/*
- * Copyright (C) 1995-2007 University of Karlsruhe. All right reserved.
+ * Copyright (C) 1995-2008 University of Karlsruhe. All right reserved.
*
* This file is part of libFirm.
*
# include "config.h"
#endif
+#include "iroptimize.h"
+
#include <assert.h>
#include "plist.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)
+
/**
- * Block walker, replacing binary Conds that jumps twice into the same block
+ * Replace binary Conds that jumps twice into the same block
* by a simple Jmp.
* E.g.
* @verbatim
* 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 *env) {
+static int remove_senseless_conds(ir_node *bl) {
int i, j;
int n = get_Block_n_cfgpreds(bl);
- int *changed = env;
-
- assert(is_Block(bl));
+ int changed = 0;
for (i = 0; i < n; ++i) {
ir_node *pred_i = get_Block_cfgpred(bl, i);
set_irn_n(bl, j, new_Bad());
DBG_OPT_IFSIM2(cond_i, jmp);
- *changed = 1;
+ changed = 1;
break;
}
}
}
}
+ return changed;
}
/** An environment for merge_blocks and collect nodes. */
typedef struct _merge_env {
- int changed;
- plist_t *list;
+ 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;
/**
}
}
-
/**
* 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) {
+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 */
+ /* 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 *pred_X = get_Block_cfgpred(block, i);
+ ir_node *skipped = skip_Tuple(pred_X);
- if (! is_Bad(pred_X)) {
- ir_node *pred_bl = get_nodes_block(skip_Proj(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 blocks */
+ set_Block_removable(block);
}
/**
* Collects all Phi nodes in link list of Block.
- * Marks all blocks "block_visited" if they contain a node other
+ * 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 *ctx) {
- ir_op *op = get_irn_op(n);
+ ir_opcode code = get_irn_opcode(n);
merge_env *env = ctx;
- if (op != op_Block) {
- ir_node *b = get_nodes_block(n);
+ 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 (op == op_Phi) {
+ 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 (op != op_Jmp && !is_Bad(b)) { /* Check for non empty block. */
- mark_Block_block_visited(b);
+ } else if (code != iro_Jmp && !is_Bad(b)) { /* Check for non-empty block. */
+ set_Block_non_removable(b);
- if (op == op_Proj) { /* link Proj nodes */
+ 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 (op == op_Cond) {
+ } 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 */
/** Returns true if pred is predecessor of block. */
static int is_pred_of(ir_node *pred, ir_node *b) {
- int i, n;
+ int i;
- for (i = 0, n = get_Block_n_cfgpreds(b); i < n; ++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;
+ if (b_pred == pred)
+ return 1;
}
return 0;
}
if (is_Block_dead(pred))
return 0;
- if (get_Block_block_visited(pred) + 1
- < get_irg_block_visited(current_ir_graph)) {
-
+ 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_block_visited(pred, get_irg_block_visited(current_ir_graph)-1);
+ set_Block_non_removable(pred);
return 1;
}
/* Seems to be empty. At least we detected this in collect_nodes. */
- if (!get_irn_link(b)) {
+ if (get_irn_link(b) == NULL) {
/* There are no Phi nodes ==> all predecessors are dispensable. */
n_preds = get_Block_n_cfgpreds(pred);
} else {
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++) {
+ 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;
return n_preds;
non_dispensable:
- set_Block_block_visited(pred, get_irg_block_visited(current_ir_graph)-1);
+ set_Block_non_removable(pred);
return 1;
}
* @@@ 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) {
+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;
ir_node **in;
- int *changed = env;
+ merge_env *env = ctx;
/* Count the number of predecessor if this block is merged with pred blocks
that are empty. */
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))) {
+ if (is_Block_dead(pred)) {
/* case Phi 1: Do nothing */
- }
- else if (get_Block_block_visited(pred) + 1
- < get_irg_block_visited(current_ir_graph)) {
+ } 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);
exchange(phi, in[0]);
else
set_irn_in(phi, p_preds, in);
- *changed = 1;
+ env->changed = 1;
phi = get_irn_link(phi);
}
for (k = 0, n = get_Block_n_cfgpreds(b); k < n; ++k) {
ir_node *predb = get_nodes_block(get_Block_cfgpred(b, k));
- if (get_Block_block_visited(predb) + 1 < get_irg_block_visited(current_ir_graph)) {
+ 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 */
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_Bad(pred)) {
+ if (is_Block_dead(pred)) {
/* Do nothing */
- } else if (get_Block_block_visited(pred) + 1
- < get_irg_block_visited(current_ir_graph)) {
+ } 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)))
/* 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));
+ pred = get_Block_cfgpred_block(b, i);
- if (is_Bad(get_Block_cfgpred(b, i))) {
+ if (is_Block_dead(pred)) {
/* Do nothing */
- } else if (get_Block_block_visited(pred) +1
- < get_irg_block_visited(current_ir_graph)) {
+ } 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)))
exchange(phi, in[0]);
else
set_irn_in(phi, q_preds, in);
- *changed = 1;
+ env->changed = 1;
assert(q_preds <= max_preds);
// assert(p_preds == q_preds && "Wrong Phi Fix");
for (i = 0; i < get_Block_n_cfgpreds(b); i++) {
pred = get_Block_cfgpred_block(b, i);
- if (is_Bad(pred)) {
+ if (is_Block_dead(pred)) {
/* case 1: Do nothing */
- } else if (get_Block_block_visited(pred) +1
- < get_irg_block_visited(current_ir_graph)) {
+ } 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);
/* 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);
+ 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_block))
- in[n_preds++] = pred_block;
+ if (! is_Bad(pred_X))
+ in[n_preds++] = pred_X;
}
/* Remove block as it might be kept alive. */
exchange(pred, b/*new_Bad()*/);
assert(n_preds <= max_preds);
set_irn_in(b, n_preds, in);
- *changed = 1;
+ 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 *env) {
+static void remove_simple_blocks(ir_node *block, void *ctx) {
ir_node *new_blk = equivalent_node(block);
- int *changed = env;
+ merge_env *env = ctx;
if (new_blk != block) {
exchange(block, new_blk);
- *changed = 1;
+ env->changed = 1;
}
}
* 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, j, n;
current_ir_graph = irg;
- /* FIXME: is this still needed? */
+ /* FIXME: control flow opt destroys block edges. So edges are deactivated here. Fix the edges! */
edges_deactivate(irg);
- env.changed = 0;
- if (get_opt_optimize() && get_opt_unreachable_code()) {
- ir_node *end;
-
- /* kill dead blocks using dom info */
- assure_doms(irg);
- irg_block_walk_graph(irg, NULL, remove_dead_block_cf, &env.changed);
-
- /* fix the keep-alives */
- end = get_irg_end(irg);
- 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) < 0) {
- set_End_keepalive(end, i, new_Bad());
- env.changed = 1;
- }
- } else if (is_Block_dead(get_nodes_block(ka)) ||
- get_Block_dom_depth(get_nodes_block(ka)) < 0) {
- /* do NOT keep nodes in dead blocks */
+ /* 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 */
+ 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());
env.changed = 1;
}
+ } else if (is_Block_dead(get_nodes_block(ka)) ||
+ get_Block_dom_depth(get_nodes_block(ka)) < 0) {
+ /* do NOT keep nodes in dead blocks */
+ set_End_keepalive(end, i, new_Bad());
+ env.changed = 1;
}
}
- irg_block_walk_graph(irg, NULL, remove_senseless_conds, &env.changed);
- /* Use block visited flag to mark non-empty blocks. */
- inc_irg_block_visited(irg);
- set_using_block_visited(irg);
- set_using_irn_link(irg);
+ ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);
env.list = plist_new();
irg_walk(end, merge_blocks, collect_nodes, &env);
- clear_using_block_visited(irg);
- clear_using_irn_link(irg);
+ 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);
+ env.changed = 0;
+ }
/* handle all collected switch-Conds */
foreach_plist(env.list, el) {
plist_free(env.list);
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);
+ /* 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(get_irg_end_block(irg), optimize_blocks, remove_simple_blocks, &env.changed);
+ irg_block_walk(get_irg_end_block(irg), optimize_blocks, remove_simple_blocks, &env);
/* Walk all keep alives, optimize them if block, add to new in-array
for end if useful. */
/* in rare cases a node may be kept alive more than once, use the visited flag to detect this */
inc_irg_visited(irg);
- set_using_visited(irg);
+ ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED);
/* fix the keep alive */
for (i = j = 0; i < n; i++) {
if (irn_not_visited(ka)) {
ir_op *op = get_irn_op(ka);
- if ((op == op_Block) && Block_not_block_visited(ka)) {
+ if ((op == op_Block) && !Block_block_visited(ka)) {
/* irg_block_walk() will increase the block visited flag, but we must visit only
these blocks that are not visited yet, so decrease it first. */
set_irg_block_visited(irg, get_irg_block_visited(irg) - 1);
irg_block_walk(ka, optimize_blocks, remove_simple_blocks, &env.changed);
mark_irn_visited(ka);
in[j++] = ka;
- } else if (op == op_Phi) {
+ } else {
mark_irn_visited(ka);
/* don't keep alive dead blocks */
if (! is_Block_dead(get_nodes_block(ka)))
in[j++] = ka;
- } else if (is_op_keep(op)) {
- mark_irn_visited(ka);
- if (! is_Block_dead(get_nodes_block(ka)))
- in[j++] = ka;
}
}
}
env.changed = 1;
}
- clear_using_visited(irg);
+ 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) {
+ 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_loopinfo_inconsistent(irg);
}
+
/* 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. */
projects / libfirm / blobdiff