/*
- * Copyright (C) 1995-2007 University of Karlsruhe. All right reserved.
+ * Copyright (C) 1995-2007 Inria Rhone-Alpes. All right reserved.
*
* This file is part of libFirm.
*
*
* 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 "irnode_t.h"
#include "irphase_t.h"
#include "iredges_t.h"
+
#include "irprintf.h"
+#include "irdom.h"
#include "irdump.h"
#include "dfs_t.h"
#include "irlivechk.h"
-#define ENABLE_STATS
-
-#ifdef ENABLE_STATS
-#define STAT_INC(memb) ++lv->stat->memb
-#else
-#define STAT_INC(memb)
-#endif
+#include "statev.h"
typedef struct _bl_info_t {
ir_node *block; /**< The block. */
- int id; /**< a tight number for the block.
+ int be_tgt_calc : 1;
+ int id : 31; /**< 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_t {
ir_phase ph;
- dfs_t *dfs;
+ const 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;
- lv_chk_stat_t *stat; /**< statistics information. */
- lv_chk_stat_t stat_data;
};
static void *init_block_data(ir_phase *ph, ir_node *irn, void *old)
lv_chk_t *lv = container_of(ph, lv_chk_t, ph);
bl_info_t *bi = phase_alloc(ph, sizeof(bi[0]));
- bi->id = dfs_get_pre_num(lv->dfs, irn);
+ bi->id = get_Block_dom_tree_pre_num(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);
+ bi->be_tgt_calc = 0;
+ (void) old;
return bi;
}
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);
+ const 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;
+ bitset_set(bi->red_reachable, bi->id);
foreach_block_succ (bl, edge) {
ir_node *succ = get_edge_src_irn(edge);
bl_info_t *si = get_block_info(lv, succ);
* 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));
+ 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. */
}
-/**
- * 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_t *lv, ir_node *bl)
+static void compute_back_edge_chain(lv_chk_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);
+ bl_info_t *bi = get_block_info(lv, bl);
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);
+ DBG((lv->dbg, LEVEL_2, "computing T_%d\n", bi->id));
- /*
- * 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.
- */
+ /* put all back edge sources reachable (reduced) from here in tmp */
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;
+ bi->be_tgt_calc = 1;
+
+ DBG((lv->dbg, LEVEL_2, "\treachable be src: %B\n", tmp));
+
+ /* iterate over them ... */
+ bitset_foreach(tmp, elm) {
+ bl_info_t *si = lv->map[elm];
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);
+ /* and find back edge targets which are not reduced reachable from bl */
+ foreach_block_succ (si->block, edge) {
+ ir_node *tgt = get_edge_src_irn(edge);
+ bl_info_t *ti = get_block_info(lv, tgt);
+ dfs_edge_kind_t kind = dfs_get_edge_kind(lv->dfs, si->block, tgt);
+
+ if (kind == DFS_EDGE_BACK && !bitset_is_set(bi->red_reachable, ti->id)) {
+ if (!ti->be_tgt_calc)
+ compute_back_edge_chain(lv, tgt);
+ bitset_set(bi->be_tgt_reach, ti->id);
+ bitset_or(bi->be_tgt_reach, ti->be_tgt_reach);
+ }
+ }
+ bitset_clear(bi->be_tgt_reach, bi->id);
+ }
+}
+
+
+static INLINE void compute_back_edge_chains(lv_chk_t *lv)
+{
+ bitset_pos_t elm;
+ int i, n;
+
+ DBG((lv->dbg, LEVEL_2, "back edge sources: %B\n", lv->back_edge_src));
+ bitset_foreach(lv->back_edge_src, elm) {
+ compute_back_edge_chain(lv, lv->map[elm]->block);
+ }
+
+ for (i = 0, n = dfs_get_n_nodes(lv->dfs); i < n; ++i) {
+ const 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;
- if (kind == DFS_EDGE_BACK) {
+ if (!bitset_is_set(lv->back_edge_tgt, bi->id)) {
+ foreach_block_succ (bl, edge) {
+ ir_node *succ = get_edge_src_irn(edge);
bl_info_t *si = get_block_info(lv, succ);
- bitset_set(bi->be_tgt_reach, si->id);
+ dfs_edge_kind_t kind = dfs_get_edge_kind(lv->dfs, bl, succ);
+
+ if (kind != DFS_EDGE_BACK) {
+ assert(dfs_get_post_num(lv->dfs, bl) > dfs_get_post_num(lv->dfs, succ));
+ bitset_or(bi->be_tgt_reach, si->be_tgt_reach);
+ }
}
}
}
+
+ for (i = 0, n = dfs_get_n_nodes(lv->dfs); i < n; ++i) {
+ const ir_node *bl = dfs_get_post_num_node(lv->dfs, i);
+ bl_info_t *bi = get_block_info(lv, bl);
+ bitset_set(bi->be_tgt_reach, bi->id);
+ }
}
-lv_chk_t *lv_chk_new(ir_graph *irg)
+lv_chk_t *lv_chk_new(ir_graph *irg, const dfs_t *dfs)
{
lv_chk_t *res = xmalloc(sizeof(res[0]));
struct obstack *obst;
int i;
+ stat_ev_tim_push();
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->dfs = dfs;
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];
/* 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);
+ ir_node *irn = (ir_node *) dfs_get_pre_num_node(res->dfs, i);
+ bl_info_t *bi = phase_get_or_set_irn_data(&res->ph, irn);
+ res->map[bi->id] = bi;
}
/* 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_NICE {
- 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));
- }
+ /* compute back edge chains */
+ compute_back_edge_chains(res);
+
+#ifndef NDEBUG
+ DBG((res->dbg, LEVEL_1, "liveness chk in %+F\n", irg));
+ for (i = res->n_blocks - 1; i >= 0; --i) {
+ const 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));
}
+#endif
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));
+ stat_ev_tim_pop("lv_chk_cons_time");
return res;
}
void lv_chk_free(lv_chk_t *lv)
{
obstack_free(phase_obst(&lv->ph), NULL);
- dfs_free(lv->dfs);
xfree(lv);
}
-const lv_chk_stat_t *lv_chk_get_stat(const lv_chk_t *lv)
-{
-#ifdef ENABLE_STATS
- return lv->stat;
-#else
- return NULL;
-#endif
-}
-
/**
* Check if a node is live at the end of a block.
* This function is for internal use as its code is shared between
* live at the end of the block.
* @return 1, if @p what is live at the end at @p bl.
*/
-unsigned lv_chk_bl_xxx(const lv_chk_t *lv, const ir_node *bl, const ir_node *what)
+unsigned lv_chk_bl_in_mask(const lv_chk_t *lv, const ir_node *bl, const ir_node *var)
+{
+ stat_ev_cnt_decl(uses);
+
+ ir_node *def_bl;
+ const ir_edge_t *edge;
+
+ int res = 0;
+
+ assert(is_Block(bl) && "can only check for liveness in a block");
+
+ if (!is_liveness_node(var))
+ return 0;
+
+ def_bl = get_nodes_block(var);
+ if (def_bl == bl || !block_dominates(def_bl, bl)) {
+ goto end;
+ }
+
+ else {
+ bitset_t *uses = bitset_alloca(lv->n_blocks);
+ bitset_t *tmp = bitset_alloca(lv->n_blocks);
+ int min_dom = get_Block_dom_tree_pre_num(def_bl) + 1;
+ int max_dom = get_Block_dom_max_subtree_pre_num(def_bl);
+ bl_info_t *bli = get_block_info(lv, bl);
+ int i;
+
+ DBG((lv->dbg, LEVEL_2, "lv check of %+F, def=%+F,%d != q=%+F,%d\n",
+ var, def_bl, min_dom - 1, bl, bli->id));
+
+ foreach_out_edge (var, 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);
+ }
+
+ if (use_bl == bl) {
+ res = lv_chk_state_in;
+ DBG((lv->dbg, LEVEL_2, "\tuse directly in block %+F by %+F\n", use_bl, user));
+ goto end;
+ }
+
+ bi = get_block_info(lv, use_bl);
+ bitset_set(uses, bi->id);
+ }
+
+ DBG((lv->dbg, LEVEL_2, "\tuses: %B\n", uses));
+
+ {
+
+ bitset_copy(tmp, bli->be_tgt_reach);
+ bitset_set(tmp, bli->id);
+
+ DBG((lv->dbg, LEVEL_2, "\tbe tgt reach: %B, dom span: [%d, %d]\n", tmp, min_dom, max_dom));
+ for (i = bitset_next_set(tmp, min_dom); i >= 0 && i <= max_dom; i = bitset_next_set(tmp, i + 1)) {
+ bl_info_t *ti = lv->map[i];
+ DBG((lv->dbg, LEVEL_2, "\tlooking from %d: seeing %B\n", ti->id, ti->red_reachable));
+ if (bitset_intersect(ti->red_reachable, uses)) {
+ res = lv_chk_state_in;
+ goto end;
+ }
+
+ bitset_andnot(tmp, ti->red_reachable);
+ }
+ }
+ }
+
+end:
+ return res;
+}
+
+unsigned lv_chk_bl_end_mask(const lv_chk_t *lv, const ir_node *bl, const ir_node *var)
{
- ir_node *what_bl;
+ stat_ev_cnt_decl(uses);
+
+ ir_node *def_bl;
+ const ir_edge_t *edge;
+
+ int res = 0;
assert(is_Block(bl) && "can only check for liveness in a block");
- if (!is_liveness_node(what))
+ if (!is_liveness_node(var))
return 0;
- what_bl = get_nodes_block(what);
- if (!block_dominates(what_bl, bl)) {
- STAT_INC(n_no_dominance);
+ def_bl = get_nodes_block(var);
+ if (!block_dominates(def_bl, bl)) {
+ goto end;
+ }
+
+ else {
+ bitset_t *uses = bitset_alloca(lv->n_blocks);
+ bitset_t *tmp = bitset_alloca(lv->n_blocks);
+ int min_dom = get_Block_dom_tree_pre_num(def_bl) + 1;
+ int max_dom = get_Block_dom_max_subtree_pre_num(def_bl);
+ bl_info_t *bli = get_block_info(lv, bl);
+ int i;
+
+ DBG((lv->dbg, LEVEL_2, "lv end check of %+F, def=%+F,%d != q=%+F,%d\n",
+ var, def_bl, min_dom - 1, bl, bli->id));
+
+ foreach_out_edge (var, 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);
+
+ if (bl == use_bl)
+ res |= lv_chk_state_end;
+ }
+
+ bi = get_block_info(lv, use_bl);
+ if (use_bl != bl || bitset_is_set(lv->back_edge_tgt, bi->id))
+ bitset_set(uses, bi->id);
+ }
+
+ DBG((lv->dbg, LEVEL_2, "\tuses: %B\n", uses));
+
+ bitset_copy(tmp, bli->be_tgt_reach);
+ bitset_set(tmp, bli->id);
+
+ DBG((lv->dbg, LEVEL_2, "\tbe tgt reach + current: %B, dom span: [%d, %d]\n", tmp, min_dom, max_dom));
+ for (i = bitset_next_set(tmp, min_dom); i >= 0 && i <= max_dom; i = bitset_next_set(tmp, i + 1)) {
+ bl_info_t *ti = lv->map[i];
+ DBG((lv->dbg, LEVEL_2, "\tlooking from %d: seeing %B\n", ti->id, ti->red_reachable));
+ if (bitset_intersect(ti->red_reachable, uses)) {
+ res = lv_chk_state_out | lv_chk_state_end;
+ goto end;
+ }
+
+ bitset_andnot(tmp, ti->red_reachable);
+ }
+ }
+
+end:
+ return res;
+}
+
+/**
+ * Check a nodes liveness situation of a block.
+ * This routine considers both cases, the live in and end/out case.
+ *
+ * @param lv The liveness check environment.
+ * @param bl The block under investigation.
+ * @param var The node to check for.
+ * @return A bitmask of lv_chk_state_XXX fields.
+ */
+unsigned lv_chk_bl_xxx(const lv_chk_t *lv, const ir_node *bl, const ir_node *var)
+{
+ stat_ev_cnt_decl(uses);
+ stat_ev_cnt_decl(iter);
+
+ int res = 0;
+ ir_node *def_bl;
+
+ assert(is_Block(bl) && "can only check for liveness in a block");
+
+ /* If the variable ist no liveness related var, bail out. */
+ if (!is_liveness_node(var))
return 0;
+
+ stat_ev_ctx_push_fmt("lv_chk", "%u", get_irn_idx(var));
+ stat_ev_tim_push();
+
+ /* If there is no dominance relation, go out, too */
+ def_bl = get_nodes_block(var);
+ if (!block_dominates(def_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) {
- int res = 0;
+ if (def_bl == bl) {
const ir_edge_t *edge;
- STAT_INC(n_def_block);
- DBG((lv->dbg, LEVEL_2, "lv check same block %+F in %+F\n", what, bl));
- foreach_out_edge (what, edge) {
+ stat_ev("lv_chk_def_block");
+ DBG((lv->dbg, LEVEL_2, "lv check same block %+F in %+F\n", var, bl));
+ foreach_out_edge (var, 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);
}
}
- if (use_bl != what_bl)
- return lv_chk_state_end | lv_chk_state_out;
+ if (use_bl != def_bl) {
+ res = lv_chk_state_end | lv_chk_state_out;
+ goto end;
+ }
}
- return res;
+ goto end;
}
- /* this is the complicated case */
+ /*
+ * this is the more complicated case.
+ * We try to gather as much information as possible during looking
+ * at the uses.
+ *
+ * Note that we know for shure that bl != def_bl. That is sometimes
+ * silently exploited below.
+ */
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);
- int res = 0;
+ bl_info_t *def = get_block_info(lv, def_bl);
+ bl_info_t *bli = get_block_info(lv, bl);
+ bitset_t *uses = bitset_alloca(lv->n_blocks);
+ bitset_t *Tq;
+ unsigned i, min_dom, max_dom;
const ir_edge_t *edge;
- foreach_out_edge (what, edge) {
- ir_node *user = get_edge_src_irn(edge);
+ /* if the block has no DFS info, it cannot be reached.
+ * This can happen in functions with endless loops.
+ * we then go out, since nothing is live there.
+ *
+ * TODO: Is that right?
+ */
+ if (!bli)
+ goto end;
+
+ (void) def;
+ DBG((lv->dbg, LEVEL_2, "lv check %+F (def in %+F #%d) in different block %+F #%d\n",
+ var, def_bl, def->id, bl, bli->id));
+
+ foreach_out_edge (var, edge) {
+ ir_node *user = get_edge_src_irn(edge);
+ int mask = lv_chk_state_in;
+
ir_node *use_bl;
bl_info_t *bi;
+ /* if the user is no liveness node, the use does not count */
if (!is_liveness_node(user))
continue;
+ stat_ev_cnt_inc(uses);
+
+ /* if the user is a phi, the use is in the predecessor
+ * furthermore, prepare a mask so that in the case where
+ * bl (the block in question) coincides with a use, it
+ * can be marked live_end there. */
use_bl = get_nodes_block(user);
if (is_Phi(user)) {
- int pos = get_edge_src_pos(edge);
+ int pos = get_edge_src_pos(edge);
+ use_bl = get_Block_cfgpred_block(use_bl, pos);
+ mask |= lv_chk_state_end;
+ }
- 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;
+ /* if the use block coincides with the query block, we
+ * already gather a little liveness information.
+ * The variable is surely live there, since bl != def_bl
+ * (that case is treated above). */
+ if (use_bl == bl)
+ res |= mask;
- bitset_set(uses, bi->id);
- }
+ bi = get_block_info(lv, use_bl);
- else {
- bi = get_block_info(lv, use_bl);
+ if (bi)
bitset_set(uses, bi->id);
- if (use_bl == bl)
- res |= lv_chk_state_in;
- }
-
}
+
+ /* get the dominance range which really matters. all uses outside
+ * the definition's dominance range are not to consider. note,
+ * that the definition itself is also not considered. The case
+ * where bl == def_bl is considered above. */
+ min_dom = get_Block_dom_tree_pre_num(def_bl) + 1;
+ max_dom = get_Block_dom_max_subtree_pre_num(def_bl);
+
DBG((lv->dbg, LEVEL_2, "\tuses: %B\n", 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];
+ /* prepare a set with all reachable back edge targets.
+ * this will determine our "looking points" from where
+ * we will search/find the calculated uses. */
+ Tq = bli->be_tgt_reach;
- DBG((lv->dbg, LEVEL_2, "\tto visit: %B\n", to_visit));
- DBG((lv->dbg, LEVEL_2, "\tvisited: %B\n", visited));
+ /* now, visit all viewing points in the temporary bitset lying
+ * in the dominance range of the variable. Note that for reducible
+ * flow-graphs the first iteration is sufficient and the loop
+ * will be left. */
+ DBG((lv->dbg, LEVEL_2, "\tbe tgt reach: %B, dom span: [%d, %d]\n", Tq, min_dom, max_dom));
+ i = bitset_next_set(Tq, min_dom);
+ while(i <= max_dom) {
+ bl_info_t *ti = lv->map[i];
+ int use_in_current_block = bitset_is_set(uses, ti->id);
- /*
- * 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))
- return lv_chk_state_end | lv_chk_state_out | lv_chk_state_in;
+ stat_ev_cnt_inc(iter);
/*
- * if not, we have to check the back edges in question, if
- * they lead to places which are reachable.
+ * This is somehat tricky. Since this routine handles both, live in
+ * and end/out we have to handle all the border cases correctly.
+ * Each node is in its own red_reachable set (see calculation
+ * function above). That means, that in the case where bl == t, the
+ * intersection check of uses and rechability below will always
+ * find an intersection, namely t.
+ *
+ * However, if a block contains a use and the variable is dead
+ * afterwards, it is not live end/out at that block. Besides
+ * back-edge target. If a var is live-in at a back-edge target it
+ * is also live out/end there since the variable is live in the
+ * underlying loop. So in the case where t == bl and that is not
+ * a back-edge target, we have to remove that use from consideration
+ * to determine if the var is live out/end there.
+ *
+ * Note that the live in information has been calculated by the
+ * uses iteration above.
*/
- 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 (ti == bli && !bitset_is_set(lv->back_edge_tgt, ti->id)) {
+ DBG((lv->dbg, LEVEL_2, "\tlooking not from a back edge target and q == t. removing use: %d\n", ti->id));
+ bitset_clear(uses, ti->id);
+ }
- if (bitset_intersect(uses, next))
- return lv_chk_state_end | lv_chk_state_out | lv_chk_state_in;
+ /* If we can reach a use, the variable is live there and we say goodbye */
+ DBG((lv->dbg, LEVEL_2, "\tlooking from %d: seeing %B\n", ti->id, ti->red_reachable));
+ if (bitset_intersect(ti->red_reachable, uses)) {
+ res |= lv_chk_state_in | lv_chk_state_out | lv_chk_state_end;
+ goto end;
+ }
- bitset_or(to_visit, next);
- bitset_andnot(to_visit, visited);
+ /*
+ * if we deleted a use do to the commentary above, we have to
+ * re-add it since it might be visible from further view points
+ * (we only need that in the non-reducible case).
+ */
+ if (use_in_current_block)
+ bitset_set(uses, ti->id);
- }
- } while (!bitset_is_empty(to_visit));
+ i = bitset_next_set(Tq, get_Block_dom_max_subtree_pre_num(ti->block) + 1);
+ }
- return res;
}
- return 0;
+end:
+ stat_ev_tim_pop("lv_chk_query_time");
+ stat_ev_cnt_done(uses, "lv_chk_uses");
+ stat_ev_cnt_done(iter, "lv_chk_iter");
+ stat_ev_ctx_pop("lv_chk");
+
+ return res;
}
projects / libfirm / blobdiff