/* 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_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. */
&& loop->pred[outer->depth] == outer;
}
+/* Returns superloop of LOOP at given DEPTH. */
+
+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
using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
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;
}
-/* 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 (bb) == 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)
{
FOR_EACH_BB (header)
{
- int num_latch;
- int want_join_latch;
int max_freq, is_heavy;
- edge heavy;
+ edge heavy, tmp_edge;
- if (!HEADER_BLOCK (header))
- continue;
-
- num_latch = HEADER_BLOCK (header);
-
- want_join_latch = (num_latch > 1);
-
- 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 ();
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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