/* Instruction scheduling pass.
Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998,
- 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
+ 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
Contributed by Michael Tiemann (tiemann@cygnus.com) Enhanced by,
and currently maintained by, Jim Wilson (wilson@cygnus.com)
#include "toplev.h"
#include "recog.h"
#include "cfglayout.h"
+#include "params.h"
#include "sched-int.h"
#include "target.h"
\f
static int sched_n_insns;
/* Implementations of the sched_info functions for region scheduling. */
-static void init_ready_list PARAMS ((struct ready_list *));
-static int can_schedule_ready_p PARAMS ((rtx));
-static int new_ready PARAMS ((rtx));
-static int schedule_more_p PARAMS ((void));
-static const char *ebb_print_insn PARAMS ((rtx, int));
-static int rank PARAMS ((rtx, rtx));
-static int contributes_to_priority PARAMS ((rtx, rtx));
-static void compute_jump_reg_dependencies PARAMS ((rtx, regset));
-static basic_block schedule_ebb PARAMS ((rtx, rtx));
-static basic_block fix_basic_block_boundaries PARAMS ((basic_block, basic_block, rtx, rtx));
-static void add_missing_bbs PARAMS ((rtx, basic_block, basic_block));
+static void init_ready_list (struct ready_list *);
+static int can_schedule_ready_p (rtx);
+static int new_ready (rtx);
+static int schedule_more_p (void);
+static const char *ebb_print_insn (rtx, int);
+static int rank (rtx, rtx);
+static int contributes_to_priority (rtx, rtx);
+static void compute_jump_reg_dependencies (rtx, regset, regset, regset);
+static basic_block earliest_block_with_similiar_load (basic_block, rtx);
+static void add_deps_for_risky_insns (rtx, rtx);
+static basic_block schedule_ebb (rtx, rtx);
+static basic_block fix_basic_block_boundaries (basic_block, basic_block, rtx,
+ rtx);
+static void add_missing_bbs (rtx, basic_block, basic_block);
/* Return nonzero if there are more insns that should be scheduled. */
static int
-schedule_more_p ()
+schedule_more_p (void)
{
return sched_n_insns < target_n_insns;
}
once before scheduling a set of insns. */
static void
-init_ready_list (ready)
- struct ready_list *ready;
+init_ready_list (struct ready_list *ready)
{
rtx prev_head = current_sched_info->prev_head;
rtx next_tail = current_sched_info->next_tail;
insn can be scheduled, nonzero if we should silently discard it. */
static int
-can_schedule_ready_p (insn)
- rtx insn ATTRIBUTE_UNUSED;
+can_schedule_ready_p (rtx insn ATTRIBUTE_UNUSED)
{
sched_n_insns++;
return 1;
if it should be moved to the ready list or the queue, or zero if we
should silently discard it. */
static int
-new_ready (next)
- rtx next ATTRIBUTE_UNUSED;
+new_ready (rtx next ATTRIBUTE_UNUSED)
{
return 1;
}
to be formatted so that multiple output lines will line up nicely. */
static const char *
-ebb_print_insn (insn, aligned)
- rtx insn;
- int aligned ATTRIBUTE_UNUSED;
+ebb_print_insn (rtx insn, int aligned ATTRIBUTE_UNUSED)
{
static char tmp[80];
is to be preferred. Zero if they are equally good. */
static int
-rank (insn1, insn2)
- rtx insn1, insn2;
+rank (rtx insn1, rtx insn2)
{
basic_block bb1 = BLOCK_FOR_INSN (insn1);
basic_block bb2 = BLOCK_FOR_INSN (insn2);
calculations. */
static int
-contributes_to_priority (next, insn)
- rtx next ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED;
+contributes_to_priority (rtx next ATTRIBUTE_UNUSED,
+ rtx insn ATTRIBUTE_UNUSED)
{
return 1;
}
-/* INSN is a JUMP_INSN. Store the set of registers that must be considered
- to be set by this jump in SET. */
+ /* INSN is a JUMP_INSN, COND_SET is the set of registers that are
+ conditionally set before INSN. Store the set of registers that
+ must be considered as used by this jump in USED and that of
+ registers that must be considered as set in SET. */
static void
-compute_jump_reg_dependencies (insn, set)
- rtx insn;
- regset set;
+compute_jump_reg_dependencies (rtx insn, regset cond_set, regset used,
+ regset set)
{
basic_block b = BLOCK_FOR_INSN (insn);
edge e;
- for (e = b->succ; e; e = e->succ_next)
- if ((e->flags & EDGE_FALLTHRU) == 0)
- {
- bitmap_operation (set, set, e->dest->global_live_at_start,
- BITMAP_IOR);
- }
+ edge_iterator ei;
+
+ FOR_EACH_EDGE (e, ei, b->succs)
+ if (e->flags & EDGE_FALLTHRU)
+ /* The jump may be a by-product of a branch that has been merged
+ in the main codepath after being conditionalized. Therefore
+ it may guard the fallthrough block from using a value that has
+ conditionally overwritten that of the main codepath. So we
+ consider that it restores the value of the main codepath. */
+ bitmap_operation (set, e->dest->global_live_at_start, cond_set,
+ BITMAP_AND);
+ else
+ bitmap_operation (used, used, e->dest->global_live_at_start,
+ BITMAP_IOR);
}
/* Used in schedule_insns to initialize current_sched_info for scheduling
NULL, NULL,
NULL, NULL,
- 0, 1
+ 0, 1, 0
};
\f
-/* It is possible that ebb scheduling elliminated some blocks.
+/* It is possible that ebb scheduling eliminated some blocks.
Place blocks from FIRST to LAST before BEFORE. */
static void
-add_missing_bbs (before, first, last)
- rtx before;
- basic_block first, last;
+add_missing_bbs (rtx before, basic_block first, basic_block last)
{
for (; last != first->prev_bb; last = last->prev_bb)
{
before = emit_note_before (NOTE_INSN_BASIC_BLOCK, before);
NOTE_BASIC_BLOCK (before) = last;
- last->head = before;
- last->end = before;
+ BB_HEAD (last) = before;
+ BB_END (last) = before;
update_bb_for_insn (last);
}
}
structures between BB and LAST. */
static basic_block
-fix_basic_block_boundaries (bb, last, head, tail)
- basic_block bb, last;
- rtx head, tail;
+fix_basic_block_boundaries (basic_block bb, basic_block last, rtx head,
+ rtx tail)
{
rtx insn = head;
- rtx last_inside = bb->head;
+ rtx last_inside = BB_HEAD (bb);
rtx aftertail = NEXT_INSN (tail);
- head = bb->head;
+ head = BB_HEAD (bb);
for (; insn != aftertail; insn = NEXT_INSN (insn))
{
- if (GET_CODE (insn) == CODE_LABEL)
- abort ();
+ gcc_assert (!LABEL_P (insn));
/* Create new basic blocks just before first insn. */
if (inside_basic_block_p (insn))
{
rtx note;
/* Re-emit the basic block note for newly found BB header. */
- if (GET_CODE (insn) == CODE_LABEL)
+ if (LABEL_P (insn))
{
note = emit_note_after (NOTE_INSN_BASIC_BLOCK, insn);
head = insn;
last_inside = insn;
}
/* Control flow instruction terminate basic block. It is possible
- that we've elliminated some basic blocks (made them empty).
+ that we've eliminated some basic blocks (made them empty).
Find the proper basic block using BLOCK_FOR_INSN and arrange things in
a sensible way by inserting empty basic blocks as needed. */
if (control_flow_insn_p (insn) || (insn == tail && last_inside))
{
edge f;
rtx h;
+ edge_iterator ei;
/* An obscure special case, where we do have partially dead
instruction scheduled after last control flow instruction.
In this case we can create new basic block. It is
always exactly one basic block last in the sequence. Handle
it by splitting the edge and repositioning the block.
- This is somewhat hackish, but at least avoid cut&paste
+ This is somewhat hackish, but at least avoid cut&paste
- Safter sollution can be to bring the code into sequence,
+ A safer solution can be to bring the code into sequence,
do the split and re-emit it back in case this will ever
trigger problem. */
- f = bb->prev_bb->succ;
- while (f && !(f->flags & EDGE_FALLTHRU))
- f = f->succ_next;
+
+ FOR_EACH_EDGE (f, ei, bb->prev_bb->succs)
+ if (f->flags & EDGE_FALLTHRU)
+ break;
if (f)
{
last = curr_bb = split_edge (f);
- h = curr_bb->head;
- curr_bb->head = head;
- curr_bb->end = insn;
- /* Edge splitting created missplaced BASIC_BLOCK note, kill
+ h = BB_HEAD (curr_bb);
+ BB_HEAD (curr_bb) = head;
+ BB_END (curr_bb) = insn;
+ /* Edge splitting created misplaced BASIC_BLOCK note, kill
it. */
delete_insn (h);
}
delete_insn_chain (head, insn);
/* We keep some notes in the way that may split barrier from the
jump. */
- if (GET_CODE (next) == BARRIER)
+ if (BARRIER_P (next))
{
emit_barrier_after (prev_nonnote_insn (head));
delete_insn (next);
}
else
{
- curr_bb->head = head;
- curr_bb->end = insn;
- add_missing_bbs (curr_bb->head, bb, curr_bb->prev_bb);
+ BB_HEAD (curr_bb) = head;
+ BB_END (curr_bb) = insn;
+ add_missing_bbs (BB_HEAD (curr_bb), bb, curr_bb->prev_bb);
}
- note = GET_CODE (head) == CODE_LABEL ? NEXT_INSN (head) : head;
+ note = LABEL_P (head) ? NEXT_INSN (head) : head;
NOTE_BASIC_BLOCK (note) = curr_bb;
update_bb_for_insn (curr_bb);
bb = curr_bb->next_bb;
break;
}
}
- add_missing_bbs (last->next_bb->head, bb, last);
+ add_missing_bbs (BB_HEAD (last->next_bb), bb, last);
return bb->prev_bb;
}
+/* Returns the earliest block in EBB currently being processed where a
+ "similar load" 'insn2' is found, and hence LOAD_INSN can move
+ speculatively into the found block. All the following must hold:
+
+ (1) both loads have 1 base register (PFREE_CANDIDATEs).
+ (2) load_insn and load2 have a def-use dependence upon
+ the same insn 'insn1'.
+
+ From all these we can conclude that the two loads access memory
+ addresses that differ at most by a constant, and hence if moving
+ load_insn would cause an exception, it would have been caused by
+ load2 anyhow.
+
+ The function uses list (given by LAST_BLOCK) of already processed
+ blocks in EBB. The list is formed in `add_deps_for_risky_insns'. */
+
+static basic_block
+earliest_block_with_similiar_load (basic_block last_block, rtx load_insn)
+{
+ rtx back_link;
+ basic_block bb, earliest_block = NULL;
+
+ for (back_link = LOG_LINKS (load_insn);
+ back_link;
+ back_link = XEXP (back_link, 1))
+ {
+ rtx insn1 = XEXP (back_link, 0);
+
+ if (GET_MODE (back_link) == VOIDmode)
+ {
+ /* Found a DEF-USE dependence (insn1, load_insn). */
+ rtx fore_link;
+
+ for (fore_link = INSN_DEPEND (insn1);
+ fore_link;
+ fore_link = XEXP (fore_link, 1))
+ {
+ rtx insn2 = XEXP (fore_link, 0);
+ basic_block insn2_block = BLOCK_FOR_INSN (insn2);
+
+ if (GET_MODE (fore_link) == VOIDmode)
+ {
+ if (earliest_block != NULL
+ && earliest_block->index < insn2_block->index)
+ continue;
+
+ /* Found a DEF-USE dependence (insn1, insn2). */
+ if (haifa_classify_insn (insn2) != PFREE_CANDIDATE)
+ /* insn2 not guaranteed to be a 1 base reg load. */
+ continue;
+
+ for (bb = last_block; bb; bb = bb->aux)
+ if (insn2_block == bb)
+ break;
+
+ if (!bb)
+ /* insn2 is the similar load. */
+ earliest_block = insn2_block;
+ }
+ }
+ }
+ }
+
+ return earliest_block;
+}
+
+/* The following function adds dependencies between jumps and risky
+ insns in given ebb. */
+
+static void
+add_deps_for_risky_insns (rtx head, rtx tail)
+{
+ rtx insn, prev;
+ int class;
+ rtx last_jump = NULL_RTX;
+ rtx next_tail = NEXT_INSN (tail);
+ basic_block last_block = NULL, bb;
+
+ for (insn = head; insn != next_tail; insn = NEXT_INSN (insn))
+ if (JUMP_P (insn))
+ {
+ bb = BLOCK_FOR_INSN (insn);
+ bb->aux = last_block;
+ last_block = bb;
+ last_jump = insn;
+ }
+ else if (INSN_P (insn) && last_jump != NULL_RTX)
+ {
+ class = haifa_classify_insn (insn);
+ prev = last_jump;
+ switch (class)
+ {
+ case PFREE_CANDIDATE:
+ if (flag_schedule_speculative_load)
+ {
+ bb = earliest_block_with_similiar_load (last_block, insn);
+ if (bb)
+ {
+ bb = bb->aux;
+ if (!bb)
+ break;
+ prev = BB_END (bb);
+ }
+ }
+ /* Fall through. */
+ case TRAP_RISKY:
+ case IRISKY:
+ case PRISKY_CANDIDATE:
+ /* ??? We could implement better checking PRISKY_CANDIDATEs
+ analogous to sched-rgn.c. */
+ /* We can not change the mode of the backward
+ dependency because REG_DEP_ANTI has the lowest
+ rank. */
+ if (add_dependence (insn, prev, REG_DEP_ANTI))
+ add_forward_dependence (prev, insn, REG_DEP_ANTI);
+ break;
+
+ default:
+ break;
+ }
+ }
+ /* Maintain the invariant that bb->aux is clear after use. */
+ while (last_block)
+ {
+ bb = last_block->aux;
+ last_block->aux = NULL;
+ last_block = bb;
+ }
+}
+
/* Schedule a single extended basic block, defined by the boundaries HEAD
and TAIL. */
static basic_block
-schedule_ebb (head, tail)
- rtx head, tail;
+schedule_ebb (rtx head, rtx tail)
{
int n_insns;
basic_block b;
/* Compute INSN_DEPEND. */
compute_forward_dependences (head, tail);
+ add_deps_for_risky_insns (head, tail);
+
if (targetm.sched.dependencies_evaluation_hook)
targetm.sched.dependencies_evaluation_hook (head, tail);
if (write_symbols != NO_DEBUG)
{
- save_line_notes (0, head, tail);
+ save_line_notes (first_bb->index, head, tail);
rm_line_notes (head, tail);
}
schedule_block (-1, n_insns);
/* Sanity check: verify that all region insns were scheduled. */
- if (sched_n_insns != n_insns)
- abort ();
+ gcc_assert (sched_n_insns == n_insns);
head = current_sched_info->head;
tail = current_sched_info->tail;
this pass. */
void
-schedule_ebbs (dump_file)
- FILE *dump_file;
+schedule_ebbs (FILE *dump_file)
{
basic_block bb;
+ int probability_cutoff;
+
+ if (profile_info && flag_branch_probabilities)
+ probability_cutoff = PARAM_VALUE (TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK);
+ else
+ probability_cutoff = PARAM_VALUE (TRACER_MIN_BRANCH_PROBABILITY);
+ probability_cutoff = REG_BR_PROB_BASE / 100 * probability_cutoff;
/* Taking care of this degenerate case makes the rest of
this code simpler. */
current_sched_info = &ebb_sched_info;
- allocate_reg_life_data ();
compute_bb_for_insn ();
/* Schedule every region in the subroutine. */
FOR_EACH_BB (bb)
{
- rtx head = bb->head;
+ rtx head = BB_HEAD (bb);
rtx tail;
for (;;)
{
edge e;
- tail = bb->end;
+ edge_iterator ei;
+ tail = BB_END (bb);
if (bb->next_bb == EXIT_BLOCK_PTR
- || GET_CODE (bb->next_bb->head) == CODE_LABEL)
+ || LABEL_P (BB_HEAD (bb->next_bb)))
break;
- for (e = bb->succ; e; e = e->succ_next)
+ FOR_EACH_EDGE (e, ei, bb->succs)
if ((e->flags & EDGE_FALLTHRU) != 0)
break;
if (! e)
break;
- if (e->probability < REG_BR_PROB_BASE / 2)
+ if (e->probability <= probability_cutoff)
break;
bb = bb->next_bb;
}
a note or two. */
while (head != tail)
{
- if (GET_CODE (head) == NOTE)
+ if (NOTE_P (head))
head = NEXT_INSN (head);
- else if (GET_CODE (tail) == NOTE)
+ else if (NOTE_P (tail))
tail = PREV_INSN (tail);
- else if (GET_CODE (head) == CODE_LABEL)
+ else if (LABEL_P (head))
head = NEXT_INSN (head);
else
break;
rm_redundant_line_notes ();
sched_finish ();
-
-#ifdef ENABLE_CHECKING
- verify_flow_info ();
-#endif
}
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