+++ /dev/null
-/*
- * Copyright (C) 1995-2007 Inria Rhone-Alpes. 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 livechk.c
- * @date 21.04.2007
- * @author Sebastian Hack
- * @version $Id: irlivechk.c 14865 2007-06-30 18:23:05Z matze $
- * @summary
- *
- * Liveness checks as developed by Benoit Boissinot, Fabrice Rastello and myself.
- *
- * The speciality here is, that nothing has to be recomputed if new nodes are created
- * or old ones deleted.
- *
- * This algo has one core routine check_live_end_internal() which performs the liveness check.
- * It only relies on the precomputation done in the constructor, which in turn needs:
- * - out edges
- * - the dominance tree
- * - data obtained from a depth-first-search
- *
- * The precomputation remains valid as long as the CFG is not altered.
- */
-#ifdef HAVE_CONFIG_H
-#include <config.h>
-#endif
-
-#include <stdio.h>
-
-#include "irgraph_t.h"
-#include "irphase_t.h"
-#include "iredges_t.h"
-#include "irprintf.h"
-#include "irdump.h"
-
-#include "dfs_t.h"
-#include "bitset.h"
-#include "util.h"
-
-#include "irlivechk_old.h"
-
-#include "statev.h"
-
-typedef struct _bl_info_t {
- ir_node *block; /**< The block. */
-
- int id; /**< a tight number for the block.
- we're just reusing the pre num from
- the DFS. */
-
- bitset_t *red_reachable; /**< Holds all id's if blocks reachable
- in the CFG modulo back edges. */
-
- bitset_t *be_tgt_reach; /**< target blocks of back edges whose
- sources are reachable from this block
- in the reduced graph. */
-
- bitset_t *be_tgt_dom; /**< target blocks of back edges which
- are dominated by this block. */
-} bl_info_t;
-
-#define get_block_info(lv, bl) ((bl_info_t *) phase_get_irn_data(&(lv)->ph, bl))
-
-struct _lv_chk_old_t {
- ir_phase ph;
- dfs_t *dfs;
- DEBUG_ONLY(firm_dbg_module_t *dbg;)
- int n_blocks;
- bitset_t *back_edge_src;
- bitset_t *back_edge_tgt;
- bl_info_t **map;
-};
-
-static void *init_block_data(ir_phase *ph, ir_node *irn, void *old)
-{
- lv_chk_old_t *lv = container_of(ph, lv_chk_old_t, ph);
- bl_info_t *bi = phase_alloc(ph, sizeof(bi[0]));
-
- bi->id = dfs_get_pre_num(lv->dfs, irn);
- bi->block = irn;
- bi->red_reachable = bitset_obstack_alloc(phase_obst(ph), lv->n_blocks);
- bi->be_tgt_reach = bitset_obstack_alloc(phase_obst(ph), lv->n_blocks);
- bi->be_tgt_dom = bitset_obstack_alloc(phase_obst(ph), lv->n_blocks);
- (void) old;
- return bi;
-}
-
-/**
- * Filter function to select all nodes for which liveness is computed.
- * @param irn A node.
- * @return 1 if the node shall be considered in liveness, 0 if not.
- */
-static INLINE int is_liveness_node(const ir_node *irn)
-{
- switch(get_irn_opcode(irn)) {
- case iro_Block:
- case iro_Bad:
- case iro_End:
- return 0;
- default:;
- }
-
- return 1;
-}
-
-/**
- * Compute the transitive closure on the reduced graph.
- * The reduced graph is the original graph without back edges.
- * Since that is a DAG, a reverse post order of the graph gives a toposort
- * which is ideally suited to compute the transitive closure.
- * Note also, that the DFS tree of the reduced graph is the same than the one
- * of the original graph. This saves us computing a new reverse post order.
- * We also can re-use the DFS tree of the original graph.
- */
-static void red_trans_closure(lv_chk_old_t *lv)
-{
- int i, n;
-
- for (i = 0, n = dfs_get_n_nodes(lv->dfs); i < n; ++i) {
- ir_node *bl = dfs_get_post_num_node(lv->dfs, i);
- bl_info_t *bi = get_block_info(lv, bl);
-
- const ir_edge_t *edge;
-
- foreach_block_succ (bl, edge) {
- ir_node *succ = get_edge_src_irn(edge);
- bl_info_t *si = get_block_info(lv, succ);
- dfs_edge_kind_t kind = dfs_get_edge_kind(lv->dfs, bl, succ);
-
- /*
- * if the successor is no back edge, include all reachable
- * blocks from there into the reachable set of the current node
- */
- if (kind != DFS_EDGE_BACK) {
- assert(dfs_get_post_num(lv->dfs, bl)
- > dfs_get_post_num(lv->dfs, succ));
- bitset_or(bi->red_reachable, si->red_reachable);
- bitset_set(bi->red_reachable, si->id);
- }
-
- /* mark the block as a back edge src and succ as back edge tgt. */
- else {
- bitset_set(lv->back_edge_src, bi->id);
- bitset_set(lv->back_edge_tgt, si->id);
- }
- }
-
- }
-
-}
-
-/**
- * Compute the two back edge sets for each block.
- * <code>be_tgt_reach</code> contains all target blocks of a back edges reachable from a node.
- * <code>be_tgt_dom</code> contains all target blocks of back edges strictly dominated
- * by a node.
- */
-static void compute_back_edge_sets(lv_chk_old_t *lv, ir_node *bl)
-{
- bl_info_t *bi = phase_get_or_set_irn_data(&(lv)->ph, bl);
- bitset_t *tmp = bitset_alloca(lv->n_blocks);
-
- bitset_pos_t elm;
- ir_node *n;
-
- dominates_for_each (bl, n) {
- bl_info_t *ni = phase_get_or_set_irn_data(&(lv)->ph, n);
-
- /* compute information for dominance sub tree */
- compute_back_edge_sets(lv, n);
-
- /*
- * of course all blocks dominated by blocks in the
- * subtree are also dominated by bl.
- */
- bitset_or(bi->be_tgt_dom, ni->be_tgt_dom);
-
- /*
- * add the immeditate dominee to the back edge tgt dominance
- * bitset if it is the target node of a back edge.
- */
- if (bitset_is_set(lv->back_edge_tgt, ni->id))
- bitset_set(bi->be_tgt_dom, ni->id);
- }
-
- /*
- * iterate over all back edge src nodes which are reachable from
- * this nodes and put the targets of the back edges in the be_tgt_reach
- * bitset of the node.
- */
- bitset_copy(tmp, bi->red_reachable);
- bitset_set(tmp, bi->id);
- bitset_and(tmp, lv->back_edge_src);
- bitset_foreach (tmp, elm) {
- ir_node *src = lv->map[elm]->block;
- const ir_edge_t *edge;
-
- foreach_block_succ (src, edge) {
- ir_node *succ = get_edge_src_irn(edge);
- dfs_edge_kind_t kind = dfs_get_edge_kind(lv->dfs, src, succ);
-
- if (kind == DFS_EDGE_BACK) {
- bl_info_t *si = get_block_info(lv, succ);
- bitset_set(bi->be_tgt_reach, si->id);
- }
- }
- }
-}
-
-lv_chk_old_t *lv_chk_old_new(ir_graph *irg)
-{
- lv_chk_old_t *res = xmalloc(sizeof(res[0]));
- struct obstack *obst;
- int i;
-
- phase_init(&res->ph, "liveness check", irg, PHASE_DEFAULT_GROWTH, init_block_data, NULL);
- obst = phase_obst(&res->ph);
-
- FIRM_DBG_REGISTER(res->dbg, "ir.ana.lvchk");
-
- res->dfs = dfs_new(&absgraph_irg_cfg_succ, irg);
- res->n_blocks = dfs_get_n_nodes(res->dfs);
- res->back_edge_src = bitset_obstack_alloc(obst, res->n_blocks);
- res->back_edge_tgt = bitset_obstack_alloc(obst, res->n_blocks);
- res->map = obstack_alloc(obst, res->n_blocks * sizeof(res->map[0]));
-
-#ifdef ENABLE_STATS
- memset(&res->stat_data, 0, sizeof(res->stat_data));
- res->stat = &res->stat_data;
-#endif
-#if 0
- {
- char name[256];
- FILE *f;
- ir_snprintf(name, sizeof(name), "dfs_%F.dot", irg);
- if ((f = fopen(name, "wt")) != NULL) {
- dfs_dump(res->dfs, f);
- fclose(f);
- }
- dump_ir_block_graph(irg, "-lvchk");
- }
-#endif
-
- /* fill the map which maps pre_num to block infos */
- for (i = res->n_blocks - 1; i >= 0; --i) {
- ir_node *irn = dfs_get_pre_num_node(res->dfs, i);
- res->map[i] = phase_get_or_set_irn_data(&res->ph, irn);
- }
-
- /* first of all, compute the transitive closure of the CFG *without* back edges */
- red_trans_closure(res);
-
- /* now fill the two remaining bitsets concerning back edges */
- compute_back_edge_sets(res, get_irg_start_block(irg));
-
- DEBUG_ONLY({
- DBG((res->dbg, LEVEL_1, "liveness chk in %+F\n", irg));
- for (i = res->n_blocks - 1; i >= 0; --i) {
- ir_node *irn = dfs_get_pre_num_node(res->dfs, i);
- bl_info_t *bi = get_block_info(res, irn);
- DBG((res->dbg, LEVEL_1, "lv_chk for %d -> %+F\n", i, irn));
- DBG((res->dbg, LEVEL_1, "\tred reach: %B\n", bi->red_reachable));
- DBG((res->dbg, LEVEL_1, "\ttgt reach: %B\n", bi->be_tgt_reach));
- DBG((res->dbg, LEVEL_1, "\ttgt dom: %B\n", bi->be_tgt_dom));
- }
- })
-
- DBG((res->dbg, LEVEL_1, "back edge src: %B\n", res->back_edge_src));
- DBG((res->dbg, LEVEL_1, "back edge tgt: %B\n", res->back_edge_tgt));
-
- return res;
-}
-
-void lv_chk_old_free(lv_chk_old_t *lv)
-{
- obstack_free(phase_obst(&lv->ph), NULL);
- dfs_free(lv->dfs);
- xfree(lv);
-}
-
-/**
- * Check if a node is live at the end of a block.
- * This function is for internal use as its code is shared between
- * the in/end routines below. It is almost the "live_end" routine
- * but passing in the bitset for recording the blocks where the variable
- * is used saves some effort in the "live_in" routine. See below for
- * details.
- *
- * @param lv The liveness check environment.
- * @param what The node to check for.
- * @param bl The block under investigation.
- * @param uses A bitset where this routine records all ids of blocks
- * where this variable is used. Note that the bitset
- * is only guaranteed to be filled if the node was not
- * live at the end of the block.
- * @return 1, if @p what is live at the end at @p bl.
- */
-unsigned lv_chk_old_bl_xxx(const lv_chk_old_t *lv, const ir_node *bl, const ir_node *what)
-{
- stat_ev_cnt_decl(uses);
- stat_ev_cnt_decl(iter);
-
- int res = 0;
- ir_node *what_bl;
-
- assert(is_Block(bl) && "can only check for liveness in a block");
-
- if (!is_liveness_node(what))
- return 0;
-
- stat_ev_ctx_push_fobj("node", what);
- stat_ev("lv_chk");
-
- what_bl = get_nodes_block(what);
- if (!block_dominates(what_bl, bl)) {
- stat_ev("lv_chk_no_dom");
- goto end;
- }
-
- /*
- * If the block in question is the same as the definition block,
- * the algorithm is simple. Just check for uses not inside this block.
- */
- if (what_bl == bl) {
- const ir_edge_t *edge;
-
- stat_ev("lv_chk_def_block");
- DBG((lv->dbg, LEVEL_2, "lv check same block %+F in %+F\n", what, bl));
- foreach_out_edge (what, edge) {
- ir_node *use = get_edge_src_irn(edge);
- ir_node *use_bl;
-
- if (!is_liveness_node(use))
- continue;
-
- stat_ev_cnt_inc(uses);
- use_bl = get_nodes_block(use);
- if (is_Phi(use)) {
- int pos = get_edge_src_pos(edge);
- use_bl = get_Block_cfgpred_block(use_bl, pos);
-
- if (use_bl == bl) {
- DBG((lv->dbg, LEVEL_2, "\tphi %+F in succ %+F,%d -> live end\n", use, use_bl, pos));
- res |= lv_chk_state_end;
- }
- }
-
- if (use_bl != what_bl) {
- res = lv_chk_state_end | lv_chk_state_out;
- goto end;
- }
- }
-
- goto end;
- }
-
- /* this is the complicated case */
- else {
- bitset_t *visited = bitset_alloca(lv->n_blocks);
- bitset_t *to_visit = bitset_alloca(lv->n_blocks);
- bitset_t *next = bitset_alloca(lv->n_blocks);
- bitset_t *uses = bitset_alloca(lv->n_blocks);
- bl_info_t *def = get_block_info(lv, what_bl);
- bl_info_t *bli = get_block_info(lv, bl);
-
- const ir_edge_t *edge;
-
- DBG((lv->dbg, LEVEL_2, "lv check different block %+F in %+F\n", what, bl));
- foreach_out_edge (what, edge) {
- ir_node *user = get_edge_src_irn(edge);
- ir_node *use_bl;
- bl_info_t *bi;
-
- if (!is_liveness_node(user))
- continue;
-
- stat_ev_cnt_inc(uses);
- use_bl = get_nodes_block(user);
- if (is_Phi(user)) {
- int pos = get_edge_src_pos(edge);
-
- use_bl = get_Block_cfgpred_block(use_bl, pos);
- bi = get_block_info(lv, use_bl);
-
- if (use_bl == bl)
- res |= lv_chk_state_end | lv_chk_state_in;
-
- bitset_set(uses, bi->id);
- }
-
- else {
- bi = get_block_info(lv, use_bl);
- bitset_set(uses, bi->id);
- if (use_bl == bl)
- res |= lv_chk_state_in;
- }
-
- }
- DBG((lv->dbg, LEVEL_2, "\tuses: %B, #: %d\n", uses, bitset_popcnt(uses)));
-
- bitset_clear(uses, def->id);
- bitset_set(to_visit, bli->id);
- do {
- int id = bitset_next_set(to_visit, 0);
- bl_info_t *bi = lv->map[id];
-
- stat_ev_cnt_inc(iter);
- DBG((lv->dbg, LEVEL_2, "\tto visit: %B\n", to_visit));
- DBG((lv->dbg, LEVEL_2, "\tvisited: %B\n", visited));
-
- /*
- * if one of the blocks is reachable, the node must be live there.
- * Note that this is not sufficient, since the nodes reachable
- * via back edges are not contained in the red_reachable set.
- */
- if (bitset_intersect(bi->red_reachable, uses)) {
- res = lv_chk_state_end | lv_chk_state_out | lv_chk_state_in;
- goto end;
- }
-
- /*
- * if not, we have to check the back edges in question, if
- * they lead to places which are reachable.
- */
- else {
- bitset_set(visited, id);
- bitset_or(visited, bi->red_reachable);
-
- bitset_copy(next, bi->be_tgt_reach);
- bitset_and(next, def->be_tgt_dom);
- DBG((lv->dbg, LEVEL_2, "\tnext: %B\n----\n", next));
-
- if (bitset_intersect(uses, next)) {
- res = lv_chk_state_end | lv_chk_state_out | lv_chk_state_in;
- goto end;
- }
-
- bitset_or(to_visit, next);
- bitset_andnot(to_visit, visited);
-
- }
- } while (!bitset_is_empty(to_visit));
- }
-
-end:
- stat_ev_cnt_done(uses, "lv_chk_uses");
- stat_ev_cnt_done(iter, "lv_chk_iter");
- stat_ev_ctx_pop();
-
- return res;
-}
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