static enum ssa_prop_result copy_prop_visit_phi_node (gimple phi) { enum ssa_prop_result retval; unsigned i; prop_value_t phi_val = { NULL_TREE }; tree lhs = gimple_phi_result (phi); if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "\nVisiting PHI node: "); print_gimple_stmt (dump_file, phi, 0, dump_flags); } for (i = 0; i < gimple_phi_num_args (phi); i++) { prop_value_t *arg_val; tree arg_value; tree arg = gimple_phi_arg_def (phi, i); edge e = gimple_phi_arg_edge (phi, i); /* We don't care about values flowing through non-executable edges. */ if (!(e->flags & EDGE_EXECUTABLE)) continue; /* Names that flow through abnormal edges cannot be used to derive copies. */ if (TREE_CODE (arg) == SSA_NAME && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (arg)) { phi_val.value = lhs; break; } if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "\tArgument #%d: ", i); dump_copy_of (dump_file, arg); fprintf (dump_file, "\n"); } if (TREE_CODE (arg) == SSA_NAME) { arg_val = get_copy_of_val (arg); /* If we didn't visit the definition of arg yet treat it as UNDEFINED. This also handles PHI arguments that are the same as lhs. We'll come here again. */ if (!arg_val->value) continue; arg_value = arg_val->value; } else arg_value = valueize_val (arg); /* Avoid copy propagation from an inner into an outer loop. Otherwise, this may move loop variant variables outside of their loops and prevent coalescing opportunities. If the value was loop invariant, it will be hoisted by LICM and exposed for copy propagation. ??? The value will be always loop invariant. In loop-closed SSA form do not copy-propagate through PHI nodes in blocks with a loop exit edge predecessor. */ if (current_loops && TREE_CODE (arg_value) == SSA_NAME && (loop_depth_of_name (arg_value) > loop_depth_of_name (lhs) || (loops_state_satisfies_p (LOOP_CLOSED_SSA) && loop_exit_edge_p (e->src->loop_father, e)))) { phi_val.value = lhs; break; } /* If the LHS didn't have a value yet, make it a copy of the first argument we find. */ if (phi_val.value == NULL_TREE) { phi_val.value = arg_value; continue; } /* If PHI_VAL and ARG don't have a common copy-of chain, then this PHI node cannot be a copy operation. */ if (phi_val.value != arg_value && !operand_equal_p (phi_val.value, arg_value, 0)) { phi_val.value = lhs; break; } } if (phi_val.value && may_propagate_copy (lhs, phi_val.value) && set_copy_of_val (lhs, phi_val.value)) retval = (phi_val.value != lhs) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING; else retval = SSA_PROP_NOT_INTERESTING; if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "PHI node "); dump_copy_of (dump_file, lhs); fprintf (dump_file, "\nTelling the propagator to "); if (retval == SSA_PROP_INTERESTING) fprintf (dump_file, "add SSA edges out of this PHI and continue."); else if (retval == SSA_PROP_VARYING) fprintf (dump_file, "add SSA edges out of this PHI and never visit again."); else fprintf (dump_file, "do nothing with SSA edges and keep iterating."); fprintf (dump_file, "\n\n"); } return retval; }
static enum ssa_prop_result copy_prop_visit_phi_node (gimple phi) { enum ssa_prop_result retval; unsigned i; prop_value_t phi_val = { 0, NULL_TREE }; tree lhs = gimple_phi_result (phi); if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "\nVisiting PHI node: "); print_gimple_stmt (dump_file, phi, 0, dump_flags); fprintf (dump_file, "\n\n"); } for (i = 0; i < gimple_phi_num_args (phi); i++) { prop_value_t *arg_val; tree arg = gimple_phi_arg_def (phi, i); edge e = gimple_phi_arg_edge (phi, i); /* We don't care about values flowing through non-executable edges. */ if (!(e->flags & EDGE_EXECUTABLE)) continue; /* Constants in the argument list never generate a useful copy. Similarly, names that flow through abnormal edges cannot be used to derive copies. */ if (TREE_CODE (arg) != SSA_NAME || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (arg)) { phi_val.value = lhs; break; } /* Avoid copy propagation from an inner into an outer loop. Otherwise, this may move loop variant variables outside of their loops and prevent coalescing opportunities. If the value was loop invariant, it will be hoisted by LICM and exposed for copy propagation. Not a problem for virtual operands though. */ if (is_gimple_reg (lhs) && loop_depth_of_name (arg) > loop_depth_of_name (lhs)) { phi_val.value = lhs; break; } /* If the LHS appears in the argument list, ignore it. It is irrelevant as a copy. */ if (arg == lhs || get_last_copy_of (arg) == lhs) continue; if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "\tArgument #%d: ", i); dump_copy_of (dump_file, arg); fprintf (dump_file, "\n"); } arg_val = get_copy_of_val (arg); /* If the LHS didn't have a value yet, make it a copy of the first argument we find. Notice that while we make the LHS be a copy of the argument itself, we take the memory reference from the argument's value so that we can compare it to the memory reference of all the other arguments. */ if (phi_val.value == NULL_TREE) { phi_val.value = arg_val->value ? arg_val->value : arg; continue; } /* If PHI_VAL and ARG don't have a common copy-of chain, then this PHI node cannot be a copy operation. Also, if we are copy propagating stores and these two arguments came from different memory references, they cannot be considered copies. */ if (get_last_copy_of (phi_val.value) != get_last_copy_of (arg)) { phi_val.value = lhs; break; } } if (phi_val.value && may_propagate_copy (lhs, phi_val.value) && set_copy_of_val (lhs, phi_val.value)) retval = (phi_val.value != lhs) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING; else retval = SSA_PROP_NOT_INTERESTING; if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "\nPHI node "); dump_copy_of (dump_file, lhs); fprintf (dump_file, "\nTelling the propagator to "); if (retval == SSA_PROP_INTERESTING) fprintf (dump_file, "add SSA edges out of this PHI and continue."); else if (retval == SSA_PROP_VARYING) fprintf (dump_file, "add SSA edges out of this PHI and never visit again."); else fprintf (dump_file, "do nothing with SSA edges and keep iterating."); fprintf (dump_file, "\n\n"); } return retval; }