/* Basic block reordering routines for the GNU compiler.
- Copyright (C) 2000, 2002, 2003 Free Software Foundation, Inc.
+ Copyright (C) 2000, 2002, 2003, 2004 Free Software Foundation, Inc.
This file is part of GCC.
#include "cfglayout.h"
#include "fibheap.h"
#include "target.h"
+#include "function.h"
+#include "tm_p.h"
+#include "obstack.h"
+#include "expr.h"
+#include "regs.h"
+
+/* The number of rounds. In most cases there will only be 4 rounds, but
+ when partitioning hot and cold basic blocks into separate sections of
+ the .o file there will be an extra round.*/
+#define N_ROUNDS 5
+
+/* Stubs in case we don't have a return insn.
+ We have to check at runtime too, not only compiletime. */
+
+#ifndef HAVE_return
+#define HAVE_return 0
+#define gen_return() NULL_RTX
+#endif
-/* The number of rounds. */
-#define N_ROUNDS 4
/* Branch thresholds in thousandths (per mille) of the REG_BR_PROB_BASE. */
-static int branch_threshold[N_ROUNDS] = {400, 200, 100, 0};
+static int branch_threshold[N_ROUNDS] = {400, 200, 100, 0, 0};
/* Exec thresholds in thousandths (per mille) of the frequency of bb 0. */
-static int exec_threshold[N_ROUNDS] = {500, 200, 50, 0};
+static int exec_threshold[N_ROUNDS] = {500, 200, 50, 0, 0};
/* If edge frequency is lower than DUPLICATION_THRESHOLD per mille of entry
block the edge destination is not duplicated while connecting traces. */
#define GET_ARRAY_SIZE(X) ((((X) / 4) + 1) * 5)
/* Free the memory and set the pointer to NULL. */
-#define FREE(P) \
- do { if (P) { free (P); P = 0; } else { abort (); } } while (0)
+#define FREE(P) (gcc_assert (P), free (P), P = 0)
/* Structure for holding information about a trace. */
struct trace
static basic_block rotate_loop (edge, struct trace *, int);
static void mark_bb_visited (basic_block, int);
static void find_traces_1_round (int, int, gcov_type, struct trace *, int *,
- int, fibheap_t *);
+ int, fibheap_t *, int);
static basic_block copy_bb (basic_block, edge, basic_block, int);
static fibheapkey_t bb_to_key (basic_block);
-static bool better_edge_p (basic_block, edge, int, int, int, int);
+static bool better_edge_p (basic_block, edge, int, int, int, int, edge);
static void connect_traces (int, struct trace *);
static bool copy_bb_p (basic_block, int);
static int get_uncond_jump_length (void);
+static bool push_to_next_round_p (basic_block, int, int, int, gcov_type);
+static void add_unlikely_executed_notes (void);
+static void find_rarely_executed_basic_blocks_and_crossing_edges (edge *,
+ int *,
+ int *);
+static void mark_bb_for_unlikely_executed_section (basic_block);
+static void add_labels_and_missing_jumps (edge *, int);
+static void add_reg_crossing_jump_notes (void);
+static void fix_up_fall_thru_edges (void);
+static void fix_edges_for_rarely_executed_code (edge *, int);
+static void fix_crossing_conditional_branches (void);
+static void fix_crossing_unconditional_branches (void);
\f
+/* Check to see if bb should be pushed into the next round of trace
+ collections or not. Reasons for pushing the block forward are 1).
+ If the block is cold, we are doing partitioning, and there will be
+ another round (cold partition blocks are not supposed to be
+ collected into traces until the very last round); or 2). There will
+ be another round, and the basic block is not "hot enough" for the
+ current round of trace collection. */
+
+static bool
+push_to_next_round_p (basic_block bb, int round, int number_of_rounds,
+ int exec_th, gcov_type count_th)
+{
+ bool there_exists_another_round;
+ bool cold_block;
+ bool block_not_hot_enough;
+ bool next_round_is_last;
+
+ there_exists_another_round = round < number_of_rounds - 1;
+ next_round_is_last = round + 1 == number_of_rounds - 1;
+
+ cold_block = (flag_reorder_blocks_and_partition
+ && BB_PARTITION (bb) == BB_COLD_PARTITION);
+
+ block_not_hot_enough = (bb->frequency < exec_th
+ || bb->count < count_th
+ || probably_never_executed_bb_p (bb));
+
+ if (flag_reorder_blocks_and_partition
+ && next_round_is_last
+ && BB_PARTITION (bb) != BB_COLD_PARTITION)
+ return false;
+ else if (there_exists_another_round
+ && (cold_block || block_not_hot_enough))
+ return true;
+ else
+ return false;
+}
+
/* Find the traces for Software Trace Cache. Chain each trace through
RBI()->next. Store the number of traces to N_TRACES and description of
traces to TRACES. */
find_traces (int *n_traces, struct trace *traces)
{
int i;
+ int number_of_rounds;
edge e;
+ edge_iterator ei;
fibheap_t heap;
+ /* Add one extra round of trace collection when partitioning hot/cold
+ basic blocks into separate sections. The last round is for all the
+ cold blocks (and ONLY the cold blocks). */
+
+ number_of_rounds = N_ROUNDS - 1;
+ if (flag_reorder_blocks_and_partition)
+ number_of_rounds = N_ROUNDS;
+
/* Insert entry points of function into heap. */
heap = fibheap_new ();
max_entry_frequency = 0;
max_entry_count = 0;
- for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
+ FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
{
bbd[e->dest->index].heap = heap;
bbd[e->dest->index].node = fibheap_insert (heap, bb_to_key (e->dest),
}
/* Find the traces. */
- for (i = 0; i < N_ROUNDS; i++)
+ for (i = 0; i < number_of_rounds; i++)
{
gcov_type count_threshold;
find_traces_1_round (REG_BR_PROB_BASE * branch_threshold[i] / 1000,
max_entry_frequency * exec_threshold[i] / 1000,
- count_threshold, traces, n_traces, i, &heap);
+ count_threshold, traces, n_traces, i, &heap,
+ number_of_rounds);
}
fibheap_delete (heap);
do
{
edge e;
- for (e = bb->succ; e; e = e->succ_next)
+ edge_iterator ei;
+
+ FOR_EACH_EDGE (e, ei, bb->succs)
if (e->dest != EXIT_BLOCK_PTR
&& e->dest->rbi->visited != trace_n
&& (e->flags & EDGE_CAN_FALLTHRU)
prev_bb->rbi->next = best_bb->rbi->next;
/* Try to get rid of uncond jump to cond jump. */
- if (prev_bb->succ && !prev_bb->succ->succ_next)
+ if (EDGE_COUNT (prev_bb->succs) == 1)
{
- basic_block header = prev_bb->succ->dest;
+ basic_block header = EDGE_SUCC (prev_bb, 0)->dest;
/* Duplicate HEADER if it is a small block containing cond jump
in the end. */
- if (any_condjump_p (BB_END (header)) && copy_bb_p (header, 0))
+ if (any_condjump_p (BB_END (header)) && copy_bb_p (header, 0)
+ && !find_reg_note (BB_END (header), REG_CROSSING_JUMP,
+ NULL_RTX))
{
- copy_bb (header, prev_bb->succ, prev_bb, trace_n);
+ copy_bb (header, EDGE_SUCC (prev_bb, 0), prev_bb, trace_n);
}
}
}
static void
find_traces_1_round (int branch_th, int exec_th, gcov_type count_th,
struct trace *traces, int *n_traces, int round,
- fibheap_t *heap)
+ fibheap_t *heap, int number_of_rounds)
{
+ /* The following variable refers to the last round in which non-"cold"
+ blocks may be collected into a trace. */
+
+ int last_round = N_ROUNDS - 1;
+
/* Heap for discarded basic blocks which are possible starting points for
the next round. */
fibheap_t new_heap = fibheap_new ();
struct trace *trace;
edge best_edge, e;
fibheapkey_t key;
+ edge_iterator ei;
bb = fibheap_extract_min (*heap);
bbd[bb->index].heap = NULL;
if (dump_file)
fprintf (dump_file, "Getting bb %d\n", bb->index);
- /* If the BB's frequency is too low send BB to the next round. */
- if (round < N_ROUNDS - 1
- && (bb->frequency < exec_th || bb->count < count_th
- || probably_never_executed_bb_p (bb)))
+ /* If the BB's frequency is too low send BB to the next round. When
+ partitioning hot/cold blocks into separate sections, make sure all
+ the cold blocks (and ONLY the cold blocks) go into the (extra) final
+ round. */
+
+ if (push_to_next_round_p (bb, round, number_of_rounds, exec_th,
+ count_th))
{
int key = bb_to_key (bb);
bbd[bb->index].heap = new_heap;
bb->index, *n_traces - 1);
/* Select the successor that will be placed after BB. */
- for (e = bb->succ; e; e = e->succ_next)
+ FOR_EACH_EDGE (e, ei, bb->succs)
{
-#ifdef ENABLE_CHECKING
- if (e->flags & EDGE_FAKE)
- abort ();
-#endif
+ gcc_assert (!(e->flags & EDGE_FAKE));
if (e->dest == EXIT_BLOCK_PTR)
continue;
&& e->dest->rbi->visited != *n_traces)
continue;
+ if (BB_PARTITION (e->dest) == BB_COLD_PARTITION
+ && round < last_round)
+ continue;
+
prob = e->probability;
freq = EDGE_FREQUENCY (e);
/* Edge that cannot be fallthru or improbable or infrequent
- successor (ie. it is unsuitable successor). */
+ successor (i.e. it is unsuitable successor). */
if (!(e->flags & EDGE_CAN_FALLTHRU) || (e->flags & EDGE_COMPLEX)
|| prob < branch_th || freq < exec_th || e->count < count_th)
continue;
- if (better_edge_p (bb, e, prob, freq, best_prob, best_freq))
+ /* If partitioning hot/cold basic blocks, don't consider edges
+ that cross section boundaries. */
+
+ if (better_edge_p (bb, e, prob, freq, best_prob, best_freq,
+ best_edge))
{
best_edge = e;
best_prob = prob;
/* If the best destination has multiple predecessors, and can be
duplicated cheaper than a jump, don't allow it to be added
to a trace. We'll duplicate it when connecting traces. */
- if (best_edge && best_edge->dest->pred->pred_next
+ if (best_edge && EDGE_COUNT (best_edge->dest->preds) >= 2
&& copy_bb_p (best_edge->dest, 0))
best_edge = NULL;
/* Add all non-selected successors to the heaps. */
- for (e = bb->succ; e; e = e->succ_next)
+ FOR_EACH_EDGE (e, ei, bb->succs)
{
if (e == best_edge
|| e->dest == EXIT_BLOCK_PTR
|| prob < branch_th || freq < exec_th
|| e->count < count_th)
{
- if (round < N_ROUNDS - 1)
+ /* When partitioning hot/cold basic blocks, make sure
+ the cold blocks (and only the cold blocks) all get
+ pushed to the last round of trace collection. */
+
+ if (push_to_next_round_p (e->dest, round,
+ number_of_rounds,
+ exec_th, count_th))
which_heap = new_heap;
}
/* Check whether there is another edge from BB. */
edge another_edge;
- for (another_edge = bb->succ;
- another_edge;
- another_edge = another_edge->succ_next)
+ FOR_EACH_EDGE (another_edge, ei, bb->succs)
if (another_edge != best_edge)
break;
*/
- for (e = bb->succ; e; e = e->succ_next)
+ FOR_EACH_EDGE (e, ei, bb->succs)
if (e != best_edge
&& (e->flags & EDGE_CAN_FALLTHRU)
&& !(e->flags & EDGE_COMPLEX)
&& !e->dest->rbi->visited
- && !e->dest->pred->pred_next
- && e->dest->succ
- && (e->dest->succ->flags & EDGE_CAN_FALLTHRU)
- && !(e->dest->succ->flags & EDGE_COMPLEX)
- && !e->dest->succ->succ_next
- && e->dest->succ->dest == best_edge->dest
+ && EDGE_COUNT (e->dest->preds) == 1
+ && !(e->flags & EDGE_CROSSING)
+ && EDGE_COUNT (e->dest->succs) == 1
+ && (EDGE_SUCC (e->dest, 0)->flags & EDGE_CAN_FALLTHRU)
+ && !(EDGE_SUCC (e->dest, 0)->flags & EDGE_COMPLEX)
+ && EDGE_SUCC (e->dest, 0)->dest == best_edge->dest
&& 2 * e->dest->frequency >= EDGE_FREQUENCY (best_edge))
{
best_edge = e;
/* The trace is terminated so we have to recount the keys in heap
(some block can have a lower key because now one of its predecessors
is an end of the trace). */
- for (e = bb->succ; e; e = e->succ_next)
+ FOR_EACH_EDGE (e, ei, bb->succs)
{
if (e->dest == EXIT_BLOCK_PTR
|| e->dest->rbi->visited)
{
basic_block new_bb;
- new_bb = cfg_layout_duplicate_bb (old_bb, e);
- if (e->dest != new_bb)
- abort ();
- if (e->dest->rbi->visited)
- abort ();
+ new_bb = duplicate_block (old_bb, e);
+ BB_COPY_PARTITION (new_bb, old_bb);
+
+ gcc_assert (e->dest == new_bb);
+ gcc_assert (!e->dest->rbi->visited);
+
if (dump_file)
fprintf (dump_file,
"Duplicated bb %d (created bb %d)\n",
bb_to_key (basic_block bb)
{
edge e;
-
+ edge_iterator ei;
int priority = 0;
/* Do not start in probably never executed blocks. */
- if (probably_never_executed_bb_p (bb))
+
+ if (BB_PARTITION (bb) == BB_COLD_PARTITION
+ || probably_never_executed_bb_p (bb))
return BB_FREQ_MAX;
/* Prefer blocks whose predecessor is an end of some trace
or whose predecessor edge is EDGE_DFS_BACK. */
- for (e = bb->pred; e; e = e->pred_next)
+ FOR_EACH_EDGE (e, ei, bb->preds)
{
if ((e->src != ENTRY_BLOCK_PTR && bbd[e->src->index].end_of_trace >= 0)
|| (e->flags & EDGE_DFS_BACK))
static bool
better_edge_p (basic_block bb, edge e, int prob, int freq, int best_prob,
- int best_freq)
+ int best_freq, edge cur_best_edge)
{
bool is_better_edge;
else
is_better_edge = false;
+ /* If we are doing hot/cold partitioning, make sure that we always favor
+ non-crossing edges over crossing edges. */
+
+ if (!is_better_edge
+ && flag_reorder_blocks_and_partition
+ && cur_best_edge
+ && (cur_best_edge->flags & EDGE_CROSSING)
+ && !(e->flags & EDGE_CROSSING))
+ is_better_edge = true;
+
return is_better_edge;
}
connect_traces (int n_traces, struct trace *traces)
{
int i;
+ int unconnected_hot_trace_count = 0;
+ bool cold_connected = true;
bool *connected;
+ bool *cold_traces;
int last_trace;
int freq_threshold;
gcov_type count_threshold;
connected = xcalloc (n_traces, sizeof (bool));
last_trace = -1;
- for (i = 0; i < n_traces; i++)
+
+ /* If we are partitioning hot/cold basic blocks, mark the cold
+ traces as already connected, to remove them from consideration
+ for connection to the hot traces. After the hot traces have all
+ been connected (determined by "unconnected_hot_trace_count"), we
+ will go back and connect the cold traces. */
+
+ cold_traces = xcalloc (n_traces, sizeof (bool));
+
+ if (flag_reorder_blocks_and_partition)
+ for (i = 0; i < n_traces; i++)
+ {
+ if (BB_PARTITION (traces[i].first) == BB_COLD_PARTITION)
+ {
+ connected[i] = true;
+ cold_traces[i] = true;
+ cold_connected = false;
+ }
+ else
+ unconnected_hot_trace_count++;
+ }
+
+ for (i = 0; i < n_traces || !cold_connected ; i++)
{
int t = i;
int t2;
edge e, best;
int best_len;
+ /* If we are partitioning hot/cold basic blocks, check to see
+ if all the hot traces have been connected. If so, go back
+ and mark the cold traces as unconnected so we can connect
+ them up too. Re-set "i" to the first (unconnected) cold
+ trace. Use flag "cold_connected" to make sure we don't do
+ this step more than once. */
+
+ if (flag_reorder_blocks_and_partition
+ && (i >= n_traces || unconnected_hot_trace_count <= 0)
+ && !cold_connected)
+ {
+ int j;
+ int first_cold_trace = -1;
+
+ for (j = 0; j < n_traces; j++)
+ if (cold_traces[j])
+ {
+ connected[j] = false;
+ if (first_cold_trace == -1)
+ first_cold_trace = j;
+ }
+ i = t = first_cold_trace;
+ cold_connected = true;
+ }
+
if (connected[t])
continue;
connected[t] = true;
+ if (unconnected_hot_trace_count > 0)
+ unconnected_hot_trace_count--;
/* Find the predecessor traces. */
for (t2 = t; t2 > 0;)
{
+ edge_iterator ei;
best = NULL;
best_len = 0;
- for (e = traces[t2].first->pred; e; e = e->pred_next)
+ FOR_EACH_EDGE (e, ei, traces[t2].first->preds)
{
int si = e->src->index;
best->src->rbi->next = best->dest;
t2 = bbd[best->src->index].end_of_trace;
connected[t2] = true;
+
+ if (unconnected_hot_trace_count > 0)
+ unconnected_hot_trace_count--;
+
if (dump_file)
{
fprintf (dump_file, "Connection: %d %d\n",
while (1)
{
/* Find the continuation of the chain. */
+ edge_iterator ei;
best = NULL;
best_len = 0;
- for (e = traces[t].last->succ; e; e = e->succ_next)
+ FOR_EACH_EDGE (e, ei, traces[t].last->succs)
{
int di = e->dest->index;
t = bbd[best->dest->index].start_of_trace;
traces[last_trace].last->rbi->next = traces[t].first;
connected[t] = true;
+ if (unconnected_hot_trace_count > 0)
+ unconnected_hot_trace_count--;
last_trace = t;
}
else
basic_block next_bb = NULL;
bool try_copy = false;
- for (e = traces[t].last->succ; e; e = e->succ_next)
+ FOR_EACH_EDGE (e, ei, traces[t].last->succs)
if (e->dest != EXIT_BLOCK_PTR
&& (e->flags & EDGE_CAN_FALLTHRU)
&& !(e->flags & EDGE_COMPLEX)
&& (!best || e->probability > best->probability))
{
+ edge_iterator ei;
edge best2 = NULL;
int best2_len = 0;
continue;
}
- for (e2 = e->dest->succ; e2; e2 = e2->succ_next)
+ FOR_EACH_EDGE (e2, ei, e->dest->succs)
{
int di = e2->dest->index;
}
}
+ if (flag_reorder_blocks_and_partition)
+ try_copy = false;
+
/* Copy tiny blocks always; copy larger blocks only when the
edge is traversed frequently enough. */
if (try_copy
t = bbd[next_bb->index].start_of_trace;
traces[last_trace].last->rbi->next = traces[t].first;
connected[t] = true;
+ if (unconnected_hot_trace_count > 0)
+ unconnected_hot_trace_count--;
last_trace = t;
}
else
}
FREE (connected);
+ FREE (cold_traces);
}
/* Return true when BB can and should be copied. CODE_MAY_GROW is true
int size = 0;
int max_size = uncond_jump_length;
rtx insn;
- int n_succ;
- edge e;
if (!bb->frequency)
return false;
- if (!bb->pred || !bb->pred->pred_next)
+ if (EDGE_COUNT (bb->preds) < 2)
return false;
- if (!cfg_layout_can_duplicate_bb_p (bb))
+ if (!can_duplicate_block_p (bb))
return false;
/* Avoid duplicating blocks which have many successors (PR/13430). */
- n_succ = 0;
- for (e = bb->succ; e; e = e->succ_next)
- {
- n_succ++;
- if (n_succ > 8)
- return false;
- }
+ if (EDGE_COUNT (bb->succs) > 8)
+ return false;
if (code_may_grow && maybe_hot_bb_p (bb))
max_size *= 8;
return length;
}
-/* Reorder basic blocks. The main entry point to this file. */
+static void
+add_unlikely_executed_notes (void)
+{
+ basic_block bb;
+
+ /* Add the UNLIKELY_EXECUTED_NOTES to each cold basic block. */
+
+ FOR_EACH_BB (bb)
+ if (BB_PARTITION (bb) == BB_COLD_PARTITION)
+ mark_bb_for_unlikely_executed_section (bb);
+}
+
+/* Find the basic blocks that are rarely executed and need to be moved to
+ a separate section of the .o file (to cut down on paging and improve
+ cache locality). */
+
+static void
+find_rarely_executed_basic_blocks_and_crossing_edges (edge *crossing_edges,
+ int *n_crossing_edges,
+ int *max_idx)
+{
+ basic_block bb;
+ bool has_hot_blocks = false;
+ edge e;
+ int i;
+ edge_iterator ei;
+
+ /* Mark which partition (hot/cold) each basic block belongs in. */
+
+ FOR_EACH_BB (bb)
+ {
+ if (probably_never_executed_bb_p (bb))
+ BB_SET_PARTITION (bb, BB_COLD_PARTITION);
+ else
+ {
+ BB_SET_PARTITION (bb, BB_HOT_PARTITION);
+ has_hot_blocks = true;
+ }
+ }
+
+ /* Since all "hot" basic blocks will eventually be scheduled before all
+ cold basic blocks, make *sure* the real function entry block is in
+ the hot partition (if there is one). */
+
+ if (has_hot_blocks)
+ FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
+ if (e->dest->index >= 0)
+ {
+ BB_SET_PARTITION (e->dest, BB_HOT_PARTITION);
+ break;
+ }
+
+ /* Mark every edge that crosses between sections. */
+
+ i = 0;
+ if (targetm.have_named_sections)
+ {
+ FOR_EACH_BB (bb)
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ {
+ if (e->src != ENTRY_BLOCK_PTR
+ && e->dest != EXIT_BLOCK_PTR
+ && BB_PARTITION (e->src) != BB_PARTITION (e->dest))
+ {
+ e->flags |= EDGE_CROSSING;
+ if (i == *max_idx)
+ {
+ *max_idx *= 2;
+ crossing_edges = xrealloc (crossing_edges,
+ (*max_idx) * sizeof (edge));
+ }
+ crossing_edges[i++] = e;
+ }
+ else
+ e->flags &= ~EDGE_CROSSING;
+ }
+ }
+ *n_crossing_edges = i;
+}
+
+/* Add NOTE_INSN_UNLIKELY_EXECUTED_CODE to top of basic block. This note
+ is later used to mark the basic block to be put in the
+ unlikely-to-be-executed section of the .o file. */
+
+static void
+mark_bb_for_unlikely_executed_section (basic_block bb)
+{
+ rtx cur_insn;
+ rtx insert_insn = NULL;
+ rtx new_note;
+
+ /* Insert new NOTE immediately after BASIC_BLOCK note. */
+
+ for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
+ cur_insn = NEXT_INSN (cur_insn))
+ if (GET_CODE (cur_insn) == NOTE
+ && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_BASIC_BLOCK)
+ {
+ insert_insn = cur_insn;
+ break;
+ }
+
+ /* If basic block does not contain a NOTE_INSN_BASIC_BLOCK, there is
+ a major problem. */
+ gcc_assert (insert_insn);
+
+ /* Insert note and assign basic block number to it. */
+
+ new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
+ insert_insn);
+ NOTE_BASIC_BLOCK (new_note) = bb;
+}
+
+/* If any destination of a crossing edge does not have a label, add label;
+ Convert any fall-through crossing edges (for blocks that do not contain
+ a jump) to unconditional jumps. */
+
+static void
+add_labels_and_missing_jumps (edge *crossing_edges, int n_crossing_edges)
+{
+ int i;
+ basic_block src;
+ basic_block dest;
+ rtx label;
+ rtx barrier;
+ rtx new_jump;
+
+ for (i=0; i < n_crossing_edges; i++)
+ {
+ if (crossing_edges[i])
+ {
+ src = crossing_edges[i]->src;
+ dest = crossing_edges[i]->dest;
+
+ /* Make sure dest has a label. */
+
+ if (dest && (dest != EXIT_BLOCK_PTR))
+ {
+ label = block_label (dest);
+
+ /* Make sure source block ends with a jump. */
+
+ if (src && (src != ENTRY_BLOCK_PTR))
+ {
+ if (!JUMP_P (BB_END (src)))
+ /* bb just falls through. */
+ {
+ /* make sure there's only one successor */
+ gcc_assert (EDGE_COUNT (src->succs) == 1);
+
+ /* Find label in dest block. */
+ label = block_label (dest);
+
+ new_jump = emit_jump_insn_after (gen_jump (label),
+ BB_END (src));
+ barrier = emit_barrier_after (new_jump);
+ JUMP_LABEL (new_jump) = label;
+ LABEL_NUSES (label) += 1;
+ src->rbi->footer = unlink_insn_chain (barrier, barrier);
+ /* Mark edge as non-fallthru. */
+ crossing_edges[i]->flags &= ~EDGE_FALLTHRU;
+ } /* end: 'if (GET_CODE ... ' */
+ } /* end: 'if (src && src->index...' */
+ } /* end: 'if (dest && dest->index...' */
+ } /* end: 'if (crossing_edges[i]...' */
+ } /* end for loop */
+}
+
+/* Find any bb's where the fall-through edge is a crossing edge (note that
+ these bb's must also contain a conditional jump; we've already
+ dealt with fall-through edges for blocks that didn't have a
+ conditional jump in the call to add_labels_and_missing_jumps).
+ Convert the fall-through edge to non-crossing edge by inserting a
+ new bb to fall-through into. The new bb will contain an
+ unconditional jump (crossing edge) to the original fall through
+ destination. */
+
+static void
+fix_up_fall_thru_edges (void)
+{
+ basic_block cur_bb;
+ basic_block new_bb;
+ edge succ1;
+ edge succ2;
+ edge fall_thru;
+ edge cond_jump = NULL;
+ edge e;
+ bool cond_jump_crosses;
+ int invert_worked;
+ rtx old_jump;
+ rtx fall_thru_label;
+ rtx barrier;
+
+ FOR_EACH_BB (cur_bb)
+ {
+ fall_thru = NULL;
+ if (EDGE_COUNT (cur_bb->succs) > 0)
+ succ1 = EDGE_SUCC (cur_bb, 0);
+ else
+ succ1 = NULL;
+
+ if (EDGE_COUNT (cur_bb->succs) > 1)
+ succ2 = EDGE_SUCC (cur_bb, 1);
+ else
+ succ2 = NULL;
+
+ /* Find the fall-through edge. */
+
+ if (succ1
+ && (succ1->flags & EDGE_FALLTHRU))
+ {
+ fall_thru = succ1;
+ cond_jump = succ2;
+ }
+ else if (succ2
+ && (succ2->flags & EDGE_FALLTHRU))
+ {
+ fall_thru = succ2;
+ cond_jump = succ1;
+ }
+
+ if (fall_thru && (fall_thru->dest != EXIT_BLOCK_PTR))
+ {
+ /* Check to see if the fall-thru edge is a crossing edge. */
+
+ if (fall_thru->flags & EDGE_CROSSING)
+ {
+ /* The fall_thru edge crosses; now check the cond jump edge, if
+ it exists. */
+
+ cond_jump_crosses = true;
+ invert_worked = 0;
+ old_jump = BB_END (cur_bb);
+
+ /* Find the jump instruction, if there is one. */
+
+ if (cond_jump)
+ {
+ if (!(cond_jump->flags & EDGE_CROSSING))
+ cond_jump_crosses = false;
+
+ /* We know the fall-thru edge crosses; if the cond
+ jump edge does NOT cross, and its destination is the
+ next block in the bb order, invert the jump
+ (i.e. fix it so the fall thru does not cross and
+ the cond jump does). */
+
+ if (!cond_jump_crosses
+ && cur_bb->rbi->next == cond_jump->dest)
+ {
+ /* Find label in fall_thru block. We've already added
+ any missing labels, so there must be one. */
+
+ fall_thru_label = block_label (fall_thru->dest);
+
+ if (old_jump && fall_thru_label)
+ invert_worked = invert_jump (old_jump,
+ fall_thru_label,0);
+ if (invert_worked)
+ {
+ fall_thru->flags &= ~EDGE_FALLTHRU;
+ cond_jump->flags |= EDGE_FALLTHRU;
+ update_br_prob_note (cur_bb);
+ e = fall_thru;
+ fall_thru = cond_jump;
+ cond_jump = e;
+ cond_jump->flags |= EDGE_CROSSING;
+ fall_thru->flags &= ~EDGE_CROSSING;
+ }
+ }
+ }
+
+ if (cond_jump_crosses || !invert_worked)
+ {
+ /* This is the case where both edges out of the basic
+ block are crossing edges. Here we will fix up the
+ fall through edge. The jump edge will be taken care
+ of later. */
+
+ new_bb = force_nonfallthru (fall_thru);
+
+ if (new_bb)
+ {
+ new_bb->rbi->next = cur_bb->rbi->next;
+ cur_bb->rbi->next = new_bb;
+
+ /* Make sure new fall-through bb is in same
+ partition as bb it's falling through from. */
+
+ BB_COPY_PARTITION (new_bb, cur_bb);
+ EDGE_SUCC (new_bb, 0)->flags |= EDGE_CROSSING;
+ }
+
+ /* Add barrier after new jump */
+
+ if (new_bb)
+ {
+ barrier = emit_barrier_after (BB_END (new_bb));
+ new_bb->rbi->footer = unlink_insn_chain (barrier,
+ barrier);
+ }
+ else
+ {
+ barrier = emit_barrier_after (BB_END (cur_bb));
+ cur_bb->rbi->footer = unlink_insn_chain (barrier,
+ barrier);
+ }
+ }
+ }
+ }
+ }
+}
+
+/* This function checks the destination blockof a "crossing jump" to
+ see if it has any crossing predecessors that begin with a code label
+ and end with an unconditional jump. If so, it returns that predecessor
+ block. (This is to avoid creating lots of new basic blocks that all
+ contain unconditional jumps to the same destination). */
+
+static basic_block
+find_jump_block (basic_block jump_dest)
+{
+ basic_block source_bb = NULL;
+ edge e;
+ rtx insn;
+ edge_iterator ei;
+
+ FOR_EACH_EDGE (e, ei, jump_dest->preds)
+ if (e->flags & EDGE_CROSSING)
+ {
+ basic_block src = e->src;
+
+ /* Check each predecessor to see if it has a label, and contains
+ only one executable instruction, which is an unconditional jump.
+ If so, we can use it. */
+
+ if (LABEL_P (BB_HEAD (src)))
+ for (insn = BB_HEAD (src);
+ !INSN_P (insn) && insn != NEXT_INSN (BB_END (src));
+ insn = NEXT_INSN (insn))
+ {
+ if (INSN_P (insn)
+ && insn == BB_END (src)
+ && JUMP_P (insn)
+ && !any_condjump_p (insn))
+ {
+ source_bb = src;
+ break;
+ }
+ }
+
+ if (source_bb)
+ break;
+ }
+
+ return source_bb;
+}
+
+/* Find all BB's with conditional jumps that are crossing edges;
+ insert a new bb and make the conditional jump branch to the new
+ bb instead (make the new bb same color so conditional branch won't
+ be a 'crossing' edge). Insert an unconditional jump from the
+ new bb to the original destination of the conditional jump. */
+
+static void
+fix_crossing_conditional_branches (void)
+{
+ basic_block cur_bb;
+ basic_block new_bb;
+ basic_block last_bb;
+ basic_block dest;
+ basic_block prev_bb;
+ edge succ1;
+ edge succ2;
+ edge crossing_edge;
+ edge new_edge;
+ rtx old_jump;
+ rtx set_src;
+ rtx old_label = NULL_RTX;
+ rtx new_label;
+ rtx new_jump;
+ rtx barrier;
+
+ last_bb = EXIT_BLOCK_PTR->prev_bb;
+
+ FOR_EACH_BB (cur_bb)
+ {
+ crossing_edge = NULL;
+ if (EDGE_COUNT (cur_bb->succs) > 0)
+ succ1 = EDGE_SUCC (cur_bb, 0);
+ else
+ succ1 = NULL;
+
+ if (EDGE_COUNT (cur_bb->succs) > 1)
+ succ2 = EDGE_SUCC (cur_bb, 1);
+ else
+ succ2 = NULL;
+
+ /* We already took care of fall-through edges, so only one successor
+ can be a crossing edge. */
+
+ if (succ1 && (succ1->flags & EDGE_CROSSING))
+ crossing_edge = succ1;
+ else if (succ2 && (succ2->flags & EDGE_CROSSING))
+ crossing_edge = succ2;
+
+ if (crossing_edge)
+ {
+ old_jump = BB_END (cur_bb);
+
+ /* Check to make sure the jump instruction is a
+ conditional jump. */
+
+ set_src = NULL_RTX;
+
+ if (any_condjump_p (old_jump))
+ {
+ if (GET_CODE (PATTERN (old_jump)) == SET)
+ set_src = SET_SRC (PATTERN (old_jump));
+ else if (GET_CODE (PATTERN (old_jump)) == PARALLEL)
+ {
+ set_src = XVECEXP (PATTERN (old_jump), 0,0);
+ if (GET_CODE (set_src) == SET)
+ set_src = SET_SRC (set_src);
+ else
+ set_src = NULL_RTX;
+ }
+ }
+
+ if (set_src && (GET_CODE (set_src) == IF_THEN_ELSE))
+ {
+ if (GET_CODE (XEXP (set_src, 1)) == PC)
+ old_label = XEXP (set_src, 2);
+ else if (GET_CODE (XEXP (set_src, 2)) == PC)
+ old_label = XEXP (set_src, 1);
+
+ /* Check to see if new bb for jumping to that dest has
+ already been created; if so, use it; if not, create
+ a new one. */
+
+ new_bb = find_jump_block (crossing_edge->dest);
+
+ if (new_bb)
+ new_label = block_label (new_bb);
+ else
+ {
+ /* Create new basic block to be dest for
+ conditional jump. */
+
+ new_bb = create_basic_block (NULL, NULL, last_bb);
+ new_bb->rbi->next = last_bb->rbi->next;
+ last_bb->rbi->next = new_bb;
+ prev_bb = last_bb;
+ last_bb = new_bb;
+
+ /* Update register liveness information. */
+
+ new_bb->global_live_at_start =
+ OBSTACK_ALLOC_REG_SET (&flow_obstack);
+ new_bb->global_live_at_end =
+ OBSTACK_ALLOC_REG_SET (&flow_obstack);
+ COPY_REG_SET (new_bb->global_live_at_end,
+ prev_bb->global_live_at_end);
+ COPY_REG_SET (new_bb->global_live_at_start,
+ prev_bb->global_live_at_end);
+
+ /* Put appropriate instructions in new bb. */
+
+ new_label = gen_label_rtx ();
+ emit_label_before (new_label, BB_HEAD (new_bb));
+ BB_HEAD (new_bb) = new_label;
+
+ if (GET_CODE (old_label) == LABEL_REF)
+ {
+ old_label = JUMP_LABEL (old_jump);
+ new_jump = emit_jump_insn_after (gen_jump
+ (old_label),
+ BB_END (new_bb));
+ }
+ else
+ {
+ gcc_assert (HAVE_return
+ && GET_CODE (old_label) == RETURN);
+ new_jump = emit_jump_insn_after (gen_return (),
+ BB_END (new_bb));
+ }
+
+ barrier = emit_barrier_after (new_jump);
+ JUMP_LABEL (new_jump) = old_label;
+ new_bb->rbi->footer = unlink_insn_chain (barrier,
+ barrier);
+
+ /* Make sure new bb is in same partition as source
+ of conditional branch. */
+ BB_COPY_PARTITION (new_bb, cur_bb);
+ }
+
+ /* Make old jump branch to new bb. */
+
+ redirect_jump (old_jump, new_label, 0);
+
+ /* Remove crossing_edge as predecessor of 'dest'. */
+
+ dest = crossing_edge->dest;
+
+ redirect_edge_succ (crossing_edge, new_bb);
+
+ /* Make a new edge from new_bb to old dest; new edge
+ will be a successor for new_bb and a predecessor
+ for 'dest'. */
+
+ if (EDGE_COUNT (new_bb->succs) == 0)
+ new_edge = make_edge (new_bb, dest, 0);
+ else
+ new_edge = EDGE_SUCC (new_bb, 0);
+
+ crossing_edge->flags &= ~EDGE_CROSSING;
+ new_edge->flags |= EDGE_CROSSING;
+ }
+ }
+ }
+}
+
+/* Find any unconditional branches that cross between hot and cold
+ sections. Convert them into indirect jumps instead. */
+
+static void
+fix_crossing_unconditional_branches (void)
+{
+ basic_block cur_bb;
+ rtx last_insn;
+ rtx label;
+ rtx label_addr;
+ rtx indirect_jump_sequence;
+ rtx jump_insn = NULL_RTX;
+ rtx new_reg;
+ rtx cur_insn;
+ edge succ;
+
+ FOR_EACH_BB (cur_bb)
+ {
+ last_insn = BB_END (cur_bb);
+ succ = EDGE_SUCC (cur_bb, 0);
+
+ /* Check to see if bb ends in a crossing (unconditional) jump. At
+ this point, no crossing jumps should be conditional. */
+
+ if (JUMP_P (last_insn)
+ && (succ->flags & EDGE_CROSSING))
+ {
+ rtx label2, table;
+
+ gcc_assert (!any_condjump_p (last_insn));
+
+ /* Make sure the jump is not already an indirect or table jump. */
+
+ if (!computed_jump_p (last_insn)
+ && !tablejump_p (last_insn, &label2, &table))
+ {
+ /* We have found a "crossing" unconditional branch. Now
+ we must convert it to an indirect jump. First create
+ reference of label, as target for jump. */
+
+ label = JUMP_LABEL (last_insn);
+ label_addr = gen_rtx_LABEL_REF (Pmode, label);
+ LABEL_NUSES (label) += 1;
+
+ /* Get a register to use for the indirect jump. */
+
+ new_reg = gen_reg_rtx (Pmode);
+
+ /* Generate indirect the jump sequence. */
+
+ start_sequence ();
+ emit_move_insn (new_reg, label_addr);
+ emit_indirect_jump (new_reg);
+ indirect_jump_sequence = get_insns ();
+ end_sequence ();
+
+ /* Make sure every instruction in the new jump sequence has
+ its basic block set to be cur_bb. */
+
+ for (cur_insn = indirect_jump_sequence; cur_insn;
+ cur_insn = NEXT_INSN (cur_insn))
+ {
+ BLOCK_FOR_INSN (cur_insn) = cur_bb;
+ if (JUMP_P (cur_insn))
+ jump_insn = cur_insn;
+ }
+
+ /* Insert the new (indirect) jump sequence immediately before
+ the unconditional jump, then delete the unconditional jump. */
+
+ emit_insn_before (indirect_jump_sequence, last_insn);
+ delete_insn (last_insn);
+
+ /* Make BB_END for cur_bb be the jump instruction (NOT the
+ barrier instruction at the end of the sequence...). */
+
+ BB_END (cur_bb) = jump_insn;
+ }
+ }
+ }
+}
+
+/* Add REG_CROSSING_JUMP note to all crossing jump insns. */
+
+static void
+add_reg_crossing_jump_notes (void)
+{
+ basic_block bb;
+ edge e;
+ edge_iterator ei;
+
+ FOR_EACH_BB (bb)
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ if ((e->flags & EDGE_CROSSING)
+ && JUMP_P (BB_END (e->src)))
+ REG_NOTES (BB_END (e->src)) = gen_rtx_EXPR_LIST (REG_CROSSING_JUMP,
+ NULL_RTX,
+ REG_NOTES (BB_END
+ (e->src)));
+}
+
+/* Basic blocks containing NOTE_INSN_UNLIKELY_EXECUTED_CODE will be
+ put in a separate section of the .o file, to reduce paging and
+ improve cache performance (hopefully). This can result in bits of
+ code from the same function being widely separated in the .o file.
+ However this is not obvious to the current bb structure. Therefore
+ we must take care to ensure that: 1). There are no fall_thru edges
+ that cross between sections; 2). For those architectures which
+ have "short" conditional branches, all conditional branches that
+ attempt to cross between sections are converted to unconditional
+ branches; and, 3). For those architectures which have "short"
+ unconditional branches, all unconditional branches that attempt
+ to cross between sections are converted to indirect jumps.
+
+ The code for fixing up fall_thru edges that cross between hot and
+ cold basic blocks does so by creating new basic blocks containing
+ unconditional branches to the appropriate label in the "other"
+ section. The new basic block is then put in the same (hot or cold)
+ section as the original conditional branch, and the fall_thru edge
+ is modified to fall into the new basic block instead. By adding
+ this level of indirection we end up with only unconditional branches
+ crossing between hot and cold sections.
+
+ Conditional branches are dealt with by adding a level of indirection.
+ A new basic block is added in the same (hot/cold) section as the
+ conditional branch, and the conditional branch is retargeted to the
+ new basic block. The new basic block contains an unconditional branch
+ to the original target of the conditional branch (in the other section).
+
+ Unconditional branches are dealt with by converting them into
+ indirect jumps. */
+
+static void
+fix_edges_for_rarely_executed_code (edge *crossing_edges,
+ int n_crossing_edges)
+{
+ /* Make sure the source of any crossing edge ends in a jump and the
+ destination of any crossing edge has a label. */
+
+ add_labels_and_missing_jumps (crossing_edges, n_crossing_edges);
+
+ /* Convert all crossing fall_thru edges to non-crossing fall
+ thrus to unconditional jumps (that jump to the original fall
+ thru dest). */
+
+ fix_up_fall_thru_edges ();
+
+ /* Only do the parts necessary for writing separate sections if
+ the target architecture has the ability to write separate sections
+ (i.e. it has named sections). Otherwise, the hot/cold partitioning
+ information will be used when reordering blocks to try to put all
+ the hot blocks together, then all the cold blocks, but no actual
+ section partitioning will be done. */
+
+ if (targetm.have_named_sections)
+ {
+ /* If the architecture does not have conditional branches that can
+ span all of memory, convert crossing conditional branches into
+ crossing unconditional branches. */
+
+ if (!HAS_LONG_COND_BRANCH)
+ fix_crossing_conditional_branches ();
+
+ /* If the architecture does not have unconditional branches that
+ can span all of memory, convert crossing unconditional branches
+ into indirect jumps. Since adding an indirect jump also adds
+ a new register usage, update the register usage information as
+ well. */
+
+ if (!HAS_LONG_UNCOND_BRANCH)
+ {
+ fix_crossing_unconditional_branches ();
+ reg_scan (get_insns(), max_reg_num (), 1);
+ }
+
+ add_reg_crossing_jump_notes ();
+ }
+}
+
+/* Reorder basic blocks. The main entry point to this file. FLAGS is
+ the set of flags to pass to cfg_layout_initialize(). */
void
-reorder_basic_blocks (void)
+reorder_basic_blocks (unsigned int flags)
{
int n_traces;
int i;
if (n_basic_blocks <= 1)
return;
- if ((* targetm.cannot_modify_jumps_p) ())
+ if (targetm.cannot_modify_jumps_p ())
return;
timevar_push (TV_REORDER_BLOCKS);
- cfg_layout_initialize ();
+ cfg_layout_initialize (flags);
set_edge_can_fallthru_flag ();
mark_dfs_back_edges ();
if (dump_file)
dump_flow_info (dump_file);
+ if (flag_reorder_blocks_and_partition
+ && targetm.have_named_sections)
+ add_unlikely_executed_notes ();
+
cfg_layout_finalize ();
timevar_pop (TV_REORDER_BLOCKS);
}
+
+/* This function is the main 'entrance' for the optimization that
+ partitions hot and cold basic blocks into separate sections of the
+ .o file (to improve performance and cache locality). Ideally it
+ would be called after all optimizations that rearrange the CFG have
+ been called. However part of this optimization may introduce new
+ register usage, so it must be called before register allocation has
+ occurred. This means that this optimization is actually called
+ well before the optimization that reorders basic blocks (see
+ function above).
+
+ This optimization checks the feedback information to determine
+ which basic blocks are hot/cold and causes reorder_basic_blocks to
+ add NOTE_INSN_UNLIKELY_EXECUTED_CODE to non-hot basic blocks. The
+ presence or absence of this note is later used for writing out
+ sections in the .o file. Because hot and cold sections can be
+ arbitrarily large (within the bounds of memory), far beyond the
+ size of a single function, it is necessary to fix up all edges that
+ cross section boundaries, to make sure the instructions used can
+ actually span the required distance. The fixes are described
+ below.
+
+ Fall-through edges must be changed into jumps; it is not safe or
+ legal to fall through across a section boundary. Whenever a
+ fall-through edge crossing a section boundary is encountered, a new
+ basic block is inserted (in the same section as the fall-through
+ source), and the fall through edge is redirected to the new basic
+ block. The new basic block contains an unconditional jump to the
+ original fall-through target. (If the unconditional jump is
+ insufficient to cross section boundaries, that is dealt with a
+ little later, see below).
+
+ In order to deal with architectures that have short conditional
+ branches (which cannot span all of memory) we take any conditional
+ jump that attempts to cross a section boundary and add a level of
+ indirection: it becomes a conditional jump to a new basic block, in
+ the same section. The new basic block contains an unconditional
+ jump to the original target, in the other section.
+
+ For those architectures whose unconditional branch is also
+ incapable of reaching all of memory, those unconditional jumps are
+ converted into indirect jumps, through a register.
+
+ IMPORTANT NOTE: This optimization causes some messy interactions
+ with the cfg cleanup optimizations; those optimizations want to
+ merge blocks wherever possible, and to collapse indirect jump
+ sequences (change "A jumps to B jumps to C" directly into "A jumps
+ to C"). Those optimizations can undo the jump fixes that
+ partitioning is required to make (see above), in order to ensure
+ that jumps attempting to cross section boundaries are really able
+ to cover whatever distance the jump requires (on many architectures
+ conditional or unconditional jumps are not able to reach all of
+ memory). Therefore tests have to be inserted into each such
+ optimization to make sure that it does not undo stuff necessary to
+ cross partition boundaries. This would be much less of a problem
+ if we could perform this optimization later in the compilation, but
+ unfortunately the fact that we may need to create indirect jumps
+ (through registers) requires that this optimization be performed
+ before register allocation. */
+
+void
+partition_hot_cold_basic_blocks (void)
+{
+ basic_block cur_bb;
+ edge *crossing_edges;
+ int n_crossing_edges;
+ int max_edges = 2 * last_basic_block;
+
+ if (n_basic_blocks <= 1)
+ return;
+
+ crossing_edges = xcalloc (max_edges, sizeof (edge));
+
+ cfg_layout_initialize (0);
+
+ FOR_EACH_BB (cur_bb)
+ if (cur_bb->index >= 0
+ && cur_bb->next_bb->index >= 0)
+ cur_bb->rbi->next = cur_bb->next_bb;
+
+ find_rarely_executed_basic_blocks_and_crossing_edges (crossing_edges,
+ &n_crossing_edges,
+ &max_edges);
+
+ if (n_crossing_edges > 0)
+ fix_edges_for_rarely_executed_code (crossing_edges, n_crossing_edges);
+
+ free (crossing_edges);
+
+ cfg_layout_finalize();
+}
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