r255802 --- gcc/tree-ssa-dom.c | 21 +++++---------------- 1 file changed, 5 insertions(+), 16 deletions(-) (limited to 'gcc/tree-ssa-dom.c') diff --git a/gcc/tree-ssa-dom.c b/gcc/tree-ssa-dom.c index 93c992a..05bc807 100644 --- a/gcc/tree-ssa-dom.c +++ b/gcc/tree-ssa-dom.c @@ -1109,7 +1109,6 @@ record_equivalences_from_phis (basic_block bb) tree rhs = NULL; size_t i; - bool ignored_phi_arg = false; for (i = 0; i < gimple_phi_num_args (phi); i++) { tree t = gimple_phi_arg_def (phi, i); @@ -1120,14 +1119,10 @@ record_equivalences_from_phis (basic_block bb) if (lhs == t) continue; - /* We want to track if we ignored any PHI arguments because - their associated edges were not executable. This impacts - whether or not we can use any equivalence we might discover. */ + /* If the associated edge is not marked as executable, then it + can be ignored. */ if ((gimple_phi_arg_edge (phi, i)->flags & EDGE_EXECUTABLE) == 0) - { - ignored_phi_arg = true; - continue; - } + continue; t = dom_valueize (t); @@ -1152,15 +1147,9 @@ record_equivalences_from_phis (basic_block bb) a useful equivalence. We do not need to record unwind data for this, since this is a true assignment and not an equivalence inferred from a comparison. All uses of this ssa name are dominated - by this assignment, so unwinding just costs time and space. - - Note that if we ignored a PHI argument and the resulting equivalence - is SSA_NAME = SSA_NAME. Then we can not use the equivalence as the - uses of the LHS SSA_NAME are not necessarily dominated by the - assignment of the RHS SSA_NAME. */ + by this assignment, so unwinding just costs time and space. */ if (i == gimple_phi_num_args (phi) - && may_propagate_copy (lhs, rhs) - && (!ignored_phi_arg || TREE_CODE (rhs) != SSA_NAME)) + && may_propagate_copy (lhs, rhs)) set_ssa_name_value (lhs, rhs); } } -- cgit v1.1