blob: fee802e4f430b61418b3a14195a20b5d540d4b48 [file] [log] [blame]
/* Instruction scheduling pass.
Copyright (C) 1992, 93-96, 1997 Free Software Foundation, Inc.
Contributed by Michael Tiemann (tiemann@cygnus.com)
Enhanced by, and currently maintained by, Jim Wilson (wilson@cygnus.com)
This file is part of GNU CC.
GNU CC 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 version.
GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING. If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
/* Instruction scheduling pass.
This pass implements list scheduling within basic blocks. It is
run after flow analysis, but before register allocation. The
scheduler works as follows:
We compute insn priorities based on data dependencies. Flow
analysis only creates a fraction of the data-dependencies we must
observe: namely, only those dependencies which the combiner can be
expected to use. For this pass, we must therefore create the
remaining dependencies we need to observe: register dependencies,
memory dependencies, dependencies to keep function calls in order,
and the dependence between a conditional branch and the setting of
condition codes are all dealt with here.
The scheduler first traverses the data flow graph, starting with
the last instruction, and proceeding to the first, assigning
values to insn_priority as it goes. This sorts the instructions
topologically by data dependence.
Once priorities have been established, we order the insns using
list scheduling. This works as follows: starting with a list of
all the ready insns, and sorted according to priority number, we
schedule the insn from the end of the list by placing its
predecessors in the list according to their priority order. We
consider this insn scheduled by setting the pointer to the "end" of
the list to point to the previous insn. When an insn has no
predecessors, we either queue it until sufficient time has elapsed
or add it to the ready list. As the instructions are scheduled or
when stalls are introduced, the queue advances and dumps insns into
the ready list. When all insns down to the lowest priority have
been scheduled, the critical path of the basic block has been made
as short as possible. The remaining insns are then scheduled in
remaining slots.
Function unit conflicts are resolved during reverse list scheduling
by tracking the time when each insn is committed to the schedule
and from that, the time the function units it uses must be free.
As insns on the ready list are considered for scheduling, those
that would result in a blockage of the already committed insns are
queued until no blockage will result. Among the remaining insns on
the ready list to be considered, the first one with the largest
potential for causing a subsequent blockage is chosen.
The following list shows the order in which we want to break ties
among insns in the ready list:
1. choose insn with lowest conflict cost, ties broken by
2. choose insn with the longest path to end of bb, ties broken by
3. choose insn that kills the most registers, ties broken by
4. choose insn that conflicts with the most ready insns, or finally
5. choose insn with lowest UID.
Memory references complicate matters. Only if we can be certain
that memory references are not part of the data dependency graph
(via true, anti, or output dependence), can we move operations past
memory references. To first approximation, reads can be done
independently, while writes introduce dependencies. Better
approximations will yield fewer dependencies.
Dependencies set up by memory references are treated in exactly the
same way as other dependencies, by using LOG_LINKS.
Having optimized the critical path, we may have also unduly
extended the lifetimes of some registers. If an operation requires
that constants be loaded into registers, it is certainly desirable
to load those constants as early as necessary, but no earlier.
I.e., it will not do to load up a bunch of registers at the
beginning of a basic block only to use them at the end, if they
could be loaded later, since this may result in excessive register
utilization.
Note that since branches are never in basic blocks, but only end
basic blocks, this pass will not do any branch scheduling. But
that is ok, since we can use GNU's delayed branch scheduling
pass to take care of this case.
Also note that no further optimizations based on algebraic identities
are performed, so this pass would be a good one to perform instruction
splitting, such as breaking up a multiply instruction into shifts
and adds where that is profitable.
Given the memory aliasing analysis that this pass should perform,
it should be possible to remove redundant stores to memory, and to
load values from registers instead of hitting memory.
This pass must update information that subsequent passes expect to be
correct. Namely: reg_n_refs, reg_n_sets, reg_n_deaths,
reg_n_calls_crossed, and reg_live_length. Also, basic_block_head,
basic_block_end.
The information in the line number notes is carefully retained by
this pass. Notes that refer to the starting and ending of
exception regions are also carefully retained by this pass. All
other NOTE insns are grouped in their same relative order at the
beginning of basic blocks that have been scheduled. */
#include "config.h"
#include <stdio.h>
#include "rtl.h"
#include "basic-block.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "flags.h"
#include "insn-config.h"
#include "insn-attr.h"
#ifdef INSN_SCHEDULING
/* Arrays set up by scheduling for the same respective purposes as
similar-named arrays set up by flow analysis. We work with these
arrays during the scheduling pass so we can compare values against
unscheduled code.
Values of these arrays are copied at the end of this pass into the
arrays set up by flow analysis. */
static int *sched_reg_n_calls_crossed;
static int *sched_reg_live_length;
/* Element N is the next insn that sets (hard or pseudo) register
N within the current basic block; or zero, if there is no
such insn. Needed for new registers which may be introduced
by splitting insns. */
static rtx *reg_last_uses;
static rtx *reg_last_sets;
static regset reg_pending_sets;
static int reg_pending_sets_all;
/* Vector indexed by INSN_UID giving the original ordering of the insns. */
static int *insn_luid;
#define INSN_LUID(INSN) (insn_luid[INSN_UID (INSN)])
/* Vector indexed by INSN_UID giving each instruction a priority. */
static int *insn_priority;
#define INSN_PRIORITY(INSN) (insn_priority[INSN_UID (INSN)])
static short *insn_costs;
#define INSN_COST(INSN) insn_costs[INSN_UID (INSN)]
/* Vector indexed by INSN_UID giving an encoding of the function units
used. */
static short *insn_units;
#define INSN_UNIT(INSN) insn_units[INSN_UID (INSN)]
/* Vector indexed by INSN_UID giving an encoding of the blockage range
function. The unit and the range are encoded. */
static unsigned int *insn_blockage;
#define INSN_BLOCKAGE(INSN) insn_blockage[INSN_UID (INSN)]
#define UNIT_BITS 5
#define BLOCKAGE_MASK ((1 << BLOCKAGE_BITS) - 1)
#define ENCODE_BLOCKAGE(U,R) \
((((U) << UNIT_BITS) << BLOCKAGE_BITS \
| MIN_BLOCKAGE_COST (R)) << BLOCKAGE_BITS \
| MAX_BLOCKAGE_COST (R))
#define UNIT_BLOCKED(B) ((B) >> (2 * BLOCKAGE_BITS))
#define BLOCKAGE_RANGE(B) \
(((((B) >> BLOCKAGE_BITS) & BLOCKAGE_MASK) << (HOST_BITS_PER_INT / 2)) \
| (B) & BLOCKAGE_MASK)
/* Encodings of the `<name>_unit_blockage_range' function. */
#define MIN_BLOCKAGE_COST(R) ((R) >> (HOST_BITS_PER_INT / 2))
#define MAX_BLOCKAGE_COST(R) ((R) & ((1 << (HOST_BITS_PER_INT / 2)) - 1))
#define DONE_PRIORITY -1
#define MAX_PRIORITY 0x7fffffff
#define TAIL_PRIORITY 0x7ffffffe
#define LAUNCH_PRIORITY 0x7f000001
#define DONE_PRIORITY_P(INSN) (INSN_PRIORITY (INSN) < 0)
#define LOW_PRIORITY_P(INSN) ((INSN_PRIORITY (INSN) & 0x7f000000) == 0)
/* Vector indexed by INSN_UID giving number of insns referring to this insn. */
static int *insn_ref_count;
#define INSN_REF_COUNT(INSN) (insn_ref_count[INSN_UID (INSN)])
/* Vector indexed by INSN_UID giving line-number note in effect for each
insn. For line-number notes, this indicates whether the note may be
reused. */
static rtx *line_note;
#define LINE_NOTE(INSN) (line_note[INSN_UID (INSN)])
/* Vector indexed by basic block number giving the starting line-number
for each basic block. */
static rtx *line_note_head;
/* List of important notes we must keep around. This is a pointer to the
last element in the list. */
static rtx note_list;
/* Regsets telling whether a given register is live or dead before the last
scheduled insn. Must scan the instructions once before scheduling to
determine what registers are live or dead at the end of the block. */
static regset bb_dead_regs;
static regset bb_live_regs;
/* Regset telling whether a given register is live after the insn currently
being scheduled. Before processing an insn, this is equal to bb_live_regs
above. This is used so that we can find registers that are newly born/dead
after processing an insn. */
static regset old_live_regs;
/* The chain of REG_DEAD notes. REG_DEAD notes are removed from all insns
during the initial scan and reused later. If there are not exactly as
many REG_DEAD notes in the post scheduled code as there were in the
prescheduled code then we trigger an abort because this indicates a bug. */
static rtx dead_notes;
/* Queues, etc. */
/* An instruction is ready to be scheduled when all insns following it
have already been scheduled. It is important to ensure that all
insns which use its result will not be executed until its result
has been computed. An insn is maintained in one of four structures:
(P) the "Pending" set of insns which cannot be scheduled until
their dependencies have been satisfied.
(Q) the "Queued" set of insns that can be scheduled when sufficient
time has passed.
(R) the "Ready" list of unscheduled, uncommitted insns.
(S) the "Scheduled" list of insns.
Initially, all insns are either "Pending" or "Ready" depending on
whether their dependencies are satisfied.
Insns move from the "Ready" list to the "Scheduled" list as they
are committed to the schedule. As this occurs, the insns in the
"Pending" list have their dependencies satisfied and move to either
the "Ready" list or the "Queued" set depending on whether
sufficient time has passed to make them ready. As time passes,
insns move from the "Queued" set to the "Ready" list. Insns may
move from the "Ready" list to the "Queued" set if they are blocked
due to a function unit conflict.
The "Pending" list (P) are the insns in the LOG_LINKS of the unscheduled
insns, i.e., those that are ready, queued, and pending.
The "Queued" set (Q) is implemented by the variable `insn_queue'.
The "Ready" list (R) is implemented by the variables `ready' and
`n_ready'.
The "Scheduled" list (S) is the new insn chain built by this pass.
The transition (R->S) is implemented in the scheduling loop in
`schedule_block' when the best insn to schedule is chosen.
The transition (R->Q) is implemented in `schedule_select' when an
insn is found to to have a function unit conflict with the already
committed insns.
The transitions (P->R and P->Q) are implemented in `schedule_insn' as
insns move from the ready list to the scheduled list.
The transition (Q->R) is implemented at the top of the scheduling
loop in `schedule_block' as time passes or stalls are introduced. */
/* Implement a circular buffer to delay instructions until sufficient
time has passed. INSN_QUEUE_SIZE is a power of two larger than
MAX_BLOCKAGE and MAX_READY_COST computed by genattr.c. This is the
longest time an isnsn may be queued. */
static rtx insn_queue[INSN_QUEUE_SIZE];
static int q_ptr = 0;
static int q_size = 0;
#define NEXT_Q(X) (((X)+1) & (INSN_QUEUE_SIZE-1))
#define NEXT_Q_AFTER(X,C) (((X)+C) & (INSN_QUEUE_SIZE-1))
/* Vector indexed by INSN_UID giving the minimum clock tick at which
the insn becomes ready. This is used to note timing constraints for
insns in the pending list. */
static int *insn_tick;
#define INSN_TICK(INSN) (insn_tick[INSN_UID (INSN)])
/* Data structure for keeping track of register information
during that register's life. */
struct sometimes
{
int regno;
int live_length;
int calls_crossed;
};
/* Forward declarations. */
static rtx canon_rtx PROTO((rtx));
static int rtx_equal_for_memref_p PROTO((rtx, rtx));
static rtx find_symbolic_term PROTO((rtx));
static int memrefs_conflict_p PROTO((int, rtx, int, rtx,
HOST_WIDE_INT));
static void add_dependence PROTO((rtx, rtx, enum reg_note));
static void remove_dependence PROTO((rtx, rtx));
static rtx find_insn_list PROTO((rtx, rtx));
static int insn_unit PROTO((rtx));
static unsigned int blockage_range PROTO((int, rtx));
static void clear_units PROTO((void));
static void prepare_unit PROTO((int));
static int actual_hazard_this_instance PROTO((int, int, rtx, int, int));
static void schedule_unit PROTO((int, rtx, int));
static int actual_hazard PROTO((int, rtx, int, int));
static int potential_hazard PROTO((int, rtx, int));
static int insn_cost PROTO((rtx, rtx, rtx));
static int priority PROTO((rtx));
static void free_pending_lists PROTO((void));
static void add_insn_mem_dependence PROTO((rtx *, rtx *, rtx, rtx));
static void flush_pending_lists PROTO((rtx, int));
static void sched_analyze_1 PROTO((rtx, rtx));
static void sched_analyze_2 PROTO((rtx, rtx));
static void sched_analyze_insn PROTO((rtx, rtx, rtx));
static int sched_analyze PROTO((rtx, rtx));
static void sched_note_set PROTO((int, rtx, int));
static int rank_for_schedule PROTO((rtx *, rtx *));
static void swap_sort PROTO((rtx *, int));
static void queue_insn PROTO((rtx, int));
static int birthing_insn_p PROTO((rtx));
static void adjust_priority PROTO((rtx));
static int schedule_insn PROTO((rtx, rtx *, int, int));
static int schedule_select PROTO((rtx *, int, int, FILE *));
static void create_reg_dead_note PROTO((rtx, rtx));
static void attach_deaths PROTO((rtx, rtx, int));
static void attach_deaths_insn PROTO((rtx));
static rtx unlink_notes PROTO((rtx, rtx));
static int new_sometimes_live PROTO((struct sometimes *, int, int));
static void finish_sometimes_live PROTO((struct sometimes *, int));
static rtx reemit_notes PROTO((rtx, rtx));
static void schedule_block PROTO((int, FILE *));
static rtx regno_use_in PROTO((int, rtx));
static void split_hard_reg_notes PROTO((rtx, rtx, rtx, rtx));
static void new_insn_dead_notes PROTO((rtx, rtx, rtx, rtx));
static void update_n_sets PROTO((rtx, int));
static void update_flow_info PROTO((rtx, rtx, rtx, rtx));
/* Main entry point of this file. */
void schedule_insns PROTO((FILE *));
#endif /* INSN_SCHEDULING */
#define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
/* Vector indexed by N giving the initial (unchanging) value known
for pseudo-register N. */
static rtx *reg_known_value;
/* Vector recording for each reg_known_value whether it is due to a
REG_EQUIV note. Future passes (viz., reload) may replace the
pseudo with the equivalent expression and so we account for the
dependences that would be introduced if that happens. */
/* ??? This is a problem only on the Convex. The REG_EQUIV notes created in
assign_parms mention the arg pointer, and there are explicit insns in the
RTL that modify the arg pointer. Thus we must ensure that such insns don't
get scheduled across each other because that would invalidate the REG_EQUIV
notes. One could argue that the REG_EQUIV notes are wrong, but solving
the problem in the scheduler will likely give better code, so we do it
here. */
static char *reg_known_equiv_p;
/* Indicates number of valid entries in reg_known_value. */
static int reg_known_value_size;
static rtx
canon_rtx (x)
rtx x;
{
/* Recursively look for equivalences. */
if (GET_CODE (x) == REG && REGNO (x) >= FIRST_PSEUDO_REGISTER
&& REGNO (x) <= reg_known_value_size)
return reg_known_value[REGNO (x)] == x
? x : canon_rtx (reg_known_value[REGNO (x)]);
else if (GET_CODE (x) == PLUS)
{
rtx x0 = canon_rtx (XEXP (x, 0));
rtx x1 = canon_rtx (XEXP (x, 1));
if (x0 != XEXP (x, 0) || x1 != XEXP (x, 1))
{
/* We can tolerate LO_SUMs being offset here; these
rtl are used for nothing other than comparisons. */
if (GET_CODE (x0) == CONST_INT)
return plus_constant_for_output (x1, INTVAL (x0));
else if (GET_CODE (x1) == CONST_INT)
return plus_constant_for_output (x0, INTVAL (x1));
return gen_rtx (PLUS, GET_MODE (x), x0, x1);
}
}
/* This gives us much better alias analysis when called from
the loop optimizer. Note we want to leave the original
MEM alone, but need to return the canonicalized MEM with
all the flags with their original values. */
else if (GET_CODE (x) == MEM)
{
rtx copy = copy_rtx (x);
XEXP (copy, 0) = canon_rtx (XEXP (copy, 0));
x = copy;
}
return x;
}
/* Set up all info needed to perform alias analysis on memory references. */
void
init_alias_analysis ()
{
int maxreg = max_reg_num ();
rtx insn;
rtx note;
rtx set;
reg_known_value_size = maxreg;
reg_known_value
= (rtx *) oballoc ((maxreg-FIRST_PSEUDO_REGISTER) * sizeof (rtx))
- FIRST_PSEUDO_REGISTER;
bzero ((char *) (reg_known_value + FIRST_PSEUDO_REGISTER),
(maxreg-FIRST_PSEUDO_REGISTER) * sizeof (rtx));
reg_known_equiv_p
= (char *) oballoc ((maxreg -FIRST_PSEUDO_REGISTER) * sizeof (char))
- FIRST_PSEUDO_REGISTER;
bzero (reg_known_equiv_p + FIRST_PSEUDO_REGISTER,
(maxreg - FIRST_PSEUDO_REGISTER) * sizeof (char));
/* Fill in the entries with known constant values. */
for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
if ((set = single_set (insn)) != 0
&& GET_CODE (SET_DEST (set)) == REG
&& REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
&& (((note = find_reg_note (insn, REG_EQUAL, 0)) != 0
&& REG_N_SETS (REGNO (SET_DEST (set))) == 1)
|| (note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) != 0)
&& GET_CODE (XEXP (note, 0)) != EXPR_LIST)
{
int regno = REGNO (SET_DEST (set));
reg_known_value[regno] = XEXP (note, 0);
reg_known_equiv_p[regno] = REG_NOTE_KIND (note) == REG_EQUIV;
}
/* Fill in the remaining entries. */
while (--maxreg >= FIRST_PSEUDO_REGISTER)
if (reg_known_value[maxreg] == 0)
reg_known_value[maxreg] = regno_reg_rtx[maxreg];
}
/* Return 1 if X and Y are identical-looking rtx's.
We use the data in reg_known_value above to see if two registers with
different numbers are, in fact, equivalent. */
static int
rtx_equal_for_memref_p (x, y)
rtx x, y;
{
register int i;
register int j;
register enum rtx_code code;
register char *fmt;
if (x == 0 && y == 0)
return 1;
if (x == 0 || y == 0)
return 0;
x = canon_rtx (x);
y = canon_rtx (y);
if (x == y)
return 1;
code = GET_CODE (x);
/* Rtx's of different codes cannot be equal. */
if (code != GET_CODE (y))
return 0;
/* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
(REG:SI x) and (REG:HI x) are NOT equivalent. */
if (GET_MODE (x) != GET_MODE (y))
return 0;
/* REG, LABEL_REF, and SYMBOL_REF can be compared nonrecursively. */
if (code == REG)
return REGNO (x) == REGNO (y);
if (code == LABEL_REF)
return XEXP (x, 0) == XEXP (y, 0);
if (code == SYMBOL_REF)
return XSTR (x, 0) == XSTR (y, 0);
/* For commutative operations, the RTX match if the operand match in any
order. Also handle the simple binary and unary cases without a loop. */
if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
return ((rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0))
&& rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1)))
|| (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 1))
&& rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 0))));
else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
return (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0))
&& rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1)));
else if (GET_RTX_CLASS (code) == '1')
return rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0));
/* Compare the elements. If any pair of corresponding elements
fail to match, return 0 for the whole things. */
fmt = GET_RTX_FORMAT (code);
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
{
switch (fmt[i])
{
case 'w':
if (XWINT (x, i) != XWINT (y, i))
return 0;
break;
case 'n':
case 'i':
if (XINT (x, i) != XINT (y, i))
return 0;
break;
case 'V':
case 'E':
/* Two vectors must have the same length. */
if (XVECLEN (x, i) != XVECLEN (y, i))
return 0;
/* And the corresponding elements must match. */
for (j = 0; j < XVECLEN (x, i); j++)
if (rtx_equal_for_memref_p (XVECEXP (x, i, j), XVECEXP (y, i, j)) == 0)
return 0;
break;
case 'e':
if (rtx_equal_for_memref_p (XEXP (x, i), XEXP (y, i)) == 0)
return 0;
break;
case 'S':
case 's':
if (strcmp (XSTR (x, i), XSTR (y, i)))
return 0;
break;
case 'u':
/* These are just backpointers, so they don't matter. */
break;
case '0':
break;
/* It is believed that rtx's at this level will never
contain anything but integers and other rtx's,
except for within LABEL_REFs and SYMBOL_REFs. */
default:
abort ();
}
}
return 1;
}
/* Given an rtx X, find a SYMBOL_REF or LABEL_REF within
X and return it, or return 0 if none found. */
static rtx
find_symbolic_term (x)
rtx x;
{
register int i;
register enum rtx_code code;
register char *fmt;
code = GET_CODE (x);
if (code == SYMBOL_REF || code == LABEL_REF)
return x;
if (GET_RTX_CLASS (code) == 'o')
return 0;
fmt = GET_RTX_FORMAT (code);
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
{
rtx t;
if (fmt[i] == 'e')
{
t = find_symbolic_term (XEXP (x, i));
if (t != 0)
return t;
}
else if (fmt[i] == 'E')
break;
}
return 0;
}
/* Return nonzero if X and Y (memory addresses) could reference the
same location in memory. C is an offset accumulator. When
C is nonzero, we are testing aliases between X and Y + C.
XSIZE is the size in bytes of the X reference,
similarly YSIZE is the size in bytes for Y.
If XSIZE or YSIZE is zero, we do not know the amount of memory being
referenced (the reference was BLKmode), so make the most pessimistic
assumptions.
We recognize the following cases of non-conflicting memory:
(1) addresses involving the frame pointer cannot conflict
with addresses involving static variables.
(2) static variables with different addresses cannot conflict.
Nice to notice that varying addresses cannot conflict with fp if no
local variables had their addresses taken, but that's too hard now. */
/* ??? In Fortran, references to a array parameter can never conflict with
another array parameter. */
static int
memrefs_conflict_p (xsize, x, ysize, y, c)
rtx x, y;
int xsize, ysize;
HOST_WIDE_INT c;
{
if (GET_CODE (x) == HIGH)
x = XEXP (x, 0);
else if (GET_CODE (x) == LO_SUM)
x = XEXP (x, 1);
else
x = canon_rtx (x);
if (GET_CODE (y) == HIGH)
y = XEXP (y, 0);
else if (GET_CODE (y) == LO_SUM)
y = XEXP (y, 1);
else
y = canon_rtx (y);
if (rtx_equal_for_memref_p (x, y))
return (xsize == 0 || ysize == 0
|| (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0));
if (y == frame_pointer_rtx || y == hard_frame_pointer_rtx
|| y == stack_pointer_rtx)
{
rtx t = y;
int tsize = ysize;
y = x; ysize = xsize;
x = t; xsize = tsize;
}
if (x == frame_pointer_rtx || x == hard_frame_pointer_rtx
|| x == stack_pointer_rtx)
{
rtx y1;
if (CONSTANT_P (y))
return 0;
if (GET_CODE (y) == PLUS
&& canon_rtx (XEXP (y, 0)) == x
&& (y1 = canon_rtx (XEXP (y, 1)))
&& GET_CODE (y1) == CONST_INT)
{
c += INTVAL (y1);
return (xsize == 0 || ysize == 0
|| (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0));
}
if (GET_CODE (y) == PLUS
&& (y1 = canon_rtx (XEXP (y, 0)))
&& CONSTANT_P (y1))
return 0;
return 1;
}
if (GET_CODE (x) == PLUS)
{
/* The fact that X is canonicalized means that this
PLUS rtx is canonicalized. */
rtx x0 = XEXP (x, 0);
rtx x1 = XEXP (x, 1);
if (GET_CODE (y) == PLUS)
{
/* The fact that Y is canonicalized means that this
PLUS rtx is canonicalized. */
rtx y0 = XEXP (y, 0);
rtx y1 = XEXP (y, 1);
if (rtx_equal_for_memref_p (x1, y1))
return memrefs_conflict_p (xsize, x0, ysize, y0, c);
if (rtx_equal_for_memref_p (x0, y0))
return memrefs_conflict_p (xsize, x1, ysize, y1, c);
if (GET_CODE (x1) == CONST_INT)
if (GET_CODE (y1) == CONST_INT)
return memrefs_conflict_p (xsize, x0, ysize, y0,
c - INTVAL (x1) + INTVAL (y1));
else
return memrefs_conflict_p (xsize, x0, ysize, y, c - INTVAL (x1));
else if (GET_CODE (y1) == CONST_INT)
return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1));
/* Handle case where we cannot understand iteration operators,
but we notice that the base addresses are distinct objects. */
x = find_symbolic_term (x);
if (x == 0)
return 1;
y = find_symbolic_term (y);
if (y == 0)
return 1;
return rtx_equal_for_memref_p (x, y);
}
else if (GET_CODE (x1) == CONST_INT)
return memrefs_conflict_p (xsize, x0, ysize, y, c - INTVAL (x1));
}
else if (GET_CODE (y) == PLUS)
{
/* The fact that Y is canonicalized means that this
PLUS rtx is canonicalized. */
rtx y0 = XEXP (y, 0);
rtx y1 = XEXP (y, 1);
if (GET_CODE (y1) == CONST_INT)
return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1));
else
return 1;
}
if (GET_CODE (x) == GET_CODE (y) && GET_CODE (x) == MULT)
{
/* Handle cases where we expect the second operands to be the
same, and check only whether the first operand would conflict
or not. */
rtx x0, y0;
rtx x1 = canon_rtx (XEXP (x, 1));
rtx y1 = canon_rtx (XEXP (y, 1));
if (! rtx_equal_for_memref_p (x1, y1))
return 1;
x0 = canon_rtx (XEXP (x, 0));
y0 = canon_rtx (XEXP (y, 0));
if (rtx_equal_for_memref_p (x0, y0))
return (xsize == 0 || ysize == 0
|| (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0));
/* Can't properly adjust our sizes. */
if (GET_CODE (x1) != CONST_INT)
return 1;
xsize /= INTVAL (x1);
ysize /= INTVAL (x1);
c /= INTVAL (x1);
return memrefs_conflict_p (xsize, x0, ysize, y0, c);
}
if (CONSTANT_P (x))
{
if (GET_CODE (x) == CONST_INT && GET_CODE (y) == CONST_INT)
{
c += (INTVAL (y) - INTVAL (x));
return (xsize == 0 || ysize == 0
|| (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0));
}
if (GET_CODE (x) == CONST)
{
if (GET_CODE (y) == CONST)
return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)),
ysize, canon_rtx (XEXP (y, 0)), c);
else
return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)),
ysize, y, c);
}
if (GET_CODE (y) == CONST)
return memrefs_conflict_p (xsize, x, ysize,
canon_rtx (XEXP (y, 0)), c);
if (CONSTANT_P (y))
return (rtx_equal_for_memref_p (x, y)
&& (xsize == 0 || ysize == 0
|| (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0)));
return 1;
}
return 1;
}
/* Functions to compute memory dependencies.
Since we process the insns in execution order, we can build tables
to keep track of what registers are fixed (and not aliased), what registers
are varying in known ways, and what registers are varying in unknown
ways.
If both memory references are volatile, then there must always be a
dependence between the two references, since their order can not be
changed. A volatile and non-volatile reference can be interchanged
though.
A MEM_IN_STRUCT reference at a non-QImode non-AND varying address can never
conflict with a non-MEM_IN_STRUCT reference at a fixed address. We must
allow QImode aliasing because the ANSI C standard allows character
pointers to alias anything. We are assuming that characters are
always QImode here. We also must allow AND addresses, because they may
generate accesses outside the object being referenced. This is used to
generate aligned addresses from unaligned addresses, for instance, the
alpha storeqi_unaligned pattern. */
/* Read dependence: X is read after read in MEM takes place. There can
only be a dependence here if both reads are volatile. */
int
read_dependence (mem, x)
rtx mem;
rtx x;
{
return MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem);
}
/* True dependence: X is read after store in MEM takes place. */
int
true_dependence (mem, x)
rtx mem;
rtx x;
{
/* If X is an unchanging read, then it can't possibly conflict with any
non-unchanging store. It may conflict with an unchanging write though,
because there may be a single store to this address to initialize it.
Just fall through to the code below to resolve the case where we have
both an unchanging read and an unchanging write. This won't handle all
cases optimally, but the possible performance loss should be
negligible. */
x = canon_rtx (x);
mem = canon_rtx (mem);
if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem))
return 0;
return ((MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
|| (memrefs_conflict_p (SIZE_FOR_MODE (mem), XEXP (mem, 0),
SIZE_FOR_MODE (x), XEXP (x, 0), 0)
&& ! (MEM_IN_STRUCT_P (mem) && rtx_addr_varies_p (mem)
&& GET_MODE (mem) != QImode
&& GET_CODE (XEXP (mem, 0)) != AND
&& ! MEM_IN_STRUCT_P (x) && ! rtx_addr_varies_p (x))
&& ! (MEM_IN_STRUCT_P (x) && rtx_addr_varies_p (x)
&& GET_MODE (x) != QImode
&& GET_CODE (XEXP (x, 0)) != AND
&& ! MEM_IN_STRUCT_P (mem) && ! rtx_addr_varies_p (mem))));
}
/* Anti dependence: X is written after read in MEM takes place. */
int
anti_dependence (mem, x)
rtx mem;
rtx x;
{
/* If MEM is an unchanging read, then it can't possibly conflict with
the store to X, because there is at most one store to MEM, and it must
have occurred somewhere before MEM. */
x = canon_rtx (x);
mem = canon_rtx (mem);
if (RTX_UNCHANGING_P (mem))
return 0;
return ((MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
|| (memrefs_conflict_p (SIZE_FOR_MODE (mem), XEXP (mem, 0),
SIZE_FOR_MODE (x), XEXP (x, 0), 0)
&& ! (MEM_IN_STRUCT_P (mem) && rtx_addr_varies_p (mem)
&& GET_MODE (mem) != QImode
&& GET_CODE (XEXP (mem, 0)) != AND
&& ! MEM_IN_STRUCT_P (x) && ! rtx_addr_varies_p (x))
&& ! (MEM_IN_STRUCT_P (x) && rtx_addr_varies_p (x)
&& GET_MODE (x) != QImode
&& GET_CODE (XEXP (x, 0)) != AND
&& ! MEM_IN_STRUCT_P (mem) && ! rtx_addr_varies_p (mem))));
}
/* Output dependence: X is written after store in MEM takes place. */
int
output_dependence (mem, x)
rtx mem;
rtx x;
{
x = canon_rtx (x);
mem = canon_rtx (mem);
return ((MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
|| (memrefs_conflict_p (SIZE_FOR_MODE (mem), XEXP (mem, 0),
SIZE_FOR_MODE (x), XEXP (x, 0), 0)
&& ! (MEM_IN_STRUCT_P (mem) && rtx_addr_varies_p (mem)
&& GET_MODE (mem) != QImode
&& GET_CODE (XEXP (mem, 0)) != AND
&& ! MEM_IN_STRUCT_P (x) && ! rtx_addr_varies_p (x))
&& ! (MEM_IN_STRUCT_P (x) && rtx_addr_varies_p (x)
&& GET_MODE (x) != QImode
&& GET_CODE (XEXP (x, 0)) != AND
&& ! MEM_IN_STRUCT_P (mem) && ! rtx_addr_varies_p (mem))));
}
/* Helper functions for instruction scheduling. */
/* Add ELEM wrapped in an INSN_LIST with reg note kind DEP_TYPE to the
LOG_LINKS of INSN, if not already there. DEP_TYPE indicates the type
of dependence that this link represents. */
static void
add_dependence (insn, elem, dep_type)
rtx insn;
rtx elem;
enum reg_note dep_type;
{
rtx link, next;
/* Don't depend an insn on itself. */
if (insn == elem)
return;
/* If elem is part of a sequence that must be scheduled together, then
make the dependence point to the last insn of the sequence.
When HAVE_cc0, it is possible for NOTEs to exist between users and
setters of the condition codes, so we must skip past notes here.
Otherwise, NOTEs are impossible here. */
next = NEXT_INSN (elem);
#ifdef HAVE_cc0
while (next && GET_CODE (next) == NOTE)
next = NEXT_INSN (next);
#endif
if (next && SCHED_GROUP_P (next)
&& GET_CODE (next) != CODE_LABEL)
{
/* Notes will never intervene here though, so don't bother checking
for them. */
/* We must reject CODE_LABELs, so that we don't get confused by one
that has LABEL_PRESERVE_P set, which is represented by the same
bit in the rtl as SCHED_GROUP_P. A CODE_LABEL can never be
SCHED_GROUP_P. */
while (NEXT_INSN (next) && SCHED_GROUP_P (NEXT_INSN (next))
&& GET_CODE (NEXT_INSN (next)) != CODE_LABEL)
next = NEXT_INSN (next);
/* Again, don't depend an insn on itself. */
if (insn == next)
return;
/* Make the dependence to NEXT, the last insn of the group, instead
of the original ELEM. */
elem = next;
}
/* Check that we don't already have this dependence. */
for (link = LOG_LINKS (insn); link; link = XEXP (link, 1))
if (XEXP (link, 0) == elem)
{
/* If this is a more restrictive type of dependence than the existing
one, then change the existing dependence to this type. */
if ((int) dep_type < (int) REG_NOTE_KIND (link))
PUT_REG_NOTE_KIND (link, dep_type);
return;
}
/* Might want to check one level of transitivity to save conses. */
link = rtx_alloc (INSN_LIST);
/* Insn dependency, not data dependency. */
PUT_REG_NOTE_KIND (link, dep_type);
XEXP (link, 0) = elem;
XEXP (link, 1) = LOG_LINKS (insn);
LOG_LINKS (insn) = link;
}
/* Remove ELEM wrapped in an INSN_LIST from the LOG_LINKS
of INSN. Abort if not found. */
static void
remove_dependence (insn, elem)
rtx insn;
rtx elem;
{
rtx prev, link;
int found = 0;
for (prev = 0, link = LOG_LINKS (insn); link; link = XEXP (link, 1))
{
if (XEXP (link, 0) == elem)
{
RTX_INTEGRATED_P (link) = 1;
if (prev)
XEXP (prev, 1) = XEXP (link, 1);
else
LOG_LINKS (insn) = XEXP (link, 1);
found = 1;
}
else
prev = link;
}
if (! found)
abort ();
return;
}
#ifndef INSN_SCHEDULING
void
schedule_insns (dump_file)
FILE *dump_file;
{
}
#else
#ifndef __GNUC__
#define __inline
#endif
/* Computation of memory dependencies. */
/* The *_insns and *_mems are paired lists. Each pending memory operation
will have a pointer to the MEM rtx on one list and a pointer to the
containing insn on the other list in the same place in the list. */
/* We can't use add_dependence like the old code did, because a single insn
may have multiple memory accesses, and hence needs to be on the list
once for each memory access. Add_dependence won't let you add an insn
to a list more than once. */
/* An INSN_LIST containing all insns with pending read operations. */
static rtx pending_read_insns;
/* An EXPR_LIST containing all MEM rtx's which are pending reads. */
static rtx pending_read_mems;
/* An INSN_LIST containing all insns with pending write operations. */
static rtx pending_write_insns;
/* An EXPR_LIST containing all MEM rtx's which are pending writes. */
static rtx pending_write_mems;
/* Indicates the combined length of the two pending lists. We must prevent
these lists from ever growing too large since the number of dependencies
produced is at least O(N*N), and execution time is at least O(4*N*N), as
a function of the length of these pending lists. */
static int pending_lists_length;
/* An INSN_LIST containing all INSN_LISTs allocated but currently unused. */
static rtx unused_insn_list;
/* An EXPR_LIST containing all EXPR_LISTs allocated but currently unused. */
static rtx unused_expr_list;
/* The last insn upon which all memory references must depend.
This is an insn which flushed the pending lists, creating a dependency
between it and all previously pending memory references. This creates
a barrier (or a checkpoint) which no memory reference is allowed to cross.
This includes all non constant CALL_INSNs. When we do interprocedural
alias analysis, this restriction can be relaxed.
This may also be an INSN that writes memory if the pending lists grow
too large. */
static rtx last_pending_memory_flush;
/* The last function call we have seen. All hard regs, and, of course,
the last function call, must depend on this. */
static rtx last_function_call;
/* The LOG_LINKS field of this is a list of insns which use a pseudo register
that does not already cross a call. We create dependencies between each
of those insn and the next call insn, to ensure that they won't cross a call
after scheduling is done. */
static rtx sched_before_next_call;
/* Pointer to the last instruction scheduled. Used by rank_for_schedule,
so that insns independent of the last scheduled insn will be preferred
over dependent instructions. */
static rtx last_scheduled_insn;
/* Process an insn's memory dependencies. There are four kinds of
dependencies:
(0) read dependence: read follows read
(1) true dependence: read follows write
(2) anti dependence: write follows read
(3) output dependence: write follows write
We are careful to build only dependencies which actually exist, and
use transitivity to avoid building too many links. */
/* Return the INSN_LIST containing INSN in LIST, or NULL
if LIST does not contain INSN. */
__inline static rtx
find_insn_list (insn, list)
rtx insn;
rtx list;
{
while (list)
{
if (XEXP (list, 0) == insn)
return list;
list = XEXP (list, 1);
}
return 0;
}
/* Compute the function units used by INSN. This caches the value
returned by function_units_used. A function unit is encoded as the
unit number if the value is non-negative and the compliment of a
mask if the value is negative. A function unit index is the
non-negative encoding. */
__inline static int
insn_unit (insn)
rtx insn;
{
register int unit = INSN_UNIT (insn);
if (unit == 0)
{
recog_memoized (insn);
/* A USE insn, or something else we don't need to understand.
We can't pass these directly to function_units_used because it will
trigger a fatal error for unrecognizable insns. */
if (INSN_CODE (insn) < 0)
unit = -1;
else
{
unit = function_units_used (insn);
/* Increment non-negative values so we can cache zero. */
if (unit >= 0) unit++;
}
/* We only cache 16 bits of the result, so if the value is out of
range, don't cache it. */
if (FUNCTION_UNITS_SIZE < HOST_BITS_PER_SHORT
|| unit >= 0
|| (~unit & ((1 << (HOST_BITS_PER_SHORT - 1)) - 1)) == 0)
INSN_UNIT (insn) = unit;
}
return (unit > 0 ? unit - 1 : unit);
}
/* Compute the blockage range for executing INSN on UNIT. This caches
the value returned by the blockage_range_function for the unit.
These values are encoded in an int where the upper half gives the
minimum value and the lower half gives the maximum value. */
__inline static unsigned int
blockage_range (unit, insn)
int unit;
rtx insn;
{
unsigned int blockage = INSN_BLOCKAGE (insn);
unsigned int range;
if (UNIT_BLOCKED (blockage) != unit + 1)
{
range = function_units[unit].blockage_range_function (insn);
/* We only cache the blockage range for one unit and then only if
the values fit. */
if (HOST_BITS_PER_INT >= UNIT_BITS + 2 * BLOCKAGE_BITS)
INSN_BLOCKAGE (insn) = ENCODE_BLOCKAGE (unit + 1, range);
}
else
range = BLOCKAGE_RANGE (blockage);
return range;
}
/* A vector indexed by function unit instance giving the last insn to use
the unit. The value of the function unit instance index for unit U
instance I is (U + I * FUNCTION_UNITS_SIZE). */
static rtx unit_last_insn[FUNCTION_UNITS_SIZE * MAX_MULTIPLICITY];
/* A vector indexed by function unit instance giving the minimum time when
the unit will unblock based on the maximum blockage cost. */
static int unit_tick[FUNCTION_UNITS_SIZE * MAX_MULTIPLICITY];
/* A vector indexed by function unit number giving the number of insns
that remain to use the unit. */
static int unit_n_insns[FUNCTION_UNITS_SIZE];
/* Reset the function unit state to the null state. */
static void
clear_units ()
{
bzero ((char *) unit_last_insn, sizeof (unit_last_insn));
bzero ((char *) unit_tick, sizeof (unit_tick));
bzero ((char *) unit_n_insns, sizeof (unit_n_insns));
}
/* Record an insn as one that will use the units encoded by UNIT. */
__inline static void
prepare_unit (unit)
int unit;
{
int i;
if (unit >= 0)
unit_n_insns[unit]++;
else
for (i = 0, unit = ~unit; unit; i++, unit >>= 1)
if ((unit & 1) != 0)
prepare_unit (i);
}
/* Return the actual hazard cost of executing INSN on the unit UNIT,
instance INSTANCE at time CLOCK if the previous actual hazard cost
was COST. */
__inline static int
actual_hazard_this_instance (unit, instance, insn, clock, cost)
int unit, instance, clock, cost;
rtx insn;
{
int tick = unit_tick[instance];
if (tick - clock > cost)
{
/* The scheduler is operating in reverse, so INSN is the executing
insn and the unit's last insn is the candidate insn. We want a
more exact measure of the blockage if we execute INSN at CLOCK
given when we committed the execution of the unit's last insn.
The blockage value is given by either the unit's max blockage
constant, blockage range function, or blockage function. Use
the most exact form for the given unit. */
if (function_units[unit].blockage_range_function)
{
if (function_units[unit].blockage_function)
tick += (function_units[unit].blockage_function
(insn, unit_last_insn[instance])
- function_units[unit].max_blockage);
else
tick += ((int) MAX_BLOCKAGE_COST (blockage_range (unit, insn))
- function_units[unit].max_blockage);
}
if (tick - clock > cost)
cost = tick - clock;
}
return cost;
}
/* Record INSN as having begun execution on the units encoded by UNIT at
time CLOCK. */
__inline static void
schedule_unit (unit, insn, clock)
int unit, clock;
rtx insn;
{
int i;
if (unit >= 0)
{
int instance = unit;
#if MAX_MULTIPLICITY > 1
/* Find the first free instance of the function unit and use that
one. We assume that one is free. */
for (i = function_units[unit].multiplicity - 1; i > 0; i--)
{
if (! actual_hazard_this_instance (unit, instance, insn, clock, 0))
break;
instance += FUNCTION_UNITS_SIZE;
}
#endif
unit_last_insn[instance] = insn;
unit_tick[instance] = (clock + function_units[unit].max_blockage);
}
else
for (i = 0, unit = ~unit; unit; i++, unit >>= 1)
if ((unit & 1) != 0)
schedule_unit (i, insn, clock);
}
/* Return the actual hazard cost of executing INSN on the units encoded by
UNIT at time CLOCK if the previous actual hazard cost was COST. */
__inline static int
actual_hazard (unit, insn, clock, cost)
int unit, clock, cost;
rtx insn;
{
int i;
if (unit >= 0)
{
/* Find the instance of the function unit with the minimum hazard. */
int instance = unit;
int best_cost = actual_hazard_this_instance (unit, instance, insn,
clock, cost);
int this_cost;
#if MAX_MULTIPLICITY > 1
if (best_cost > cost)
{
for (i = function_units[unit].multiplicity - 1; i > 0; i--)
{
instance += FUNCTION_UNITS_SIZE;
this_cost = actual_hazard_this_instance (unit, instance, insn,
clock, cost);
if (this_cost < best_cost)
{
best_cost = this_cost;
if (this_cost <= cost)
break;
}
}
}
#endif
cost = MAX (cost, best_cost);
}
else
for (i = 0, unit = ~unit; unit; i++, unit >>= 1)
if ((unit & 1) != 0)
cost = actual_hazard (i, insn, clock, cost);
return cost;
}
/* Return the potential hazard cost of executing an instruction on the
units encoded by UNIT if the previous potential hazard cost was COST.
An insn with a large blockage time is chosen in preference to one
with a smaller time; an insn that uses a unit that is more likely
to be used is chosen in preference to one with a unit that is less
used. We are trying to minimize a subsequent actual hazard. */
__inline static int
potential_hazard (unit, insn, cost)
int unit, cost;
rtx insn;
{
int i, ncost;
unsigned int minb, maxb;
if (unit >= 0)
{
minb = maxb = function_units[unit].max_blockage;
if (maxb > 1)
{
if (function_units[unit].blockage_range_function)
{
maxb = minb = blockage_range (unit, insn);
maxb = MAX_BLOCKAGE_COST (maxb);
minb = MIN_BLOCKAGE_COST (minb);
}
if (maxb > 1)
{
/* Make the number of instructions left dominate. Make the
minimum delay dominate the maximum delay. If all these
are the same, use the unit number to add an arbitrary
ordering. Other terms can be added. */
ncost = minb * 0x40 + maxb;
ncost *= (unit_n_insns[unit] - 1) * 0x1000 + unit;
if (ncost > cost)
cost = ncost;
}
}
}
else
for (i = 0, unit = ~unit; unit; i++, unit >>= 1)
if ((unit & 1) != 0)
cost = potential_hazard (i, insn, cost);
return cost;
}
/* Compute cost of executing INSN given the dependence LINK on the insn USED.
This is the number of virtual cycles taken between instruction issue and
instruction results. */
__inline static int
insn_cost (insn, link, used)
rtx insn, link, used;
{
register int cost = INSN_COST (insn);
if (cost == 0)
{
recog_memoized (insn);
/* A USE insn, or something else we don't need to understand.
We can't pass these directly to result_ready_cost because it will
trigger a fatal error for unrecognizable insns. */
if (INSN_CODE (insn) < 0)
{
INSN_COST (insn) = 1;
return 1;
}
else
{
cost = result_ready_cost (insn);
if (cost < 1)
cost = 1;
INSN_COST (insn) = cost;
}
}
/* A USE insn should never require the value used to be computed. This
allows the computation of a function's result and parameter values to
overlap the return and call. */
recog_memoized (used);
if (INSN_CODE (used) < 0)
LINK_COST_FREE (link) = 1;
/* If some dependencies vary the cost, compute the adjustment. Most
commonly, the adjustment is complete: either the cost is ignored
(in the case of an output- or anti-dependence), or the cost is
unchanged. These values are cached in the link as LINK_COST_FREE
and LINK_COST_ZERO. */
if (LINK_COST_FREE (link))
cost = 1;
#ifdef ADJUST_COST
else if (! LINK_COST_ZERO (link))
{
int ncost = cost;
ADJUST_COST (used, link, insn, ncost);
if (ncost <= 1)
LINK_COST_FREE (link) = ncost = 1;
if (cost == ncost)
LINK_COST_ZERO (link) = 1;
cost = ncost;
}
#endif
return cost;
}
/* Compute the priority number for INSN. */
static int
priority (insn)
rtx insn;
{
if (insn && GET_RTX_CLASS (GET_CODE (insn)) == 'i')
{
int prev_priority;
int max_priority;
int this_priority = INSN_PRIORITY (insn);
rtx prev;
if (this_priority > 0)
return this_priority;
max_priority = 1;
/* Nonzero if these insns must be scheduled together. */
if (SCHED_GROUP_P (insn))
{
prev = insn;
while (SCHED_GROUP_P (prev))
{
prev = PREV_INSN (prev);
INSN_REF_COUNT (prev) += 1;
}
}
for (prev = LOG_LINKS (insn); prev; prev = XEXP (prev, 1))
{
rtx x = XEXP (prev, 0);
/* If this was a duplicate of a dependence we already deleted,
ignore it. */
if (RTX_INTEGRATED_P (prev))
continue;
/* A dependence pointing to a note or deleted insn is always
obsolete, because sched_analyze_insn will have created any
necessary new dependences which replace it. Notes and deleted
insns can be created when instructions are deleted by insn
splitting, or by register allocation. */
if (GET_CODE (x) == NOTE || INSN_DELETED_P (x))
{
remove_dependence (insn, x);
continue;
}
/* Clear the link cost adjustment bits. */
LINK_COST_FREE (prev) = 0;
#ifdef ADJUST_COST
LINK_COST_ZERO (prev) = 0;
#endif
/* This priority calculation was chosen because it results in the
least instruction movement, and does not hurt the performance
of the resulting code compared to the old algorithm.
This makes the sched algorithm more stable, which results
in better code, because there is less register pressure,
cross jumping is more likely to work, and debugging is easier.
When all instructions have a latency of 1, there is no need to
move any instructions. Subtracting one here ensures that in such
cases all instructions will end up with a priority of one, and
hence no scheduling will be done.
The original code did not subtract the one, and added the
insn_cost of the current instruction to its priority (e.g.
move the insn_cost call down to the end). */
prev_priority = priority (x) + insn_cost (x, prev, insn) - 1;
if (prev_priority > max_priority)
max_priority = prev_priority;
INSN_REF_COUNT (x) += 1;
}
prepare_unit (insn_unit (insn));
INSN_PRIORITY (insn) = max_priority;
return INSN_PRIORITY (insn);
}
return 0;
}
/* Remove all INSN_LISTs and EXPR_LISTs from the pending lists and add
them to the unused_*_list variables, so that they can be reused. */
static void
free_pending_lists ()
{
register rtx link, prev_link;
if (pending_read_insns)
{
prev_link = pending_read_insns;
link = XEXP (prev_link, 1);
while (link)
{
prev_link = link;
link = XEXP (link, 1);
}
XEXP (prev_link, 1) = unused_insn_list;
unused_insn_list = pending_read_insns;
pending_read_insns = 0;
}
if (pending_write_insns)
{
prev_link = pending_write_insns;
link = XEXP (prev_link, 1);
while (link)
{
prev_link = link;
link = XEXP (link, 1);
}
XEXP (prev_link, 1) = unused_insn_list;
unused_insn_list = pending_write_insns;
pending_write_insns = 0;
}
if (pending_read_mems)
{
prev_link = pending_read_mems;
link = XEXP (prev_link, 1);
while (link)
{
prev_link = link;
link = XEXP (link, 1);
}
XEXP (prev_link, 1) = unused_expr_list;
unused_expr_list = pending_read_mems;
pending_read_mems = 0;
}
if (pending_write_mems)
{
prev_link = pending_write_mems;
link = XEXP (prev_link, 1);
while (link)
{
prev_link = link;
link = XEXP (link, 1);
}
XEXP (prev_link, 1) = unused_expr_list;
unused_expr_list = pending_write_mems;
pending_write_mems = 0;
}
}
/* Add an INSN and MEM reference pair to a pending INSN_LIST and MEM_LIST.
The MEM is a memory reference contained within INSN, which we are saving
so that we can do memory aliasing on it. */
static void
add_insn_mem_dependence (insn_list, mem_list, insn, mem)
rtx *insn_list, *mem_list, insn, mem;
{
register rtx link;
if (unused_insn_list)
{
link = unused_insn_list;
unused_insn_list = XEXP (link, 1);
}
else
link = rtx_alloc (INSN_LIST);
XEXP (link, 0) = insn;
XEXP (link, 1) = *insn_list;
*insn_list = link;
if (unused_expr_list)
{
link = unused_expr_list;
unused_expr_list = XEXP (link, 1);
}
else
link = rtx_alloc (EXPR_LIST);
XEXP (link, 0) = mem;
XEXP (link, 1) = *mem_list;
*mem_list = link;
pending_lists_length++;
}
/* Make a dependency between every memory reference on the pending lists
and INSN, thus flushing the pending lists. If ONLY_WRITE, don't flush
the read list. */
static void
flush_pending_lists (insn, only_write)
rtx insn;
int only_write;
{
rtx link;
while (pending_read_insns && ! only_write)
{
add_dependence (insn, XEXP (pending_read_insns, 0), REG_DEP_ANTI);
link = pending_read_insns;
pending_read_insns = XEXP (pending_read_insns, 1);
XEXP (link, 1) = unused_insn_list;
unused_insn_list = link;
link = pending_read_mems;
pending_read_mems = XEXP (pending_read_mems, 1);
XEXP (link, 1) = unused_expr_list;
unused_expr_list = link;
}
while (pending_write_insns)
{
add_dependence (insn, XEXP (pending_write_insns, 0), REG_DEP_ANTI);
link = pending_write_insns;
pending_write_insns = XEXP (pending_write_insns, 1);
XEXP (link, 1) = unused_insn_list;
unused_insn_list = link;
link = pending_write_mems;
pending_write_mems = XEXP (pending_write_mems, 1);
XEXP (link, 1) = unused_expr_list;
unused_expr_list = link;
}
pending_lists_length = 0;
if (last_pending_memory_flush)
add_dependence (insn, last_pending_memory_flush, REG_DEP_ANTI);
last_pending_memory_flush = insn;
}
/* Analyze a single SET or CLOBBER rtx, X, creating all dependencies generated
by the write to the destination of X, and reads of everything mentioned. */
static void
sched_analyze_1 (x, insn)
rtx x;
rtx insn;
{
register int regno;
register rtx dest = SET_DEST (x);
if (dest == 0)
return;
while (GET_CODE (dest) == STRICT_LOW_PART || GET_CODE (dest) == SUBREG
|| GET_CODE (dest) == ZERO_EXTRACT || GET_CODE (dest) == SIGN_EXTRACT)
{
if (GET_CODE (dest) == ZERO_EXTRACT || GET_CODE (dest) == SIGN_EXTRACT)
{
/* The second and third arguments are values read by this insn. */
sched_analyze_2 (XEXP (dest, 1), insn);
sched_analyze_2 (XEXP (dest, 2), insn);
}
dest = SUBREG_REG (dest);
}
if (GET_CODE (dest) == REG)
{
register int i;
regno = REGNO (dest);
/* A hard reg in a wide mode may really be multiple registers.
If so, mark all of them just like the first. */
if (regno < FIRST_PSEUDO_REGISTER)
{
i = HARD_REGNO_NREGS (regno, GET_MODE (dest));
while (--i >= 0)
{
rtx u;
for (u = reg_last_uses[regno+i]; u; u = XEXP (u, 1))
add_dependence (insn, XEXP (u, 0), REG_DEP_ANTI);
reg_last_uses[regno + i] = 0;
if (reg_last_sets[regno + i])
add_dependence (insn, reg_last_sets[regno + i],
REG_DEP_OUTPUT);
SET_REGNO_REG_SET (reg_pending_sets, regno + i);
if ((call_used_regs[i] || global_regs[i])
&& last_function_call)
/* Function calls clobber all call_used regs. */
add_dependence (insn, last_function_call, REG_DEP_ANTI);
}
}
else
{
rtx u;
for (u = reg_last_uses[regno]; u; u = XEXP (u, 1))
add_dependence (insn, XEXP (u, 0), REG_DEP_ANTI);
reg_last_uses[regno] = 0;
if (reg_last_sets[regno])
add_dependence (insn, reg_last_sets[regno], REG_DEP_OUTPUT);
SET_REGNO_REG_SET (reg_pending_sets, regno);
/* Pseudos that are REG_EQUIV to something may be replaced
by that during reloading. We need only add dependencies for
the address in the REG_EQUIV note. */
if (! reload_completed
&& reg_known_equiv_p[regno]
&& GET_CODE (reg_known_value[regno]) == MEM)
sched_analyze_2 (XEXP (reg_known_value[regno], 0), insn);
/* Don't let it cross a call after scheduling if it doesn't
already cross one. */
if (REG_N_CALLS_CROSSED (regno) == 0 && last_function_call)
add_dependence (insn, last_function_call, REG_DEP_ANTI);
}
}
else if (GET_CODE (dest) == MEM)
{
/* Writing memory. */
if (pending_lists_length > 32)
{
/* Flush all pending reads and writes to prevent the pending lists
from getting any larger. Insn scheduling runs too slowly when
these lists get long. The number 32 was chosen because it
seems like a reasonable number. When compiling GCC with itself,
this flush occurs 8 times for sparc, and 10 times for m88k using
the number 32. */
flush_pending_lists (insn, 0);
}
else
{
rtx pending, pending_mem;
pending = pending_read_insns;
pending_mem = pending_read_mems;
while (pending)
{
/* If a dependency already exists, don't create a new one. */
if (! find_insn_list (XEXP (pending, 0), LOG_LINKS (insn)))
if (anti_dependence (XEXP (pending_mem, 0), dest))
add_dependence (insn, XEXP (pending, 0), REG_DEP_ANTI);
pending = XEXP (pending, 1);
pending_mem = XEXP (pending_mem, 1);
}
pending = pending_write_insns;
pending_mem = pending_write_mems;
while (pending)
{
/* If a dependency already exists, don't create a new one. */
if (! find_insn_list (XEXP (pending, 0), LOG_LINKS (insn)))
if (output_dependence (XEXP (pending_mem, 0), dest))
add_dependence (insn, XEXP (pending, 0), REG_DEP_OUTPUT);
pending = XEXP (pending, 1);
pending_mem = XEXP (pending_mem, 1);
}
if (last_pending_memory_flush)
add_dependence (insn, last_pending_memory_flush, REG_DEP_ANTI);
add_insn_mem_dependence (&pending_write_insns, &pending_write_mems,
insn, dest);
}
sched_analyze_2 (XEXP (dest, 0), insn);
}
/* Analyze reads. */
if (GET_CODE (x) == SET)
sched_analyze_2 (SET_SRC (x), insn);
}
/* Analyze the uses of memory and registers in rtx X in INSN. */
static void
sched_analyze_2 (x, insn)
rtx x;
rtx insn;
{
register int i;
register int j;
register enum rtx_code code;
register char *fmt;
if (x == 0)
return;
code = GET_CODE (x);
switch (code)
{
case CONST_INT:
case CONST_DOUBLE:
case SYMBOL_REF:
case CONST:
case LABEL_REF:
/* Ignore constants. Note that we must handle CONST_DOUBLE here
because it may have a cc0_rtx in its CONST_DOUBLE_CHAIN field, but
this does not mean that this insn is using cc0. */
return;
#ifdef HAVE_cc0
case CC0:
{
rtx link, prev;
/* User of CC0 depends on immediately preceding insn. */
SCHED_GROUP_P (insn) = 1;
/* There may be a note before this insn now, but all notes will
be removed before we actually try to schedule the insns, so
it won't cause a problem later. We must avoid it here though. */
prev = prev_nonnote_insn (insn);
/* Make a copy of all dependencies on the immediately previous insn,
and add to this insn. This is so that all the dependencies will
apply to the group. Remove an explicit dependence on this insn
as SCHED_GROUP_P now represents it. */
if (find_insn_list (prev, LOG_LINKS (insn)))
remove_dependence (insn, prev);
for (link = LOG_LINKS (prev); link; link = XEXP (link, 1))
add_dependence (insn, XEXP (link, 0), REG_NOTE_KIND (link));
return;
}
#endif
case REG:
{
int regno = REGNO (x);
if (regno < FIRST_PSEUDO_REGISTER)
{
int i;
i = HARD_REGNO_NREGS (regno, GET_MODE (x));
while (--i >= 0)
{
reg_last_uses[regno + i]
= gen_rtx (INSN_LIST, VOIDmode,
insn, reg_last_uses[regno + i]);
if (reg_last_sets[regno + i])
add_dependence (insn, reg_last_sets[regno + i], 0);
if ((call_used_regs[regno + i] || global_regs[regno + i])
&& last_function_call)
/* Function calls clobber all call_used regs. */
add_dependence (insn, last_function_call, REG_DEP_ANTI);
}
}
else
{
reg_last_uses[regno]
= gen_rtx (INSN_LIST, VOIDmode, insn, reg_last_uses[regno]);
if (reg_last_sets[regno])
add_dependence (insn, reg_last_sets[regno], 0);
/* Pseudos that are REG_EQUIV to something may be replaced
by that during reloading. We need only add dependencies for
the address in the REG_EQUIV note. */
if (! reload_completed
&& reg_known_equiv_p[regno]
&& GET_CODE (reg_known_value[regno]) == MEM)
sched_analyze_2 (XEXP (reg_known_value[regno], 0), insn);
/* If the register does not already cross any calls, then add this
insn to the sched_before_next_call list so that it will still
not cross calls after scheduling. */
if (REG_N_CALLS_CROSSED (regno) == 0)
add_dependence (sched_before_next_call, insn, REG_DEP_ANTI);
}
return;
}
case MEM:
{
/* Reading memory. */
rtx pending, pending_mem;
pending = pending_read_insns;
pending_mem = pending_read_mems;
while (pending)
{
/* If a dependency already exists, don't create a new one. */
if (! find_insn_list (XEXP (pending, 0), LOG_LINKS (insn)))
if (read_dependence (XEXP (pending_mem, 0), x))
add_dependence (insn, XEXP (pending, 0), REG_DEP_ANTI);
pending = XEXP (pending, 1);
pending_mem = XEXP (pending_mem, 1);
}
pending = pending_write_insns;
pending_mem = pending_write_mems;
while (pending)
{
/* If a dependency already exists, don't create a new one. */
if (! find_insn_list (XEXP (pending, 0), LOG_LINKS (insn)))
if (true_dependence (XEXP (pending_mem, 0), x))
add_dependence (insn, XEXP (pending, 0), 0);
pending = XEXP (pending, 1);
pending_mem = XEXP (pending_mem, 1);
}
if (last_pending_memory_flush)
add_dependence (insn, last_pending_memory_flush, REG_DEP_ANTI);
/* Always add these dependencies to pending_reads, since
this insn may be followed by a write. */
add_insn_mem_dependence (&pending_read_insns, &pending_read_mems,
insn, x);
/* Take advantage of tail recursion here. */
sched_analyze_2 (XEXP (x, 0), insn);
return;
}
case ASM_OPERANDS:
case ASM_INPUT:
case UNSPEC_VOLATILE:
case TRAP_IF:
{
rtx u;
/* Traditional and volatile asm instructions must be considered to use
and clobber all hard registers, all pseudo-registers and all of
memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
Consider for instance a volatile asm that changes the fpu rounding
mode. An insn should not be moved across this even if it only uses
pseudo-regs because it might give an incorrectly rounded result. */
if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
{
int max_reg = max_reg_num ();
for (i = 0; i < max_reg; i++)
{
for (u = reg_last_uses[i]; u; u = XEXP (u, 1))
add_dependence (insn, XEXP (u, 0), REG_DEP_ANTI);
reg_last_uses[i] = 0;
if (reg_last_sets[i])
add_dependence (insn, reg_last_sets[i], 0);
}
reg_pending_sets_all = 1;
flush_pending_lists (insn, 0);
}
/* For all ASM_OPERANDS, we must traverse the vector of input operands.
We can not just fall through here since then we would be confused
by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
traditional asms unlike their normal usage. */
if (code == ASM_OPERANDS)
{
for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
sched_analyze_2 (ASM_OPERANDS_INPUT (x, j), insn);
return;
}
break;
}
case PRE_DEC:
case POST_DEC:
case PRE_INC:
case POST_INC:
/* These both read and modify the result. We must handle them as writes
to get proper dependencies for following instructions. We must handle
them as reads to get proper dependencies from this to previous
instructions. Thus we need to pass them to both sched_analyze_1
and sched_analyze_2. We must call sched_analyze_2 first in order
to get the proper antecedent for the read. */
sched_analyze_2 (XEXP (x, 0), insn);
sched_analyze_1 (x, insn);
return;
default:
break;
}
/* Other cases: walk the insn. */
fmt = GET_RTX_FORMAT (code);
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
{
if (fmt[i] == 'e')
sched_analyze_2 (XEXP (x, i), insn);
else if (fmt[i] == 'E')
for (j = 0; j < XVECLEN (x, i); j++)
sched_analyze_2 (XVECEXP (x, i, j), insn);
}
}
/* Analyze an INSN with pattern X to find all dependencies. */
static void
sched_analyze_insn (x, insn, loop_notes)
rtx x, insn;
rtx loop_notes;
{
register RTX_CODE code = GET_CODE (x);
rtx link;
int maxreg = max_reg_num ();
int i;
if (code == SET || code == CLOBBER)
sched_analyze_1 (x, insn);
else if (code == PARALLEL)
{
register int i;
for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
{
code = GET_CODE (XVECEXP (x, 0, i));
if (code == SET || code == CLOBBER)
sched_analyze_1 (XVECEXP (x, 0, i), insn);
else
sched_analyze_2 (XVECEXP (x, 0, i), insn);
}
}
else
sched_analyze_2 (x, insn);
/* Mark registers CLOBBERED or used by called function. */
if (GET_CODE (insn) == CALL_INSN)
for (link = CALL_INSN_FUNCTION_USAGE (insn); link; link = XEXP (link, 1))
{
if (GET_CODE (XEXP (link, 0)) == CLOBBER)
sched_analyze_1 (XEXP (link, 0), insn);
else
sched_analyze_2 (XEXP (link, 0), insn);
}
/* If there is a {LOOP,EHREGION}_{BEG,END} note in the middle of a basic block, then
we must be sure that no instructions are scheduled across it.
Otherwise, the reg_n_refs info (which depends on loop_depth) would
become incorrect. */
if (loop_notes)
{
int max_reg = max_reg_num ();
rtx link;
for (i = 0; i < max_reg; i++)
{
rtx u;
for (u = reg_last_uses[i]; u; u = XEXP (u, 1))
add_dependence (insn, XEXP (u, 0), REG_DEP_ANTI);
reg_last_uses[i] = 0;
if (reg_last_sets[i])
add_dependence (insn, reg_last_sets[i], 0);
}
reg_pending_sets_all = 1;
flush_pending_lists (insn, 0);
link = loop_notes;
while (XEXP (link, 1))
link = XEXP (link, 1);
XEXP (link, 1) = REG_NOTES (insn);
REG_NOTES (insn) = loop_notes;
}
/* After reload, it is possible for an instruction to have a REG_DEAD note
for a register that actually dies a few instructions earlier. For
example, this can happen with SECONDARY_MEMORY_NEEDED reloads.
In this case, we must consider the insn to use the register mentioned
in the REG_DEAD note. Otherwise, we may accidentally move this insn
after another insn that sets the register, thus getting obviously invalid
rtl. This confuses reorg which believes that REG_DEAD notes are still
meaningful.
??? We would get better code if we fixed reload to put the REG_DEAD
notes in the right places, but that may not be worth the effort. */
if (reload_completed)
{
rtx note;
for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
if (REG_NOTE_KIND (note) == REG_DEAD)
sched_analyze_2 (XEXP (note, 0), insn);
}
EXECUTE_IF_SET_IN_REG_SET (reg_pending_sets, 0, i,
{
reg_last_sets[i] = insn;
});
CLEAR_REG_SET (reg_pending_sets);
if (reg_pending_sets_all)
{
for (i = 0; i < maxreg; i++)
reg_last_sets[i] = insn;
reg_pending_sets_all = 0;
}
/* Handle function calls and function returns created by the epilogue
threading code. */
if (GET_CODE (insn) == CALL_INSN || GET_CODE (insn) == JUMP_INSN)
{
rtx dep_insn;
rtx prev_dep_insn;
/* When scheduling instructions, we make sure calls don't lose their
accompanying USE insns by depending them one on another in order.
Also, we must do the same thing for returns created by the epilogue
threading code. Note this code works only in this special case,
because other passes make no guarantee that they will never emit
an instruction between a USE and a RETURN. There is such a guarantee
for USE instructions immediately before a call. */
prev_dep_insn = insn;
dep_insn = PREV_INSN (insn);
while (GET_CODE (dep_insn) == INSN
&& GET_CODE (PATTERN (dep_insn)) == USE
&& GET_CODE (XEXP (PATTERN (dep_insn), 0)) == REG)
{
SCHED_GROUP_P (prev_dep_insn) = 1;
/* Make a copy of all dependencies on dep_insn, and add to insn.
This is so that all of the dependencies will apply to the
group. */
for (link = LOG_LINKS (dep_insn); link; link = XEXP (link, 1))
add_dependence (insn, XEXP (link, 0), REG_NOTE_KIND (link));
prev_dep_insn = dep_insn;
dep_insn = PREV_INSN (dep_insn);
}
}
}
/* Analyze every insn between HEAD and TAIL inclusive, creating LOG_LINKS
for every dependency. */
static int
sched_analyze (head, tail)
rtx head, tail;
{
register rtx insn;
register int n_insns = 0;
register rtx u;
register int luid = 0;
rtx loop_notes = 0;
for (insn = head; ; insn = NEXT_INSN (insn))
{
INSN_LUID (insn) = luid++;
if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
{
sched_analyze_insn (PATTERN (insn), insn, loop_notes);
loop_notes = 0;
n_insns += 1;
}
else if (GET_CODE (insn) == CALL_INSN)
{
rtx x;
register int i;
/* Any instruction using a hard register which may get clobbered
by a call needs to be marked as dependent on this call.
This prevents a use of a hard return reg from being moved
past a void call (i.e. it does not explicitly set the hard
return reg). */
/* If this call is followed by a NOTE_INSN_SETJMP, then assume that
all registers, not just hard registers, may be clobbered by this
call. */
/* Insn, being a CALL_INSN, magically depends on
`last_function_call' already. */
if (NEXT_INSN (insn) && GET_CODE (NEXT_INSN (insn)) == NOTE
&& NOTE_LINE_NUMBER (NEXT_INSN (insn)) == NOTE_INSN_SETJMP)
{
int max_reg = max_reg_num ();
for (i = 0; i < max_reg; i++)
{
for (u = reg_last_uses[i]; u; u = XEXP (u, 1))
add_dependence (insn, XEXP (u, 0), REG_DEP_ANTI);
reg_last_uses[i] = 0;
if (reg_last_sets[i])
add_dependence (insn, reg_last_sets[i], 0);
}
reg_pending_sets_all = 1;
/* Add a pair of fake REG_NOTEs which we will later
convert back into a NOTE_INSN_SETJMP note. See
reemit_notes for why we use a pair of of NOTEs. */
REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_DEAD,
GEN_INT (0),
REG_NOTES (insn));
REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_DEAD,
GEN_INT (NOTE_INSN_SETJMP),
REG_NOTES (insn));
}
else
{
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
if (call_used_regs[i] || global_regs[i])
{
for (u = reg_last_uses[i]; u; u = XEXP (u, 1))
add_dependence (insn, XEXP (u, 0), REG_DEP_ANTI);
reg_last_uses[i] = 0;
if (reg_last_sets[i])
add_dependence (insn, reg_last_sets[i], REG_DEP_ANTI);
SET_REGNO_REG_SET (reg_pending_sets, i);
}
}
/* For each insn which shouldn't cross a call, add a dependence
between that insn and this call insn. */
x = LOG_LINKS (sched_before_next_call);
while (x)
{
add_dependence (insn, XEXP (x, 0), REG_DEP_ANTI);
x = XEXP (x, 1);
}
LOG_LINKS (sched_before_next_call) = 0;
sched_analyze_insn (PATTERN (insn), insn, loop_notes);
loop_notes = 0;
/* In the absence of interprocedural alias analysis, we must flush
all pending reads and writes, and start new dependencies starting
from here. But only flush writes for constant calls (which may
be passed a pointer to something we haven't written yet). */
flush_pending_lists (insn, CONST_CALL_P (insn));
/* Depend this function call (actually, the user of this
function call) on all hard register clobberage. */
last_function_call = insn;
n_insns += 1;
}
/* See comments on reemit_notes as to why we do this. */
else if (GET_CODE (insn) == NOTE
&& (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
|| NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
|| NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG
|| NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END
|| (NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP
&& GET_CODE (PREV_INSN (insn)) != CALL_INSN)))
{
loop_notes = gen_rtx (EXPR_LIST, REG_DEAD,
GEN_INT (NOTE_BLOCK_NUMBER (insn)), loop_notes);
loop_notes = gen_rtx (EXPR_LIST, REG_DEAD,
GEN_INT (NOTE_LINE_NUMBER (insn)), loop_notes);
CONST_CALL_P (loop_notes) = CONST_CALL_P (insn);
}
if (insn == tail)
return n_insns;
}
abort ();
}
/* Called when we see a set of a register. If death is true, then we are
scanning backwards. Mark that register as unborn. If nobody says
otherwise, that is how things will remain. If death is false, then we
are scanning forwards. Mark that register as being born. */
static void
sched_note_set (b, x, death)
int b;
rtx x;
int death;
{
register int regno;
register rtx reg = SET_DEST (x);
int subreg_p = 0;
if (reg == 0)
return;
while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == STRICT_LOW_PART
|| GET_CODE (reg) == SIGN_EXTRACT || GET_CODE (reg) == ZERO_EXTRACT)
{
/* Must treat modification of just one hardware register of a multi-reg
value or just a byte field of a register exactly the same way that
mark_set_1 in flow.c does, i.e. anything except a paradoxical subreg
does not kill the entire register. */
if (GET_CODE (reg) != SUBREG
|| REG_SIZE (SUBREG_REG (reg)) > REG_SIZE (reg))
subreg_p = 1;
reg = SUBREG_REG (reg);
}
if (GET_CODE (reg) != REG)
return;
/* Global registers are always live, so the code below does not apply
to them. */
regno = REGNO (reg);
if (regno >= FIRST_PSEUDO_REGISTER || ! global_regs[regno])
{
if (death)
{
/* If we only set part of the register, then this set does not
kill it. */
if (subreg_p)
return;
/* Try killing this register. */
if (regno < FIRST_PSEUDO_REGISTER)
{
int j = HARD_REGNO_NREGS (regno, GET_MODE (reg));
while (--j >= 0)
{
CLEAR_REGNO_REG_SET (bb_live_regs, regno + j);
SET_REGNO_REG_SET (bb_dead_regs, regno + j);
}
}
else
{
CLEAR_REGNO_REG_SET (bb_live_regs, regno);
SET_REGNO_REG_SET (bb_dead_regs, regno);
}
}
else
{
/* Make the register live again. */
if (regno < FIRST_PSEUDO_REGISTER)
{
int j = HARD_REGNO_NREGS (regno, GET_MODE (reg));
while (--j >= 0)
{
SET_REGNO_REG_SET (bb_live_regs, regno + j);
CLEAR_REGNO_REG_SET (bb_dead_regs, regno + j);
}
}
else
{
SET_REGNO_REG_SET (bb_live_regs, regno);
CLEAR_REGNO_REG_SET (bb_dead_regs, regno);
}
}
}
}
/* Macros and functions for keeping the priority queue sorted, and
dealing with queueing and dequeueing of instructions. */
#define SCHED_SORT(READY, NEW_READY, OLD_READY) \
do { if ((NEW_READY) - (OLD_READY) == 1) \
swap_sort (READY, NEW_READY); \
else if ((NEW_READY) - (OLD_READY) > 1) \
qsort (READY, NEW_READY, sizeof (rtx), rank_for_schedule); } \
while (0)
/* Returns a positive value if y is preferred; returns a negative value if
x is preferred. Should never return 0, since that will make the sort
unstable. */
static int
rank_for_schedule (x, y)
rtx *x, *y;
{
rtx tmp = *y;
rtx tmp2 = *x;
rtx link;
int tmp_class, tmp2_class;
int value;
/* Choose the instruction with the highest priority, if different. */
if (value = INSN_PRIORITY (tmp) - INSN_PRIORITY (tmp2))
return value;
if (last_scheduled_insn)
{
/* Classify the instructions into three classes:
1) Data dependent on last schedule insn.
2) Anti/Output dependent on last scheduled insn.
3) Independent of last scheduled insn, or has latency of one.
Choose the insn from the highest numbered class if different. */
link = find_insn_list (tmp, LOG_LINKS (last_scheduled_insn));
if (link == 0 || insn_cost (tmp, link, last_scheduled_insn) == 1)
tmp_class = 3;
else if (REG_NOTE_KIND (link) == 0) /* Data dependence. */
tmp_class = 1;
else
tmp_class = 2;
link = find_insn_list (tmp2, LOG_LINKS (last_scheduled_insn));
if (link == 0 || insn_cost (tmp2, link, last_scheduled_insn) == 1)
tmp2_class = 3;
else if (REG_NOTE_KIND (link) == 0) /* Data dependence. */
tmp2_class = 1;
else
tmp2_class = 2;
if (value = tmp_class - tmp2_class)
return value;
}
/* If insns are equally good, sort by INSN_LUID (original insn order),
so that we make the sort stable. This minimizes instruction movement,
thus minimizing sched's effect on debugging and cross-jumping. */
return INSN_LUID (tmp) - INSN_LUID (tmp2);
}
/* Resort the array A in which only element at index N may be out of order. */
__inline static void
swap_sort (a, n)
rtx *a;
int n;
{
rtx insn = a[n-1];
int i = n-2;
while (i >= 0 && rank_for_schedule (a+i, &insn) >= 0)
{
a[i+1] = a[i];
i -= 1;
}
a[i+1] = insn;
}
static int max_priority;
/* Add INSN to the insn queue so that it fires at least N_CYCLES
before the currently executing insn. */
__inline static void
queue_insn (insn, n_cycles)
rtx insn;
int n_cycles;
{
int next_q = NEXT_Q_AFTER (q_ptr, n_cycles);
NEXT_INSN (insn) = insn_queue[next_q];
insn_queue[next_q] = insn;
q_size += 1;
}
/* Return nonzero if PAT is the pattern of an insn which makes a
register live. */
__inline static int
birthing_insn_p (pat)
rtx pat;
{
int j;
if (reload_completed == 1)
return 0;
if (GET_CODE (pat) == SET
&& GET_CODE (SET_DEST (pat)) == REG)
{
rtx dest = SET_DEST (pat);
int i = REGNO (dest);
/* It would be more accurate to use refers_to_regno_p or
reg_mentioned_p to determine when the dest is not live before this
insn. */
if (REGNO_REG_SET_P (bb_live_regs, i))
return (REG_N_SETS (i) == 1);
return 0;
}
if (GET_CODE (pat) == PARALLEL)
{
for (j = 0; j < XVECLEN (pat, 0); j++)
if (birthing_insn_p (XVECEXP (pat, 0, j)))
return 1;
}
return 0;
}
/* PREV is an insn that is ready to execute. Adjust its priority if that
will help shorten register lifetimes. */
__inline static void
adjust_priority (prev)
rtx prev;
{
/* Trying to shorten register lives after reload has completed
is useless and wrong. It gives inaccurate schedules. */
if (reload_completed == 0)
{
rtx note;
int n_deaths = 0;
/* ??? This code has no effect, because REG_DEAD notes are removed
before we ever get here. */
for (note = REG_NOTES (prev); note; note = XEXP (note, 1))
if (REG_NOTE_KIND (note) == REG_DEAD)
n_deaths += 1;
/* Defer scheduling insns which kill registers, since that
shortens register lives. Prefer scheduling insns which
make registers live for the same reason. */
switch (n_deaths)
{
default:
INSN_PRIORITY (prev) >>= 3;
break;
case 3:
INSN_PRIORITY (prev) >>= 2;
break;
case 2:
case 1:
INSN_PRIORITY (prev) >>= 1;
break;
case 0:
if (birthing_insn_p (PATTERN (prev)))
{
int max = max_priority;
if (max > INSN_PRIORITY (prev))
INSN_PRIORITY (prev) = max;
}
break;
}
#ifdef ADJUST_PRIORITY
ADJUST_PRIORITY (prev);
#endif
}
}
/* INSN is the "currently executing insn". Launch each insn which was
waiting on INSN (in the backwards dataflow sense). READY is a
vector of insns which are ready to fire. N_READY is the number of
elements in READY. CLOCK is the current virtual cycle. */
static int
schedule_insn (insn, ready, n_ready, clock)
rtx insn;
rtx *ready;
int n_ready;
int clock;
{
rtx link;
int new_ready = n_ready;
if (MAX_BLOCKAGE > 1)
schedule_unit (insn_unit (insn), insn, clock);
if (LOG_LINKS (insn) == 0)
return n_ready;
/* This is used by the function adjust_priority above. */
if (n_ready > 0)
max_priority = MAX (INSN_PRIORITY (ready[0]), INSN_PRIORITY (insn));
else
max_priority = INSN_PRIORITY (insn);
for (link = LOG_LINKS (insn); link != 0; link = XEXP (link, 1))
{
rtx prev = XEXP (link, 0);
int cost = insn_cost (prev, link, insn);
if ((INSN_REF_COUNT (prev) -= 1) != 0)
{
/* We satisfied one requirement to fire PREV. Record the earliest
time when PREV can fire. No need to do this if the cost is 1,
because PREV can fire no sooner than the next cycle. */
if (cost > 1)
INSN_TICK (prev) = MAX (INSN_TICK (prev), clock + cost);
}
else
{
/* We satisfied the last requirement to fire PREV. Ensure that all
timing requirements are satisfied. */
if (INSN_TICK (prev) - clock > cost)
cost = INSN_TICK (prev) - clock;
/* Adjust the priority of PREV and either put it on the ready
list or queue it. */
adjust_priority (prev);
if (cost <= 1)
ready[new_ready++] = prev;
else
queue_insn (prev, cost);
}
}
return new_ready;
}
/* Given N_READY insns in the ready list READY at time CLOCK, queue
those that are blocked due to function unit hazards and rearrange
the remaining ones to minimize subsequent function unit hazards. */
static int
schedule_select (ready, n_ready, clock, file)
rtx *ready;
int n_ready, clock;
FILE *file;
{
int pri = INSN_PRIORITY (ready[0]);
int i, j, k, q, cost, best_cost, best_insn = 0, new_ready = n_ready;
rtx insn;
/* Work down the ready list in groups of instructions with the same
priority value. Queue insns in the group that are blocked and
select among those that remain for the one with the largest
potential hazard. */
for (i = 0; i < n_ready; i = j)
{
int opri = pri;
for (j = i + 1; j < n_ready; j++)
if ((pri = INSN_PRIORITY (ready[j])) != opri)
break;
/* Queue insns in the group that are blocked. */
for (k = i, q = 0; k < j; k++)
{
insn = ready[k];
if ((cost = actual_hazard (insn_unit (insn), insn, clock, 0)) != 0)
{
q++;
ready[k] = 0;
queue_insn (insn, cost);
if (file)
fprintf (file, "\n;; blocking insn %d for %d cycles",
INSN_UID (insn), cost);
}
}
new_ready -= q;
/* Check the next group if all insns were queued. */
if (j - i - q == 0)
continue;
/* If more than one remains, select the first one with the largest
potential hazard. */
else if (j - i - q > 1)
{
best_cost = -1;
for (k = i; k < j; k++)
{
if ((insn = ready[k]) == 0)
continue;
if ((cost = potential_hazard (insn_unit (insn), insn, 0))
> best_cost)
{
best_cost = cost;
best_insn = k;
}
}
}
/* We have found a suitable insn to schedule. */
break;
}
/* Move the best insn to be front of the ready list. */
if (best_insn != 0)
{
if (file)
{
fprintf (file, ", now");
for (i = 0; i < n_ready; i++)
if (ready[i])
fprintf (file, " %d", INSN_UID (ready[i]));
fprintf (file, "\n;; insn %d has a greater potential hazard",
INSN_UID (ready[best_insn]));
}
for (i = best_insn; i > 0; i--)
{
insn = ready[i-1];
ready[i-1] = ready[i];
ready[i] = insn;
}
}
/* Compact the ready list. */
if (new_ready < n_ready)
for (i = j = 0; i < n_ready; i++)
if (ready[i])
ready[j++] = ready[i];
return new_ready;
}
/* Add a REG_DEAD note for REG to INSN, reusing a REG_DEAD note from the
dead_notes list. */
static void
create_reg_dead_note (reg, insn)
rtx reg, insn;
{
rtx link;
/* The number of registers killed after scheduling must be the same as the
number of registers killed before scheduling. The number of REG_DEAD
notes may not be conserved, i.e. two SImode hard register REG_DEAD notes
might become one DImode hard register REG_DEAD note, but the number of
registers killed will be conserved.
We carefully remove REG_DEAD notes from the dead_notes list, so that
there will be none left at the end. If we run out early, then there
is a bug somewhere in flow, combine and/or sched. */
if (dead_notes == 0)
{
#if 1
abort ();
#else
link = rtx_alloc (EXPR_LIST);
PUT_REG_NOTE_KIND (link, REG_DEAD);
#endif
}
else
{
/* Number of regs killed by REG. */
int regs_killed = (REGNO (reg) >= FIRST_PSEUDO_REGISTER ? 1
: HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg)));
/* Number of regs killed by REG_DEAD notes taken off the list. */
int reg_note_regs;
link = dead_notes;
reg_note_regs = (REGNO (XEXP (link, 0)) >= FIRST_PSEUDO_REGISTER ? 1
: HARD_REGNO_NREGS (REGNO (XEXP (link, 0)),
GET_MODE (XEXP (link, 0))));
while (reg_note_regs < regs_killed)
{
link = XEXP (link, 1);
reg_note_regs += (REGNO (XEXP (link, 0)) >= FIRST_PSEUDO_REGISTER ? 1
: HARD_REGNO_NREGS (REGNO (XEXP (link, 0)),
GET_MODE (XEXP (link, 0))));
}
dead_notes = XEXP (link, 1);
/* If we took too many regs kills off, put the extra ones back. */
while (reg_note_regs > regs_killed)
{
rtx temp_reg, temp_link;
temp_reg = gen_rtx (REG, word_mode, 0);
temp_link = rtx_alloc (EXPR_LIST);
PUT_REG_NOTE_KIND (temp_link, REG_DEAD);
XEXP (temp_link, 0) = temp_reg;
XEXP (temp_link, 1) = dead_notes;
dead_notes = temp_link;
reg_note_regs--;
}
}
XEXP (link, 0) = reg;
XEXP (link, 1) = REG_NOTES (insn);
REG_NOTES (insn) = link;
}
/* Subroutine on attach_deaths_insn--handles the recursive search
through INSN. If SET_P is true, then x is being modified by the insn. */
static void
attach_deaths (x, insn, set_p)
rtx x;
rtx insn;
int set_p;
{
register int i;
register int j;
register enum rtx_code code;
register char *fmt;
if (x == 0)
return;
code = GET_CODE (x);
switch (code)
{
case CONST_INT:
case CONST_DOUBLE:
case LABEL_REF:
case SYMBOL_REF:
case CONST:
case CODE_LABEL:
case PC:
case CC0:
/* Get rid of the easy cases first. */
return;
case REG:
{
/* If the register dies in this insn, queue that note, and mark
this register as needing to die. */
/* This code is very similar to mark_used_1 (if set_p is false)
and mark_set_1 (if set_p is true) in flow.c. */
register int regno;
int some_needed;
int all_needed;
if (set_p)
return;
regno = REGNO (x);
all_needed = some_needed = REGNO_REG_SET_P (old_live_regs, regno);
if (regno < FIRST_PSEUDO_REGISTER)
{
int n;
n = HARD_REGNO_NREGS (regno, GET_MODE (x));
while (--n > 0)
{
int needed = (REGNO_REG_SET_P (old_live_regs, regno + n));
some_needed |= needed;
all_needed &= needed;
}
}
/* If it wasn't live before we started, then add a REG_DEAD note.
We must check the previous lifetime info not the current info,
because we may have to execute this code several times, e.g.
once for a clobber (which doesn't add a note) and later
for a use (which does add a note).
Always make the register live. We must do this even if it was
live before, because this may be an insn which sets and uses
the same register, in which case the register has already been
killed, so we must make it live again.
Global registers are always live, and should never have a REG_DEAD
note added for them, so none of the code below applies to them. */
if (regno >= FIRST_PSEUDO_REGISTER || ! global_regs[regno])
{
/* Never add REG_DEAD notes for the FRAME_POINTER_REGNUM or the
STACK_POINTER_REGNUM, since these are always considered to be
live. Similarly for ARG_POINTER_REGNUM if it is fixed. */
if (regno != FRAME_POINTER_REGNUM
#if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
&& ! (regno == HARD_FRAME_POINTER_REGNUM)
#endif
#if ARG_POINTER_REGNUM != FRAME_POINTER_REGNUM
&& ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
#endif
&& regno != STACK_POINTER_REGNUM)
{
/* ??? It is perhaps a dead_or_set_p bug that it does
not check for REG_UNUSED notes itself. This is necessary
for the case where the SET_DEST is a subreg of regno, as
dead_or_set_p handles subregs specially. */
if (! all_needed && ! dead_or_set_p (insn, x)
&& ! find_reg_note (insn, REG_UNUSED, x))
{
/* Check for the case where the register dying partially
overlaps the register set by this insn. */
if (regno < FIRST_PSEUDO_REGISTER
&& HARD_REGNO_NREGS (regno, GET_MODE (x)) > 1)
{
int n = HARD_REGNO_NREGS (regno, GET_MODE (x));
while (--n >= 0)
some_needed |= dead_or_set_regno_p (insn, regno + n);
}
/* If none of the words in X is needed, make a REG_DEAD
note. Otherwise, we must make partial REG_DEAD
notes. */
if (! some_needed)
create_reg_dead_note (x, insn);
else
{
int i;
/* Don't make a REG_DEAD note for a part of a
register that is set in the insn. */
for (i = HARD_REGNO_NREGS (regno, GET_MODE (x)) - 1;
i >= 0; i--)
if (! REGNO_REG_SET_P (old_live_regs, regno + i)
&& ! dead_or_set_regno_p (insn, regno + i))
create_reg_dead_note (gen_rtx (REG,
reg_raw_mode[regno + i],
regno + i),
insn);
}
}
}
if (regno < FIRST_PSEUDO_REGISTER)
{
int j = HARD_REGNO_NREGS (regno, GET_MODE (x));
while (--j >= 0)
{
CLEAR_REGNO_REG_SET (bb_dead_regs, regno + j);
SET_REGNO_REG_SET (bb_live_regs, regno + j);
}
}
else
{
CLEAR_REGNO_REG_SET (bb_dead_regs, regno);
SET_REGNO_REG_SET (bb_live_regs, regno);
}
}
return;
}
case MEM:
/* Handle tail-recursive case. */
attach_deaths (XEXP (x, 0), insn, 0);
return;
case SUBREG:
case STRICT_LOW_PART:
/* These two cases preserve the value of SET_P, so handle them
separately. */
attach_deaths (XEXP (x, 0), insn, set_p);
return;
case ZERO_EXTRACT:
case SIGN_EXTRACT:
/* This case preserves the value of SET_P for the first operand, but
clears it for the other two. */
attach_deaths (XEXP (x, 0), insn, set_p);
attach_deaths (XEXP (x, 1), insn, 0);
attach_deaths (XEXP (x, 2), insn, 0);
return;
default:
/* Other cases: walk the insn. */
fmt = GET_RTX_FORMAT (code);
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
{
if (fmt[i] == 'e')
attach_deaths (XEXP (x, i), insn, 0);
else if (fmt[i] == 'E')
for (j = 0; j < XVECLEN (x, i); j++)
attach_deaths (XVECEXP (x, i, j), insn, 0);
}
}
}
/* After INSN has executed, add register death notes for each register
that is dead after INSN. */
static void
attach_deaths_insn (insn)
rtx insn;
{
rtx x = PATTERN (insn);
register RTX_CODE code = GET_CODE (x);
rtx link;
if (code == SET)
{
attach_deaths (SET_SRC (x), insn, 0);
/* A register might die here even if it is the destination, e.g.
it is the target of a volatile read and is otherwise unused.
Hence we must always call attach_deaths for the SET_DEST. */
attach_deaths (SET_DEST (x), insn, 1);
}
else if (code == PARALLEL)
{
register int i;
for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
{
code = GET_CODE (XVECEXP (x, 0, i));
if (code == SET)
{
attach_deaths (SET_SRC (XVECEXP (x, 0, i)), insn, 0);
attach_deaths (SET_DEST (XVECEXP (x, 0, i)), insn, 1);
}
/* Flow does not add REG_DEAD notes to registers that die in
clobbers, so we can't either. */
else if (code != CLOBBER)
attach_deaths (XVECEXP (x, 0, i), insn, 0);
}
}
/* If this is a CLOBBER, only add REG_DEAD notes to registers inside a
MEM being clobbered, just like flow. */
else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == MEM)
attach_deaths (XEXP (XEXP (x, 0), 0), insn, 0);
/* Otherwise don't add a death note to things being clobbered. */
else if (code != CLOBBER)
attach_deaths (x, insn, 0);
/* Make death notes for things used in the called function. */
if (GET_CODE (insn) == CALL_INSN)
for (link = CALL_INSN_FUNCTION_USAGE (insn); link; link = XEXP (link, 1))
attach_deaths (XEXP (XEXP (link, 0), 0), insn,
GET_CODE (XEXP (link, 0)) == CLOBBER);
}
/* Delete notes beginning with INSN and maybe put them in the chain
of notes ended by NOTE_LIST.
Returns the insn following the notes. */
static rtx
unlink_notes (insn, tail)
rtx insn, tail;
{
rtx prev = PREV_INSN (insn);
while (insn != tail && GET_CODE (insn) == NOTE)
{
rtx next = NEXT_INSN (insn);
/* Delete the note from its current position. */
if (prev)
NEXT_INSN (prev) = next;
if (next)
PREV_INSN (next) = prev;
if (write_symbols != NO_DEBUG && NOTE_LINE_NUMBER (insn) > 0)
/* Record line-number notes so they can be reused. */
LINE_NOTE (insn) = insn;
/* Don't save away NOTE_INSN_SETJMPs, because they must remain
immediately after the call they follow. We use a fake
(REG_DEAD (const_int -1)) note to remember them.
Likewise with NOTE_INSN_{LOOP,EHREGION}_{BEG, END}. */
else if (NOTE_LINE_NUMBER (insn) != NOTE_INSN_SETJMP
&& NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_BEG
&& NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_END
&& NOTE_LINE_NUMBER (insn) != NOTE_INSN_EH_REGION_BEG
&& NOTE_LINE_NUMBER (insn) != NOTE_INSN_EH_REGION_END)
{
/* Insert the note at the end of the notes list. */
PREV_INSN (insn) = note_list;
if (note_list)
NEXT_INSN (note_list) = insn;
note_list = insn;
}
insn = next;
}
return insn;
}
/* Constructor for `sometimes' data structure. */
static int
new_sometimes_live (regs_sometimes_live, regno, sometimes_max)
struct sometimes *regs_sometimes_live;
int regno;
int sometimes_max;
{
register struct sometimes *p;
/* There should never be a register greater than max_regno here. If there
is, it means that a define_split has created a new pseudo reg. This
is not allowed, since there will not be flow info available for any
new register, so catch the error here. */
if (regno >= max_regno)
abort ();
p = &regs_sometimes_live[sometimes_max];
p->regno = regno;
p->live_length = 0;
p->calls_crossed = 0;
sometimes_max++;
return sometimes_max;
}
/* Count lengths of all regs we are currently tracking,
and find new registers no longer live. */
static void
finish_sometimes_live (regs_sometimes_live, sometimes_max)
struct sometimes *regs_sometimes_live;
int sometimes_max;
{
int i;
for (i = 0; i < sometimes_max; i++)
{
register struct sometimes *p = &regs_sometimes_live[i];
int regno = p->regno;