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"
39 static int n_opt_applications = 0;
42 * the environment for colelcting data
44 typedef struct _collect_t {
45 ir_node *proj_X; /**< initial exec proj */
46 ir_node *block; /**< old first block */
47 int blk_idx; /**< cfgpred index of the initial exec in block */
48 ir_node *proj_m; /**< linked list of memory from start proj's */
49 ir_node *proj_data; /**< linked list of all parameter access proj's */
53 * walker for collecting data
55 static void collect_data(ir_node *node, void *env)
57 collect_t *data = env;
61 switch (get_irn_opcode(node)) {
63 pred = get_Proj_pred(node);
65 op = get_irn_op(pred);
67 ir_node *start = get_Proj_pred(pred);
69 if (get_irn_op(start) == op_Start) {
70 if (get_Proj_proj(pred) == pn_Start_T_args) {
71 /* found Proj(ProjT(Start)) */
72 set_irn_link(node, data->proj_data);
73 data->proj_data = node;
77 else if (op == op_Start) {
78 switch (get_Proj_proj(node)) {
80 /* found ProjM(Start) */
81 set_irn_link(node, data->proj_m);
84 case pn_Start_X_initial_exec:
85 /* found ProjX(Start) */
94 int i, n_pred = get_Block_n_cfgpreds(node);
97 * the first block has the initial exec as cfg predecessor
99 if (node != current_ir_graph->start_block) {
100 for (i = 0; i < n_pred; ++i) {
101 if (get_Block_cfgpred(node, i) == data->proj_X) {
116 * do the graph reconstruction for tail-recursion elimination
118 * @param irg the graph that will reconstructed
119 * @param rets linked list of all rets
120 * @param n_tail_calls number of tail-recursion calls
122 static void do_opt_tail_rec(ir_graph *irg, ir_node *rets, int n_tail_calls)
124 ir_graph *rem_irg = current_ir_graph;
125 ir_node *end_block = irg->end_block;
126 ir_node *block, *jmp, *call, *calls;
129 ir_node ***call_params;
133 int rem = get_optimize();
135 assert(n_tail_calls);
137 /* we add nwe nodes, so the outs are inconsistant */
138 set_irg_outs_inconsistent(irg);
140 /* we add new blocks and change the control flow */
141 set_irg_dom_inconsistent(irg);
143 /* we add a new loop */
144 set_irg_loopinfo_inconsistent(irg);
148 /* collect needed data */
153 data.proj_data = NULL;
154 irg_walk_graph(irg, NULL, collect_data, &data);
156 /* check number of arguments */
157 call = get_irn_link(end_block);
158 n_params = get_Call_n_params(call);
160 assert(data.proj_X && "Could not find initial exec from Start");
161 assert(data.block && "Could not find first block");
162 assert(data.proj_m && "Could not find ProjM(Start)");
163 assert((data.proj_data || n_params == 0) && "Could not find Proj(ProjT(Start)) of non-void function");
165 current_ir_graph = irg;
167 /* allocate in's for phi and block construction */
168 NEW_ARR_A(ir_node *, in, n_tail_calls + 1);
172 /* turn Return's into Jmp's */
173 for (i = 1, p = rets; p; p = get_irn_link(p)) {
176 set_cur_block(get_nodes_block(p));
179 exchange(p, new_Bad());
182 add_End_keepalive(get_irg_end(irg), jmp);
185 /* create a new block at start */
186 block = new_Block(n_tail_calls + 1, in);
189 /* the old first block is now the second one */
190 set_Block_cfgpred(data.block, data.blk_idx, jmp);
192 /* allocate phi's, position 0 contains the memory phi */
193 NEW_ARR_A(ir_node *, phis, n_params + 1);
195 /* build the memory phi */
197 in[i] = new_rd_Proj(NULL, irg, irg->start_block, irg->start, mode_M, pn_Start_M);
200 for (calls = call; calls; calls = get_irn_link(calls)) {
201 in[i] = get_Call_mem(calls);
204 assert(i == n_tail_calls + 1);
206 phis[0] = new_rd_Phi(NULL, irg, block, n_tail_calls + 1, in, mode_M);
208 /* build the data phi's */
212 NEW_ARR_A(ir_node **, call_params, n_params);
214 /* collect all parameters */
215 for (i = 0, calls = call; calls; calls = get_irn_link(calls)) {
216 call_params[i] = get_Call_param_arr(calls);
220 /* build new projs and Phi's */
221 for (i = 0; i < n_params; ++i) {
222 ir_mode *mode = get_irn_mode(call_params[0][i]);
224 in[0] = new_rd_Proj(NULL, irg, block, irg->args, mode, i);
225 for (j = 0; j < n_tail_calls; ++j)
226 in[j + 1] = call_params[j][i];
228 phis[i + 1] = new_rd_Phi(NULL, irg, block, n_tail_calls + 1, in, mode);
233 * ok, we are here, so we have build and collected all needed Phi's
234 * now exchange all Projs into links to Phi
236 for (p = data.proj_m; p; p = get_irn_link(p)) {
237 exchange(p, phis[0]);
239 for (p = data.proj_data; p; p = get_irn_link(p)) {
240 long proj = get_Proj_proj(p);
242 assert(0 <= proj && proj < n_params);
243 exchange(p, phis[proj + 1]);
246 current_ir_graph = rem_irg;
251 * convert simple tail-calls into loops
253 void opt_tail_rec_irg(ir_graph *irg)
255 ir_node *end_block = irg->end_block;
257 int i, n_tail_calls = 0;
258 ir_node *rets = NULL;
260 if (! get_opt_tail_recursion() || ! get_opt_optimize())
263 set_irn_link(end_block, NULL);
265 n_preds = get_Block_n_cfgpreds(end_block);
266 for (i = 0; i < n_preds; ++i) {
267 ir_node *ret = get_Block_cfgpred(end_block, i);
268 ir_node *call, *call_ptr;
273 /* search all returns of a block */
274 if (get_irn_op(ret) != op_Return)
277 /* check, if it's a Return self() */
278 call = skip_Proj(get_Return_mem(ret));
279 if (get_irn_op(call) != op_Call)
282 /* check if it's a recursive call */
283 call_ptr = get_Call_ptr(call);
285 if (get_irn_op(call_ptr) != op_SymConst)
288 if (get_SymConst_kind(call_ptr) != symconst_addr_ent)
291 ent = get_SymConst_entity(call_ptr);
292 if (!ent || get_entity_irg(ent) != irg)
295 /* ok, mem is routed to a recursive call, check return args */
296 n_ress = get_Return_n_ress(ret);
297 ress = get_Return_res_arr(ret);
299 for (j = 0; j < n_ress; ++j) {
300 ir_node *irn = skip_Proj(skip_Proj(ress[j]));
303 /* not routed to a call */
310 /* here, we have found a call */
311 set_irn_link(call, get_irn_link(end_block));
312 set_irn_link(end_block, call);
315 /* link all returns, we will need this */
316 set_irn_link(ret, rets);
320 /* now, end_block->link contains the list of all tail calls */
324 if (get_opt_tail_recursion_verbose() && get_firm_verbosity() > 1)
325 printf(" Performing tail recursion for graph %s and %d Calls\n",
326 get_entity_ld_name(get_irg_entity(irg)), n_tail_calls);
327 n_opt_applications++;
329 do_opt_tail_rec(irg, rets, n_tail_calls);
333 * optimize tail recursion away
335 void opt_tail_recursion(void)
339 if (! get_opt_tail_recursion() || ! get_opt_optimize())
342 n_opt_applications = 0;
344 for (i = 0; i < get_irp_n_irgs(); i++) {
345 current_ir_graph = get_irp_irg(i);
347 opt_tail_rec_irg(current_ir_graph);
350 if (get_opt_tail_recursion_verbose())
351 printf("Performed tail recursion for %d of %d graphs\n", n_opt_applications, get_irp_n_irgs());