diff options
Diffstat (limited to 'gcc/tree-ssa-sccvn.c')
| -rw-r--r-- | gcc/tree-ssa-sccvn.c | 27 |
1 files changed, 22 insertions, 5 deletions
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c index 39e99007c7e..4b3f31c12cb 100644 --- a/gcc/tree-ssa-sccvn.c +++ b/gcc/tree-ssa-sccvn.c @@ -4472,6 +4472,8 @@ set_ssa_val_to (tree from, tree to) vn_ssa_aux_t from_info = VN_INFO (from); tree currval = from_info->valnum; // SSA_VAL (from) poly_int64 toff, coff; + bool curr_undefined = false; + bool curr_invariant = false; /* The only thing we allow as value numbers are ssa_names and invariants. So assert that here. We don't allow VN_TOP @@ -4514,9 +4516,9 @@ set_ssa_val_to (tree from, tree to) } return false; } - bool curr_invariant = is_gimple_min_invariant (currval); - bool curr_undefined = (TREE_CODE (currval) == SSA_NAME - && ssa_undefined_value_p (currval, false)); + curr_invariant = is_gimple_min_invariant (currval); + curr_undefined = (TREE_CODE (currval) == SSA_NAME + && ssa_undefined_value_p (currval, false)); if (currval != VN_TOP && !curr_invariant && !curr_undefined @@ -4571,9 +4573,8 @@ set_and_exit: && !operand_equal_p (currval, to, 0) /* Different undefined SSA names are not actually different. See PR82320 for a testcase were we'd otherwise not terminate iteration. */ - && !(TREE_CODE (currval) == SSA_NAME + && !(curr_undefined && TREE_CODE (to) == SSA_NAME - && ssa_undefined_value_p (currval, false) && ssa_undefined_value_p (to, false)) /* ??? For addresses involving volatile objects or types operand_equal_p does not reliably detect ADDR_EXPRs as equal. We know we are only @@ -4585,6 +4586,22 @@ set_and_exit: == get_addr_base_and_unit_offset (TREE_OPERAND (to, 0), &toff)) && known_eq (coff, toff))) { + if (to != from + && currval != VN_TOP + && !curr_undefined + /* We do not want to allow lattice transitions from one value + to another since that may lead to not terminating iteration + (see PR95049). Since there's no convenient way to check + for the allowed transition of VAL -> PHI (loop entry value, + same on two PHIs, to same PHI result) we restrict the check + to invariants. */ + && curr_invariant + && is_gimple_min_invariant (to)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, " forced VARYING"); + to = from; + } if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, " (changed)\n"); from_info->valnum = to; |