/* Control flow graph analysis code for GNU compiler.
Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
- 1999, 2000, 2001, 2003, 2004 Free Software Foundation, Inc.
+ 1999, 2000, 2001, 2003, 2004, 2005 Free Software Foundation, Inc.
This file is part of GCC.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING. If not, write to the Free
-Software Foundation, 59 Temple Place - Suite 330, Boston, MA
-02111-1307, USA. */
+Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301, USA. */
/* This file contains various simple utilities to analyze the CFG. */
#include "config.h"
programs that fail to return a value. Its effect is to
keep the return value from being live across the entire
function. If we allow it to be skipped, we introduce the
- possibility for register livetime aborts. */
+ possibility for register lifetime confusion. */
if (GET_CODE (PATTERN (insn)) == CLOBBER
&& REG_P (XEXP (PATTERN (insn), 0))
&& REG_FUNCTION_VALUE_P (XEXP (PATTERN (insn), 0)))
rtx insn;
if (bb == EXIT_BLOCK_PTR || bb == ENTRY_BLOCK_PTR
- || EDGE_COUNT (bb->succs) != 1)
+ || !single_succ_p (bb))
return false;
for (insn = BB_HEAD (bb); insn != BB_END (bb); insn = NEXT_INSN (insn))
Steven Muchnick
Morgan Kaufmann, 1997
- and heavily borrowed from flow_depth_first_order_compute. */
+ and heavily borrowed from pre_and_rev_post_order_compute. */
bool
mark_dfs_back_edges (void)
bool found = false;
/* Allocate the preorder and postorder number arrays. */
- pre = xcalloc (last_basic_block, sizeof (int));
- post = xcalloc (last_basic_block, sizeof (int));
+ pre = XCNEWVEC (int, last_basic_block);
+ post = XCNEWVEC (int, last_basic_block);
/* Allocate stack for back-tracking up CFG. */
- stack = xmalloc ((n_basic_blocks + 1) * sizeof (edge_iterator));
+ stack = XNEWVEC (edge_iterator, n_basic_blocks + 1);
sp = 0;
/* Allocate bitmap to track nodes that have been visited. */
edge_iterator ei;
basic_block *tos, *worklist, bb;
- tos = worklist = xmalloc (sizeof (basic_block) * n_basic_blocks);
+ tos = worklist = XNEWVEC (basic_block, n_basic_blocks);
/* Clear all the reachability flags. */
basic_block b = *--tos;
FOR_EACH_EDGE (e, ei, b->succs)
- if (!(e->dest->flags & BB_REACHABLE))
- {
- *tos++ = e->dest;
- e->dest->flags |= BB_REACHABLE;
- }
+ {
+ basic_block dest = e->dest;
+
+ if (!(dest->flags & BB_REACHABLE))
+ {
+ *tos++ = dest;
+ dest->flags |= BB_REACHABLE;
+ }
+ }
}
free (worklist);
basic_block bb;
edge_iterator ei;
- block_count = n_basic_blocks + 2; /* Include the entry and exit blocks. */
+ block_count = n_basic_blocks; /* Include the entry and exit blocks. */
num_edges = 0;
num_edges += EDGE_COUNT (bb->succs);
}
- elist = xmalloc (sizeof (struct edge_list));
+ elist = XNEW (struct edge_list);
elist->num_blocks = block_count;
elist->num_edges = num_edges;
- elist->index_to_edge = xmalloc (sizeof (edge) * num_edges);
+ elist->index_to_edge = XNEWVEC (edge, num_edges);
num_edges = 0;
int x;
fprintf (f, "Compressed edge list, %d BBs + entry & exit, and %d edges\n",
- elist->num_blocks - 2, elist->num_edges);
+ elist->num_blocks, elist->num_edges);
for (x = 0; x < elist->num_edges; x++)
{
void
flow_nodes_print (const char *str, const sbitmap nodes, FILE *file)
{
- int node;
+ unsigned int node = 0;
+ sbitmap_iterator sbi;
if (! nodes)
return;
fprintf (file, "%s { ", str);
- EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {fprintf (file, "%d ", node);});
+ EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, sbi)
+ fprintf (file, "%d ", node);
fputs ("}\n", file);
}
return;
}
\f
-/* Compute reverse top sort order. */
+/* Compute reverse top sort order.
+ This is computing a post order numbering of the graph. */
-void
-flow_reverse_top_sort_order_compute (int *rts_order)
+int
+post_order_compute (int *post_order, bool include_entry_exit)
{
edge_iterator *stack;
int sp;
- int postnum = 0;
+ int post_order_num = 0;
sbitmap visited;
+ if (include_entry_exit)
+ post_order[post_order_num++] = EXIT_BLOCK;
+
/* Allocate stack for back-tracking up CFG. */
- stack = xmalloc ((n_basic_blocks + 1) * sizeof (edge_iterator));
+ stack = XNEWVEC (edge_iterator, n_basic_blocks + 1);
sp = 0;
/* Allocate bitmap to track nodes that have been visited. */
time, check its successors. */
stack[sp++] = ei_start (dest->succs);
else
- rts_order[postnum++] = dest->index;
+ post_order[post_order_num++] = dest->index;
}
else
{
if (ei_one_before_end_p (ei) && src != ENTRY_BLOCK_PTR)
- rts_order[postnum++] = src->index;
+ post_order[post_order_num++] = src->index;
if (!ei_one_before_end_p (ei))
ei_next (&stack[sp - 1]);
}
}
+ if (include_entry_exit)
+ post_order[post_order_num++] = ENTRY_BLOCK;
+
free (stack);
sbitmap_free (visited);
+ return post_order_num;
}
/* Compute the depth first search order and store in the array
- DFS_ORDER if nonzero, marking the nodes visited in VISITED. If
- RC_ORDER is nonzero, return the reverse completion number for each
+ PRE_ORDER if nonzero, marking the nodes visited in VISITED. If
+ REV_POST_ORDER is nonzero, return the reverse completion number for each
node. Returns the number of nodes visited. A depth first search
tries to get as far away from the starting point as quickly as
- possible. */
+ possible.
+
+ pre_order is a really a preorder numbering of the graph.
+ rev_post_order is really a reverse postorder numbering of the graph.
+ */
int
-flow_depth_first_order_compute (int *dfs_order, int *rc_order)
+pre_and_rev_post_order_compute (int *pre_order, int *rev_post_order,
+ bool include_entry_exit)
{
edge_iterator *stack;
int sp;
- int dfsnum = 0;
- int rcnum = n_basic_blocks - 1;
+ int pre_order_num = 0;
+ int rev_post_order_num = n_basic_blocks - 1;
sbitmap visited;
/* Allocate stack for back-tracking up CFG. */
- stack = xmalloc ((n_basic_blocks + 1) * sizeof (edge_iterator));
+ stack = XNEWVEC (edge_iterator, n_basic_blocks + 1);
sp = 0;
+ if (include_entry_exit)
+ {
+ if (pre_order)
+ pre_order[pre_order_num] = ENTRY_BLOCK;
+ pre_order_num++;
+ if (rev_post_order)
+ rev_post_order[rev_post_order_num--] = ENTRY_BLOCK;
+ }
+ else
+ rev_post_order_num -= NUM_FIXED_BLOCKS;
+
/* Allocate bitmap to track nodes that have been visited. */
visited = sbitmap_alloc (last_basic_block);
/* Mark that we have visited the destination. */
SET_BIT (visited, dest->index);
- if (dfs_order)
- dfs_order[dfsnum] = dest->index;
+ if (pre_order)
+ pre_order[pre_order_num] = dest->index;
- dfsnum++;
+ pre_order_num++;
if (EDGE_COUNT (dest->succs) > 0)
/* Since the DEST node has been visited for the first
time, check its successors. */
stack[sp++] = ei_start (dest->succs);
- else if (rc_order)
+ else if (rev_post_order)
/* There are no successors for the DEST node so assign
its reverse completion number. */
- rc_order[rcnum--] = dest->index;
+ rev_post_order[rev_post_order_num--] = dest->index;
}
else
{
if (ei_one_before_end_p (ei) && src != ENTRY_BLOCK_PTR
- && rc_order)
+ && rev_post_order)
/* There are no more successors for the SRC node
so assign its reverse completion number. */
- rc_order[rcnum--] = src->index;
+ rev_post_order[rev_post_order_num--] = src->index;
if (!ei_one_before_end_p (ei))
ei_next (&stack[sp - 1]);
free (stack);
sbitmap_free (visited);
- /* The number of nodes visited should be the number of blocks. */
- gcc_assert (dfsnum == n_basic_blocks);
+ if (include_entry_exit)
+ {
+ if (pre_order)
+ pre_order[pre_order_num] = EXIT_BLOCK;
+ pre_order_num++;
+ if (rev_post_order)
+ rev_post_order[rev_post_order_num--] = EXIT_BLOCK;
+ /* The number of nodes visited should be the number of blocks. */
+ gcc_assert (pre_order_num == n_basic_blocks);
+ }
+ else
+ /* The number of nodes visited should be the number of blocks minus
+ the entry and exit blocks which are not visited here. */
+ gcc_assert (pre_order_num == n_basic_blocks - NUM_FIXED_BLOCKS);
- return dfsnum;
+ return pre_order_num;
}
/* Compute the depth first search order on the _reverse_ graph and
flow_dfs_compute_reverse_init (depth_first_search_ds data)
{
/* Allocate stack for back-tracking up CFG. */
- data->stack = xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1))
- * sizeof (basic_block));
+ data->stack = XNEWVEC (basic_block, n_basic_blocks);
data->sp = 0;
/* Allocate bitmap to track nodes that have been visited. */
- data->visited_blocks = sbitmap_alloc (last_basic_block - (INVALID_BLOCK + 1));
+ data->visited_blocks = sbitmap_alloc (last_basic_block);
/* None of the nodes in the CFG have been visited yet. */
sbitmap_zero (data->visited_blocks);
flow_dfs_compute_reverse_add_bb (depth_first_search_ds data, basic_block bb)
{
data->stack[data->sp++] = bb;
- SET_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1));
+ SET_BIT (data->visited_blocks, bb->index);
}
/* Continue the depth-first search through the reverse graph starting with the
/* Perform depth-first search on adjacent vertices. */
FOR_EACH_EDGE (e, ei, bb->preds)
- if (!TEST_BIT (data->visited_blocks,
- e->src->index - (INVALID_BLOCK + 1)))
+ if (!TEST_BIT (data->visited_blocks, e->src->index))
flow_dfs_compute_reverse_add_bb (data, e->src);
}
/* Determine if there are unvisited basic blocks. */
FOR_BB_BETWEEN (bb, last_unvisited, NULL, prev_bb)
- if (!TEST_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1)))
+ if (!TEST_BIT (data->visited_blocks, bb->index))
return bb;
return NULL;
{
basic_block *st, lbb;
int sp = 0, tv = 0;
+ unsigned size;
+
+ /* A bitmap to keep track of visited blocks. Allocating it each time
+ this function is called is not possible, since dfs_enumerate_from
+ is often used on small (almost) disjoint parts of cfg (bodies of
+ loops), and allocating a large sbitmap would lead to quadratic
+ behavior. */
+ static sbitmap visited;
+ static unsigned v_size;
+
+#define MARK_VISITED(BB) (SET_BIT (visited, (BB)->index))
+#define UNMARK_VISITED(BB) (RESET_BIT (visited, (BB)->index))
+#define VISITED_P(BB) (TEST_BIT (visited, (BB)->index))
+
+ /* Resize the VISITED sbitmap if necessary. */
+ size = last_basic_block;
+ if (size < 10)
+ size = 10;
+
+ if (!visited)
+ {
+
+ visited = sbitmap_alloc (size);
+ sbitmap_zero (visited);
+ v_size = size;
+ }
+ else if (v_size < size)
+ {
+ /* Ensure that we increase the size of the sbitmap exponentially. */
+ if (2 * v_size > size)
+ size = 2 * v_size;
+
+ visited = sbitmap_resize (visited, size, 0);
+ v_size = size;
+ }
- st = xcalloc (rslt_max, sizeof (basic_block));
+ st = XCNEWVEC (basic_block, rslt_max);
rslt[tv++] = st[sp++] = bb;
- bb->flags |= BB_VISITED;
+ MARK_VISITED (bb);
while (sp)
{
edge e;
edge_iterator ei;
lbb = st[--sp];
if (reverse)
- {
+ {
FOR_EACH_EDGE (e, ei, lbb->preds)
- if (!(e->src->flags & BB_VISITED) && predicate (e->src, data))
+ if (!VISITED_P (e->src) && predicate (e->src, data))
{
- gcc_assert (tv != rslt_max);
- rslt[tv++] = st[sp++] = e->src;
- e->src->flags |= BB_VISITED;
+ gcc_assert (tv != rslt_max);
+ rslt[tv++] = st[sp++] = e->src;
+ MARK_VISITED (e->src);
}
- }
+ }
else
- {
+ {
FOR_EACH_EDGE (e, ei, lbb->succs)
- if (!(e->dest->flags & BB_VISITED) && predicate (e->dest, data))
+ if (!VISITED_P (e->dest) && predicate (e->dest, data))
{
- gcc_assert (tv != rslt_max);
- rslt[tv++] = st[sp++] = e->dest;
- e->dest->flags |= BB_VISITED;
+ gcc_assert (tv != rslt_max);
+ rslt[tv++] = st[sp++] = e->dest;
+ MARK_VISITED (e->dest);
}
}
}
free (st);
for (sp = 0; sp < tv; sp++)
- rslt[sp]->flags &= ~BB_VISITED;
+ UNMARK_VISITED (rslt[sp]);
return tv;
+#undef MARK_VISITED
+#undef UNMARK_VISITED
+#undef VISITED_P
}
-/* Computing the Dominance Frontier:
+/* Compute dominance frontiers, ala Harvey, Ferrante, et al.
- As described in Morgan, section 3.5, this may be done simply by
- walking the dominator tree bottom-up, computing the frontier for
- the children before the parent. When considering a block B,
- there are two cases:
+ This algorithm can be found in Timothy Harvey's PhD thesis, at
+ http://www.cs.rice.edu/~harv/dissertation.pdf in the section on iterative
+ dominance algorithms.
- (1) A flow graph edge leaving B that does not lead to a child
- of B in the dominator tree must be a block that is either equal
- to B or not dominated by B. Such blocks belong in the frontier
- of B.
+ First, we identify each join point, j (any node with more than one
+ incoming edge is a join point).
- (2) Consider a block X in the frontier of one of the children C
- of B. If X is not equal to B and is not dominated by B, it
- is in the frontier of B. */
+ We then examine each predecessor, p, of j and walk up the dominator tree
+ starting at p.
-static void
-compute_dominance_frontiers_1 (bitmap *frontiers, basic_block bb, sbitmap done)
-{
- edge e;
- edge_iterator ei;
- basic_block c;
+ We stop the walk when we reach j's immediate dominator - j is in the
+ dominance frontier of each of the nodes in the walk, except for j's
+ immediate dominator. Intuitively, all of the rest of j's dominators are
+ shared by j's predecessors as well.
+ Since they dominate j, they will not have j in their dominance frontiers.
- SET_BIT (done, bb->index);
+ The number of nodes touched by this algorithm is equal to the size
+ of the dominance frontiers, no more, no less.
+*/
- /* Do the frontier of the children first. Not all children in the
- dominator tree (blocks dominated by this one) are children in the
- CFG, so check all blocks. */
- for (c = first_dom_son (CDI_DOMINATORS, bb);
- c;
- c = next_dom_son (CDI_DOMINATORS, c))
- {
- if (! TEST_BIT (done, c->index))
- compute_dominance_frontiers_1 (frontiers, c, done);
- }
-
- /* Find blocks conforming to rule (1) above. */
- FOR_EACH_EDGE (e, ei, bb->succs)
- {
- if (e->dest == EXIT_BLOCK_PTR)
- continue;
- if (get_immediate_dominator (CDI_DOMINATORS, e->dest) != bb)
- bitmap_set_bit (frontiers[bb->index], e->dest->index);
- }
- /* Find blocks conforming to rule (2). */
- for (c = first_dom_son (CDI_DOMINATORS, bb);
- c;
- c = next_dom_son (CDI_DOMINATORS, c))
+static void
+compute_dominance_frontiers_1 (bitmap *frontiers)
+{
+ edge p;
+ edge_iterator ei;
+ basic_block b;
+ FOR_EACH_BB (b)
{
- unsigned x;
- bitmap_iterator bi;
-
- EXECUTE_IF_SET_IN_BITMAP (frontiers[c->index], 0, x, bi)
+ if (EDGE_COUNT (b->preds) >= 2)
{
- if (get_immediate_dominator (CDI_DOMINATORS, BASIC_BLOCK (x)) != bb)
- bitmap_set_bit (frontiers[bb->index], x);
+ FOR_EACH_EDGE (p, ei, b->preds)
+ {
+ basic_block runner = p->src;
+ basic_block domsb;
+ if (runner == ENTRY_BLOCK_PTR)
+ continue;
+
+ domsb = get_immediate_dominator (CDI_DOMINATORS, b);
+ while (runner != domsb)
+ {
+ if (bitmap_bit_p (frontiers[runner->index], b->index))
+ break;
+ bitmap_set_bit (frontiers[runner->index],
+ b->index);
+ runner = get_immediate_dominator (CDI_DOMINATORS,
+ runner);
+ }
+ }
}
}
}
void
compute_dominance_frontiers (bitmap *frontiers)
{
- sbitmap done = sbitmap_alloc (last_basic_block);
-
timevar_push (TV_DOM_FRONTIERS);
- sbitmap_zero (done);
-
- compute_dominance_frontiers_1 (frontiers, EDGE_SUCC (ENTRY_BLOCK_PTR, 0)->dest, done);
-
- sbitmap_free (done);
+ compute_dominance_frontiers_1 (frontiers);
timevar_pop (TV_DOM_FRONTIERS);
}
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