Commit c2eb9779 by Matthias Braun

### recursively optimize phi to get real minimal SSA-form for reducible CFGs

`[r28343]`
parent b69024b1
 ... ... @@ -185,6 +185,42 @@ static inline ir_node *new_rd_Phi0(dbg_info *dbgi, ir_node *block, static ir_node *get_r_value_internal(ir_node *block, int pos, ir_mode *mode); static void try_remove_unnecessary_phi(ir_node *phi) { ir_node *phi_value = NULL; int arity = get_irn_arity(phi); int i; /* see if all inputs are either pointing to a single value or * are self references */ for (i = 0; i < arity; ++i) { ir_node *in = get_irn_n(phi, i); if (in == phi) continue; if (in == phi_value) continue; /** found a different value from the one we already found, can't remove * the phi (yet) */ if (phi_value != NULL) return; phi_value = in; } if (phi_value == NULL) return; /* if we're here then all phi inputs have been either phi_value * or self-references, we can replace the phi by phi_value. * We do this with an Id-node */ exchange(phi, phi_value); /* recursively check phi_value, because it could be that we were the last * phi-node in a loop-body. Then our arguments is an unnecessary phi in * the loop header which can be eliminated now */ if (is_Phi(phi_value)) { try_remove_unnecessary_phi(phi_value); } } /** * Computes the predecessors for the real phi node, and then * allocates and returns this node. The routine called to allocate the ... ... @@ -198,8 +234,6 @@ static ir_node *set_phi_arguments(ir_node *phi, int pos) int arity = get_irn_arity(block); ir_node **in = ALLOCAN(ir_node*, arity); ir_mode *mode = get_irn_mode(phi); ir_node *phi_value = NULL; bool no_phi_value = false; int i; /* This loop goes to all predecessor blocks of the block the Phi node ... ... @@ -213,33 +247,21 @@ static ir_node *set_phi_arguments(ir_node *phi, int pos) } else { value = get_r_value_internal(cfgpred, pos, mode); } if (!no_phi_value && value != phi) { if (phi_value == NULL) { phi_value = value; } else if (value != phi_value) { no_phi_value = true; phi_value = NULL; } } in[i] = value; } if (phi_value != NULL && !no_phi_value) { exchange(phi, phi_value); return phi_value; } phi->attr.phi.u.backedge = new_backedge_arr(irg->obst, arity); set_irn_in(phi, arity, in); set_irn_op(phi, op_Phi); phi = optimize_in_place_2(phi); irn_verify_irg(phi, irg); /* Memory Phis in endless loops must be kept alive. As we can't distinguish these easily we keep all of them alive. */ if (is_Phi(phi) && mode == mode_M) add_End_keepalive(get_irg_end(irg), phi); try_remove_unnecessary_phi(phi); return phi; } ... ...
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