/*
- * 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
+ *
+ * Removes Bad control flow predecessors and empty blocks. A block 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).
*/
+#include "config.h"
-#ifdef HAVE_CONFIG_H
-# include "config.h"
-#endif
+#include "iroptimize.h"
#include <assert.h>
+#include <stdbool.h>
#include "xmalloc.h"
#include "irnode_t.h"
#include "irgwalk.h"
#include "irgmod.h"
#include "irdump.h"
-#include "irvrfy.h"
+#include "irverify.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 "irpass.h"
+#include "irnodehashmap.h"
+#include "irtools.h"
-#include "cfopt.h"
+#include "iropt_dbg.h"
-/*------------------------------------------------------------------*/
-/* Control flow optimization. */
-/* */
-/* Removes Bad control flow predecessors and empty blocks. A block */
-/* 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. */
-/*------------------------------------------------------------------*/
+/** An environment for merge_blocks and collect nodes. */
+typedef struct merge_env {
+ bool changed; /**< Set if the graph was changed. */
+ bool phis_moved; /**< Set if Phi nodes were moved. */
+} merge_env;
-/**
- * Removes Tuples from Block control flow predecessors.
- * Optimizes blocks with equivalent_node(). This is tricky,
- * as we want to avoid nodes that have as block predecessor Bads.
- * 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_Bad(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_Bad(b)) {
- new_block = equivalent_node(b);
-
- while (irn_not_visited(b) && (!is_Bad(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_Bad(new_block))
- exchange(n, new_Bad());
- }
- }
+/** set or reset the removable property of a block. */
+static void set_Block_removable(ir_node *block, bool removable)
+{
+ set_Block_mark(block, removable);
}
-/**
- * Remove cf from dead block by inspecting dominance info
- * Do not replace blocks by Bad. This optimization shall
- * ensure, that all Bad cfg preds are removed, and no new
- * other Bads are introduced.
- *
- * Must be run in the post walker.
- */
-static void remove_dead_block_cf(ir_node *block, void *env)
+/** check if a block has the removable property set. */
+static bool is_Block_removable(const ir_node *block)
{
- 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);
+ return get_Block_mark(block);
+}
- if (! is_Bad(pred_X)) {
- ir_node *pred_bl = get_nodes_block(skip_Proj(pred_X));
+/** checks if a given Cond node is a switch Cond. */
+static bool is_switch_Cond(const ir_node *cond)
+{
+ ir_node *sel = get_Cond_selector(cond);
+ return get_irn_mode(sel) != mode_b;
+}
- if (is_Bad(pred_bl) || (get_Block_dom_depth(pred_bl) == -1))
- exchange (pred_X, new_Bad());
- }
- }
+/** Walker: clear link fields and mark all blocks as removable. */
+static void clear_link_and_mark_blocks_removable(ir_node *node, void *ctx)
+{
+ (void) ctx;
+ set_irn_link(node, NULL);
+ if (is_Block(node)) {
+ set_Block_removable(node, true);
+ set_Block_phis(node, NULL);
+ } else if (is_Phi(node)) {
+ set_Phi_next(node, NULL);
+ }
}
/**
* 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)
+{
+ (void) ctx;
+ if (is_Phi(n)) {
+ /* Collect Phi nodes to compact ins along with block's ins. */
+ ir_node *block = get_nodes_block(n);
+ add_Block_phi(block, n);
+ } else if (is_Block(n)) {
+ if (get_Block_entity(n) != NULL) {
+ /* block with a jump label attached cannot be removed. */
+ set_Block_removable(n, false);
+ }
+ } else if (is_Bad(n) || is_Jmp(n)) {
+ /* ignore these */
+ return;
+ } else {
+ /* Check for non-empty block. */
+ ir_node *block = get_nodes_block(n);
+
+ set_Block_removable(block, false);
+
+ if (is_Proj(n)) {
+ /* link Proj nodes */
+ ir_node *pred = get_Proj_pred(n);
+ set_irn_link(n, get_irn_link(pred));
+ set_irn_link(pred, 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;
+/** Returns true if pred is predecessor of block b. */
+static bool is_pred_of(const ir_node *pred, const ir_node *b)
+{
+ 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 true;
+ }
+ return false;
}
-
-/** Test wether we can optimize away pred block pos of b.
+/** Test whether we can optimize away pred block pos of b.
*
* @param b A block node.
* @param pos The position of the predecessor block to judge about.
* The test is rather tricky.
*
* The situation is something like the following:
- *
+ * @verbatim
* if-block
* / \
* then-b else-b
* \ /
* b
+ * @endverbatim
*
- * b merges the control flow of an if-then-else. We may not remove
- * the 'then' _and_ the 'else' block of an 'if' if there is a Phi
- * node in b, even if both are empty. The destruction of this Phi
- * requires that a copy is added before the merge. We have to
- * keep one of the case blocks to place the copies in.
+ * b merges the control flow of an if-then-else. We may not remove
+ * the 'then' _and_ the 'else' block of an 'if' if there is a Phi
+ * node in b, even if both are empty. The destruction of this Phi
+ * requires that a copy is added before the merge. We have to
+ * keep one of the case blocks to place the copies in.
*
- * To perform the test for pos, we must regard preds before pos
- * as already removed.
+ * To perform the test for pos, we must regard predecessors before pos
+ * as already removed.
**/
-static int test_whether_dispensable(ir_node *b, int pos) {
- int i, j, n_preds = 1;
- int dispensable = 1;
- ir_node *cfop = get_Block_cfgpred(b, pos);
- ir_node *pred = get_nodes_block(cfop);
-
- /* Bad blocks will be optimized away, so we don't need space for them */
- if (is_Bad(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.
- Work preds < pos as if they were already removed. */
- for (i = 0; i < pos; i++) {
- ir_node *b_pred = get_nodes_block(get_Block_cfgpred(b, i));
- if (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_nodes_block(get_Block_cfgpred(b_pred, j));
- if (is_pred_of(b_pred_pred, pred)) dispensable = 0;
- }
- } else {
- if (is_pred_of(b_pred, pred)) dispensable = 0;
- }
- }
- for (i = pos +1; i < get_Block_n_cfgpreds(b); i++) {
- ir_node *b_pred = get_nodes_block(get_Block_cfgpred(b, i));
- if (is_pred_of(b_pred, pred)) dispensable = 0;
- }
- if (!dispensable) {
- set_Block_block_visited(pred, get_irg_block_visited(current_ir_graph)-1);
- n_preds = 1;
- } else {
- n_preds = get_Block_n_cfgpreds(pred);
- }
- }
- }
-
- return n_preds;
+static unsigned test_whether_dispensable(const ir_node *b, int pos)
+{
+ ir_node *pred = get_Block_cfgpred(b, pos);
+ ir_node *predb = get_nodes_block(pred);
+
+ if (is_Bad(pred) || !is_Block_removable(predb))
+ return 1;
+
+ /* can't remove self-loops */
+ if (predb == b)
+ goto non_dispensable;
+ if (is_unknown_jump(pred))
+ goto non_dispensable;
+
+ /* Seems to be empty. At least we detected this in collect_nodes. */
+ if (get_Block_phis(b) != NULL) {
+ int n_cfgpreds = get_Block_n_cfgpreds(b);
+ int i;
+ /* there are Phi nodes */
+
+ /* 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 *other_pred = get_Block_cfgpred(b, i);
+ ir_node *other_predb = get_nodes_block(other_pred);
+ if (is_Bad(other_pred))
+ continue;
+ if (is_Block_removable(other_predb)
+ && !Block_block_visited(other_predb)) {
+ int j;
+ for (j = get_Block_n_cfgpreds(other_predb) - 1; j >= 0; --j) {
+ ir_node *other_predpred
+ = get_Block_cfgpred_block(other_predb, j);
+ if (is_pred_of(other_predpred, predb))
+ goto non_dispensable;
+ }
+ } else if (is_pred_of(other_predb, predb)) {
+ goto non_dispensable;
+ }
+ }
+ for (i = pos+1; i < n_cfgpreds; i++) {
+ ir_node *other_predb = get_Block_cfgpred_block(b, i);
+ if (is_pred_of(other_predb, predb))
+ goto non_dispensable;
+ }
+ }
+ /* we will not dispense already visited blocks */
+ if (Block_block_visited(predb))
+ return 1;
+ /* if we get here, the block is dispensable, count useful preds */
+ return get_irn_arity(predb);
+
+non_dispensable:
+ set_Block_removable(predb, false);
+ return 1;
}
+/**
+ * This method merges blocks. A block is applicable to be merged, if it
+ * has only one predecessor with an unconditional jump to this block;
+ * and if this block does not contain any phis.
+ */
+static void merge_blocks(ir_node *b, void *env)
+{
+ (void) env;
+
+ if (get_Block_n_cfgpreds(b) == 1) {
+ ir_node* pred = get_Block_cfgpred(b, 0);
+ if (is_Jmp(pred)) {
+ ir_node* pred_block = get_nodes_block(pred);
+ if (get_Block_phis(b) == NULL) {
+ exchange(b, pred_block);
+ }
+ }
+ }
+}
/**
- * This method removed Bad cf preds from Blocks and Phis, and removes
- * empty blocks. A block is empty if it only contains Phi and Jmp nodes.
+ * This method removes empty blocks. A block is empty if it only contains Phi
+ * and Jmp nodes.
*
* We first adapt Phi nodes, then Block nodes, as we need the old ins
* of the Block to adapt the Phi nodes. We do this by computing new
* for all nodes, not regarding whether there is a possibility for optimization.
*
* For each predecessor p of a Block b there are three cases:
- * 1. The predecessor p is a Bad node: just skip it. The in array of b shrinks by one.
- * 2. The predecessor p is empty. Remove p. All predecessors of p are now
- * predecessors of b.
- * 3. The predecessor p is a block containing useful code. Just keep p as is.
+ * - The predecessor p is a Bad node: just skip it. The in array of b shrinks
+ * by one.
+ * - The predecessor p is empty. Remove p. All predecessors of p are now
+ * predecessors of b.
+ * - The predecessor p is a block containing useful code. Just keep p as is.
*
* For Phi nodes f we have to check the conditions at the Block of f.
* For cases 1 and 3 we proceed as for Blocks. For case 2 we can have two
* cases:
- * 2a: The old precessor of the Phi f is a Phi pred_f IN THE BLOCK REMOVED. In this
- * case we proceed as for blocks. We remove pred_f. All
- * predecessors of pred_f now are predecessors of f.
- * 2b: The old predecessor of f is NOT in the block removed. It might be a Phi, too.
- * We have to replicate f for each predecessor of the removed block. Or, with
- * other words, the removed predecessor block has exactly one predecessor.
+ * -2a: The old predecessor of the Phi f is a Phi pred_f IN THE BLOCK REMOVED.
+ * In this case we proceed as for blocks. We remove pred_f. All
+ * predecessors of pred_f now are predecessors of f.
+ * -2b: The old predecessor of f is NOT in the block removed. It might be a Phi
+ * too. We have to replicate f for each predecessor of the removed block.
+ * Or, with other words, the removed predecessor block has exactly one
+ * predecessor.
*
* Further there is a special case for self referencing blocks:
+ * @verbatim
*
* then_b else_b then_b else_b
* \ / \ /
* \ / | /
* pred_b | /
- * | ____ | /
+ * | ____ | / ____
* | | | | | | |
* | | | === optimized to ===> \ | | |
* loop_b | loop_b |
* | | | | | |
* | |____| | |____|
* | |
+ * @endverbatim
*
* If there is a Phi in pred_b, but we remove pred_b, we have to generate a
* Phi in loop_b, that has the ins of the Phi in pred_b and a self referencing
* backedge.
- * @@@ 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;
-
- /* 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));
-
-/*-
- 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_nodes_block(get_Block_cfgpred(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.
-
- Further we have to remove the old Phi node by replacing it
- by Bad. Else it will remain in the keepalive 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) {
- /* remove the Phi as it might be kept alive. Further there
- might be other users. */
- exchange(phi_pred, phi); /* geht, ist aber doch semantisch falsch! Warum?? */
- }
- } 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);
- }
-
- /*- 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 *phi;
+ ir_node *next;
+ ir_node **in;
+ merge_env *env = (merge_env*)ctx;
+
+ if (get_Block_dom_depth(b) < 0) {
+ /* ignore unreachable blocks */
+ return;
+ }
+
+ /* 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_Block_phis(b); phi != NULL; phi = next) {
+ next = get_Phi_next(phi);
+
+ /* Find the new predecessors for the Phi */
+ p_preds = 0;
+ for (i = 0, n = get_Block_n_cfgpreds(b); i < n; ++i) {
+ ir_graph *irg = get_irn_irg(b);
+ ir_node *predx = get_Block_cfgpred(b, i);
+ ir_node *pred;
+
+ /* case Phi 1: maintain Bads, as somebody else is responsible to
+ * remove them */
+ if (is_Bad(predx)) {
+ in[p_preds++] = new_r_Bad(irg, get_irn_mode(phi));
+ continue;
+ }
+
+ pred = get_nodes_block(predx);
+
+ /* case Phi 2: It's an empty block and not yet visited. */
+ if (is_Block_removable(pred) && !Block_block_visited(pred)) {
+ ir_node *phi_pred = get_Phi_pred(phi, i);
+
+ for (j = 0, k = get_Block_n_cfgpreds(pred); j < k; j++) {
+ ir_node *pred_pred = get_Block_cfgpred(pred, j);
+
+ if (is_Bad(pred_pred)) {
+ in[p_preds++] = new_r_Bad(irg, get_irn_mode(phi));
+ continue;
+ }
+
+ 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) {
+ exchange(phi, in[0]);
+ } else {
+ set_irn_in(phi, p_preds, in);
+ }
+ env->changed = true;
+ }
+
+ /*- 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 *pred = get_Block_cfgpred(b, k);
+ ir_node *predb = get_nodes_block(pred);
+ if (is_Bad(pred))
+ continue;
+
+ 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_Block_phis(predb); phi != NULL; phi = next_phi) {
+ int q_preds = 0;
+ next_phi = get_Phi_next(phi);
+
+ if (get_Block_idom(b) != predb) {
+ /* predb is not the dominator. There can't be uses of
+ * pred's Phi nodes, kill them .*/
+ ir_graph *irg = get_irn_irg(b);
+ ir_mode *mode = get_irn_mode(phi);
+ exchange(phi, new_r_Bad(irg, mode));
+ } 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_Phi_next(phi, get_Block_phis(b));
+ set_Block_phis(b, phi);
+ env->phis_moved = true;
+
+ /* first, copy all 0..k-1 predecessors */
+ for (i = 0; i < k; i++) {
+ ir_node *predx = get_Block_cfgpred(b, i);
+ ir_node *pred_block;
+
+ if (is_Bad(predx)) {
+ ir_graph *irg = get_irn_irg(b);
+ ir_mode *mode = get_irn_mode(phi);
+ in[q_preds++] = new_r_Bad(irg, mode);
+ continue;
+ }
+ pred_block = get_nodes_block(predx);
+ if (is_Block_removable(pred_block)
+ && !Block_block_visited(pred_block)) {
+ int n_cfgpreds = get_Block_n_cfgpreds(pred_block);
+ /* It's an empty block and not yet visited. */
+ for (j = 0; j < n_cfgpreds; j++) {
+ if (!is_Bad(get_Block_cfgpred(pred_block, j))) {
+ in[q_preds++] = phi;
+ } else {
+ ir_graph *irg = get_irn_irg(b);
+ ir_mode *mode = get_irn_mode(phi);
+ in[q_preds++] = new_r_Bad(irg, mode);
+ }
+ }
+ } 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++) {
+ 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_Bad(pred)) {
+ ir_graph *irg = get_irn_irg(b);
+ ir_mode *mode = get_irn_mode(phi);
+ in[q_preds++] = new_r_Bad(irg, mode);
+ } 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 {
+ ir_graph *irg = get_irn_irg(b);
+ ir_mode *mode = get_irn_mode(phi);
+ in[q_preds++] = new_r_Bad(irg, mode);
+ }
+ }
+ } 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 = true;
+
+ 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++) {
+ ir_node *pred = get_Block_cfgpred(b, i);
+ ir_node *predb = get_nodes_block(pred);
+ ir_graph *irg = get_irn_irg(pred);
+
+ /* case 1: Bad predecessor */
+ if (is_Bad(pred)) {
+ in[n_preds++] = new_r_Bad(irg, mode_X);
+ continue;
+ }
+ if (is_Block_removable(predb) && !Block_block_visited(predb)) {
+ /* case 2: It's an empty block and not yet visited. */
+ for (j = 0; j < get_Block_n_cfgpreds(predb); j++) {
+ ir_node *predpred = get_Block_cfgpred(predb, j);
+
+ if (is_Bad(predpred)) {
+ in[n_preds++] = new_r_Bad(irg, mode_X);
+ continue;
+ }
+
+ in[n_preds++] = predpred;
+ }
+ /* Remove block+jump as it might be kept alive. */
+ exchange(pred, new_r_Bad(get_irn_irg(b), mode_X));
+ exchange(predb, new_r_Bad(get_irn_irg(b), mode_BB));
+ } else {
+ /* case 3: */
+ in[n_preds++] = pred;
+ }
+ }
+ assert(n_preds == max_preds);
+
+ set_irn_in(b, n_preds, in);
+ env->changed = true;
+
+ /* see if phi-fix was correct */
+ assert(get_Block_phis(b) == NULL || p_preds == -1 || (n_preds == p_preds));
+ xfree(in);
}
-
-/* Optimizations of the control flow that also require changes of Phi nodes.
- *
- * This optimization performs two passes over the graph.
- *
- * The first pass collects all Phi nodes in a link list in the block
- * nodes. Further it performs simple control flow optimizations.
- * Finally it marks all blocks that do not contain useful
- * computations, i.e., these blocks might be removed.
+/**
+ * Optimize boolean Conds, where true and false jump to the same block into a Jmp
+ * Block must contain no Phi nodes.
*
- * The second pass performs the optimizations intended by this algorithm.
- * 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.
+ * Cond
+ * / \
+ * projA projB => Jmp Bad
+ * \ / \ /
+ * block block
+ */
+static bool optimize_pred_cond(ir_node *block, int i, int j)
+{
+ ir_node *projA, *projB, *cond, *pred_block, *jmp, *bad;
+ assert(i != j);
+
+ projA = get_Block_cfgpred(block, i);
+ if (!is_Proj(projA)) return false;
+ projB = get_Block_cfgpred(block, j);
+ if (!is_Proj(projB)) return false;
+ cond = get_Proj_pred(projA);
+ if (!is_Cond(cond)) return false;
+
+ if (cond != get_Proj_pred(projB)) return false;
+ if (is_switch_Cond(cond)) return false;
+
+ /* cond should actually be a Jmp */
+ pred_block = get_nodes_block(cond);
+ jmp = new_r_Jmp(pred_block);
+ bad = new_r_Bad(get_irn_irg(block), mode_X);
+
+ assert(projA != projB);
+ exchange(projA, jmp);
+ exchange(projB, bad);
+ return true;
+}
+
+typedef enum block_flags_t {
+ BF_HAS_OPERATIONS = 1 << 0,
+ BF_HAS_PHIS = 1 << 1,
+ BF_IS_UNKNOWN_JUMP_TARGET = 1 << 2,
+} block_flags_t;
+
+static bool get_block_flag(const ir_nodehashmap_t *infos, const ir_node *block,
+ int flag)
+{
+ return PTR_TO_INT(ir_nodehashmap_get(void, infos, block)) & flag;
+}
+
+static void set_block_flag(ir_nodehashmap_t *infos, ir_node *block,
+ block_flags_t flag)
+{
+ int data = PTR_TO_INT(ir_nodehashmap_get(void, infos, block));
+ data |= flag;
+ ir_nodehashmap_insert(infos, block, INT_TO_PTR(data));
+}
+
+static void clear_block_flag(ir_nodehashmap_t *infos, const ir_node *block)
+{
+ ir_nodehashmap_remove(infos, block);
+}
+
+static bool has_operations(ir_nodehashmap_t *infos, const ir_node *block)
+{
+ return get_block_flag(infos, block, BF_HAS_OPERATIONS);
+}
+
+static void set_has_operations(ir_nodehashmap_t *infos, ir_node *block)
+{
+ set_block_flag(infos, block, BF_HAS_OPERATIONS);
+}
+
+static bool has_phis(ir_nodehashmap_t *infos, const ir_node *block)
+{
+ return get_block_flag(infos, block, BF_HAS_PHIS);
+}
+
+static void set_has_phis(ir_nodehashmap_t *infos, ir_node *block)
+{
+ set_block_flag(infos, block, BF_HAS_PHIS);
+}
+
+static bool is_unknown_jump_target(ir_nodehashmap_t *infos, const ir_node *block)
+{
+ return get_block_flag(infos, block, BF_IS_UNKNOWN_JUMP_TARGET);
+}
+
+static void set_is_unknown_jump_target(ir_nodehashmap_t *infos, ir_node *block)
+{
+ set_block_flag(infos, block, BF_IS_UNKNOWN_JUMP_TARGET);
+}
+
+/**
+ * Pre-Walker: fill block info information.
+ */
+static void compute_block_info(ir_node *n, void *x)
+{
+ ir_nodehashmap_t *infos = (ir_nodehashmap_t*)x;
+
+ if (is_Block(n)) {
+ int i, max = get_Block_n_cfgpreds(n);
+ for (i=0; i<max; i++) {
+ ir_node *pred = get_Block_cfgpred(n,i);
+ if (is_unknown_jump(pred)) {
+ set_is_unknown_jump_target(infos, n);
+ }
+ }
+ } else if (is_Phi(n)) {
+ ir_node *block = get_nodes_block(n);
+ set_has_phis(infos, block);
+ } else if (is_Jmp(n) || is_Cond(n) || is_Proj(n)) {
+ /* ignore */
+ } else {
+ ir_node *block = get_nodes_block(n);
+ set_has_operations(infos, block);
+ }
+}
+
+static void clear_block_info(ir_node *block, void *x)
+{
+ ir_nodehashmap_t *infos = (ir_nodehashmap_t*)x;
+ clear_block_flag(infos, block);
+}
+
+typedef struct skip_env {
+ bool changed;
+ ir_nodehashmap_t block_infos;
+} skip_env;
+
+/**
+ * Post-Block-walker: Optimize useless if's (boolean Cond nodes
+ * with same true/false target) away.
+ */
+static void optimize_ifs(ir_node *block, void *x)
+{
+ skip_env *env = (skip_env*)x;
+ int i, j;
+ int n_preds = get_Block_n_cfgpreds(block);
+
+ if (has_phis(&env->block_infos, block))
+ return;
+
+ /* optimize Cond predecessors (might produce Bad predecessors) */
+ for (i = 0; i < n_preds; ++i) {
+ for (j = i+1; j < n_preds; ++j) {
+ optimize_pred_cond(block, i, j);
+ }
+ }
+}
+
+/**
+ * Pre-Block walker: remove empty blocks (only contain a Jmp)
+ * that are control flow predecessors of the current block.
+ */
+static void remove_empty_blocks(ir_node *block, void *x)
+{
+ skip_env *env = (skip_env*)x;
+ int i;
+ int n_preds = get_Block_n_cfgpreds(block);
+
+ for (i = 0; i < n_preds; ++i) {
+ ir_node *jmp, *jmp_block;
+ int n_jpreds = 0;
+
+ jmp = get_Block_cfgpred(block, i);
+ if (!is_Jmp(jmp))
+ continue;
+ jmp_block = get_nodes_block(jmp);
+ if (jmp_block == block)
+ continue; /* this infinite loop cannot be optimized any further */
+ if (is_unknown_jump_target(&env->block_infos, jmp_block))
+ continue; /* unknown jump target must not be optimized */
+ if (has_phis(&env->block_infos,jmp_block))
+ continue; /* this block contains Phis and is not skipped */
+ if (Block_block_visited(jmp_block)) {
+ continue;
+ /* otherwise we could break the walker,
+ * if block was reached via
+ * KeepAlive edge -> jmp_block -> A ---> block,
+ * because the walker cannot handle Id nodes.
+ *
+ * A B
+ * \ /
+ * jmp_block
+ * / \
+ * block End
+ */
+ }
+
+ /* jmp_block is an empty block and can be optimized! */
+
+ n_jpreds = get_Block_n_cfgpreds(jmp_block);
+ /**
+ * If the jmp block has only one predecessor this is straightforward.
+ * However, if there are more predecessors, we only handle this,
+ * if block has no Phis.
+ */
+ if (n_jpreds == 1) {
+ ir_node *pred = get_Block_cfgpred(jmp_block, 0);
+ ir_node *pred_block = get_nodes_block(pred);
+ if (has_operations(&env->block_infos,jmp_block)) {
+ if (get_irg_start_block(get_irn_irg(pred_block)) == pred_block)
+ continue; /* must not merge operations into start block */
+ if (!is_Jmp(pred))
+ continue; /* must not create partially dead code, especially when it is mode_M */
+ }
+
+ /* skip jmp block by rerouting its predecessor to block
+ *
+ * A A
+ * | |
+ * jmp_block => |
+ * | |
+ * block block
+ */
+ exchange(jmp, pred);
+
+ /* cleanup: jmp_block might have a Keep edge! */
+ exchange(jmp_block, pred_block);
+ env->changed = true;
+ } else if ( !has_phis(&env->block_infos, block) &&
+ !has_operations(&env->block_infos,jmp_block))
+ {
+ /* all predecessors can skip the jmp block, so block gets some new
+ * predecessors
+ *
+ * A B A B
+ * \ / | |
+ * jmp_block C => Bad C | |
+ * \ / \ | | /
+ * block block
+ */
+ ir_node **ins = ALLOCAN(ir_node*, n_preds+n_jpreds);
+ int j;
+ /* first copy the old predecessors, because the outer loop (i)
+ * still walks over them */
+ for (j = 0; j < n_preds; ++j) {
+ ins[j] = get_Block_cfgpred(block, j);
+ }
+ /* now append the new predecessors */
+ for (j = 0; j < n_jpreds; ++j) {
+ ir_node *pred = get_Block_cfgpred(jmp_block, j);
+ ins[n_preds+j] = pred;
+ }
+ set_irn_in(block, n_preds+n_jpreds, ins);
+ /* convert the jmp_block to Bad */
+ ir_graph *irg = get_irn_irg(block);
+ exchange(jmp_block, new_r_Bad(irg, mode_BB));
+ exchange(jmp, new_r_Bad(irg, mode_X));
+ /* let the outer loop walk over the new predecessors as well */
+ n_preds += n_jpreds;
+ env->changed = true;
+ // TODO What if jmp_block had a KeepAlive edge?
+ } else {
+ /* This would involve Phis ... */
+ }
+ }
+}
+
+/*
+ * All cfg optimizations, which do not touch Phi nodes.
*
- * We use the block_visited flag to mark empty 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 mem leaks.
+ * Note that this might create critical edges.
*/
-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;
-
- /* 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);
- if (get_irg_dom_state(current_ir_graph) == dom_consistent)
- set_irg_dom_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 dominace 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) && (get_Block_dom_depth(ka) == -1))
- set_End_keepalive(end, i, new_Bad());
- if (is_Phi(ka) && (get_Block_dom_depth(get_nodes_block(ka)) == -1))
- set_End_keepalive(end, i, new_Bad());
- }
- }
-
- /* 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);
-
- for (i = 0; i < get_End_n_keepalives(end); i++) {
- ir_node *ka = get_End_keepalive(end, i);
-
- if (irn_not_visited(ka)) {
- if ((get_irn_op(ka) == 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 (get_irn_op(ka) == op_Phi) {
- mark_irn_visited(ka);
- ARR_APP1 (ir_node *, in, ka);
- }
- }
- }
- /* DEL_ARR_F(end->in); GL @@@ tut nicht ! */
- end->in = in;
-
- /* the verifyer 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;
+static void cfgopt_ignoring_phis(ir_graph *irg)
+{
+ skip_env env;
+
+ env.changed = true;
+ ir_nodehashmap_init(&env.block_infos);
+
+ while (env.changed) {
+ irg_walk_graph(irg, compute_block_info, NULL, &env.block_infos);
+ env.changed = false;
+
+ /* Remove blocks, which only consist of a Jmp */
+ irg_block_walk_graph(irg, remove_empty_blocks, NULL, &env);
+
+ /* Optimize Cond->Jmp, where then- and else-block are the same. */
+ irg_block_walk_graph(irg, NULL, optimize_ifs, &env);
+
+ if (env.changed) {
+ confirm_irg_properties(irg, IR_GRAPH_PROPERTIES_NONE);
+ /* clear block info, because it must be recomputed */
+ irg_block_walk_graph(irg, clear_block_info, NULL, &env.block_infos);
+ /* Removing blocks and Conds might enable more optimizations */
+ continue;
+ } else {
+ confirm_irg_properties(irg, IR_GRAPH_PROPERTIES_ALL);
+ break;
+ }
+ }
+
+ ir_nodehashmap_destroy(&env.block_infos);
+}
+
+/* Optimizations of the control flow that also require changes of Phi nodes. */
+void optimize_cf(ir_graph *irg)
+{
+ int i, j, n;
+ ir_node **in = NULL;
+ ir_node *end = get_irg_end(irg);
+ ir_node *new_end;
+ merge_env env;
+
+ env.changed = false;
+ env.phis_moved = false;
+
+ /* 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");
+
+ assure_irg_properties(irg, IR_GRAPH_PROPERTY_NO_UNREACHABLE_CODE);
+
+ /* First the "simple" optimizations, which do not touch Phis */
+ cfgopt_ignoring_phis(irg);
+
+ /* we use the mark flag to mark removable blocks */
+ ir_reserve_resources(irg, IR_RESOURCE_BLOCK_MARK | IR_RESOURCE_IRN_LINK
+ | IR_RESOURCE_PHI_LIST);
+
+ /*
+ * This pass collects all Phi nodes in a link list in the block
+ * nodes. Further it performs simple control flow optimizations.
+ * Finally it marks all blocks that do not contain useful
+ * computations, i.e., these blocks might be removed.
+ */
+ irg_walk(end, clear_link_and_mark_blocks_removable, collect_nodes, NULL);
+
+ /* assert due to collect_nodes:
+ * 1. removable blocks are now marked as such
+ * 2. phi lists are up to date
+ */
+
+ /* Optimize the standard code.
+ * It walks only over block nodes and adapts these and the Phi nodes in
+ * these blocks, which it finds in a linked list computed before.
+ */
+ assure_irg_properties(irg, IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE);
+ irg_block_walk_graph(irg, optimize_blocks, merge_blocks, &env);
+
+ new_end = optimize_in_place(end);
+ if (new_end != end) {
+ set_irg_end(irg, new_end);
+ end = new_end;
+ }
+ remove_End_Bads_and_doublets(end);
+
+ ir_free_resources(irg, IR_RESOURCE_BLOCK_MARK | IR_RESOURCE_IRN_LINK
+ | IR_RESOURCE_PHI_LIST);
+
+ 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 kill them.
+ */
+ n = get_End_n_keepalives(end);
+ if (n > 0) {
+ NEW_ARR_A(ir_node *, in, n);
+ 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 = true;
+ }
+ }
+ }
+
+ confirm_irg_properties(irg,
+ env.changed ? IR_GRAPH_PROPERTIES_NONE : IR_GRAPH_PROPERTIES_ALL);
+}
+
+/* Creates an ir_graph pass for optimize_cf. */
+ir_graph_pass_t *optimize_cf_pass(const char *name)
+{
+ return def_graph_pass(name ? name : "optimize_cf", optimize_cf);
}
projects / libfirm / blobdiff