/*
- * 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.
*/
-#ifdef HAVE_CONFIG_H
-# include <config.h>
-#endif
+/**
+ * @file
+ * @brief Control flow optimizations.
+ * @author Goetz Lindenmaier, Michael Beck, Sebastian Hack
+ * @version $Id$
+ *
+ * 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"
+
+#include "iroptimize.h"
#include <assert.h>
+#include <stdbool.h>
+#include "xmalloc.h"
#include "irnode_t.h"
#include "irgraph_t.h"
#include "irprog_t.h"
#include "ircons.h"
#include "iropt_t.h"
#include "irgwalk.h"
-#include "irvrfy.h"
+#include "irgmod.h"
+#include "irdump.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 "irphase_t.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;
-
- 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)));
- }
- new_block = equivalent_node(n);
- if (new_block != n)
- 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(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 somtimes 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(((b == new_block) ||
- 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);
- }
- b = new_block;
- }
-
- /*
- * BEWARE: do not kill floating notes here as they might be needed in
- * valid blocks because of global CSE.
- */
- if (is_Bad(b) && get_opt_normalize() &&
- get_op_pinned(get_irn_op(n)) == op_pin_state_pinned)
- exchange(n, new_Bad());
- }
+static void set_Block_removable(ir_node *block, bool removable)
+{
+ set_Block_mark(block, removable);
+}
+
+static bool is_Block_removable(ir_node *block)
+{
+ return get_Block_mark(block);
+}
+
+static bool is_switch_Cond(ir_node *cond) {
+ ir_node *sel = get_Cond_selector(cond);
+ return get_irn_mode(sel) != mode_b;
+}
+
+static void clear_link(ir_node *node, void *ctx)
+{
+ (void) ctx;
+ set_irn_link(node, NULL);
+ if (is_Block(node))
+ set_Block_removable(node, true);
}
/**
* 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) {
- irg_dom_state *dom_state = env;
-
- if (is_no_Block(n)) {
- ir_node *b = get_nodes_block(n);
-
- /*
- * BEWARE: do not kill floating notes here as they might be needed in
- * valid blocks because of global CSE.
- */
- if (is_Bad(b) &&
- get_op_pinned(get_irn_op(n)) == op_pin_state_pinned) {
- /* previous merge_blocks() may have killed dead blocks */
- exchange(n, new_Bad());
- }
- else 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);
- }
- }
- else {
- /* delete dead blocks: if we have dominator information, this can easily be detected
- * BEWARE: don't kill the end block */
- if (*dom_state == dom_consistent &&
- n != get_irg_end_block(current_ir_graph) &&
- get_Block_dom_depth(n) == -1 &&
- get_opt_unreachable_code()) {
- exchange (n, new_Bad());
- }
- }
+static void collect_nodes(ir_node *n, void *ctx)
+{
+ ir_node ***switch_conds = (ir_node***)ctx;
+
+ if (is_Phi(n)) {
+ /* Collect Phi nodes to compact ins along with block's ins. */
+ ir_node *block = get_nodes_block(n);
+ set_irn_link(n, get_irn_link(block));
+ set_irn_link(block, n);
+ } else if (is_Block(n)) {
+ if (has_Block_entity(n))
+ set_Block_removable(n, false);
+ return;
+ } else if (!is_Jmp(n)) { /* 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);
+ } else if (is_Cond(n) && is_switch_Cond(n)) {
+ /* found a switch-Cond, collect */
+ ARR_APP1(ir_node*, *switch_conds, n);
+ }
+ }
}
/** Returns true if pred is predecessor of block. */
-static int is_pred_of(ir_node *pred, ir_node *b) {
- int i;
- for (i = 0; i < get_Block_n_cfgpreds(b); i++) {
- ir_node *b_pred = get_nodes_block(get_Block_cfgpred(b, i));
- if (b_pred == pred) return 1;
- }
- return 0;
+static bool is_pred_of(ir_node *pred, 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 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.
+ *
+ * @returns The number of predecessors
+ *
+ * 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.
+ *
+ * To perform the test for pos, we must regard predecessors before pos
+ * as already removed.
+ **/
+static unsigned test_whether_dispensable(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_irn_link(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 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
+ * in arrays, and then replacing the old ones. So far we compute new in arrays
+ * for all nodes, not regarding whether there is a possibility for optimization.
+ *
+ * For each predecessor p of a Block b there are three cases:
+ * - 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 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.
+ */
+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 = (merge_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 = (ir_node*)get_irn_link(b); phi != NULL; phi = (ir_node*)next) {
+ assert(is_Phi(phi));
+ next = (ir_node*)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) {
+ ir_graph *irg = get_irn_irg(b);
+ pred = get_Block_cfgpred_block(b, i);
+
+ if (is_Bad(pred)) {
+ /* case Phi 1: maintain Bads, as somebody else is responsible to remove them */
+ in[p_preds++] = new_r_Bad(irg, get_irn_mode(phi));
+ } 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++) {
+ 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 = (ir_node*)get_irn_link(predb); phi; phi = next_phi) {
+ int q_preds = 0;
+ next_phi = (ir_node*)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 .*/
+ 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_irn_link(phi, get_irn_link(b));
+ set_irn_link(b, phi);
+ env->phis_moved = true;
+
+ /* first, copy all 0..k-1 predecessors */
+ for (i = 0; i < k; i++) {
+ pred = get_Block_cfgpred_block(b, i);
+
+ if (is_Bad(pred)) {
+ in[q_preds++] = pred;
+ } 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++) {
+ 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 {
+ 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_irn_link(b) == NULL || p_preds == -1 || (n_preds == p_preds));
+ xfree(in);
+}
-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);
-
- 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. */
- set_Block_block_visited(pred, get_irg_block_visited(current_ir_graph)-1);
- return 1;
- }
- /* Seems to be empty. */
- if (!get_irn_link(b)) {
- /* There are no Phi nodes ==> 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;
+/**
+ * Optimize table-switch Conds.
+ *
+ * @param cond the switch-Cond
+ * @return true if the switch-Cond was optimized
+ */
+static bool handle_switch_cond(ir_node *cond)
+{
+ ir_node *sel = get_Cond_selector(cond);
+ ir_node *proj1 = (ir_node*)get_irn_link(cond);
+ ir_node *proj2 = (ir_node*)get_irn_link(proj1);
+ ir_node *blk = get_nodes_block(cond);
+
+ /* exactly 1 Proj on the Cond node: must be the defaultProj */
+ if (proj2 == NULL) {
+ ir_node *jmp = new_r_Jmp(blk);
+ assert(get_Cond_default_proj(cond) == get_Proj_proj(proj1));
+ /* convert it into a Jmp */
+ exchange(proj1, jmp);
+ return true;
+ }
+
+ /* handle Cond nodes with constant argument. In this case the localopt rules
+ * should have killed all obviously impossible cases.
+ * So the only case left to handle here is 1 defaultProj + 1case
+ * (this one case should be the one taken) */
+ if (get_irn_link(proj2) == NULL) {
+ ir_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);
+ ir_graph *irg = get_irn_irg(cond);
+ ir_node *bad = new_r_Bad(irg, mode_X);
+
+ if (def_num == get_Proj_proj(proj1)) {
+ /* first one is the defProj */
+ if (num == get_Proj_proj(proj2)) {
+ ir_node *jmp = new_r_Jmp(blk);
+ exchange(proj2, jmp);
+ exchange(proj1, bad);
+ return true;
+ }
+ } else if (def_num == get_Proj_proj(proj2)) {
+ /* second one is the defProj */
+ if (num == get_Proj_proj(proj1)) {
+ ir_node *jmp = new_r_Jmp(blk);
+ exchange(proj1, jmp);
+ exchange(proj2, bad);
+ return true;
+ }
+ } else {
+ /* neither: strange, Cond was not optimized so far */
+ if (num == get_Proj_proj(proj1)) {
+ ir_node *jmp = new_r_Jmp(blk);
+ exchange(proj1, jmp);
+ exchange(proj2, bad);
+ return true;
+ } else if (num == get_Proj_proj(proj2)) {
+ ir_node *jmp = new_r_Jmp(blk);
+ exchange(proj2, jmp);
+ exchange(proj1, bad);
+ return true;
+ }
+ }
+ }
+ }
+ return false;
+}
+
+static bool get_phase_flag(ir_phase *block_info, ir_node *block, int offset) {
+ return ((int)phase_get_irn_data(block_info, block)) & (1<<offset);
+}
+static void set_phase_flag(ir_phase *block_info, ir_node *block, int offset) {
+ int data = (int)phase_get_irn_data(block_info, block);
+ data |= (1<<offset);
+ phase_set_irn_data(block_info, block, (void*)data);
+}
+
+static bool has_operations(ir_phase *block_info, ir_node *block) {
+ return get_phase_flag(block_info, block, 1);
+}
+static void set_has_operations(ir_phase *block_info, ir_node *block) {
+ set_phase_flag(block_info, block, 1);
+}
+
+static bool has_phis(ir_phase *block_info, ir_node *block) {
+ return get_phase_flag(block_info, block, 2);
+}
+static void set_has_phis(ir_phase *block_info, ir_node *block) {
+ set_phase_flag(block_info, block, 2);
+}
+
+static bool is_unknown_jump_target(ir_phase *block_info, ir_node *block) {
+ return get_phase_flag(block_info, block, 3);
+}
+static void set_is_unknown_jump_target(ir_phase *block_info, ir_node *block) {
+ set_phase_flag(block_info, block, 3);
+}
+
+/**
+ * Optimize Conds, where true and false jump to the same block into a Jmp
+ *
+ * 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;
+}
+
+static void compute_block_info(ir_node *n, void *x)
+{
+ ir_phase *block_info = (ir_phase *)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(block_info, n);
+ }
+ }
+ } else if (is_Phi(n)) {
+ ir_node *block = get_nodes_block(n);
+ set_has_phis(block_info, block);
+ } else if (is_Jmp(n) || is_Cond(n) || is_Cmp(n) || is_Proj(n)) {
+ /* ignore */
+ } else {
+ ir_node *block = get_nodes_block(n);
+ set_has_operations(block_info, block);
+ }
+}
+
+typedef struct skip_env {
+ bool changed;
+ ir_phase *phase;
+} skip_env;
+
+static void optimize_conds(ir_node *b, void *x)
+{
+ skip_env *env = (skip_env*)x;
+ int i, j;
+ int n_preds = get_Block_n_cfgpreds(b);
+
+ if (has_phis(env->phase,b)) 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(b, i, j);
+ }
+ }
+}
+
+static void remove_empty_blocks(ir_node *b, void *x)
+{
+ skip_env *env = (skip_env*)x;
+ int i;
+ int n_preds = get_Block_n_cfgpreds(b);
+
+ for (i = 0; i < n_preds; ++i) {
+ ir_node *jmp, *jmp_block, *pred, *pred_block;
+
+ jmp = get_Block_cfgpred(b, i);
+ if (!is_Jmp(jmp)) continue;
+ if (is_unknown_jump(jmp)) continue;
+ jmp_block = get_nodes_block(jmp);
+ if (is_unknown_jump_target(env->phase, jmp_block)) continue;
+ if (has_operations(env->phase,jmp_block)) continue;
+ /* jmp_block is an empty block! */
+
+ if (get_Block_n_cfgpreds(jmp_block) != 1) continue;
+ pred = get_Block_cfgpred(jmp_block, 0);
+ exchange(jmp, pred);
+ env->changed = true;
+
+ /* cleanup: jmp_block might have a Keep edge! */
+ pred_block = get_nodes_block(pred);
+ exchange(jmp_block, pred_block);
+ }
+}
+
+/*
+ * Some cfg optimizations, which do not touch Phi nodes */
+static void cfgopt_ignoring_phis(ir_graph *irg) {
+ ir_phase *block_info = new_phase(irg, NULL);
+ skip_env env = { false, block_info };
+
+ irg_walk_graph(irg, compute_block_info, NULL, block_info);
+
+ for(;;) {
+ env.changed = false;
+
+ /* Conds => Jmp optimization; might produce empty blocks */
+ irg_block_walk_graph(irg, optimize_conds, NULL, &env);
+
+ /* Remove empty blocks */
+ irg_block_walk_graph(irg, remove_empty_blocks, NULL, &env);
+ if (env.changed) {
+ set_irg_doms_inconsistent(irg);
+ /* Removing blocks might enable more Cond optimizations */
+ continue;
+ } else {
+ break;
+ }
+ }
+
+ phase_free(block_info);
}
-static void optimize_blocks(ir_node *b, void *env) {
- int i, j, k, max_preds, n_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; i < get_Block_n_cfgpreds(b); i++) {
- max_preds += test_whether_dispensable(b, i);
- }
- in = (ir_node **) malloc(max_preds * sizeof(ir_node *));
-
-/*-
- 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 -*/
- phi = get_irn_link(b);
- while (phi) {
- assert(get_irn_op(phi) == op_Phi);
- /* Find the new predecessors for the Phi */
- 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))) {
- /* 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. */
- ir_node *phi_pred = get_Phi_pred(phi, i);
-
- for (j = 0; j < get_Block_n_cfgpreds(pred); j++) {
- if (get_nodes_block(phi_pred) == pred) {
- assert(get_irn_op(phi_pred) == op_Phi); /* Block is empty!! */
- in[n_preds] = get_Phi_pred(phi_pred, j);
- } else {
- in[n_preds] = phi_pred;
- }
- n_preds++;
- }
- /* The Phi_pred node is replaced now if it is a Phi.
- In Schleifen kann offenbar der entfernte Phi Knoten legal verwendet werden.
- Daher muss der Phiknoten durch den neuen ersetzt werden.
- Weiter muss der alte Phiknoten entfernt werden (durch ersetzen oder
- durch einen Bad) damit er aus den keep_alive verschwinden kann.
- Man sollte also, falls keine Schleife vorliegt, exchange mit new_Bad
- aufrufen. */
- 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 {
- in[n_preds] = get_Phi_pred(phi, i);
- n_preds ++;
- }
- }
- /* Fix the node */
- if (n_preds == 1)
- exchange(phi, in[0]);
- else
- set_irn_in(phi, n_preds, in);
-
- phi = get_irn_link(phi);
- }
-
- /*- This happens only if merge between loop backedge and single loop entry. -*/
- for (k = 0; k < get_Block_n_cfgpreds(b); k++) {
- pred = get_nodes_block(get_Block_cfgpred(b, k));
- if (get_Block_block_visited(pred)+1 < get_irg_block_visited(current_ir_graph)) {
- phi = get_irn_link(pred);
- while (phi) {
- if (get_irn_op(phi) == op_Phi) {
- set_nodes_block(phi, b);
-
- n_preds = 0;
- 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[n_preds] = phi
- Anweisungen.) Trotzdem tuts bisher!! */
- in[n_preds] = phi;
- n_preds++;
- }
- } else {
- in[n_preds] = phi;
- n_preds++;
- }
- }
- for (i = 0; i < get_Phi_n_preds(phi); i++) {
- in[n_preds] = get_Phi_pred(phi, i);
- n_preds++;
- }
- 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++) {
- in[n_preds] = phi;
- n_preds++;
- }
- } else {
- in[n_preds] = phi;
- n_preds++;
- }
- }
- if (n_preds == 1)
- exchange(phi, in[0]);
- else
- set_irn_in(phi, n_preds, in);
- }
- 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))) {
- /* 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. */
- 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++) {
- in[n_preds] = get_Block_cfgpred(pred, j);
- n_preds++;
- }
- /* Remove block as it might be kept alive. */
- exchange(pred, b/*new_Bad()*/);
- } else {
- in[n_preds] = get_Block_cfgpred(b, i);
- n_preds ++;
- }
- }
- set_irn_in(b, n_preds, in);
- free(in);
+/* 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;
+
+ 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");
+
+ /* FIXME: control flow opt destroys block edges. So edges are deactivated
+ * here. Fix the edges! */
+ edges_deactivate(irg);
+
+ 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);
+
+ /* The switch Cond optimization might expose unreachable code, so we loop */
+ for (;;) {
+ int length;
+ ir_node **switch_conds = NULL;
+ env.changed = false;
+ env.phis_moved = false;
+
+ assure_doms(irg);
+
+ /*
+ * 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.
+ */
+ switch_conds = NEW_ARR_F(ir_node*, 0);
+ irg_walk(end, clear_link, collect_nodes, &switch_conds);
+
+ /* handle all collected switch-Conds */
+ length = ARR_LEN(switch_conds);
+ for (i = 0; i < length; ++i) {
+ ir_node *cond = switch_conds[i];
+ env.changed |= handle_switch_cond(cond);
+ }
+ DEL_ARR_F(switch_conds);
+
+ if (!env.changed) break;
+
+ set_irg_doms_inconsistent(irg);
+ set_irg_extblk_inconsistent(irg);
+ set_irg_entity_usage_state(irg, ir_entity_usage_not_computed);
+ }
+
+ /* 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_doms(irg);
+ irg_block_walk_graph(irg, optimize_blocks, NULL, &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);
+
+ 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);
+ 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;
+ }
+ }
+ }
+
+ if (env.changed) {
+ /* Handle graph state if was changed. */
+ set_irg_doms_inconsistent(irg);
+ set_irg_extblk_inconsistent(irg);
+ set_irg_entity_usage_state(irg, ir_entity_usage_not_computed);
+ }
}
-void optimize_cf(ir_graph *irg) {
- int i;
- 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);
-
- /* Use block visited flag to mark non-empty blocks. */
- inc_irg_block_visited(irg);
- irg_walk(end, merge_blocks, collect_nodes, &dom_state);
-
- /* 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;
-
- /* 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;
+/* 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);
}