/* Natural loop analysis code for GNU compiler.
- Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
+ Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
-Software Foundation; either version 2, or (at your option) any later
+Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
for more details.
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. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "cfgloop.h"
#include "expr.h"
#include "output.h"
+#include "graphds.h"
/* Checks whether BB is executed exactly once in each LOOP iteration. */
bool
-just_once_each_iteration_p (struct loop *loop, basic_block bb)
+just_once_each_iteration_p (const struct loop *loop, const_basic_block bb)
{
/* It must be executed at least once each iteration. */
if (!dominated_by_p (CDI_DOMINATORS, loop->latch, bb))
return true;
}
-/* Structure representing edge of a graph. */
-
-struct edge
-{
- int src, dest; /* Source and destination. */
- struct edge *pred_next, *succ_next;
- /* Next edge in predecessor and successor lists. */
- void *data; /* Data attached to the edge. */
-};
-
-/* Structure representing vertex of a graph. */
-
-struct vertex
-{
- struct edge *pred, *succ;
- /* Lists of predecessors and successors. */
- int component; /* Number of dfs restarts before reaching the
- vertex. */
- int post; /* Postorder number. */
-};
-
-/* Structure representing a graph. */
-
-struct graph
-{
- int n_vertices; /* Number of vertices. */
- struct vertex *vertices;
- /* The vertices. */
-};
-
-/* Dumps graph G into F. */
-
-extern void dump_graph (FILE *, struct graph *);
-void dump_graph (FILE *f, struct graph *g)
-{
- int i;
- struct edge *e;
-
- for (i = 0; i < g->n_vertices; i++)
- {
- if (!g->vertices[i].pred
- && !g->vertices[i].succ)
- continue;
-
- fprintf (f, "%d (%d)\t<-", i, g->vertices[i].component);
- for (e = g->vertices[i].pred; e; e = e->pred_next)
- fprintf (f, " %d", e->src);
- fprintf (f, "\n");
-
- fprintf (f, "\t->");
- for (e = g->vertices[i].succ; e; e = e->succ_next)
- fprintf (f, " %d", e->dest);
- fprintf (f, "\n");
- }
-}
-
-/* Creates a new graph with N_VERTICES vertices. */
-
-static struct graph *
-new_graph (int n_vertices)
-{
- struct graph *g = xmalloc (sizeof (struct graph));
-
- g->n_vertices = n_vertices;
- g->vertices = xcalloc (n_vertices, sizeof (struct vertex));
-
- return g;
-}
-
-/* Adds an edge from F to T to graph G, with DATA attached. */
-
-static void
-add_edge (struct graph *g, int f, int t, void *data)
-{
- struct edge *e = xmalloc (sizeof (struct edge));
-
- e->src = f;
- e->dest = t;
- e->data = data;
-
- e->pred_next = g->vertices[t].pred;
- g->vertices[t].pred = e;
-
- e->succ_next = g->vertices[f].succ;
- g->vertices[f].succ = e;
-}
-
-/* Runs dfs search over vertices of G, from NQ vertices in queue QS.
- The vertices in postorder are stored into QT. If FORWARD is false,
- backward dfs is run. */
-
-static void
-dfs (struct graph *g, int *qs, int nq, int *qt, bool forward)
-{
- int i, tick = 0, v, comp = 0, top;
- struct edge *e;
- struct edge **stack = xmalloc (sizeof (struct edge *) * g->n_vertices);
-
- for (i = 0; i < g->n_vertices; i++)
- {
- g->vertices[i].component = -1;
- g->vertices[i].post = -1;
- }
-
-#define FST_EDGE(V) (forward ? g->vertices[(V)].succ : g->vertices[(V)].pred)
-#define NEXT_EDGE(E) (forward ? (E)->succ_next : (E)->pred_next)
-#define EDGE_SRC(E) (forward ? (E)->src : (E)->dest)
-#define EDGE_DEST(E) (forward ? (E)->dest : (E)->src)
-
- for (i = 0; i < nq; i++)
- {
- v = qs[i];
- if (g->vertices[v].post != -1)
- continue;
-
- g->vertices[v].component = comp++;
- e = FST_EDGE (v);
- top = 0;
-
- while (1)
- {
- while (e && g->vertices[EDGE_DEST (e)].component != -1)
- e = NEXT_EDGE (e);
-
- if (!e)
- {
- if (qt)
- qt[tick] = v;
- g->vertices[v].post = tick++;
-
- if (!top)
- break;
-
- e = stack[--top];
- v = EDGE_SRC (e);
- e = NEXT_EDGE (e);
- continue;
- }
-
- stack[top++] = e;
- v = EDGE_DEST (e);
- e = FST_EDGE (v);
- g->vertices[v].component = comp - 1;
- }
- }
-
- free (stack);
-}
-
/* Marks the edge E in graph G irreducible if it connects two vertices in the
same scc. */
static void
-check_irred (struct graph *g, struct edge *e)
+check_irred (struct graph *g, struct graph_edge *e)
{
- edge real = e->data;
+ edge real = (edge) e->data;
/* All edges should lead from a component with higher number to the
one with lower one. */
real->src->flags |= BB_IRREDUCIBLE_LOOP;
}
-/* Runs CALLBACK for all edges in G. */
-
-static void
-for_each_edge (struct graph *g,
- void (callback) (struct graph *, struct edge *))
-{
- struct edge *e;
- int i;
-
- for (i = 0; i < g->n_vertices; i++)
- for (e = g->vertices[i].succ; e; e = e->succ_next)
- callback (g, e);
-}
-
-/* Releases the memory occupied by G. */
-
-static void
-free_graph (struct graph *g)
-{
- struct edge *e, *n;
- int i;
-
- for (i = 0; i < g->n_vertices; i++)
- for (e = g->vertices[i].succ; e; e = n)
- {
- n = e->succ_next;
- free (e);
- }
- free (g->vertices);
- free (g);
-}
-
/* Marks blocks and edges that are part of non-recognized loops; i.e. we
throw away all latch edges and mark blocks inside any remaining cycle.
Everything is a bit complicated due to fact we do not want to do this
for parts of cycles that only "pass" through some loop -- i.e. for
each cycle, we want to mark blocks that belong directly to innermost
loop containing the whole cycle.
-
+
LOOPS is the loop tree. */
#define LOOP_REPR(LOOP) ((LOOP)->num + last_basic_block)
#define BB_REPR(BB) ((BB)->index + 1)
void
-mark_irreducible_loops (struct loops *loops)
+mark_irreducible_loops (void)
{
basic_block act;
edge e;
edge_iterator ei;
- int i, src, dest;
+ int src, dest;
+ unsigned depth;
struct graph *g;
- int *queue1 = xmalloc ((last_basic_block + loops->num) * sizeof (int));
- int *queue2 = xmalloc ((last_basic_block + loops->num) * sizeof (int));
- int nq, depth;
+ int num = number_of_loops ();
struct loop *cloop;
+ gcc_assert (current_loops != NULL);
+
/* Reset the flags. */
FOR_BB_BETWEEN (act, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
{
}
/* Create the edge lists. */
- g = new_graph (last_basic_block + loops->num);
+ g = new_graph (last_basic_block + num);
FOR_BB_BETWEEN (act, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
FOR_EACH_EDGE (e, ei, act->succs)
{
- /* Ignore edges to exit. */
- if (e->dest == EXIT_BLOCK_PTR)
+ /* Ignore edges to exit. */
+ if (e->dest == EXIT_BLOCK_PTR)
continue;
- /* And latch edges. */
+ src = BB_REPR (act);
+ dest = BB_REPR (e->dest);
+
+ /* Ignore latch edges. */
if (e->dest->loop_father->header == e->dest
&& e->dest->loop_father->latch == act)
continue;
of the son of nearest common ancestor of the loops in that
act lays. */
- src = BB_REPR (act);
- dest = BB_REPR (e->dest);
-
if (e->dest->loop_father->header == e->dest)
dest = LOOP_REPR (e->dest->loop_father);
if (!flow_bb_inside_loop_p (act->loop_father, e->dest))
{
- depth = find_common_loop (act->loop_father,
- e->dest->loop_father)->depth + 1;
- if (depth == act->loop_father->depth)
+ depth = 1 + loop_depth (find_common_loop (act->loop_father,
+ e->dest->loop_father));
+ if (depth == loop_depth (act->loop_father))
cloop = act->loop_father;
else
- cloop = act->loop_father->pred[depth];
+ cloop = VEC_index (loop_p, act->loop_father->superloops, depth);
src = LOOP_REPR (cloop);
}
- add_edge (g, src, dest, e);
+ add_edge (g, src, dest)->data = e;
}
- /* Find the strongly connected components. Use the algorithm of Tarjan --
- first determine the postorder dfs numbering in reversed graph, then
- run the dfs on the original graph in the order given by decreasing
- numbers assigned by the previous pass. */
- nq = 0;
- FOR_BB_BETWEEN (act, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
- {
- queue1[nq++] = BB_REPR (act);
- }
- for (i = 1; i < (int) loops->num; i++)
- if (loops->parray[i])
- queue1[nq++] = LOOP_REPR (loops->parray[i]);
- dfs (g, queue1, nq, queue2, false);
- for (i = 0; i < nq; i++)
- queue1[i] = queue2[nq - i - 1];
- dfs (g, queue1, nq, NULL, true);
+ /* Find the strongly connected components. */
+ graphds_scc (g, NULL);
/* Mark the irreducible loops. */
for_each_edge (g, check_irred);
free_graph (g);
- free (queue1);
- free (queue2);
- loops->state |= LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS;
+ loops_state_set (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS);
}
/* Counts number of insns inside LOOP. */
int
-num_loop_insns (struct loop *loop)
+num_loop_insns (const struct loop *loop)
{
basic_block *bbs, bb;
unsigned i, ninsns = 0;
/* Counts number of insns executed on average per iteration LOOP. */
int
-average_num_loop_insns (struct loop *loop)
+average_num_loop_insns (const struct loop *loop)
{
basic_block *bbs, bb;
unsigned i, binsns, ninsns, ratio;
return ninsns;
}
-/* Returns expected number of LOOP iterations.
- Compute upper bound on number of iterations in case they do not fit integer
- to help loop peeling heuristics. Use exact counts if at all possible. */
-unsigned
-expected_loop_iterations (const struct loop *loop)
+/* Returns expected number of iterations of LOOP, according to
+ measured or guessed profile. No bounding is done on the
+ value. */
+
+gcov_type
+expected_loop_iterations_unbounded (const struct loop *loop)
{
edge e;
edge_iterator ei;
- if (loop->header->count)
+ if (loop->latch->count || loop->header->count)
{
gcov_type count_in, count_latch, expected;
count_in += e->count;
if (count_in == 0)
- expected = count_latch * 2;
+ expected = count_latch * 2;
else
- expected = (count_latch + count_in - 1) / count_in;
+ expected = (count_latch + count_in - 1) / count_in;
- /* Avoid overflows. */
- return (expected > REG_BR_PROB_BASE ? REG_BR_PROB_BASE : expected);
+ return expected;
}
else
{
}
}
+/* Returns expected number of LOOP iterations. The returned value is bounded
+ by REG_BR_PROB_BASE. */
+
+unsigned
+expected_loop_iterations (const struct loop *loop)
+{
+ gcov_type expected = expected_loop_iterations_unbounded (loop);
+ return (expected > REG_BR_PROB_BASE ? REG_BR_PROB_BASE : expected);
+}
+
/* Returns the maximum level of nesting of subloops of LOOP. */
unsigned
/* Returns estimate on cost of computing SEQ. */
static unsigned
-seq_cost (rtx seq)
+seq_cost (const_rtx seq)
{
unsigned cost = 0;
rtx set;
/* The properties of the target. */
unsigned target_avail_regs; /* Number of available registers. */
-unsigned target_res_regs; /* Number of reserved registers. */
-unsigned target_small_cost; /* The cost for register when there is a free one. */
-unsigned target_pres_cost; /* The cost for register when there are not too many
- free ones. */
-unsigned target_spill_cost; /* The cost for register when we need to spill. */
+unsigned target_res_regs; /* Number of registers reserved for temporary
+ expressions. */
+unsigned target_reg_cost; /* The cost for register when there still
+ is some reserve, but we are approaching
+ the number of available registers. */
+unsigned target_spill_cost; /* The cost for register when we need
+ to spill. */
/* Initialize the constants for computing set costs. */
rtx mem = validize_mem (gen_rtx_MEM (SImode, addr));
unsigned i;
+ target_avail_regs = 0;
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
if (TEST_HARD_REG_BIT (reg_class_contents[GENERAL_REGS], i)
&& !fixed_regs[i])
target_res_regs = 3;
- /* These are really just heuristic values. */
-
+ /* Set up the costs for using extra registers:
+
+ 1) If not many free registers remain, we should prefer having an
+ additional move to decreasing the number of available registers.
+ (TARGET_REG_COST).
+ 2) If no registers are available, we need to spill, which may require
+ storing the old value to memory and loading it back
+ (TARGET_SPILL_COST). */
+
start_sequence ();
emit_move_insn (reg1, reg2);
seq = get_insns ();
end_sequence ();
- target_small_cost = seq_cost (seq);
- target_pres_cost = 2 * target_small_cost;
+ target_reg_cost = seq_cost (seq);
start_sequence ();
emit_move_insn (mem, reg1);
target_spill_cost = seq_cost (seq);
}
-/* Calculates cost for having SIZE new loop global variables. REGS_USED is the
- number of global registers used in loop. N_USES is the number of relevant
- variable uses. */
+/* Estimates cost of increased register pressure caused by making N_NEW new
+ registers live around the loop. N_OLD is the number of registers live
+ around the loop. */
unsigned
-global_cost_for_size (unsigned size, unsigned regs_used, unsigned n_uses)
+estimate_reg_pressure_cost (unsigned n_new, unsigned n_old)
{
- unsigned regs_needed = regs_used + size;
- unsigned cost = 0;
+ unsigned regs_needed = n_new + n_old;
+ /* If we have enough registers, we should use them and not restrict
+ the transformations unnecessarily. */
if (regs_needed + target_res_regs <= target_avail_regs)
- cost += target_small_cost * size;
- else if (regs_needed <= target_avail_regs)
- cost += target_pres_cost * size;
- else
- {
- cost += target_pres_cost * size;
- cost += target_spill_cost * n_uses * (regs_needed - target_avail_regs) / regs_needed;
- }
+ return 0;
- return cost;
+ /* If we are close to running out of registers, try to preserve them. */
+ if (regs_needed <= target_avail_regs)
+ return target_reg_cost * n_new;
+
+ /* If we run out of registers, it is very expensive to add another one. */
+ return target_spill_cost * n_new;
}
-/* Sets EDGE_LOOP_EXIT flag for all exits of LOOPS. */
+/* Sets EDGE_LOOP_EXIT flag for all loop exits. */
void
-mark_loop_exit_edges (struct loops *loops)
+mark_loop_exit_edges (void)
{
basic_block bb;
edge e;
-
- if (loops->num <= 1)
+
+ if (number_of_loops () <= 1)
return;
FOR_EACH_BB (bb)
{
edge_iterator ei;
- /* Do not mark exits from the fake outermost loop. */
- if (!bb->loop_father->outer)
- continue;
-
FOR_EACH_EDGE (e, ei, bb->succs)
{
- if (loop_exit_edge_p (bb->loop_father, e))
+ if (loop_outer (bb->loop_father)
+ && loop_exit_edge_p (bb->loop_father, e))
e->flags |= EDGE_LOOP_EXIT;
else
e->flags &= ~EDGE_LOOP_EXIT;
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