--- /dev/null
+/*
+ * Project: libFIRM
+ * File name: ir/opt/tailrec.c
+ * Purpose: tail-recursion optimization
+ * Author: Michael Beck
+ * Modified by:
+ * Created: 08.06.2004
+ * CVS-ID: $Id$
+ * Copyright: (c) 2002-2004 Universität Karlsruhe
+ * Licence: This file protected by GPL - GNU GENERAL PUBLIC LICENSE.
+ */
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <assert.h>
+#include "tailrec.h"
+#include "array.h"
+#include "irgwalk.h"
+#include "irgmod.h"
+#include "irop.h"
+#include "irnode_t.h"
+#include "irgraph_t.h"
+#include "ircons.h"
+#include "irflag.h"
+#include "tv.h"
+#include "firmstat.h"
+
+/**
+ * the environment for colelcting data
+ */
+typedef struct _collect_t {
+ ir_node *proj_X; /**< initial exec proj */
+ ir_node *block; /**< old first block */
+ ir_node *proj_m; /**< linked list of memory from start proj's */
+ ir_node *proj_data; /**< linked list of all parameter access proj's */
+} collect_t;
+
+/**
+ * walker for collecting data
+ */
+static void collect_data(ir_node *node, void *env)
+{
+ collect_t *data = env;
+ ir_node *pred;
+ ir_op *op;
+
+ switch (intern_get_irn_opcode(node)) {
+ case iro_Proj:
+ pred = get_Proj_pred(node);
+
+ op = intern_get_irn_op(pred);
+ if (op == op_Proj) {
+ ir_node *start = get_Proj_pred(pred);
+
+ if (intern_get_irn_op(start) == op_Start) {
+ if (get_Proj_proj(pred) == pn_Start_T_args) {
+ /* found Proj(ProjT(Start)) */
+ set_irn_link(node, data->proj_data);
+ data->proj_data = node;
+ }
+ }
+ }
+ else if (op == op_Start) {
+ switch (get_Proj_proj(node)) {
+ case pn_Start_M:
+ /* found ProjM(Start) */
+ set_irn_link(node, data->proj_m);
+ data->proj_m = node;
+ break;
+ case pn_Start_X_initial_exec:
+ /* found ProjX(Start) */
+ data->proj_X = node;
+ break;
+ default:
+ break;
+ }
+ }
+ break;
+ case iro_Block: {
+ int i, n_pred = get_Block_n_cfgpreds(node);
+
+ /*
+ * the first block has the initial exec as cfg predecessor
+ */
+ if (node != current_ir_graph->start_block) {
+ for (i = 0; i < n_pred; ++i) {
+ if (get_Block_cfgpred(node, i) == data->proj_X) {
+ data->block = node;
+ break;
+ }
+ }
+ }
+ break;
+ }
+ default:
+ break;
+ }
+}
+
+/**
+ * do the graph reconstruction for tail-recursion elimination
+ *
+ * @param irg the graph that will reconstructed
+ * @param rets linked list of all rets
+ * @param n_tail_calls number of tail-recursion calls
+ */
+static void do_opt_tail_rec(ir_graph *irg, ir_node *rets, int n_tail_calls)
+{
+ ir_graph *rem_irg = current_ir_graph;
+ ir_node *end_block = irg->end_block;
+ ir_node *block, *jmp, *call, *calls;
+ ir_node **in;
+ ir_node **phis;
+ ir_node ***call_params;
+ ir_node *p;
+ int i, j, n_params;
+ collect_t data;
+ int rem = get_optimize();
+
+ assert(n_tail_calls);
+
+ set_optimize(0);
+
+ /* collect needed data */
+ data.proj_X = NULL;
+ data.block = NULL;
+ data.proj_m = NULL;
+ data.proj_data = NULL;
+ irg_walk_graph(irg, NULL, collect_data, &data);
+
+ /* check number of arguments */
+ call = get_irn_link(end_block);
+ n_params = get_Call_n_params(call);
+
+ assert(data.proj_X && "Could not find initial exec from Start");
+ assert(data.block && "Could not find first block");
+ assert(data.proj_m && "Could not find ProjM(Start)");
+ assert((data.proj_data || n_params == 0) && "Could not find Proj(ProjT(Start)) of non-void function");
+
+ current_ir_graph = irg;
+
+ /* allocate in's for phi and block construction */
+ NEW_ARR_A(ir_node *, in, n_tail_calls + 1);
+
+ in[0] = data.proj_X;
+
+ /* turn Return's into Jmp's */
+ for (i = 1, p = rets; p; p = get_irn_link(p)) {
+ ir_node *jmp;
+
+ switch_block(get_nodes_Block(p));
+ jmp = new_Jmp();
+
+ exchange(p, new_Bad());
+ in[i++] = jmp;
+
+ add_End_keepalive(get_irg_end(irg), jmp);
+ }
+
+ /* create a new block at start */
+ block = new_Block(n_tail_calls + 1, in);
+ jmp = new_Jmp();
+
+ /* the old first block is now the second one */
+ for (i = 0; i < get_Block_n_cfgpreds(data.block); ++i) {
+ if (get_Block_cfgpred(data.block, i) == data.proj_X) {
+ set_Block_cfgpred(data.block, i, jmp);
+ break;
+ }
+ }
+
+ /* allocate phi's, position 0 contains the memory phi */
+ NEW_ARR_A(ir_node *, phis, n_params + 1);
+
+ /* build the memory phi */
+ i = 0;
+ in[i] = new_rd_Proj(NULL, irg, irg->start_block, irg->start, mode_M, pn_Start_M);
+ ++i;
+
+ for (calls = call; calls; calls = get_irn_link(calls)) {
+ in[i] = get_Call_mem(calls);
+ ++i;
+ }
+ phis[0] = new_rd_Phi(NULL, irg, block, n_tail_calls + 1, in, mode_M);
+
+ /* build the data phi's */
+ if (n_params > 0) {
+ ir_node *calls;
+
+ NEW_ARR_A(ir_node **, call_params, n_params);
+
+ /* collect all parameters */
+ for (i = 0, calls = call; calls; calls = get_irn_link(calls)) {
+ call_params[i] = get_Call_param_arr(calls);
+ ++i;
+ }
+
+ /* build new projs and Phi's */
+ for (i = 0; i < n_params; ++i) {
+ ir_mode *mode = get_irn_mode(call_params[0][i]);
+
+ in[0] = new_rd_Proj(NULL, irg, block, irg->args, mode, i);
+ for (j = 0; j < n_tail_calls; ++j)
+ in[j + 1] = call_params[j][i];
+
+ phis[i + 1] = new_rd_Phi(NULL, irg, block, n_tail_calls + 1, in, mode);
+ }
+ }
+
+ /*
+ * ok, we are here, so we have build and collected all needed Phi's
+ * now exchange all Projs into links to Phi
+ */
+ for (p = data.proj_m; p; p = get_irn_link(p)) {
+ exchange(p, phis[0]);
+ }
+ for (p = data.proj_data; p; p = get_irn_link(p)) {
+ long proj = get_Proj_proj(p);
+
+ assert(0 <= proj && proj < n_params);
+ exchange(p, phis[proj + 1]);
+ }
+
+ current_ir_graph = rem_irg;
+ set_optimize(rem);
+}
+
+/**
+ * convert simple tail-calls into loops
+ */
+void optimize_tail_rec_irg(ir_graph *irg)
+{
+ ir_node *end_block = irg->end_block;
+ int n_preds;
+ int i, n_tail_calls = 0;
+ ir_node *rets = NULL;
+
+ if (! get_opt_tail_recursion() || ! get_opt_optimize())
+ return;
+
+ set_irn_link(end_block, NULL);
+
+ n_preds = get_Block_n_cfgpreds(end_block);
+ for (i = 0; i < n_preds; ++i) {
+ ir_node *ret = get_Block_cfgpred(end_block, i);
+ ir_node *proj_m, *call, *call_ptr;
+ tarval *tv;
+ entity *ent;
+ int j, n_ress;
+ ir_node **ress;
+
+ /* search all returns of a block */
+ if (intern_get_irn_op(ret) != op_Return)
+ continue;
+
+ /* check, if it's a Return self() */
+ proj_m = get_Return_mem(ret);
+
+ if (intern_get_irn_op(proj_m) != op_Proj)
+ continue;
+
+ call = get_Proj_pred(proj_m);
+ if (intern_get_irn_op(call) != op_Call)
+ continue;
+
+ /* check if it's a recursive call */
+ call_ptr = get_Call_ptr(call);
+
+ if (intern_get_irn_op(call_ptr) != op_Const)
+ continue;
+
+ tv = get_Const_tarval(call_ptr);
+ if (! tarval_is_entity(tv))
+ continue;
+
+ ent = tarval_to_entity(tv);
+ if (!ent || get_entity_irg(ent) != irg)
+ continue;
+
+ /* ok, mem is routed to a recursive call, check return args */
+ n_ress = get_Return_n_ress(ret);
+ ress = get_Return_res_arr(ret);
+
+ for (j = 0; j < n_ress; ++j) {
+ ir_node *proj = ress[j];
+ ir_node *proj_proj;
+ ir_node *irn;
+
+ if (intern_get_irn_op(proj) != op_Proj) {
+ /* not routed to a call */
+ break;
+ }
+
+ proj_proj = get_Proj_pred(proj);
+
+ if (intern_get_irn_op(proj) != op_Proj) {
+ /* not routed to a call */
+ break;
+ }
+
+ irn = get_Proj_pred(proj_proj);
+
+ if (irn != call) {
+ /* not routed to a call */
+ break;
+ }
+ }
+ if (j < n_ress)
+ continue;
+
+ /* here, we have found a call */
+ set_irn_link(call, get_irn_link(end_block));
+ set_irn_link(end_block, call);
+ ++n_tail_calls;
+
+ /* link all returns, we will need this */
+ set_irn_link(ret, rets);
+ rets = ret;
+ }
+
+ /* now, end_block->link contains the list of all tail calls */
+ if (! n_tail_calls)
+ return;
+
+ do_opt_tail_rec(irg, rets, n_tail_calls);
+}
+
+/**
+ * optimize tail recursion away
+ */
+void optimize_tail_recursion(void)
+{
+ if (! get_opt_tail_recursion() || ! get_opt_optimize())
+ return;
+
+ for (i = 0; i < get_irp_n_irgs(); i++) {
+ current_ir_graph = get_irp_irg(i);
+
+ optimize_tail_rec_irg(current_ir_graph);
+ }
+}
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