+++ /dev/null
-/*
- * Copyright (C) 1995-2011 University of Karlsruhe. All right reserved.
- *
- * This file is part of libFirm.
- *
- * This file may be distributed and/or modified under the terms of the
- * GNU General Public License version 2 as published by the Free Software
- * Foundation and appearing in the file LICENSE.GPL included in the
- * packaging of this file.
- *
- * Licensees holding valid libFirm Professional Edition licenses may use
- * this file in accordance with the libFirm Commercial License.
- * Agreement provided with the Software.
- *
- * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
- * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE.
- */
-
-/**
- * @file
- * @brief Structure Analysis
- * @author Michael Beck
- * @date 5.4.2007
- * @version $Id$
- */
-#include "config.h"
-
-#include <stdbool.h>
-
-#include "firm_common.h"
-#include "irnode_t.h"
-#include "structure.h"
-#include "irdom.h"
-#include "irouts.h"
-#include "irtools.h"
-#include "irgwalk.h"
-#include "array.h"
-#include "irdump.h"
-
-#include "debug.h"
-
-typedef union ir_reg_or_blk ir_reg_or_blk;
-
-/* The structure tree. */
-struct ir_reg_tree {
- struct obstack obst; /**< The obstack where the data is allocated. */
- ir_region *top; /**< The top region. */
- ir_graph *irg; /**< Associated graph. */
-};
-
-/* A region. */
-struct ir_region {
- firm_kind kind; /**< Must be k_ir_region. */
- ir_region_kind type; /**< The type of this region. */
- ir_region *parent; /**< points to the parent. */
- ir_reg_or_blk *parts; /**< The list of all region parts. */
- ir_region **pred; /**< The predecessor (control flow) regions of this region. */
- ir_region **succ; /**< The successor (control flow) regions of this region. */
- size_t prenum; /**< DFS pre-oder number */
- size_t postnum; /**< DFS post-oder number */
- void *link; /**< A link field. */
- unsigned long nr; /**< for debugging */
- unsigned visited:1; /**< The visited flag. */
- unsigned exit:1; /**< If set, the parent region can be left by this node. */
- unsigned enter:1; /**< If set, the parent region can be entered by this node. */
-};
-
-/* A helper type for unioning blocks and regions. */
-union ir_reg_or_blk {
- firm_kind *kind; /**< For easier check. */
- ir_node *blk; /**< A node */
- ir_region *region; /**< A region. */
-};
-
-/* The debug handle. */
-DEBUG_ONLY(static firm_dbg_module_t *dbg;)
-
-/**
- * Returns the link of a region.
- */
-void *get_region_link(const ir_region *reg)
-{
- return reg->link;
-}
-
-/**
- * Sets the link of a region.
- */
-void set_region_link(ir_region *reg, void *data)
-{
- reg->link = data;
-}
-
-/**
- * Get the immediate region of a block.
- */
-ir_region *get_block_region(const ir_node *block)
-{
- assert(is_Block(block));
- return block->attr.block.region;
-}
-
-/**
- * Sets the immediate region of a block.
- */
-void set_block_region(ir_node *block, ir_region *reg)
-{
- assert(is_Block(block));
- block->attr.block.region = reg;
-}
-
-/**
- * Get the immediate region of a node.
- */
-ir_region *get_irn_region(ir_node *n)
-{
- if (!is_Block(n))
- n = get_nodes_block(n);
- return get_block_region(n);
-}
-
-/**
- * Return non-zero if a given firm thing is a region.
- */
-int is_region(const void *thing)
-{
- const firm_kind *kind = (const firm_kind*) thing;
- return *kind == k_ir_region;
-}
-
-/**
- * Return the number of predecessors of a region.
- */
-size_t get_region_n_preds(const ir_region *reg)
-{
- return ARR_LEN(reg->pred);
-}
-
-/**
- * Return the predecessor region at position pos.
- */
-ir_region *get_region_pred(const ir_region *reg, size_t pos)
-{
- assert(pos <= get_region_n_preds(reg));
- return reg->pred[pos];
-}
-
-/**
- * Set the predecessor region at position pos.
- */
-void set_region_pred(ir_region *reg, size_t pos, ir_region *n)
-{
- assert(pos <= get_region_n_preds(reg));
- reg->pred[pos] = n;
-}
-
-/**
- * Return the number of successors in a region.
- */
-size_t get_region_n_succs(const ir_region *reg)
-{
- return ARR_LEN(reg->succ);
-}
-
-/**
- * Return the successor region at position pos.
- */
-ir_region *get_region_succ(const ir_region *reg, size_t pos)
-{
- assert(pos <= get_region_n_succs(reg));
- return reg->succ[pos];
-}
-
-/**
- * Set the successor region at position pos.
- */
-void set_region_succ(ir_region *reg, size_t pos, ir_region *n)
-{
- assert(pos <= get_region_n_succs(reg));
- reg->succ[pos] = n;
-}
-
-/* ----------------------- construction -------------------------- */
-
-/** Walker environment. */
-typedef struct walk_env {
- struct obstack *obst; /**< An obstack to allocate from. */
- ir_region **post; /**< The list of all currently existent top regions. */
- size_t l_post; /**< The length of the allocated regions array. */
- size_t premax; /**< maximum pre counter */
- size_t postmax; /**< maximum post counter */
- ir_node *start_block; /**< The start block of the graph. */
- ir_node *end_block; /**< The end block of the graph. */
-} walk_env;
-
-/**
- * Do a DFS search on the initial regions, assign a prenum and a postnum to every
- * node and store the region nodes into the post array.
- */
-static void dfs_walk2(ir_region *reg, walk_env *env)
-{
- size_t i, n;
-
- if (reg->visited == 0) {
- reg->visited = 1;
-
- reg->prenum = env->premax++;
- for (i = 0, n = get_region_n_succs(reg); i < n; ++i) {
- /* recursion */
- ir_region *succ = get_region_succ(reg, i);
- dfs_walk2(succ, env);
- }
-
- env->post[env->postmax] = reg;
- reg->postnum = env->postmax++;
- }
-}
-
-/**
- * Do a DFS search on the initial regions, assign a prenum and a postnum to every
- * node and store the region nodes into the post array.
- */
-static void dfs_walk(ir_graph *irg, walk_env *env)
-{
- ir_graph *rem = current_ir_graph;
- ir_region *reg;
-
- current_ir_graph = irg;
- reg = (ir_region*) get_irn_link(get_irg_start_block(irg));
-
- env->premax = 0;
- env->postmax = 0;
- dfs_walk2(reg, env);
- current_ir_graph = rem;
-}
-
-/**
- * Post-walker: wrap all blocks with a BasicBlock region
- * and count them
- */
-static void wrap_BasicBlocks(ir_node *block, void *ctx)
-{
- walk_env *env = (walk_env*) ctx;
- ir_region *reg;
-
- /* Allocate a Block wrapper */
- reg = OALLOC(env->obst, ir_region);
- reg->kind = k_ir_region;
- reg->type = ir_rk_BasicBlock;
- reg->parent = NULL;
- reg->prenum = 0;
- reg->postnum = 0;
- reg->visited = 0;
- reg->exit = 0;
- reg->enter = 0;
- reg->link = NULL;
- reg->nr = get_irn_node_nr(block);
- reg->parts = NEW_ARR_D(ir_reg_or_blk, env->obst, 1);
-
- reg->parts[0].blk = block;
- set_irn_link(block, reg);
-
- ++env->l_post;
-} /* wrap_BasicBlocks */
-
-/**
- * Post-walker: Create the pred and succ edges for Block wrapper.
- * Kill edges to the Start and End blocks.
- */
-static void update_BasicBlock_regions(ir_node *blk, void *ctx)
-{
- walk_env *env = (walk_env*) ctx;
- ir_region *reg = (ir_region*) get_irn_link(blk);
- int i, len;
- size_t j;
-
- if (blk == env->start_block) {
- /* handle Firm's self loop: Start block has no predecessors */
- reg->pred = NEW_ARR_D(ir_region *, env->obst, 0);
- } else {
- len = get_Block_n_cfgpreds(blk);
- reg->pred = NEW_ARR_D(ir_region *, env->obst, len);
- for (j = i = 0; i < len; ++i) {
- ir_node *pred = get_Block_cfgpred_block(blk, i);
- reg->pred[j++] = (ir_region*) get_irn_link(pred);
- }
- ARR_SHRINKLEN(reg->pred, j);
- }
-
- len = get_Block_n_cfg_outs(blk);
- reg->succ = NEW_ARR_D(ir_region *, env->obst, len);
- for (j = i = 0; i < len; ++i) {
- ir_node *succ = get_Block_cfg_out(blk, i);
- reg->succ[j++] = (ir_region*) get_irn_link(succ);
- }
- ARR_SHRINKLEN(reg->succ, j);
-} /* update_BasicBlock_regions */
-
-/** Allocate a new region on an obstack */
-static ir_region *alloc_region(struct obstack *obst, ir_region_kind type)
-{
- ir_region *reg = OALLOC(obst, ir_region);
- reg->kind = k_ir_region;
- reg->type = type;
- reg->parent = NULL;
- reg->prenum = 0;
- reg->postnum = 0;
- reg->visited = 0;
- reg->exit = 0;
- reg->enter = 0;
- reg->link = NULL;
-
- return reg;
-} /* alloc_region */
-
-/**
- * Creates a new Sequence region.
- */
-static ir_region *new_Sequence(struct obstack *obst, ir_region *nset, size_t nset_len)
-{
- ir_region *reg = alloc_region(obst, ir_rk_Sequence);
- ir_region *next;
- size_t i;
-
- reg->parts = NEW_ARR_D(ir_reg_or_blk, obst, nset_len);
-
- /* beware: list is in reverse order, reverse */
- next = nset;
- for (i = nset_len; i > 0;) {
- --i;
- nset = next;
- reg->parts[i].region = nset;
- nset->parent = reg;
- next = (ir_region*) nset->link;
- nset->link = NULL;
- }
-
- reg->nr = reg->parts[0].region->nr;
- reg->pred = DUP_ARR_D(ir_region *, obst, reg->parts[0].region->pred);
- reg->succ = DUP_ARR_D(ir_region *, obst, reg->parts[nset_len - 1].region->succ);
-
- DEBUG_ONLY(
- DB((dbg, LEVEL_2, " Created Sequence "));
- for (i = 0; i < nset_len; ++i) {
- DB((dbg, LEVEL_2, "(%lu)", reg->parts[i].region->nr));
- }
- DB((dbg, LEVEL_2, "\n"));
- )
- return reg;
-} /* new_Sequence */
-
-/**
- * Create a new IfThenElse region.
- */
-static ir_region *new_IfThenElse(struct obstack *obst, ir_region *if_b, ir_region *then_b, ir_region *else_b)
-{
- ir_region *reg = alloc_region(obst, ir_rk_IfThenElse);
-
- reg->nr = if_b->nr;
- reg->parts = NEW_ARR_D(ir_reg_or_blk, obst, 3);
-
- reg->parts[0].region = if_b; if_b->parent = reg;
- reg->parts[1].region = then_b; then_b->parent = reg;
- reg->parts[2].region = else_b; else_b->parent = reg;
-
- reg->pred = DUP_ARR_D(ir_region *, obst, if_b->pred);
- reg->succ = DUP_ARR_D(ir_region *, obst, then_b->succ);
-
- DB((dbg, LEVEL_2, " Created If(%lu)Then(%lu)Else(%lu)\n", reg->nr, then_b->nr, else_b->nr));
-
- return reg;
-} /* new_IfThenElse */
-
-/**
- * Create a new IfThen region.
- */
-static ir_region *new_IfThen(struct obstack *obst, ir_region *if_b, ir_region *then_b)
-{
- ir_region *reg = alloc_region(obst, ir_rk_IfThen);
-
- reg->nr = if_b->nr;
- reg->parts = NEW_ARR_D(ir_reg_or_blk, obst, 2);
-
- reg->parts[0].region = if_b; if_b->parent = reg;
- reg->parts[1].region = then_b; then_b->parent = reg;
-
- reg->pred = DUP_ARR_D(ir_region *, obst, if_b->pred);
- reg->succ = DUP_ARR_D(ir_region *, obst, then_b->succ);
-
- DB((dbg, LEVEL_2, " Created If(%lu)Then(%lu)\n", reg->nr, then_b->nr));
-
- return reg;
-} /* new_IfThenElse */
-
-/**
- * Create a new Switch/case region.
- */
-static ir_region *new_SwitchCase(struct obstack *obst, ir_region_kind type, ir_region *head, ir_region *exit,
- ir_region *cases, size_t cases_len)
-{
- ir_region *reg = alloc_region(obst, type);
- ir_region *c, *n;
- int add = 1;
- size_t i;
-
- /* check, if the exit block is in the list */
- for (c = cases; c != NULL; c = (ir_region*) c->link) {
- if (c == exit) {
- add = 0;
- break;
- }
- }
-
- reg->nr = head->nr;
- reg->parts = NEW_ARR_D(ir_reg_or_blk, obst, cases_len + add);
-
- reg->parts[0].region = head; head->parent = reg;
- i = 1;
- for (c = cases; c != NULL; c = n) {
- n = (ir_region*) c->link;
- if (c != exit) {
- reg->parts[i++].region = c;
- c->parent = reg;
- }
- c->link = NULL;
- }
-
- reg->pred = DUP_ARR_D(ir_region *, obst, head->pred);
- reg->succ = NEW_ARR_D(ir_region *, obst, 1);
- reg->succ[0] = exit;
-
- DEBUG_ONLY({
- DB((dbg, LEVEL_2, " Created %s(%u)\n", reg->type == ir_rk_Switch ? "Switch" : "Case", reg->nr));
- for (i = 1; i < ARR_LEN(reg->parts); ++i) {
- DB((dbg, LEVEL_2, " Case(%lu)\n", reg->parts[i].region->nr));
- }
- DB((dbg, LEVEL_2, " Exit(%lu)\n", exit->nr));
- })
- return reg;
-} /* new_SwitchCase */
-
-/**
- * Create a new SelfLoop region.
- */
-static ir_region *new_SelfLoop(struct obstack *obst, ir_region *head)
-{
- ir_region *reg = alloc_region(obst, ir_rk_SelfLoop);
- ir_region *succ;
- size_t i, j, len;
-
- reg->nr = head->nr;
- reg->parts = NEW_ARR_D(ir_reg_or_blk, obst, 1);
-
- reg->parts[0].region = head; head->parent = reg;
-
- len = ARR_LEN(head->pred);
- reg->pred = NEW_ARR_D(ir_region *, obst, len - 1);
- for (i = j = 0; i < len; ++i) {
- ir_region *pred = get_region_pred(head, i);
- if (pred != head)
- reg->pred[j++] = pred;
- }
- assert(j == len - 1);
-
- reg->succ = NEW_ARR_D(ir_region *, obst, 1);
- assert(ARR_LEN(head->succ) == 2);
-
- succ = get_region_succ(head, 0);
- if (succ != head)
- reg->succ[0] = succ;
- else
- reg->succ[0] = get_region_succ(head, 1);
-
- DB((dbg, LEVEL_2, " Created SelfLoop(%lu)\n", reg->nr));
-
- return reg;
-} /* new_SelfLoop */
-
-/**
- * Create a new RepeatLoop region.
- */
-static ir_region *new_RepeatLoop(struct obstack *obst, ir_region *head, ir_region *body)
-{
- ir_region *reg = alloc_region(obst, ir_rk_RepeatLoop);
- ir_region *succ;
-
- reg->nr = head->nr;
- reg->parts = NEW_ARR_D(ir_reg_or_blk, obst, 2);
-
- reg->parts[0].region = head; head->parent = reg;
- reg->parts[1].region = body; body->parent = reg;
-
- reg->pred = DUP_ARR_D(ir_region *, obst, head->pred);
- reg->succ = NEW_ARR_D(ir_region *, obst, 1);
- assert(ARR_LEN(body->succ) == 2);
-
- succ = get_region_succ(body, 0);
- if (succ != head)
- reg->succ[0] = succ;
- else
- reg->succ[0] = get_region_succ(body, 1);
-
- DB((dbg, LEVEL_2, " Created RepeatLoop(%lu)Body(%lu)\n", reg->nr, body->nr));
-
- return reg;
-} /* new_RepeatLoop */
-
-/**
- * Create a new WhileLoop region.
- */
-static ir_region *new_WhileLoop(struct obstack *obst, ir_region *head)
-{
- ir_region *reg = alloc_region(obst, ir_rk_WhileLoop);
- ir_region *body = (ir_region*) head->link;
- ir_region *succ;
- size_t i, j, len;
-
- head->link = NULL;
-
- reg->nr = head->nr;
- reg->parts = NEW_ARR_D(ir_reg_or_blk, obst, 2);
-
- reg->parts[0].region = head; head->parent = reg;
- reg->parts[1].region = body; body->parent = reg;
-
- len = ARR_LEN(head->pred);
- reg->pred = NEW_ARR_D(ir_region *, obst, len - 1);
- for (i = j = 0; i < len; ++i) {
- ir_region *pred = get_region_pred(head, i);
- if (pred != body)
- reg->pred[j++] = pred;
- }
- assert(j == len - 1);
-
- reg->succ = NEW_ARR_D(ir_region *, obst, 1);
- assert(ARR_LEN(head->succ) == 2);
-
- succ = get_region_succ(head, 0);
- if (succ != body)
- reg->succ[0] = succ;
- else
- reg->succ[0] = get_region_succ(head, 1);
-
- DB((dbg, LEVEL_2, " Created WhileLoop(%lu)Body(%lu)\n", reg->nr, body->nr));
-
- return reg;
-} /* new_WhileLoop */
-
-/**
- * Create a new new_NaturalLoop region.
- */
-static ir_region *new_NaturalLoop(struct obstack *obst, ir_region *head)
-{
- ir_region *reg = alloc_region(obst, ir_rk_WhileLoop);
- ir_region *c, *n;
- size_t i, j, k, len, n_pred, n_succ;
-
- /* count number of parts */
- for (len = 0, c = head; c != NULL; c = (ir_region*) c->link)
- ++len;
-
- reg->nr = head->nr;
- reg->parts = NEW_ARR_D(ir_reg_or_blk, obst, len);
-
- /* enter all parts */
- for (i = 0, c = head; c != NULL; c = n) {
- reg->parts[i++].region = c;
- c->parent = reg;
- n = (ir_region*) c->link;
- c->link = NULL;
- }
-
- /* count number of preds */
- n_pred = 0;
- for (i = get_region_n_preds(head); i > 0;) {
- ir_region *pred = get_region_pred(head, --i);
- if (pred->parent != reg)
- ++n_pred;
- }
- reg->pred = NEW_ARR_D(ir_region *, obst, n_pred);
- for (j = 0, i = get_region_n_preds(head); i > 0;) {
- ir_region *pred = get_region_pred(head, --i);
- if (pred->parent != reg)
- reg->pred[j++] = pred;
- }
-
- /* count number of succs */
- n_succ = 0;
- for (j = 0; j < len; ++j) {
- ir_region *pc = reg->parts[j].region;
- for (i = get_region_n_succs(pc); i > 0;) {
- ir_region *succ = get_region_succ(pc, --i);
- if (succ->parent != reg)
- ++n_succ;
- }
- }
- reg->succ = NEW_ARR_D(ir_region *, obst, n_succ);
- k = 0;
- for (j = 0; j < len; ++j) {
- ir_region *pc = reg->parts[j].region;
- for (i = get_region_n_succs(pc); i > 0;) {
- ir_region *succ = get_region_succ(pc, --i);
- if (succ->parent != reg)
- reg->succ[k++] = succ;
- }
- }
-
- DEBUG_ONLY(
- DB((dbg, LEVEL_2, " Created NaturalLoop(%u)Head(%u)\n", reg->nr, head->nr));
- for (i = 1; i < len; ++i) {
- ir_region *p = reg->parts[i].region;
- DB((dbg, LEVEL_2, " Body(%u)\n", p->nr));
- }
- )
- return reg;
-} /* new_NaturalLoop */
-
-/**
- * Return true if region a is an ancestor of region b in DFS search.
- */
-static int is_ancestor(const ir_region *a, const ir_region *b)
-{
- return (a->prenum <= b->prenum && a->postnum > b->postnum);
-}
-
-/**
- * Return true if region pred is a predecessor of region n.
- */
-static bool pred_of(const ir_region *pred, const ir_region *n)
-{
- size_t i, n_preds;
- for (i = 0, n_preds = get_region_n_preds(n); i < n_preds; ++i) {
- if (get_region_pred(n, i) == pred)
- return true;
- }
- return false;
-}
-
-/**
- * Return true if region succ is a successor of region n.
- */
-static bool succ_of(const ir_region *succ, const ir_region *n)
-{
- size_t i, n_succs;
- for (i = 0, n_succs = get_region_n_succs(n); i < n_succs; ++i) {
- if (get_region_succ(n, i) == succ)
- return true;
- }
- return false;
-}
-
-/**
- * Reverse a linked list of regions.
- */
-static struct ir_region *reverse_list(ir_region *n)
-{
- ir_region *prev = NULL, *next;
-
- for (; n; n = next) {
- next = (ir_region*) n->link;
- n->link = prev;
- prev = n;
- }
- return prev;
-}
-
-/**
- * Find the cyclic region in the subgraph entered by node.
- */
-static ir_region *find_cyclic_region(ir_region *node)
-{
- size_t i;
- ir_region *last = node;
- int improper = 0;
-
- for (i = get_region_n_preds(node); i > 0;) {
- ir_region *pred = get_region_pred(node, --i);
-
- /* search backedges */
- if (!pred->link && pred != last && is_ancestor(node, pred)) {
- ir_region *rem = last;
- size_t j;
-
- last->link = pred;
- last = pred;
- for (j = get_region_n_preds(pred); j > 0;) {
- ir_region *p = get_region_pred(pred, --j);
-
- /* Search regions we didn't visited yet and
- link them into the list. */
- if (!p->link && p != last) {
- if (is_ancestor(node, p)) {
- last->link = p;
- last = p;
- } else {
- improper = 1;
- }
- }
- }
- /* reverse the list. */
- last = (ir_region*) rem->link;
- rem->link = reverse_list(last);
- }
- }
-
- if (node->link && improper) {
- /* found an improper region, do minimization */
-
- }
- return node;
-}
-
-/**
- * Detect a cyclic region.
- */
-static ir_region *cyclic_region_type(struct obstack *obst, ir_region *node)
-{
- ir_region *list, *next;
-
- /* simple cases first */
- if (succ_of(node, node)) {
- return new_SelfLoop(obst, node);
- }
- if (get_region_n_succs(node) == 1) {
- ir_region *succ = get_region_succ(node, 0);
- if (get_region_n_preds(succ) == 1 && succ_of(node, succ)) {
- return new_RepeatLoop(obst, node, succ);
- }
- }
- list = find_cyclic_region(node);
-
- next = (ir_region*) list->link;
- if (next) {
- if (!next->link && get_region_n_succs(next) == 1) {
- /* only one body block with only one successor (the head) */
- return new_WhileLoop(obst, list);
- }
- /* A Loop with one head */
- return new_NaturalLoop(obst, list);
- }
-
- return NULL;
-}
-
-/**
- * Clear all links on a list. Needed, because we expect cleared links.
- */
-static void clear_list(ir_region *list)
-{
- ir_region *next;
-
- for (next = list; next; list = next) {
- next = (ir_region*) list->link;
- list->link = NULL;
- }
-}
-
-#define ADD_LIST(list, n) do { n->link = list; list = n; ++list##_len; } while (0)
-
-/**
- * Detect an acyclic region.
- */
-static ir_region *acyclic_region_type(struct obstack *obst, ir_region *node)
-{
- ir_region *n, *m;
- bool p, s;
- size_t k;
- ir_region *nset = NULL;
- size_t nset_len = 0;
- ir_region *res;
-
- /* check for a block containing node */
- n = node;
- p = get_region_n_preds(n) == 1;
- s = true;
- while (p & s) {
- n = get_region_pred(n, 0);
- p = get_region_n_preds(n) == 1;
- s = get_region_n_succs(n) == 1;
- }
- p = true;
- s = get_region_n_succs(n) == 1;
- while (p & s) {
- ADD_LIST(nset, n);
- n = get_region_succ(n, 0);
- p = get_region_n_preds(n) == 1;
- s = get_region_n_succs(n) == 1;
- }
- if (p) {
- ADD_LIST(nset, n);
- }
- if (nset_len > 1) {
- /* node --> .. --> .. */
- res = new_Sequence(obst, nset, nset_len);
- return res;
- }
- node = n;
-
- /* check for IfThenElse */
- k = get_region_n_succs(node);
- if (k == 2) {
- size_t n_succs, m_succs, n_preds, m_preds;
-
- n = get_region_succ(node, 0);
- m = get_region_succ(node, 1);
-
- n_succs = get_region_n_succs(n);
- m_succs = get_region_n_succs(m);
- n_preds = get_region_n_preds(n);
- m_preds = get_region_n_preds(m);
- if (n_succs == 1 && n_succs == m_succs && n_preds == m_preds &&
- get_region_succ(n, 0) == get_region_succ(m, 0)) {
- /*
- * /-->n---\
- * node ...
- * \-->m---/
- */
- return new_IfThenElse(obst, node, n, m);
- }
- if (n_succs == 1 &&
- get_region_succ(n, 0) == m &&
- pred_of(node, m)) {
- /*
- * node -->n-->m
- * \-------/
- */
- return new_IfThen(obst, node, n);
- }
- if (m_succs == 1 &&
- get_region_succ(m, 0) == m &&
- pred_of(node, n)) {
- /*
- * node -->m-->n
- * \-------/
- */
- return new_IfThen(obst, node, m);
- }
- }
- /* check for Switch, case */
- if (k > 0) {
- ir_region *rexit = NULL;
- size_t i, pos = 0;
- nset = NULL; nset_len = 0;
- for (i = k; i > 0;) {
- n = get_region_succ(node, i--);
- ADD_LIST(nset, n);
- if (get_region_n_succs(n) != 1) {
- /* must be the exit */
- rexit = n;
- ++pos;
- if (pos > 1)
- break;
- }
- }
- if (pos <= 1) {
- ir_region_kind kind = ir_rk_Case;
- ir_region *pos_exit_1 = NULL;
- ir_region *pos_exit_2 = NULL;
-
- /* find the exit */
- for (m = nset; m != NULL; m = (ir_region*) m->link) {
- if (get_region_n_succs(m) != 1) {
- /* must be the exit block */
- if (rexit == NULL) {
- rexit = m;
- } else if (rexit != m) {
- /* two exits */
- rexit = NULL;
- break;
- }
- } else {
- ir_region *succ = get_region_succ(m, 0);
-
- if (succ->link == NULL) {
- if (rexit == NULL) {
- if (succ == pos_exit_1)
- rexit = succ;
- else if (succ == pos_exit_2)
- rexit = succ;
- else if (pos_exit_1 == NULL)
- pos_exit_1 = succ;
- else if (pos_exit_2 == NULL)
- pos_exit_2 = succ;
- else {
- /* more than two possible exits */
- break;
- }
- } else if (rexit != succ) {
- /* two exits */
- rexit = NULL;
- break;
- }
- }
- }
- }
- if (rexit != NULL) {
- /* do the checks */
- for (n = nset; n != NULL; n = (ir_region*) n->link) {
- ir_region *succ;
- if (n == rexit) {
- /* good, default fall through */
- continue;
- }
- succ = get_region_succ(n, 0);
- if (succ == rexit) {
- /* good, switch to exit */
- continue;
- }
- if (succ->link == NULL) {
- /* another exit */
- break;
- } else {
- /* a fall through */
- kind = ir_rk_Switch;
- }
- }
-
- if (n == NULL) {
- /* detected */
- return new_SwitchCase(obst, kind, node, rexit, nset, nset_len);
- }
- }
- }
- clear_list(nset);
- }
- return NULL;
-}
-
-/**
- * replace all pred edges from region pred that points to any of the set set
- * to ONE edge to reg.
- */
-static void replace_pred(ir_region *succ, ir_region *reg)
-{
- int have_one = 0;
- size_t len = get_region_n_preds(succ);
- size_t i;
-
- for (i = 0; i < len; ++i) {
- ir_region *pred = get_region_pred(succ, i);
-
- if (pred->parent == reg) {
- ir_region *r;
-
- if (have_one) {
- /* kill it */
- r = get_region_pred(succ, --len);
- } else {
- /* replace it */
- have_one = 1;
- r = reg;
- }
- set_region_pred(succ, i, r);
- } else {
- /* the current region can be entered by this node */
- pred->enter = 1;
- }
- }
- ARR_SHRINKLEN(succ->pred, len);
-}
-
-/**
- * replace all succ edges from region pred that points to any of the set set
- * to ONE edge to reg.
- */
-static void replace_succ(ir_region *pred, ir_region *reg)
-{
- int have_one = 0;
- size_t len = get_region_n_succs(pred);
- size_t i;
-
- for (i = 0; i < len; ++i) {
- ir_region *succ = get_region_succ(pred, i);
-
- if (succ->parent == reg) {
- ir_region *r;
-
- if (have_one) {
- /* kill it */
- r = get_region_succ(pred, --len);
- } else {
- /* replace it */
- have_one = 1;
- r = reg;
- }
- set_region_succ(pred, i, r);
- } else {
- /* current region can be left by this node */
- succ->exit = 1;
- }
- }
- ARR_SHRINKLEN(pred->succ, len);
-}
-
-/**
- * Reduce the graph by the node reg.
- */
-static void reduce(walk_env *env, ir_region *reg)
-{
- size_t i;
- ir_region *head = reg->parts[0].region;
- size_t maxorder = head->postnum;
- size_t minorder = head->prenum;
-
- /* second step: replace all preds in successors */
- for (i = get_region_n_succs(reg); i > 0;) {
- ir_region *succ = get_region_succ(reg, --i);
-
- replace_pred(succ, reg);
- }
-
- /* third step: replace all succs in predessors */
- for (i = get_region_n_preds(reg); i > 0;) {
- ir_region *pred = get_region_pred(reg, --i);
-
- replace_succ(pred, reg);
- }
-
- reg->prenum = minorder;
- reg->postnum = maxorder;
- env->post[maxorder] = reg;
-}
-
-/**
- * Construct the region tree of a graph by doing
- * structural analysis.
- *
- * Uses link fields of nodes.
- *
- * @param irg the graph
- */
-ir_reg_tree *construct_region_tree(ir_graph *irg)
-{
- walk_env env;
- ir_graph *rem = current_ir_graph;
- ir_reg_tree *res = XMALLOC(ir_reg_tree);
-
- obstack_init(&res->obst);
-
- current_ir_graph = irg;
-
- FIRM_DBG_REGISTER(dbg, "firm.ana.structure");
- firm_dbg_set_mask(dbg, SET_LEVEL_5);
-
- DB((dbg, LEVEL_1, "Structural analysis on %+F started ...\n", irg));
-
- /* we need dominance info */
- assure_doms(irg);
- /* and out edges */
- assure_irg_outs(irg);
-
- env.start_block = get_irg_start_block(irg);
- env.end_block = get_irg_end_block(irg);
-
- ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);
-
- /* create the Block wrapper and count them */
- env.l_post = 0;
- env.obst = &res->obst;
- irg_block_walk_graph(irg, NULL, wrap_BasicBlocks, &env);
- irg_block_walk_graph(irg, NULL, update_BasicBlock_regions, &env);
-
- env.post = NEW_ARR_F(ir_region *, env.l_post);
-
- /* do the DFS walk */
- dfs_walk(irg, &env);
-
- DB((dbg, LEVEL_1, "%zu regions left\n", env.postmax));
- if (env.postmax > 1) {
- size_t postctr = 0;
- do {
- ir_region *reg, *n = env.post[postctr];
- do {
- if (n->parent != NULL) {
- /* already folded */
- break;
- }
- /* locate an acyclic region if present */
- reg = acyclic_region_type(env.obst, n);
- if (reg == NULL) {
- /* locate a cyclic region */
- reg = cyclic_region_type(env.obst, n);
- }
- if (reg != NULL) {
- /* found a new region */
- reduce(&env, reg);
- n = reg;
- }
- } while (reg != NULL);
- ++postctr;
- } while (postctr < env.postmax);
- }
- DB((dbg, LEVEL_1, "Structural analysis finished.\n"));
-
- ir_free_resources(irg, IR_RESOURCE_IRN_LINK);
-
- DEL_ARR_F(env.post);
- current_ir_graph = rem;
-
- res->top = env.post[0];
- res->irg = irg;
- return res;
-}
-
-/**
- * Walk over the region tree.
- *
- * @param reg a region node
- * @param pre walker function, executed before the children of a tree node are visited
- * @param post walker function, executed after the children of a tree node are visited
- * @param env environment, passed to pre and post
- */
-static void region_tree_walk2(ir_region *reg, irg_reg_walk_func *pre, irg_reg_walk_func *post, void *env)
-{
- size_t i, n;
-
- if (pre)
- pre(reg, env);
- if (reg->type != ir_rk_BasicBlock) {
- for (i = 0, n = ARR_LEN(reg->parts); i < n; ++i)
- region_tree_walk2(reg->parts[i].region, pre, post, env);
- }
- if (post)
- post(reg, env);
-}
-
-/**
- * Walk over the region tree.
- *
- * @param tree the tree
- * @param pre walker function, executed before the children of a tree node are visited
- * @param post walker function, executed after the children of a tree node are visited
- * @param env environment, passed to pre and post
- */
-void region_tree_walk(ir_reg_tree *tree, irg_reg_walk_func *pre, irg_reg_walk_func *post, void *env)
-{
- region_tree_walk2(tree->top, pre, post, env);
-}
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