3 * File name: ir/opt/tailrec.c
4 * Purpose: tail-recursion optimization
9 * Copyright: (c) 2002-2004 Universität Karlsruhe
10 * Licence: This file protected by GPL - GNU GENERAL PUBLIC LICENSE.
34 #include "irgraph_t.h"
40 * the environment for collecting data
42 typedef struct _collect_t {
43 ir_node *proj_X; /**< initial exec proj */
44 ir_node *block; /**< old first block */
45 int blk_idx; /**< cfgpred index of the initial exec in block */
46 ir_node *proj_m; /**< linked list of memory from start proj's */
47 ir_node *proj_data; /**< linked list of all parameter access proj's */
51 * walker for collecting data, fills a collect_t environment
53 static void collect_data(ir_node *node, void *env)
55 collect_t *data = env;
59 switch (get_irn_opcode(node)) {
61 pred = get_Proj_pred(node);
63 op = get_irn_op(pred);
65 ir_node *start = get_Proj_pred(pred);
67 if (get_irn_op(start) == op_Start) {
68 if (get_Proj_proj(pred) == pn_Start_T_args) {
69 /* found Proj(ProjT(Start)) */
70 set_irn_link(node, data->proj_data);
71 data->proj_data = node;
75 else if (op == op_Start) {
76 switch (get_Proj_proj(node)) {
78 /* found ProjM(Start) */
79 set_irn_link(node, data->proj_m);
82 case pn_Start_X_initial_exec:
83 /* found ProjX(Start) */
92 int i, n_pred = get_Block_n_cfgpreds(node);
95 * the first block has the initial exec as cfg predecessor
97 if (node != current_ir_graph->start_block) {
98 for (i = 0; i < n_pred; ++i) {
99 if (get_Block_cfgpred(node, i) == data->proj_X) {
114 * do the graph reconstruction for tail-recursion elimination
116 * @param irg the graph that will reconstructed
117 * @param rets linked list of all rets
118 * @param n_tail_calls number of tail-recursion calls
120 static void do_opt_tail_rec(ir_graph *irg, ir_node *rets, int n_tail_calls)
122 ir_graph *rem_irg = current_ir_graph;
123 ir_node *end_block = irg->end_block;
124 ir_node *block, *jmp, *call, *calls;
127 ir_node ***call_params;
131 int rem = get_optimize();
133 assert(n_tail_calls);
135 /* we add nwe nodes, so the outs are inconsistant */
136 set_irg_outs_inconsistent(irg);
138 /* we add new blocks and change the control flow */
139 set_irg_dom_inconsistent(irg);
141 /* we add a new loop */
142 set_irg_loopinfo_inconsistent(irg);
146 /* collect needed data */
151 data.proj_data = NULL;
152 irg_walk_graph(irg, NULL, collect_data, &data);
154 /* check number of arguments */
155 call = get_irn_link(end_block);
156 n_params = get_Call_n_params(call);
158 assert(data.proj_X && "Could not find initial exec from Start");
159 assert(data.block && "Could not find first block");
160 assert(data.proj_m && "Could not find ProjM(Start)");
161 assert((data.proj_data || n_params == 0) && "Could not find Proj(ProjT(Start)) of non-void function");
163 current_ir_graph = irg;
165 /* allocate in's for phi and block construction */
166 NEW_ARR_A(ir_node *, in, n_tail_calls + 1);
170 /* turn Return's into Jmp's */
171 for (i = 1, p = rets; p; p = get_irn_link(p)) {
174 set_cur_block(get_nodes_block(p));
177 exchange(p, new_Bad());
180 add_End_keepalive(get_irg_end(irg), jmp);
183 /* create a new block at start */
184 block = new_Block(n_tail_calls + 1, in);
187 /* the old first block is now the second one */
188 set_Block_cfgpred(data.block, data.blk_idx, jmp);
190 /* allocate phi's, position 0 contains the memory phi */
191 NEW_ARR_A(ir_node *, phis, n_params + 1);
193 /* build the memory phi */
195 in[i] = new_rd_Proj(NULL, irg, irg->start_block, irg->start, mode_M, pn_Start_M);
198 for (calls = call; calls; calls = get_irn_link(calls)) {
199 in[i] = get_Call_mem(calls);
202 assert(i == n_tail_calls + 1);
204 phis[0] = new_rd_Phi(NULL, irg, block, n_tail_calls + 1, in, mode_M);
206 /* build the data phi's */
210 NEW_ARR_A(ir_node **, call_params, n_params);
212 /* collect all parameters */
213 for (i = 0, calls = call; calls; calls = get_irn_link(calls)) {
214 call_params[i] = get_Call_param_arr(calls);
218 /* build new projs and Phi's */
219 for (i = 0; i < n_params; ++i) {
220 ir_mode *mode = get_irn_mode(call_params[0][i]);
222 in[0] = new_rd_Proj(NULL, irg, block, irg->args, mode, i);
223 for (j = 0; j < n_tail_calls; ++j)
224 in[j + 1] = call_params[j][i];
226 phis[i + 1] = new_rd_Phi(NULL, irg, block, n_tail_calls + 1, in, mode);
231 * ok, we are here, so we have build and collected all needed Phi's
232 * now exchange all Projs into links to Phi
234 for (p = data.proj_m; p; p = get_irn_link(p)) {
235 exchange(p, phis[0]);
237 for (p = data.proj_data; p; p = get_irn_link(p)) {
238 long proj = get_Proj_proj(p);
240 assert(0 <= proj && proj < n_params);
241 exchange(p, phis[proj + 1]);
244 current_ir_graph = rem_irg;
249 * convert simple tail-calls into loops
251 int opt_tail_rec_irg(ir_graph *irg)
253 ir_node *end_block = irg->end_block;
255 int i, n_tail_calls = 0;
256 ir_node *rets = NULL;
258 if (! get_opt_tail_recursion() || ! get_opt_optimize())
261 set_irn_link(end_block, NULL);
263 n_preds = get_Block_n_cfgpreds(end_block);
264 for (i = 0; i < n_preds; ++i) {
265 ir_node *ret = get_Block_cfgpred(end_block, i);
266 ir_node *call, *call_ptr;
271 /* search all returns of a block */
272 if (get_irn_op(ret) != op_Return)
275 /* check, if it's a Return self() */
276 call = skip_Proj(get_Return_mem(ret));
277 if (get_irn_op(call) != op_Call)
280 /* check if it's a recursive call */
281 call_ptr = get_Call_ptr(call);
283 if (get_irn_op(call_ptr) != op_SymConst)
286 if (get_SymConst_kind(call_ptr) != symconst_addr_ent)
289 ent = get_SymConst_entity(call_ptr);
290 if (!ent || get_entity_irg(ent) != irg)
293 /* ok, mem is routed to a recursive call, check return args */
294 n_ress = get_Return_n_ress(ret);
295 ress = get_Return_res_arr(ret);
297 for (j = 0; j < n_ress; ++j) {
298 ir_node *irn = skip_Proj(skip_Proj(ress[j]));
301 /* not routed to a call */
308 /* here, we have found a call */
309 set_irn_link(call, get_irn_link(end_block));
310 set_irn_link(end_block, call);
313 /* link all returns, we will need this */
314 set_irn_link(ret, rets);
318 /* now, end_block->link contains the list of all tail calls */
322 if (get_opt_tail_recursion_verbose() && get_firm_verbosity() > 1)
323 printf(" Performing tail recursion for graph %s and %d Calls\n",
324 get_entity_ld_name(get_irg_entity(irg)), n_tail_calls);
326 do_opt_tail_rec(irg, rets, n_tail_calls);
332 * optimize tail recursion away
334 void opt_tail_recursion(void)
337 int n_opt_applications = 0;
339 if (! get_opt_tail_recursion() || ! get_opt_optimize())
342 for (i = 0; i < get_irp_n_irgs(); i++) {
343 current_ir_graph = get_irp_irg(i);
345 if (opt_tail_rec_irg(current_ir_graph))
346 ++n_opt_applications;
349 if (get_opt_tail_recursion_verbose())
350 printf("Performed tail recursion for %d of %d graphs\n", n_opt_applications, get_irp_n_irgs());