/*
- * Project: libFIRM
- * File name: ir/opt/cfopt.c
- * Purpose: control flow optimizations
- * Author:
- * Created:
- * CVS-ID: $Id$
- * Copyright: (c) 1998-2004 Universität Karlsruhe
- * Licence: This file protected by GPL - GNU GENERAL PUBLIC LICENSE.
+ * Copyright (C) 1995-2008 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 Control flow optimizations.
+ * @author Goetz Lindenmaier, Michael Beck, Sebastian Hack
+ * @version $Id$
*/
+#include "config.h"
-#ifdef HAVE_CONFIG_H
-# include "config.h"
-#endif
+#include "iroptimize.h"
#include <assert.h>
+#include "plist.h"
#include "xmalloc.h"
#include "irnode_t.h"
#include "irgraph_t.h"
#include "irgmod.h"
#include "irdump.h"
#include "irvrfy.h"
+#include "iredges.h"
-#include "array.h"
+#include "array_t.h"
#include "irouts.h"
#include "irbackedge_t.h"
#include "irflag_t.h"
#include "firmstat.h"
-#include "cfopt.h"
#include "iropt_dbg.h"
/*------------------------------------------------------------------*/
/* is empty if it contains only a Jmp node. */
/* Blocks can only be removed if they are not needed for the */
/* semantics of Phi nodes. */
+/* Further, we NEVER remove labeled blocks (even if we could move */
+/* the label. */
/*------------------------------------------------------------------*/
+#define set_Block_removable(block) set_Block_mark(block, 1)
+#define set_Block_non_removable(block) set_Block_mark(block, 0)
+#define is_Block_removable(block) (get_Block_mark(block) != 0)
+
/**
* Replace binary Conds that jumps twice into the same block
* by a simple Jmp.
* Note that the simple case that Block has only these two
* predecessors are already handled in equivalent_node_Block().
*/
-static void remove_senseless_conds(ir_node *bl, void *data)
-{
- int i, j;
- int n = get_Block_n_cfgpreds(bl);
-
- assert(is_Block(bl));
-
- for (i = 0; i < n; ++i) {
- ir_node *pred_i = get_Block_cfgpred(bl, i);
- ir_node *cond_i = skip_Proj(pred_i);
-
- for (j = i + 1; j < n; ++j) {
- ir_node *pred_j = get_Block_cfgpred(bl, j);
- ir_node *cond_j = skip_Proj(pred_j);
-
- if (cond_j == cond_i
- && get_irn_op(cond_i) == op_Cond
- && get_irn_mode(get_Cond_selector(cond_i)) == mode_b) {
-
- ir_node *jmp = new_r_Jmp(current_ir_graph, get_nodes_block(cond_i));
- set_irn_n(bl, i, jmp);
- set_irn_n(bl, j, new_Bad());
-
- DBG_OPT_IFSIM2(cond_i, jmp);
- break;
- }
- }
- }
+static int remove_senseless_conds(ir_node *bl) {
+ int i, j;
+ int n = get_Block_n_cfgpreds(bl);
+ int changed = 0;
+
+ for (i = 0; i < n; ++i) {
+ ir_node *pred_i = get_Block_cfgpred(bl, i);
+ ir_node *cond_i = skip_Proj(pred_i);
+
+ /* binary Cond */
+ if (is_Cond(cond_i) && get_irn_mode(get_Cond_selector(cond_i)) == mode_b) {
+
+ for (j = i + 1; j < n; ++j) {
+ ir_node *pred_j = get_Block_cfgpred(bl, j);
+ ir_node *cond_j = skip_Proj(pred_j);
+
+ if (cond_j == cond_i) {
+ ir_node *jmp = new_r_Jmp(current_ir_graph, get_nodes_block(cond_i));
+ set_irn_n(bl, i, jmp);
+ set_irn_n(bl, j, new_Bad());
+
+ DBG_OPT_IFSIM2(cond_i, jmp);
+ changed = 1;
+ break;
+ }
+ }
+ }
+ }
+ return changed;
}
+/** An environment for merge_blocks and collect nodes. */
+typedef struct _merge_env {
+ int changed; /**< Set if the graph was changed. */
+ int phis_moved; /**< Set if Phi nodes were moved. */
+ plist_t *list; /**< Helper list for all found Switch Conds. */
+} merge_env;
/**
* Removes Tuples from Block control flow predecessors.
* Therefore we also optimize at control flow operations, depending
* how we first reach the Block.
*/
-static void merge_blocks(ir_node *n, void *env) {
- int i;
- ir_node *new_block;
-
- /* clear the link field for ALL nodes first */
- set_irn_link(n, NULL);
-
- if (get_irn_op(n) == op_Block) {
- /* Remove Tuples */
- for (i = 0; i < get_Block_n_cfgpreds(n); i++) {
- /* GL @@@ : is this possible? if (get_opt_normalize()) -- added, all tests go through.
- A different order of optimizations might cause problems. */
- if (get_opt_normalize())
- set_Block_cfgpred(n, i, skip_Tuple(get_Block_cfgpred(n, i)));
- }
-
- /* see below */
- new_block = equivalent_node(n);
- if (new_block != n && ! is_Block_dead(new_block))
- exchange (n, new_block);
-
- } else if (get_opt_optimize() && (get_irn_mode(n) == mode_X)) {
- /* We will soon visit a block. Optimize it before visiting! */
- ir_node *b = get_nodes_block(skip_Proj(n));
-
- if (!is_Block_dead(b)) {
- new_block = equivalent_node(b);
-
- while (irn_not_visited(b) && (!is_Block_dead(new_block)) && (new_block != b)) {
- /* We would have to run gigo() if new is bad, so we
- promote it directly below. Nevertheless, we sometimes reach a block
- the first time through a dataflow node. In this case we optimized the
- block as such and have to promote the Bad here. */
- assert((get_opt_control_flow_straightening() ||
- get_opt_control_flow_weak_simplification()) &&
- ("strange flag setting"));
- exchange (b, new_block);
- b = new_block;
- new_block = equivalent_node(b);
- }
-
- /* normally, we would create a Bad block here, but this must be
- * prevented, so just set it's cf to Bad.
- */
- if (is_Block_dead(new_block))
- exchange(n, new_Bad());
- }
- }
+static void merge_blocks(ir_node *node, void *ctx) {
+ int i;
+ ir_node *new_block;
+ merge_env *env = ctx;
+
+ /* clear the link field for ALL nodes first */
+ set_irn_link(node, NULL);
+
+ if (is_Block(node)) {
+ /* Remove Tuples */
+ for (i = get_Block_n_cfgpreds(node) - 1; i >= 0; --i) {
+ ir_node *pred = get_Block_cfgpred(node, i);
+ ir_node *skipped = skip_Tuple(pred);
+ if (pred != skipped) {
+ set_Block_cfgpred(node, i, skipped);
+ env->changed = 1;
+ }
+ }
+
+ /* see below */
+ new_block = equivalent_node(node);
+ if (new_block != node && ! is_Block_dead(new_block)) {
+ exchange(node, new_block);
+ env->changed = 1;
+ }
+
+ } else if (get_opt_optimize() && (get_irn_mode(node) == mode_X)) {
+ /* We will soon visit a block. Optimize it before visiting! */
+ ir_node *b = get_nodes_block(skip_Proj(node));
+
+ if (!is_Block_dead(b)) {
+ new_block = equivalent_node(b);
+
+ while (!irn_visited(b) && !is_Block_dead(new_block) && new_block != b) {
+ /* We would have to run gigo() if new is bad, so we
+ promote it directly below. Nevertheless, we sometimes reach a block
+ the first time through a dataflow node. In this case we optimized the
+ block as such and have to promote the Bad here. */
+ assert((get_opt_control_flow_straightening() ||
+ get_opt_control_flow_weak_simplification()) &&
+ ("strange flag setting"));
+ exchange(b, new_block);
+ env->changed = 1;
+ b = new_block;
+ new_block = equivalent_node(b);
+ }
+
+ /* normally, we would create a Bad block here, but this must be
+ * prevented, so just set it's cf to Bad.
+ */
+ if (is_Block_dead(new_block)) {
+ exchange(node, new_Bad());
+ env->changed = 1;
+ }
+ }
+ }
}
/**
- * Remove cf from dead block by inspecting dominance info
+ * Block walker removing control flow from dead block by
+ * inspecting dominance info.
* Do not replace blocks by Bad. This optimization shall
* ensure, that all Bad control flow predecessors are
* removed, and no new other Bads are introduced.
+ * Further removed useless Conds and clear the mark of all blocks.
*
* Must be run in the post walker.
*/
-static void remove_dead_block_cf(ir_node *block, void *env)
-{
- int i, n;
-
- /* check block predecessors and turn control flow into bad */
- for (i = 0, n = get_Block_n_cfgpreds(block); i < n; ++i) {
- ir_node *pred_X = get_Block_cfgpred(block, i);
-
- if (! is_Bad(pred_X)) {
- ir_node *pred_bl = get_nodes_block(skip_Proj(pred_X));
-
- if (is_Block_dead(pred_bl) || (get_Block_dom_depth(pred_bl) < 0))
- exchange (pred_X, new_Bad());
- }
- }
+static void remove_unreachable_blocks_and_conds(ir_node *block, void *env) {
+ int i;
+ int *changed = env;
+
+ /* Check block predecessors and turn control flow into bad.
+ Beware of Tuple, kill them. */
+ for (i = get_Block_n_cfgpreds(block) - 1; i >= 0; --i) {
+ ir_node *pred_X = get_Block_cfgpred(block, i);
+ ir_node *skipped = skip_Tuple(pred_X);
+
+ if (! is_Bad(skipped)) {
+ ir_node *pred_bl = get_nodes_block(skip_Proj(skipped));
+
+ if (is_Block_dead(pred_bl) || (get_Block_dom_depth(pred_bl) < 0)) {
+ set_Block_dead(pred_bl);
+ exchange(pred_X, new_Bad());
+ *changed = 1;
+ } else if (skipped != pred_X) {
+ set_Block_cfgpred(block, i, skipped);
+ *changed = 1;
+ }
+ }
+ }
+
+ *changed |= remove_senseless_conds(block);
+
+ /* clear the block mark of all non labeled blocks */
+ if (has_Block_label(block))
+ set_Block_non_removable(block);
+ else
+ set_Block_removable(block);
}
/**
* Collects all Phi nodes in link list of Block.
- * Marks all blocks "block_visited" if they contain a node other
- * than Jmp.
- * Replaces n by Bad if n is unreachable control flow. We do that
- * in the post walker, so we catch all blocks.
+ * Marks all blocks "non_removable" if they contain a node other
+ * than Jmp (and Proj).
+ * Links all Proj nodes to their predecessors.
+ * Collects all switch-Conds in a list.
*/
-static void collect_nodes(ir_node *n, void *env) {
- if (is_no_Block(n)) {
- ir_node *b = get_nodes_block(n);
-
- if ((get_irn_op(n) == op_Phi)) {
- /* Collect Phi nodes to compact ins along with block's ins. */
- set_irn_link(n, get_irn_link(b));
- set_irn_link(b, n);
- }
- else if ((get_irn_op(n) != op_Jmp) && !is_Bad(b)) { /* Check for non empty block. */
- mark_Block_block_visited(b);
- }
- }
+static void collect_nodes(ir_node *n, void *ctx) {
+ ir_opcode code = get_irn_opcode(n);
+ merge_env *env = ctx;
+
+ if (code == iro_Block) {
+ /* mark the block as non-removable if it is labeled */
+ if (has_Block_label(n))
+ set_Block_non_removable(n);
+ } else {
+ ir_node *b = get_nodes_block(n);
+
+ if (code == iro_Phi && get_irn_arity(n) > 0) {
+ /* Collect Phi nodes to compact ins along with block's ins. */
+ set_irn_link(n, get_irn_link(b));
+ set_irn_link(b, n);
+ } else if (code != iro_Jmp && !is_Bad(b)) { /* Check for non-empty block. */
+ set_Block_non_removable(b);
+
+ if (code == iro_Proj) { /* link Proj nodes */
+ ir_node *pred = get_Proj_pred(n);
+
+ set_irn_link(n, get_irn_link(pred));
+ set_irn_link(pred, n);
+ } else if (code == iro_Cond) {
+ ir_node *sel = get_Cond_selector(n);
+ if (mode_is_int(get_irn_mode(sel))) {
+ /* found a switch-Cond, collect */
+ plist_insert_back(env->list, n);
+ }
+ }
+ }
+ }
}
/** Returns true if pred is predecessor of block. */
static int is_pred_of(ir_node *pred, ir_node *b) {
- int i, n;
-
- for (i = 0, n = get_Block_n_cfgpreds(b); i < n; ++i) {
- ir_node *b_pred = get_nodes_block(get_Block_cfgpred(b, i));
- if (b_pred == pred) return 1;
- }
- return 0;
+ int i;
+
+ for (i = get_Block_n_cfgpreds(b) - 1; i >= 0; --i) {
+ ir_node *b_pred = get_Block_cfgpred_block(b, i);
+ if (b_pred == pred)
+ return 1;
+ }
+ return 0;
}
-
/** Test whether we can optimize away pred block pos of b.
*
* @param b A block node.
* as already removed.
**/
static int test_whether_dispensable(ir_node *b, int pos) {
- int i, j, n_preds = 1;
- ir_node *pred = get_Block_cfgpred_block(b, pos);
-
- /* Bad blocks will be optimized away, so we don't need space for them */
- if (is_Block_dead(pred))
- return 0;
-
- if (get_Block_block_visited(pred) + 1
- < get_irg_block_visited(current_ir_graph)) {
-
- if (!get_opt_optimize() || !get_opt_control_flow_strong_simplification()) {
- /* Mark block so that is will not be removed: optimization is turned off. */
- set_Block_block_visited(pred, get_irg_block_visited(current_ir_graph)-1);
- return 1;
- }
-
- /* Seems to be empty. At least we detected this in collect_nodes. */
- if (!get_irn_link(b)) {
- /* There are no Phi nodes ==> all predecessors are dispensable. */
- n_preds = get_Block_n_cfgpreds(pred);
- } else {
- /* b's pred blocks and pred's pred blocks must be pairwise disjunct.
- Handle all pred blocks with preds < pos as if they were already removed. */
- for (i = 0; i < pos; i++) {
- ir_node *b_pred = get_Block_cfgpred_block(b, i);
- if (! is_Block_dead(b_pred) &&
- get_Block_block_visited(b_pred) + 1
- < get_irg_block_visited(current_ir_graph)) {
- for (j = 0; j < get_Block_n_cfgpreds(b_pred); j++) {
- ir_node *b_pred_pred = get_Block_cfgpred_block(b_pred, j);
- if (is_pred_of(b_pred_pred, pred))
- goto non_dispensable;
- }
- } else {
- if (is_pred_of(b_pred, pred))
- goto non_dispensable;
- }
- }
- for (i = pos +1; i < get_Block_n_cfgpreds(b); i++) {
- ir_node *b_pred = get_Block_cfgpred_block(b, i);
- if (is_pred_of(b_pred, pred))
- goto non_dispensable;
- }
- /* if we get here, the block is dispensable */
- n_preds = get_Block_n_cfgpreds(pred);
- }
- }
-
- return n_preds;
+ int i, j, n_preds = 1;
+ ir_node *pred = get_Block_cfgpred_block(b, pos);
+
+ /* Bad blocks will be optimized away, so we don't need space for them */
+ if (is_Block_dead(pred))
+ return 0;
+
+ if (is_Block_removable(pred)) {
+ if (!get_opt_optimize() || !get_opt_control_flow_strong_simplification()) {
+ /* Mark block so that is will not be removed: optimization is turned off. */
+ set_Block_non_removable(pred);
+ return 1;
+ }
+
+ /* Seems to be empty. At least we detected this in collect_nodes. */
+ if (get_irn_link(b) == NULL) {
+ /* There are no Phi nodes ==> all predecessors are dispensable. */
+ n_preds = get_Block_n_cfgpreds(pred);
+ } else {
+ /* b's pred blocks and pred's pred blocks must be pairwise disjunct.
+ Handle all pred blocks with preds < pos as if they were already removed. */
+ for (i = 0; i < pos; i++) {
+ ir_node *b_pred = get_Block_cfgpred_block(b, i);
+ if (! is_Block_dead(b_pred) && is_Block_removable(b_pred)) {
+ for (j = get_Block_n_cfgpreds(b_pred) - 1; j >= 0; --j) {
+ ir_node *b_pred_pred = get_Block_cfgpred_block(b_pred, j);
+ if (is_pred_of(b_pred_pred, pred))
+ goto non_dispensable;
+ }
+ } else {
+ if (is_pred_of(b_pred, pred))
+ goto non_dispensable;
+ }
+ }
+ for (i = pos +1; i < get_Block_n_cfgpreds(b); i++) {
+ ir_node *b_pred = get_Block_cfgpred_block(b, i);
+ if (is_pred_of(b_pred, pred))
+ goto non_dispensable;
+ }
+ /* if we get here, the block is dispensable */
+ n_preds = get_Block_n_cfgpreds(pred);
+ }
+ }
+
+ return n_preds;
non_dispensable:
- set_Block_block_visited(pred, get_irg_block_visited(current_ir_graph)-1);
- return 1;
+ set_Block_non_removable(pred);
+ return 1;
}
-/**
- * Store to defer the exchanged of Phi nodes.
- */
-typedef struct _defer_ex_phi {
- ir_node *phi_pred; /**< the previous Phi node that will be replaced */
- ir_node *phi; /**< the new Phi node that replaces phi_pred */
-} defer_ex_phi;
-
/**
* This method removed Bad cf predecessors from Blocks and Phis, and removes
* empty blocks. A block is empty if it only contains Phi and Jmp nodes.
* @@@ It is negotiable whether we should do this ... there might end up a copy
* from the Phi in the loop when removing the Phis.
*/
-static void optimize_blocks(ir_node *b, void *env) {
- int i, j, k, n, max_preds, n_preds, p_preds;
- ir_node *pred, *phi;
- ir_node **in;
- defer_ex_phi *defers;
-
- /* Count the number of predecessor if this block is merged with pred blocks
- that are empty. */
- max_preds = 0;
- for (i = 0, k = get_Block_n_cfgpreds(b); i < k; ++i) {
- max_preds += test_whether_dispensable(b, i);
- }
- in = xmalloc(max_preds * sizeof(*in));
-
- defers = NEW_ARR_F(defer_ex_phi, 0);
-
-/*-
- printf(" working on "); DDMN(b);
- for (i = 0; i < get_Block_n_cfgpreds(b); i++) {
- pred = get_nodes_block(get_Block_cfgpred(b, i));
- if (is_Bad(get_Block_cfgpred(b, i))) {
- printf(" removing Bad %i\n ", i);
- } else if (get_Block_block_visited(pred) +1
- < get_irg_block_visited(current_ir_graph)) {
- printf(" removing pred %i ", i); DDMN(pred);
- } else { printf(" Nothing to do for "); DDMN(pred); }
- }
- * end Debug output -*/
-
- /*- Fix the Phi nodes of the current block -*/
- for (phi = get_irn_link(b); phi; ) {
- assert(get_irn_op(phi) == op_Phi);
-
- /* Find the new predecessors for the Phi */
- p_preds = 0;
- for (i = 0, n = get_Block_n_cfgpreds(b); i < n; ++i) {
- pred = get_Block_cfgpred_block(b, i);
-
- if (is_Bad(get_Block_cfgpred(b, i))) {
- /* case Phi 1: Do nothing */
- }
- else if (get_Block_block_visited(pred) + 1
- < get_irg_block_visited(current_ir_graph)) {
- /* case Phi 2: It's an empty block and not yet visited. */
- ir_node *phi_pred = get_Phi_pred(phi, i);
-
- for (j = 0, k = get_Block_n_cfgpreds(pred); j < k; j++) {
- /* because of breaking loops, not all predecessors are Bad-clean,
- * so we must check this here again */
- if (! is_Bad(get_Block_cfgpred(pred, j))) {
- if (get_nodes_block(phi_pred) == pred) {
- /* case Phi 2a: */
- assert(get_irn_op(phi_pred) == op_Phi); /* Block is empty!! */
-
- in[p_preds++] = get_Phi_pred(phi_pred, j);
- } else {
- /* case Phi 2b: */
- in[p_preds++] = phi_pred;
- }
- }
- }
-
- /* The Phi_pred node is replaced now if it is a Phi.
-
- Somehow the removed Phi node can be used legally in loops.
- Therefore we replace the old phi by the new one.
- This must be done _AFTER_ all Phis are optimized, or
- it will fail if two Phis use the same pred_Phi.
-
- FIXME: Is the following true? We ALWAYS replace it by the new one.
-
- Further we have to remove the old Phi node by replacing it
- by Bad. Else it will remain in the keep alive array of End
- and cause illegal situations. So if there is no loop, we should
- replace it by Bad.
- */
- if (get_nodes_block(phi_pred) == pred) {
- int i;
- /* remove the Phi as it might be kept alive. Further there
- might be other users. */
- for (i = ARR_LEN(defers) - 1; i >= 0; --i)
- if (defers[i].phi_pred == phi_pred)
- break;
-
- if (i < 0) {
- /* we have a new replacement */
- defer_ex_phi elem;
-
- elem.phi_pred = phi_pred;
- elem.phi = phi;
- ARR_APP1(defer_ex_phi, defers, elem);
- }
- }
- } else {
- /* case Phi 3: */
- in[p_preds++] = get_Phi_pred(phi, i);
- }
- }
- assert(p_preds <= max_preds);
-
- /* Fix the node */
- if (p_preds == 1)
- /* By removal of Bad ins the Phi might be degenerated. */
- exchange(phi, in[0]);
- else
- set_irn_in(phi, p_preds, in);
-
- phi = get_irn_link(phi);
- }
-
- /* now, exchange all Phis */
- for (i = ARR_LEN(defers) - 1; i >= 0; --i) {
- exchange(defers[i].phi_pred, defers[i].phi);
- }
- DEL_ARR_F(defers);
-
- /*- This happens only if merge between loop backedge and single loop entry.
- See special case above. -*/
- for (k = 0, n = get_Block_n_cfgpreds(b); k < n; ++k) {
- pred = get_nodes_block(get_Block_cfgpred(b, k));
-
- if (get_Block_block_visited(pred) + 1 < get_irg_block_visited(current_ir_graph)) {
- /* we found a predecessor block at position k that will be removed */
- for (phi = get_irn_link(pred); phi;) {
- /*
- * the previous phase may already changed the phi, and even
- * removed it at all, so check here if this node is still a phi
- */
- if (get_irn_op(phi) == op_Phi) {
- int q_preds = 0;
-
- /* move this phi from the predecessor into the block b */
- set_nodes_block(phi, b);
-
- /* first, copy all 0..k-1 predecessors */
- for (i = 0; i < k; i++) {
- pred = get_nodes_block(get_Block_cfgpred(b, i));
-
- if (is_Bad(get_Block_cfgpred(b, i))) {
- /* Do nothing */
- } else if (get_Block_block_visited(pred) + 1
- < get_irg_block_visited(current_ir_graph)) {
- /* It's an empty block and not yet visited. */
- for (j = 0; j < get_Block_n_cfgpreds(pred); j++) {
- /* @@@ Hier brauche ich Schleifeninformation!!! Kontrollflusskante
- muss Rueckwaertskante sein! (An allen vier in[q_preds] = phi
- Anweisungen.) Trotzdem tuts bisher!! */
- if (! is_Bad(get_Block_cfgpred(pred, j)))
- in[q_preds++] = phi;
- }
- } else {
- in[q_preds++] = phi;
- }
- }
-
- /* now we are at k, copy the phi predecessors */
- pred = get_nodes_block(get_Block_cfgpred(b, k));
- for (i = 0; i < get_Phi_n_preds(phi); i++) {
- if (! is_Bad(get_Block_cfgpred(pred, i)))
- in[q_preds++] = get_Phi_pred(phi, i);
- }
-
- /* and now all the rest */
- for (i = k+1; i < get_Block_n_cfgpreds(b); i++) {
- pred = get_nodes_block(get_Block_cfgpred(b, i));
-
- if (is_Bad(get_Block_cfgpred(b, i))) {
- /* Do nothing */
- } else if (get_Block_block_visited(pred) +1
- < get_irg_block_visited(current_ir_graph)) {
- /* It's an empty block and not yet visited. */
- for (j = 0; j < get_Block_n_cfgpreds(pred); j++) {
- if (! is_Bad(get_Block_cfgpred(pred, j)))
- in[q_preds++] = phi;
- }
- } else {
- in[q_preds++] = phi;
- }
- }
-
- /* Fix the node */
- if (q_preds == 1)
- exchange(phi, in[0]);
- else
- set_irn_in(phi, q_preds, in);
-
- assert(q_preds <= max_preds);
-// assert(p_preds == q_preds && "Wrong Phi Fix");
- }
- phi = get_irn_link(phi);
- }
- }
- }
-
- /*- Fix the block -*/
- n_preds = 0;
- for (i = 0; i < get_Block_n_cfgpreds(b); i++) {
- pred = get_nodes_block(get_Block_cfgpred(b, i));
-
- if (is_Bad(get_Block_cfgpred(b, i))) {
- /* case 1: Do nothing */
- } else if (get_Block_block_visited(pred) +1
- < get_irg_block_visited(current_ir_graph)) {
- /* case 2: It's an empty block and not yet visited. */
- assert(get_Block_n_cfgpreds(b) > 1);
- /* Else it should be optimized by equivalent_node. */
- for (j = 0; j < get_Block_n_cfgpreds(pred); j++) {
- ir_node *pred_block = get_Block_cfgpred(pred, j);
-
- /* because of breaking loops, not all predecessors are Bad-clean,
- * so we must check this here again */
- if (! is_Bad(pred_block))
- in[n_preds++] = pred_block;
- }
- /* Remove block as it might be kept alive. */
- exchange(pred, b/*new_Bad()*/);
- } else {
- /* case 3: */
- in[n_preds++] = get_Block_cfgpred(b, i);
- }
- }
- assert(n_preds <= max_preds);
-
- set_irn_in(b, n_preds, in);
-
- assert(get_irn_link(b) == NULL || (n_preds == p_preds && "Wrong Phi Fix"));
-
- xfree(in);
+static void optimize_blocks(ir_node *b, void *ctx) {
+ int i, j, k, n, max_preds, n_preds, p_preds = -1;
+ ir_node *pred, *phi, *next;
+ ir_node **in;
+ merge_env *env = ctx;
+
+ /* Count the number of predecessor if this block is merged with pred blocks
+ that are empty. */
+ max_preds = 0;
+ for (i = 0, k = get_Block_n_cfgpreds(b); i < k; ++i) {
+ max_preds += test_whether_dispensable(b, i);
+ }
+ in = XMALLOCN(ir_node*, max_preds);
+
+ /*- Fix the Phi nodes of the current block -*/
+ for (phi = get_irn_link(b); phi != NULL; phi = next) {
+ assert(is_Phi(phi));
+ next = get_irn_link(phi);
+
+ /* Find the new predecessors for the Phi */
+ p_preds = 0;
+ for (i = 0, n = get_Block_n_cfgpreds(b); i < n; ++i) {
+ pred = get_Block_cfgpred_block(b, i);
+
+ if (is_Block_dead(pred)) {
+ /* case Phi 1: Do nothing */
+ } else if (is_Block_removable(pred) && !Block_block_visited(pred)) {
+ /* case Phi 2: It's an empty block and not yet visited. */
+ ir_node *phi_pred = get_Phi_pred(phi, i);
+
+ for (j = 0, k = get_Block_n_cfgpreds(pred); j < k; j++) {
+ /* because of breaking loops, not all predecessors are Bad-clean,
+ * so we must check this here again */
+ if (! is_Bad(get_Block_cfgpred(pred, j))) {
+ if (get_nodes_block(phi_pred) == pred) {
+ /* case Phi 2a: */
+ assert(is_Phi(phi_pred)); /* Block is empty!! */
+
+ in[p_preds++] = get_Phi_pred(phi_pred, j);
+ } else {
+ /* case Phi 2b: */
+ in[p_preds++] = phi_pred;
+ }
+ }
+ }
+ } else {
+ /* case Phi 3: */
+ in[p_preds++] = get_Phi_pred(phi, i);
+ }
+ }
+ assert(p_preds <= max_preds);
+
+ /* Fix the node */
+ if (p_preds == 1)
+ /* By removal of Bad ins the Phi might be degenerated. */
+ exchange(phi, in[0]);
+ else
+ set_irn_in(phi, p_preds, in);
+ env->changed = 1;
+ }
+
+ /*- This happens only if merge between loop backedge and single loop entry.
+ Moreover, it is only needed if predb is the direct dominator of b, else there can be no uses
+ of the Phi's in predb ... -*/
+ for (k = 0, n = get_Block_n_cfgpreds(b); k < n; ++k) {
+ ir_node *predb = get_nodes_block(get_Block_cfgpred(b, k));
+
+ if (is_Block_removable(predb) && !Block_block_visited(predb)) {
+ ir_node *next_phi;
+
+ /* we found a predecessor block at position k that will be removed */
+ for (phi = get_irn_link(predb); phi; phi = next_phi) {
+ int q_preds = 0;
+ next_phi = get_irn_link(phi);
+
+ assert(is_Phi(phi));
+
+ if (get_Block_idom(b) != predb) {
+ /* predb is not the dominator. There can't be uses of pred's Phi nodes, kill them .*/
+ exchange(phi, new_Bad());
+ } else {
+ /* predb is the direct dominator of b. There might be uses of the Phi nodes from
+ predb in further block, so move this phi from the predecessor into the block b */
+ set_nodes_block(phi, b);
+ set_irn_link(phi, get_irn_link(b));
+ set_irn_link(b, phi);
+ env->phis_moved = 1;
+
+ /* first, copy all 0..k-1 predecessors */
+ for (i = 0; i < k; i++) {
+ pred = get_Block_cfgpred_block(b, i);
+
+ if (is_Block_dead(pred)) {
+ /* Do nothing */
+ } else if (is_Block_removable(pred) && !Block_block_visited(pred)) {
+ /* It's an empty block and not yet visited. */
+ for (j = 0; j < get_Block_n_cfgpreds(pred); j++) {
+ if (! is_Bad(get_Block_cfgpred(pred, j)))
+ in[q_preds++] = phi;
+ }
+ } else {
+ in[q_preds++] = phi;
+ }
+ }
+
+ /* now we are at k, copy the phi predecessors */
+ pred = get_nodes_block(get_Block_cfgpred(b, k));
+ for (i = 0; i < get_Phi_n_preds(phi); i++) {
+ if (! is_Bad(get_Block_cfgpred(pred, i)))
+ in[q_preds++] = get_Phi_pred(phi, i);
+ }
+
+ /* and now all the rest */
+ for (i = k+1; i < get_Block_n_cfgpreds(b); i++) {
+ pred = get_Block_cfgpred_block(b, i);
+
+ if (is_Block_dead(pred)) {
+ /* Do nothing */
+ } else if (is_Block_removable(pred) && !Block_block_visited(pred)) {
+ /* It's an empty block and not yet visited. */
+ for (j = 0; j < get_Block_n_cfgpreds(pred); j++) {
+ if (! is_Bad(get_Block_cfgpred(pred, j)))
+ in[q_preds++] = phi;
+ }
+ } else {
+ in[q_preds++] = phi;
+ }
+ }
+
+ /* Fix the node */
+ if (q_preds == 1)
+ exchange(phi, in[0]);
+ else
+ set_irn_in(phi, q_preds, in);
+ env->changed = 1;
+
+ assert(q_preds <= max_preds);
+ // assert(p_preds == q_preds && "Wrong Phi Fix");
+ }
+ }
+ }
+ }
+
+ /*- Fix the block -*/
+ n_preds = 0;
+ for (i = 0; i < get_Block_n_cfgpreds(b); i++) {
+ pred = get_Block_cfgpred_block(b, i);
+
+ if (is_Block_dead(pred)) {
+ /* case 1: Do nothing */
+ } else if (is_Block_removable(pred) && !Block_block_visited(pred)) {
+ /* case 2: It's an empty block and not yet visited. */
+ assert(get_Block_n_cfgpreds(b) > 1 || has_Block_label(b));
+ /* Else it should be optimized by equivalent_node. */
+ for (j = 0; j < get_Block_n_cfgpreds(pred); j++) {
+ ir_node *pred_X = get_Block_cfgpred(pred, j);
+
+ /* because of breaking loops, not all predecessors are Bad-clean,
+ * so we must check this here again */
+ if (! is_Bad(pred_X))
+ in[n_preds++] = pred_X;
+ }
+ /* Remove block as it might be kept alive. */
+ exchange(pred, b/*new_Bad()*/);
+ } else {
+ /* case 3: */
+ in[n_preds++] = get_Block_cfgpred(b, i);
+ }
+ }
+ assert(n_preds <= max_preds);
+
+ set_irn_in(b, n_preds, in);
+ env->changed = 1;
+
+ assert(get_irn_link(b) == NULL || p_preds == -1 || (n_preds == p_preds && "Wrong Phi Fix"));
+ xfree(in);
+}
+
+/**
+ * Block walker: optimize all blocks using the default optimizations.
+ * This removes Blocks that with only a Jmp predecessor.
+ */
+static void remove_simple_blocks(ir_node *block, void *ctx) {
+ ir_node *new_blk = equivalent_node(block);
+ merge_env *env = ctx;
+
+ if (new_blk != block) {
+ exchange(block, new_blk);
+ env->changed = 1;
+ }
}
+/**
+ * Handle pre-optimized table switch Cond's.
+ * During iropt, all Projs from a switch-Cond are already removed except
+ * the defProj and maybe the taken one.
+ * The defProj cannot be removed WITHOUT looking backwards, so we do this here.
+ *
+ * @param cond the switch-Cond
+ *
+ * @return non-zero if a switch-Cond was optimized
+ *
+ * Expects all Proj's linked to the cond node
+ */
+static int handle_switch_cond(ir_node *cond) {
+ ir_node *sel = get_Cond_selector(cond);
+
+ ir_node *proj1 = get_irn_link(cond);
+ ir_node *proj2 = get_irn_link(proj1);
+ ir_node *jmp, *blk;
+
+ blk = get_nodes_block(cond);
+
+ if (proj2 == NULL) {
+ /* this Cond has only one Proj: must be the defProj */
+ assert(get_Cond_default_proj(cond) == get_Proj_proj(proj1));
+ /* convert it into a Jmp */
+ jmp = new_r_Jmp(current_ir_graph, blk);
+ exchange(proj1, jmp);
+ return 1;
+ } else if (get_irn_link(proj2) == NULL) {
+ /* We have two Proj's here. Check if the Cond has
+ a constant argument */
+ tarval *tv = value_of(sel);
+
+ if (tv != tarval_bad) {
+ /* we have a constant switch */
+ long num = get_tarval_long(tv);
+ long def_num = get_Cond_default_proj(cond);
+
+ if (def_num == get_Proj_proj(proj1)) {
+ /* first one is the defProj */
+ if (num == get_Proj_proj(proj2)) {
+ jmp = new_r_Jmp(current_ir_graph, blk);
+ exchange(proj2, jmp);
+ exchange(proj1, new_Bad());
+ return 1;
+ }
+ } else if (def_num == get_Proj_proj(proj2)) {
+ /* second one is the defProj */
+ if (num == get_Proj_proj(proj1)) {
+ jmp = new_r_Jmp(current_ir_graph, blk);
+ exchange(proj1, jmp);
+ exchange(proj2, new_Bad());
+ return 1;
+ }
+ } else {
+ /* neither: strange, Cond was not optimized so far */
+ if (num == get_Proj_proj(proj1)) {
+ jmp = new_r_Jmp(current_ir_graph, blk);
+ exchange(proj1, jmp);
+ exchange(proj2, new_Bad());
+ return 1;
+ } else if (num == get_Proj_proj(proj2)) {
+ jmp = new_r_Jmp(current_ir_graph, blk);
+ exchange(proj2, jmp);
+ exchange(proj1, new_Bad());
+ return 1;
+ }
+ }
+ }
+ }
+ return 0;
+}
/* Optimizations of the control flow that also require changes of Phi nodes.
*
* It walks only over block nodes and adapts these and the Phi nodes in these blocks,
* which it finds in a linked list computed by the first pass.
*
- * We use the block_visited flag to mark empty blocks in the first
+ * We use the mark flag to mark removable blocks in the first
* phase.
- * @@@ It would be better to add a struct in the link field
- * that keeps the Phi list and the mark. Place it on an obstack, as
- * we will lose blocks and thereby generate memory leaks.
*/
void optimize_cf(ir_graph *irg) {
- int i, n;
- ir_node **in;
- ir_node *end = get_irg_end(irg);
- ir_graph *rem = current_ir_graph;
- irg_dom_state dom_state = get_irg_dom_state(current_ir_graph);
- current_ir_graph = irg;
-
- /* if the graph is not pinned, we cannot determine empty blocks */
- assert(get_irg_pinned(irg) != op_pin_state_floats &&
- "Control flow optimization need a pinned graph");
-
- /* Handle graph state */
- assert(get_irg_phase_state(irg) != phase_building);
- if (get_irg_outs_state(current_ir_graph) == outs_consistent)
- set_irg_outs_inconsistent(current_ir_graph);
- set_irg_doms_inconsistent(current_ir_graph);
-
- if (dom_state == dom_consistent && get_opt_optimize() && get_opt_unreachable_code()) {
- ir_node *end = get_irg_end(irg);
-
- /* we have dominance info, we can kill dead block */
- irg_block_walk_graph(irg, NULL, remove_dead_block_cf, NULL);
-
- /* fix the keep-alives */
- for (i = 0, n = get_End_n_keepalives(end); i < n; ++i) {
- ir_node *ka = get_End_keepalive(end, i);
-
- if (is_Block(ka)) {
- /* do NOT keep dead blocks */
- if (get_Block_dom_depth(ka) == -1)
- set_End_keepalive(end, i, new_Bad());
- }
- else if (is_Block_dead(get_nodes_block(ka)) ||
- get_Block_dom_depth(get_nodes_block(ka)) == -1)
- /* do NOT keep nodes in dead blocks */
- set_End_keepalive(end, i, new_Bad());
- }
- }
- irg_block_walk_graph(current_ir_graph, NULL, remove_senseless_conds, NULL);
-
- /* Use block visited flag to mark non-empty blocks. */
- inc_irg_block_visited(irg);
- irg_walk(end, merge_blocks, collect_nodes, NULL);
-
- /* Optimize the standard code. */
- irg_block_walk(get_irg_end_block(irg), optimize_blocks, NULL, NULL);
-
- /* Walk all keep alives, optimize them if block, add to new in-array
- for end if useful. */
- in = NEW_ARR_F (ir_node *, 1);
- in[0] = get_nodes_block(end);
- inc_irg_visited(current_ir_graph);
-
- /* fix the keep alive */
- for (i = 0, n = get_End_n_keepalives(end); i < n; i++) {
- ir_node *ka = get_End_keepalive(end, i);
-
- if (irn_not_visited(ka)) {
- ir_op *op = get_irn_op(ka);
-
- if ((op == op_Block) && Block_not_block_visited(ka)) {
- set_irg_block_visited(current_ir_graph, /* Don't walk all the way to Start. */
- get_irg_block_visited(current_ir_graph)-1);
- irg_block_walk(ka, optimize_blocks, NULL, NULL);
- mark_irn_visited(ka);
- ARR_APP1 (ir_node *, in, ka);
- } else if (op == op_Phi) {
- mark_irn_visited(ka);
- if (! is_Block_dead(get_nodes_block(ka)))
- ARR_APP1 (ir_node *, in, ka);
- } else if (is_op_keep(op)) {
- mark_irn_visited(ka);
- if (! is_Block_dead(get_nodes_block(ka)))
- ARR_APP1 (ir_node *, in, ka);
- }
- }
- }
- DEL_ARR_F(end->in);
- end->in = in;
-
- /* the verifier doesn't work yet with floating nodes */
- if (get_irg_pinned(irg) == op_pin_state_pinned) {
- /* after optimize_cf(), only Bad data flow may remain. */
- if (irg_vrfy_bads(irg, BAD_DF | BAD_BLOCK | TUPLE)) {
- dump_ir_block_graph(irg, "-vrfy-cf");
- dump_ir_graph(irg, "-vrfy-cf");
- fprintf(stderr, "VRFY_BAD in optimize_cf()\n");
- }
- }
-
- current_ir_graph = rem;
+ int i, j, n, changed;
+ ir_node **in = NULL;
+ ir_node *cond, *end = get_irg_end(irg);
+ ir_graph *rem = current_ir_graph;
+ plist_element_t *el;
+ merge_env env;
+
+ assert(get_irg_phase_state(irg) != phase_building);
+
+ /* if the graph is not pinned, we cannot determine empty blocks */
+ assert(get_irg_pinned(irg) != op_pin_state_floats &&
+ "Control flow optimization need a pinned graph");
+
+ current_ir_graph = irg;
+
+ /* FIXME: control flow opt destroys block edges. So edges are deactivated here. Fix the edges! */
+ edges_deactivate(irg);
+
+ /* we use the mark flag to mark removable blocks */
+ ir_reserve_resources(irg, IR_RESOURCE_BLOCK_MARK);
+restart:
+ env.changed = 0;
+ env.phis_moved = 0;
+
+ /* ALWAYS kill unreachable control flow. Backend cannot handle it anyway.
+ Use dominator info to kill blocks. Also optimize useless Conds. */
+ assure_doms(irg);
+ irg_block_walk_graph(irg, NULL, remove_unreachable_blocks_and_conds, &env.changed);
+
+ /* fix the keep-alives */
+ changed = 0;
+ for (i = 0, n = get_End_n_keepalives(end); i < n; ++i) {
+ ir_node *ka = get_End_keepalive(end, i);
+
+ if (is_Block(ka)) {
+ /* do NOT keep dead blocks */
+ if (is_Block_dead(ka) || get_Block_dom_depth(ka) < 0) {
+ set_End_keepalive(end, i, new_Bad());
+ changed = 1;
+ }
+ } else {
+ ir_node *block = get_nodes_block(ka);
+
+ if (is_Bad(block) || is_Block_dead(block) || get_Block_dom_depth(block) < 0) {
+ /* do NOT keep nodes in dead blocks */
+ set_End_keepalive(end, i, new_Bad());
+ changed = 1;
+ }
+ }
+ }
+ env.changed |= changed;
+
+ ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);
+
+ env.list = plist_new();
+ irg_walk(end, merge_blocks, collect_nodes, &env);
+
+ ir_free_resources(irg, IR_RESOURCE_IRN_LINK);
+
+ if (env.changed) {
+ /* Handle graph state if was changed. */
+ set_irg_outs_inconsistent(irg);
+ set_irg_doms_inconsistent(irg);
+ set_irg_extblk_inconsistent(irg);
+ set_irg_loopinfo_inconsistent(irg);
+ set_irg_entity_usage_state(irg, ir_entity_usage_not_computed);
+ env.changed = 0;
+ }
+
+ /* handle all collected switch-Conds */
+ foreach_plist(env.list, el) {
+ cond = plist_element_get_value(el);
+ env.changed |= handle_switch_cond(cond);
+ }
+ plist_free(env.list);
+
+ if (env.changed) {
+ /* The Cond optimization might generate unreachable code, so restart if
+ it happens. */
+ goto restart;
+ }
+
+ /* Optimize the standard code. */
+ env.changed = 0;
+ assure_doms(irg);
+ irg_block_walk_graph(irg, optimize_blocks, remove_simple_blocks, &env);
+
+ /* in rare cases a node may be kept alive more than once, use the visited flag to detect this */
+ ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED);
+ inc_irg_visited(irg);
+
+ /* fix the keep-alives again */
+ changed = 0;
+ for (i = 0, n = get_End_n_keepalives(end); i < n; ++i) {
+ ir_node *ka = get_End_keepalive(end, i);
+
+ if (is_Block(ka)) {
+ /* do NOT keep dead blocks */
+ if (is_Block_dead(ka) || get_Block_dom_depth(ka) < 0) {
+ set_End_keepalive(end, i, new_Bad());
+ changed = 1;
+ }
+ } else {
+ ir_node *block = get_nodes_block(ka);
+
+ if (is_Bad(block) || is_Block_dead(block) || get_Block_dom_depth(block) < 0) {
+ /* do NOT keep nodes in dead blocks */
+ set_End_keepalive(end, i, new_Bad());
+ changed = 1;
+ }
+ }
+ }
+ env.changed |= changed;
+
+ remove_End_Bads_and_doublets(end);
+
+
+ ir_free_resources(irg, IR_RESOURCE_BLOCK_MARK | IR_RESOURCE_IRN_VISITED);
+
+ if (env.phis_moved) {
+ /* Bad: when we moved Phi's, we might produce dead Phi nodes
+ that are kept-alive.
+ Some other phases cannot copy with this, so will them.
+ */
+ n = get_End_n_keepalives(end);
+ if (n > 0) {
+ NEW_ARR_A(ir_node *, in, n);
+ if (env.changed) {
+ /* Handle graph state if was changed. */
+ set_irg_outs_inconsistent(irg);
+ }
+ assure_irg_outs(irg);
+
+ for (i = j = 0; i < n; ++i) {
+ ir_node *ka = get_End_keepalive(end, i);
+
+ if (is_Phi(ka)) {
+ int k;
+
+ for (k = get_irn_n_outs(ka) - 1; k >= 0; --k) {
+ ir_node *user = get_irn_out(ka, k);
+
+ if (user != ka && user != end) {
+ /* Is it a real user or just a self loop ? */
+ break;
+ }
+ }
+ if (k >= 0)
+ in[j++] = ka;
+ } else
+ in[j++] = ka;
+ }
+ if (j != n) {
+ set_End_keepalives(end, j, in);
+ env.changed = 1;
+ }
+ }
+ }
+
+ if (env.changed) {
+ /* Handle graph state if was changed. */
+ set_irg_outs_inconsistent(irg);
+ set_irg_doms_inconsistent(irg);
+ set_irg_extblk_inconsistent(irg);
+ set_irg_loopinfo_inconsistent(irg);
+ set_irg_entity_usage_state(irg, ir_entity_usage_not_computed);
+ }
+
+
+ /* the verifier doesn't work yet with floating nodes */
+ if (get_irg_pinned(irg) == op_pin_state_pinned) {
+ /* after optimize_cf(), only Bad data flow may remain. */
+ if (irg_vrfy_bads(irg, BAD_DF | BAD_BLOCK | TUPLE)) {
+ dump_ir_block_graph(irg, "-vrfy-cf");
+ dump_ir_graph(irg, "-vrfy-cf");
+ fprintf(stderr, "VRFY_BAD in optimize_cf()\n");
+ }
+ }
+
+ current_ir_graph = rem;
}
projects / libfirm / blobdiff