/* Natural loop discovery code for GNU compiler.
- Copyright (C) 2000, 2001, 2003 Free Software Foundation, Inc.
+ Copyright (C) 2000, 2001, 2003, 2004 Free Software Foundation, Inc.
This file is part of GCC.
#include "toplev.h"
#include "cfgloop.h"
#include "flags.h"
+#include "tree.h"
+#include "tree-flow.h"
/* Ratio of frequencies of edges so that one of more latch edges is
considered to belong to inner loop with same header. */
#define HEAVY_EDGE_RATIO 8
+#define HEADER_BLOCK(B) (* (int *) (B)->aux)
+#define LATCH_EDGE(E) (*(int *) (E)->aux)
+
static void flow_loops_cfg_dump (const struct loops *, FILE *);
static void flow_loop_entry_edges_find (struct loop *);
static void flow_loop_exit_edges_find (struct loop *);
static int flow_loop_nodes_find (basic_block, struct loop *);
static void flow_loop_pre_header_scan (struct loop *);
-static basic_block flow_loop_pre_header_find (basic_block, dominance_info);
+static basic_block flow_loop_pre_header_find (basic_block);
static int flow_loop_level_compute (struct loop *);
static int flow_loops_level_compute (struct loops *);
static void establish_preds (struct loop *);
-static basic_block make_forwarder_block (basic_block, int, int, edge, int);
static void canonicalize_loop_headers (void);
static bool glb_enum_p (basic_block, void *);
-static void redirect_edge_with_latch_update (edge, basic_block);
\f
/* Dump loop related CFG information. */
int i;
basic_block bb;
- if (! loops->num || ! file || ! loops->cfg.dom)
+ if (! loops->num || ! file)
return;
FOR_EACH_BB (bb)
bool
flow_loop_nested_p (const struct loop *outer, const struct loop *loop)
{
- return loop->depth > outer->depth
- && loop->pred[outer->depth] == outer;
+ return (loop->depth > outer->depth
+ && loop->pred[outer->depth] == outer);
+}
+
+/* Returns the loop such that LOOP is nested DEPTH (indexed from zero)
+ loops within LOOP. */
+
+struct loop *
+superloop_at_depth (struct loop *loop, unsigned depth)
+{
+ if (depth > (unsigned) loop->depth)
+ abort ();
+
+ if (depth == (unsigned) loop->depth)
+ return loop;
+
+ return loop->pred[depth];
}
/* Dump the loop information specified by LOOP to the stream FILE
free (loops->parray);
loops->parray = NULL;
- if (loops->cfg.dom)
- free_dominance_info (loops->cfg.dom);
-
if (loops->cfg.dfs_order)
free (loops->cfg.dfs_order);
if (loops->cfg.rc_order)
if (! num_entries)
abort ();
- loop->entry_edges = (edge *) xmalloc (num_entries * sizeof (edge *));
+ loop->entry_edges = xmalloc (num_entries * sizeof (edge *));
num_entries = 0;
for (e = loop->header->pred; e; e = e->pred_next)
return;
}
- loop->exit_edges = (edge *) xmalloc (num_exits * sizeof (edge *));
+ loop->exit_edges = xmalloc (num_exits * sizeof (edge *));
/* Store all exiting edges into an array. */
num_exits = 0;
if (loop->latch->loop_father != loop)
{
- stack = (basic_block *) xmalloc (n_basic_blocks * sizeof (basic_block));
+ stack = xmalloc (n_basic_blocks * sizeof (basic_block));
sp = 0;
num_nodes++;
stack[sp++] = loop->latch;
num++)
ebb = ebb->pred->src;
- loop->pre_header_edges = (edge *) xmalloc (num * sizeof (edge));
+ loop->pre_header_edges = xmalloc (num * sizeof (edge));
loop->num_pre_header_edges = num;
/* Store edges in order that they are followed. The source of the first edge
}
/* Return the block for the pre-header of the loop with header
- HEADER where DOM specifies the dominator information. Return NULL if
- there is no pre-header. */
+ HEADER. Return NULL if there is no pre-header. */
static basic_block
-flow_loop_pre_header_find (basic_block header, dominance_info dom)
+flow_loop_pre_header_find (basic_block header)
{
basic_block pre_header;
edge e;
basic_block node = e->src;
if (node != ENTRY_BLOCK_PTR
- && ! dominated_by_p (dom, node, header))
+ && ! dominated_by_p (CDI_DOMINATORS, node, header))
{
if (pre_header == NULL)
pre_header = node;
about it specified by FLAGS. */
int
-flow_loop_scan (struct loops *loops, struct loop *loop, int flags)
+flow_loop_scan (struct loop *loop, int flags)
{
if (flags & LOOP_ENTRY_EDGES)
{
if (flags & LOOP_PRE_HEADER)
{
/* Look to see if the loop has a pre-header node. */
- loop->pre_header
- = flow_loop_pre_header_find (loop->header, loops->cfg.dom);
+ loop->pre_header = flow_loop_pre_header_find (loop->header);
/* Find the blocks within the extended basic block of
the loop pre-header. */
return 1;
}
-#define HEADER_BLOCK(B) (* (int *) (B)->aux)
-#define LATCH_EDGE(E) (*(int *) (E)->aux)
+/* A callback to update latch and header info for basic block JUMP created
+ by redirecting an edge. */
-/* Redirect edge and update latch and header info. */
static void
-redirect_edge_with_latch_update (edge e, basic_block to)
+update_latch_info (basic_block jump)
{
- basic_block jump;
-
- jump = redirect_edge_and_branch_force (e, to);
- if (jump)
- {
- alloc_aux_for_block (jump, sizeof (int));
- HEADER_BLOCK (jump) = 0;
- alloc_aux_for_edge (jump->pred, sizeof (int));
- LATCH_EDGE (jump->succ) = LATCH_EDGE (e);
- LATCH_EDGE (jump->pred) = 0;
- }
+ alloc_aux_for_block (jump, sizeof (int));
+ HEADER_BLOCK (jump) = 0;
+ alloc_aux_for_edge (jump->pred, sizeof (int));
+ LATCH_EDGE (jump->pred) = 0;
+ set_immediate_dominator (CDI_DOMINATORS, jump, jump->pred->src);
}
-/* Split BB into entry part and rest; if REDIRECT_LATCH, redirect edges
- marked as latch into entry part, analogically for REDIRECT_NONLATCH.
- In both of these cases, ignore edge EXCEPT. If CONN_LATCH, set edge
- between created entry part and BB as latch one. Return created entry
- part. */
+/* A callback for make_forwarder block, to redirect all edges except for
+ MFB_KJ_EDGE to the entry part. E is the edge for that we should decide
+ whether to redirect it. */
-static basic_block
-make_forwarder_block (basic_block bb, int redirect_latch, int redirect_nonlatch, edge except, int conn_latch)
+static edge mfb_kj_edge;
+static bool
+mfb_keep_just (edge e)
{
- edge e, next_e, fallthru;
- basic_block dummy;
- rtx insn;
-
- insn = PREV_INSN (first_insn_after_basic_block_note (bb));
-
- /* For empty block split_block will return NULL. */
- if (bb->end == insn)
- emit_note_after (NOTE_INSN_DELETED, insn);
-
- fallthru = split_block (bb, insn);
- dummy = fallthru->src;
- bb = fallthru->dest;
-
- bb->aux = xmalloc (sizeof (int));
- HEADER_BLOCK (dummy) = 0;
- HEADER_BLOCK (bb) = 1;
-
- /* Redirect back edges we want to keep. */
- for (e = dummy->pred; e; e = next_e)
- {
- next_e = e->pred_next;
- if (e == except
- || !((redirect_latch && LATCH_EDGE (e))
- || (redirect_nonlatch && !LATCH_EDGE (e))))
- {
- dummy->frequency -= EDGE_FREQUENCY (e);
- dummy->count -= e->count;
- if (dummy->frequency < 0)
- dummy->frequency = 0;
- if (dummy->count < 0)
- dummy->count = 0;
- redirect_edge_with_latch_update (e, bb);
- }
- }
+ return e != mfb_kj_edge;
+}
- alloc_aux_for_edge (fallthru, sizeof (int));
- LATCH_EDGE (fallthru) = conn_latch;
+/* A callback for make_forwarder block, to redirect the latch edges into an
+ entry part. E is the edge for that we should decide whether to redirect
+ it. */
- return dummy;
+static bool
+mfb_keep_nonlatch (edge e)
+{
+ return LATCH_EDGE (e);
}
/* Takes care of merging natural loops with shared headers. */
+
static void
canonicalize_loop_headers (void)
{
- dominance_info dom;
basic_block header;
edge e;
- /* Compute the dominators. */
- dom = calculate_dominance_info (CDI_DOMINATORS);
-
alloc_aux_for_blocks (sizeof (int));
alloc_aux_for_edges (sizeof (int));
have_abnormal_edge = 1;
if (latch != ENTRY_BLOCK_PTR
- && dominated_by_p (dom, latch, header))
+ && dominated_by_p (CDI_DOMINATORS, latch, header))
{
num_latches++;
LATCH_EDGE (e) = 1;
FOR_EACH_BB (header)
{
- int num_latch;
- int want_join_latch;
int max_freq, is_heavy;
- edge heavy;
-
- if (!HEADER_BLOCK (header))
- continue;
-
- num_latch = HEADER_BLOCK (header);
-
- want_join_latch = (num_latch > 1);
+ edge heavy, tmp_edge;
- if (!want_join_latch)
+ if (HEADER_BLOCK (header) <= 1)
continue;
/* Find a heavy edge. */
if (is_heavy)
{
- basic_block new_header =
- make_forwarder_block (header, true, true, heavy, 0);
- if (num_latch > 2)
- make_forwarder_block (new_header, true, false, NULL, 1);
+ /* Split out the heavy edge, and create inner loop for it. */
+ mfb_kj_edge = heavy;
+ tmp_edge = make_forwarder_block (header, mfb_keep_just,
+ update_latch_info);
+ alloc_aux_for_block (tmp_edge->dest, sizeof (int));
+ HEADER_BLOCK (tmp_edge->dest) = 1;
+ alloc_aux_for_edge (tmp_edge, sizeof (int));
+ LATCH_EDGE (tmp_edge) = 0;
+ HEADER_BLOCK (header)--;
+ }
+
+ if (HEADER_BLOCK (header) > 1)
+ {
+ /* Create a new latch block. */
+ tmp_edge = make_forwarder_block (header, mfb_keep_nonlatch,
+ update_latch_info);
+ alloc_aux_for_block (tmp_edge->dest, sizeof (int));
+ HEADER_BLOCK (tmp_edge->src) = 0;
+ HEADER_BLOCK (tmp_edge->dest) = 1;
+ alloc_aux_for_edge (tmp_edge, sizeof (int));
+ LATCH_EDGE (tmp_edge) = 1;
}
- else
- make_forwarder_block (header, true, false, NULL, 1);
}
free_aux_for_blocks ();
free_aux_for_edges ();
- free_dominance_info (dom);
+
+#ifdef ENABLE_CHECKING
+ verify_dominators (CDI_DOMINATORS);
+#endif
}
/* Find all the natural loops in the function and save in LOOPS structure and
int num_loops;
edge e;
sbitmap headers;
- dominance_info dom;
int *dfs_order;
int *rc_order;
basic_block header;
dfs_order = NULL;
rc_order = NULL;
+ /* Ensure that the dominators are computed. */
+ calculate_dominance_info (CDI_DOMINATORS);
+
/* Join loops with shared headers. */
canonicalize_loop_headers ();
- /* Compute the dominators. */
- dom = loops->cfg.dom = calculate_dominance_info (CDI_DOMINATORS);
-
/* Count the number of loop headers. This should be the
same as the number of natural loops. */
headers = sbitmap_alloc (last_basic_block);
node (header) that dominates all the nodes in the
loop. It also has single back edge to the header
from a latch node. */
- if (latch != ENTRY_BLOCK_PTR && dominated_by_p (dom, latch, header))
+ if (latch != ENTRY_BLOCK_PTR
+ && dominated_by_p (CDI_DOMINATORS, latch, header))
{
/* Shared headers should be eliminated by now. */
if (more_latches)
}
/* Allocate loop structures. */
- loops->parray = (struct loop **) xcalloc (num_loops + 1, sizeof (struct loop *));
+ loops->parray = xcalloc (num_loops + 1, sizeof (struct loop *));
/* Dummy loop containing whole function. */
loops->parray[0] = xcalloc (1, sizeof (struct loop));
{
/* Compute depth first search order of the CFG so that outer
natural loops will be found before inner natural loops. */
- dfs_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
- rc_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
+ dfs_order = xmalloc (n_basic_blocks * sizeof (int));
+ rc_order = xmalloc (n_basic_blocks * sizeof (int));
flow_depth_first_order_compute (dfs_order, rc_order);
/* Save CFG derived information to avoid recomputing it. */
- loops->cfg.dom = dom;
loops->cfg.dfs_order = dfs_order;
loops->cfg.rc_order = rc_order;
basic_block latch = e->src;
if (latch != ENTRY_BLOCK_PTR
- && dominated_by_p (dom, latch, header))
+ && dominated_by_p (CDI_DOMINATORS, latch, header))
{
loop->latch = latch;
break;
loop->num_nodes = flow_loop_nodes_find (loop->header, loop);
}
- sbitmap_free (headers);
-
/* Assign the loop nesting depth and enclosed loop level for each
loop. */
loops->levels = flow_loops_level_compute (loops);
/* Scan the loops. */
for (i = 1; i < num_loops; i++)
- flow_loop_scan (loops, loops->parray[i], flags);
+ flow_loop_scan (loops->parray[i], flags);
loops->num = num_loops;
}
- else
- {
- loops->cfg.dom = NULL;
- free_dominance_info (dom);
- }
+
+ sbitmap_free (headers);
loops->state = 0;
#ifdef ENABLE_CHECKING
return bb != (basic_block) glb_header;
}
-/* Gets basic blocks of a loop. */
+/* Gets basic blocks of a LOOP. Header is the 0-th block, rest is in dfs
+ order against direction of edges from latch. Specially, if
+ header != latch, latch is the 1-st block. */
basic_block *
get_loop_body (const struct loop *loop)
{
return tovisit;
}
+/* Fills dominance descendants inside LOOP of the basic block BB into
+ array TOVISIT from index *TV. */
+
+static void
+fill_sons_in_loop (const struct loop *loop, basic_block bb,
+ basic_block *tovisit, int *tv)
+{
+ basic_block son, postpone = NULL;
+
+ tovisit[(*tv)++] = bb;
+ for (son = first_dom_son (CDI_DOMINATORS, bb);
+ son;
+ son = next_dom_son (CDI_DOMINATORS, son))
+ {
+ if (!flow_bb_inside_loop_p (loop, son))
+ continue;
+
+ if (dominated_by_p (CDI_DOMINATORS, loop->latch, son))
+ {
+ postpone = son;
+ continue;
+ }
+ fill_sons_in_loop (loop, son, tovisit, tv);
+ }
+
+ if (postpone)
+ fill_sons_in_loop (loop, postpone, tovisit, tv);
+}
+
+/* Gets body of a LOOP (that must be different from the outermost loop)
+ sorted by dominance relation. Additionally, if a basic block s dominates
+ the latch, then only blocks dominated by s are be after it. */
+
+basic_block *
+get_loop_body_in_dom_order (const struct loop *loop)
+{
+ basic_block *tovisit;
+ int tv;
+
+ if (!loop->num_nodes)
+ abort ();
+
+ tovisit = xcalloc (loop->num_nodes, sizeof (basic_block));
+
+ if (loop->latch == EXIT_BLOCK_PTR)
+ abort ();
+
+ tv = 0;
+ fill_sons_in_loop (loop, loop->header, tovisit, &tv);
+
+ if (tv != (int) loop->num_nodes)
+ abort ();
+
+ return tovisit;
+}
+
/* Gets exit edges of a LOOP, returning their number in N_EDGES. */
edge *
get_loop_exit_edges (const struct loop *loop, unsigned int *n_edges)
return edges;
}
+/* Counts the number of conditional branches inside LOOP. */
+
+unsigned
+num_loop_branches (const struct loop *loop)
+{
+ unsigned i, n;
+ basic_block * body;
+
+ if (loop->latch == EXIT_BLOCK_PTR)
+ abort ();
+
+ body = get_loop_body (loop);
+ n = 0;
+ for (i = 0; i < loop->num_nodes; i++)
+ if (body[i]->succ && body[i]->succ->succ_next)
+ n++;
+ free (body);
+
+ return n;
+}
+
/* Adds basic block BB to LOOP. */
void
add_bb_to_loop (basic_block bb, struct loop *loop)
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