+/* Copyright (C) 2002 by Universitaet Karlsruhe
+** All rights reserved.
+**
+** Authors: Goetz Lindenmaier
+**
+** irdom.c --- Dominator tree.
+**
+*/
+
+/* $Id$ */
+
+#include "irouts.h"
+
+#include "irdom_t.h"
+#include "irgraph_t.h" /* To access state field. */
+#include "irnode_t.h"
+
+/**********************************************************************/
+/** Accessing the dominator datastructures **/
+/**********************************************************************/
+
+ir_node *get_Block_idom(ir_node *bl) {
+ assert(get_irn_op(bl) == op_Block);
+ return bl->attr.block.dom.idom;
+}
+
+void set_Block_idom(ir_node *bl, ir_node *n) {
+ assert(get_irn_op(bl) == op_Block);
+ bl->attr.block.dom.idom = n;
+}
+
+int get_Block_pre_num(ir_node *bl) {
+ assert(get_irn_op(bl) == op_Block);
+ return bl->attr.block.dom.pre_num;
+}
+
+void set_Block_pre_num(ir_node *bl, int num) {
+ assert(get_irn_op(bl) == op_Block);
+ bl->attr.block.dom.pre_num = num;
+}
+
+int get_Block_dom_depth(ir_node *bl) {
+ assert(get_irn_op(bl) == op_Block);
+ return bl->attr.block.dom.dom_depth;
+}
+
+void set_Block_dom_depth(ir_node *bl, int depth) {
+ assert(get_irn_op(bl) == op_Block);
+ bl->attr.block.dom.dom_depth = depth;
+}
+
+
+
+/**********************************************************************/
+/** Building and Removing the dominator datasturcture **/
+/** **/
+/** **/
+/** **/
+/** **/
+/** **/
+/** **/
+/** **/
+/** .**/
+/** **/
+/** **/
+/** **/
+/** **/
+/** **/
+/** **/
+/**********************************************************************/
+
+void count_and_init_blocks(ir_node *bl, void *env) {
+ int *n_blocks = (int *) env;
+ (*n_blocks) ++;
+
+ set_Block_idom(bl, NULL);
+ set_Block_pre_num(bl, -1);
+ set_Block_dom_depth(bl, -1);
+}
+
+/* temporary type used while constructing the dominator tree. */
+typedef struct tmp_dom_info {
+ ir_node *block; /* backlink */
+
+ struct tmp_dom_info *semi; /* semidominator */
+ struct tmp_dom_info *parent;
+ struct tmp_dom_info *label; /* used for LINK and EVAL */
+ struct tmp_dom_info *ancestor;/* used for LINK and EVAL */
+ struct tmp_dom_info *dom; /* After step 3, if the semidominator of w is
+ its immediate dominator, then w->dom is the
+ immediate dominator of w. Otherwise w->dom
+ is a vertex v whose number is smaller than
+ w and whose immediate dominator is also w's
+ immediate dominator. After step 4, w->dom
+ is the immediate dominator of w. */
+ struct tmp_dom_info *bucket; /* set of vertices with same semidominator */
+} tmp_dom_info;
+
+/* Struct to pass info through walker. */
+typedef struct {
+ tmp_dom_info *d;
+ int used;
+
+} dom_env;
+
+void init_tmp_dom_info(ir_node *bl, tmp_dom_info *parent, tmp_dom_info *tdi_list, int* used) {
+ tmp_dom_info *tdi;
+ int i;
+
+ assert(get_irn_op(bl) == op_Block);
+ if (get_irg_block_visited(current_ir_graph) == get_Block_block_visited(bl)) return;
+ mark_Block_block_visited(bl);
+ set_Block_pre_num(bl, *used);
+
+ //printf(" used: %d ", *used); DDMN(bl);
+
+ tdi = &tdi_list[*used];
+ ++(*used);
+
+ tdi->semi = tdi;
+ tdi->label = tdi;
+ tdi->ancestor = NULL;
+ tdi->bucket = NULL;
+ tdi->parent = parent;
+ tdi->block = bl;
+
+ /* Iterate */
+ for(i = 0; i < get_Block_n_cfg_outs(bl); i++) {
+ ir_node *pred = get_Block_cfg_out(bl, i);
+ assert(get_irn_opcode(pred) == iro_Block);
+ init_tmp_dom_info(pred, tdi, tdi_list, used);
+ }
+}
+
+
+static void
+dom_compress (tmp_dom_info *v)
+{
+ assert (v->ancestor);
+ if (v->ancestor->ancestor) {
+ dom_compress (v->ancestor);
+ if (v->ancestor->label->semi < v->label->semi) {
+ v->label = v->ancestor->label;
+ }
+ v->ancestor = v->ancestor->ancestor;
+ }
+}
+
+/* if V is a root, return v, else return the vertex u, not being the
+ root, with minimum u->semi on the path from v to its root. */
+inline static tmp_dom_info*
+dom_eval (tmp_dom_info *v)
+{
+ if (!v->ancestor) return v;
+ dom_compress (v);
+ return v->label;
+}
+
+/* make V W's ancestor */
+inline static void
+dom_link (tmp_dom_info *v, tmp_dom_info *w)
+{
+ w->ancestor = v;
+}
+
+/* Computes the dominator trees. Sets a flag in irg to "dom_consistent".
+ If the control flow of the graph is changed this flag must be set to
+ "dom_inconsistent". */
+void compute_doms(ir_graph *irg) {
+ ir_graph *rem = current_ir_graph;
+ int n_blocks, used, i, j;
+ tmp_dom_info *tdi_list; /* Ein Golf? */
+ dom_env de;
+
+ current_ir_graph = irg;
+
+ /* Update graph state */
+ assert(get_irg_phase_state(current_ir_graph) != phase_building);
+ current_ir_graph->dom_state = dom_consistent;
+
+ /* Count the number of blocks in the graph. */
+ n_blocks = 0;
+ irg_block_walk(get_irg_end(current_ir_graph), count_and_init_blocks, NULL, &n_blocks);
+
+ //printf("n_blocks is %d\n", n_blocks);
+
+ /* Memory for temporary information. */
+ tdi_list = (tmp_dom_info *) calloc(n_blocks, sizeof(tmp_dom_info));
+
+ /* We need the out datastructure. */
+ if (current_ir_graph->outs_state != outs_consistent)
+ compute_outs(current_ir_graph);
+
+ /** Initialize the temporary information, add link to parent. We don't do
+ this with a standard walker as passing the parent to the sons isn't
+ simple. **/
+ used = 0;
+ inc_irg_block_visited(current_ir_graph);
+ init_tmp_dom_info(get_irg_start_block(current_ir_graph), NULL, tdi_list, &used);
+ /* If not all blocks are reachable from Start by out edges this assertion
+ fails. */
+ //assert(used == n_blocks && "Precondition for dom construction violated");
+ n_blocks = used;
+
+ //printf("used is %d\n", used);
+
+
+ for (i = n_blocks-1; i > 0; i--) { /* Don't iterate the root, it's done. */
+ tmp_dom_info *w = &tdi_list[i];
+ tmp_dom_info *v;
+
+ //printf(" cfgpreds: %d ", get_Block_n_cfgpreds(w->block)); DDMN(w->block);
+
+ /* Step 2 */
+ for (j = 0; j < get_irn_arity(w->block); j++) {
+ ir_node *pred = get_nodes_Block(get_Block_cfgpred(w->block, j));
+ tmp_dom_info *u;
+
+ if ((is_Bad(pred)) || (get_Block_pre_num (pred) == -1))
+ continue; /* control-dead */
+
+ u = dom_eval (&tdi_list[get_Block_pre_num(pred)]);
+ if (u->semi < w->semi) w->semi = u->semi;
+ }
+ /* Add w to w->semi's bucket. w is in exactly one bucket, so
+ buckets can ben implemented as linked lists. */
+ w->bucket = w->semi->bucket;
+ w->semi->bucket = w;
+
+ dom_link (w->parent, w);
+
+ /* Step 3 */
+ while (w->parent->bucket) {
+ tmp_dom_info *u;
+ v = w->parent->bucket;
+ /* remove v from w->parent->bucket */
+ w->parent->bucket = v->bucket;
+ v->bucket = NULL;
+
+ u = dom_eval (v);
+ if (u->semi < v->semi)
+ v->dom = u;
+ else
+ v->dom = w->parent;
+ }
+ }
+ /* Step 4 */
+ tdi_list[0].dom = NULL;
+ set_Block_idom(tdi_list[0].block, NULL);
+ set_Block_dom_depth(tdi_list[0].block, 1);
+ for (i = 1; i < n_blocks; i++) {
+ tmp_dom_info *w = &tdi_list[i];
+
+ if (w->dom != w->semi) w->dom = w->dom->dom;
+ set_Block_idom(w->block, w->dom->block);
+ set_Block_dom_depth(w->block, get_Block_dom_depth(w->dom->block) + 1);
+ }
+
+ /* clean up */
+ free(tdi_list);
+ current_ir_graph = rem;
+}
+
+void free_dom_and_peace(ir_graph *irg) {
+ /* Update graph state */
+ assert(get_irg_phase_state(current_ir_graph) != phase_building);
+ current_ir_graph->dom_state = no_dom;
+
+ /* @@@ free */
+}
+
+
+#if 0
+/* Dominator Tree */
+
+/* temporary type used while constructing the dominator tree. */
+typedef struct tmp_dom_info tmp_dom_info;
+struct tmp_dom_info {
+ ir_node *region;
+
+ tmp_dom_info *semi; /* semidominator */
+ tmp_dom_info *parent;
+ tmp_dom_info *label; /* used for LINK and EVAL */
+ tmp_dom_info *ancestor; /* used for LINK and EVAL */
+ tmp_dom_info *dom; /* After step 3, if the semidominator
+ of w is its immediate dominator, then w->dom is the immediate
+ dominator of w. Otherwise w->dom is a vertex v whose number is
+ smaller than w and whose immediate dominator is also w's immediate
+ dominator. After step 4, w->dom is the immediate dominator of w. */
+ tmp_dom_info *bucket; /* set of vertices with same semidominator */
+};
+
+static int
+dom_count_regions (ir_node *n)
+{
+ int i, count = 1;
+
+ n->visit = ir_visited;
+
+ for (i = IR_ARITY (n); i > 0; --i) {
+ ir_node *pr = prev_region (n, i);
+ if (pr && pr->visit != ir_visited) {
+ count += dom_count_regions (pr);
+ }
+ }
+ return count;
+}
+
+struct dt_desc { tmp_dom_info *dt; int used;};
+
+static void
+dom_setup (ir_node *n, tmp_dom_info *parent, struct dt_desc *dt_desc)
+{
+ tmp_dom_info *dt = &dt_desc->dt[dt_desc->used];
+ int i;
+
+ if (n->visit == ir_visited) return;
+ n->visit = ir_visited;
+
+ assert (IR_CFG_NODE (n));
+
+ n->data.r.pre_num = dt_desc->used;
+ dt->semi = dt;
+ dt->label = dt;
+ dt->ancestor = NULL;
+ dt->bucket = NULL;
+ dt->parent = parent;
+ dt->region = n;
+ ++(dt_desc->used);
+
+ for (i = 0; i < n->data.r.cfg_outs; ++i) {
+ dom_setup (n->data.r.cfg_out[i], dt, dt_desc);
+ }
+}
+
+static void
+dom_compress (tmp_dom_info *v)
+{
+ assert (v->ancestor);
+ if (v->ancestor->ancestor) {
+ dom_compress (v->ancestor);
+ if (v->ancestor->label->semi < v->label->semi) {
+ v->label = v->ancestor->label;
+ }
+ v->ancestor = v->ancestor->ancestor;
+ }
+}
+
+/* if V is a root, return v, else return the vertex u, not being the
+ root, with minimum u->semi on the path from v to its root. */
+static tmp_dom_info*
+dom_eval (tmp_dom_info *v)
+{
+ if (!v->ancestor) return v;
+ dom_compress (v);
+ return v->label;
+}
+
+/* make V W's ancestor */
+static void
+dom_link (tmp_dom_info *v, tmp_dom_info *w)
+{
+ w->ancestor = v;
+}
+
+void
+irg_gen_idom (ir_graph *irg)
+{
+ int regions, i;
+ tmp_dom_info *dt;
+ struct dt_desc dt_desc;
+
+ if (!(irg->state & irgs_has_CFG)) irg_gen_out (irg);
+
+ ++ir_visited;
+ regions = 0;
+ /* walk all the artificially kept alive parts of the CFG instead of
+ the CFG beginning from the Start just for fun and safety */
+ keep_alives_in_arr (irg);
+ for (i = ARR_LEN (irg->keep.alive) - 1; i >= 0; --i)
+ if ( IR_CFG_NODE (irg->keep.alive[i])
+ && irg->keep.alive[i]->visit != ir_visited)
+ regions += dom_count_regions (irg->keep.alive[i]);
+
+ dt = alloca ((regions+1) * sizeof (tmp_dom_info));
+ memset (dt, 0, (regions+1) * sizeof (tmp_dom_info));
+
+ /* Step 1 */
+ dt_desc.dt = dt;
+ dt_desc.used = 1;
+ ++ir_visited;
+ dom_setup (irg->start, NULL, &dt_desc);
+
+ /* This assert will fail, if not all Regions are reachable by
+ walking the CFG starting from Start, that is when there is
+ [control] dead code, violating the single entry precondition of
+ this algorithm. */
+ assert (dt_desc.used == regions + 1);
+
+ for (i = regions; i > 1; --i) {
+ tmp_dom_info *w = &dt[i];
+ tmp_dom_info *v;
+ int j, r_ins;
+
+ /* Step 2 */
+ r_ins = IR_ARITY (w->region);
+ for (j = 1; j <= r_ins; ++j) {
+ ir_node *prev = prev_region (w->region, j);
+ tmp_dom_info *u;
+
+ if (!prev) continue; /* control-dead */
+
+ u = dom_eval (&dt[prev->data.r.pre_num]);
+ if (u->semi < w->semi) w->semi = u->semi;
+ }
+ /* Add w to w->semi's bucket. w is in exactly one bucket, so
+ buckets can ben implemented as linked lists. */
+ w->bucket = w->semi->bucket;
+ w->semi->bucket = w;
+
+ dom_link (w->parent, w);
+
+ /* Step 3 */
+ while ((v = w->parent->bucket)) {
+ tmp_dom_info *u;
+ /* remove v from w->parent->bucket */
+ w->parent->bucket = v->bucket;
+ v->bucket = NULL;
+
+ u = dom_eval (v);
+ v->dom = u->semi < v->semi ? u : w->parent;
+ }
+ }
+ /* Step 4 */
+ dt[1].dom = NULL;
+ dt[1].region->data.r.idom = NULL;
+ dt[1].region->data.r.dom_depth = 1;
+ for (i = 2; i <= regions; ++i) {
+ tmp_dom_info *w = &dt[i];
+
+ if (w->dom != w->semi) w->dom = w->dom->dom;
+ w->region->data.r.idom = w->dom->region;
+ w->region->data.r.dom_depth = w->dom->region->data.r.dom_depth + 1;
+ }
+ current_ir_graph = sirg;
+}
+
+#endif
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