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global.c
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global.c
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/* Allocate registers for pseudo-registers that span basic blocks.
Copyright (C) 1987, 1988, 1991, 1994, 1996, 1997, 1998,
1999, 2000, 2002, 2003, 2004, 2005, 2007 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC 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 GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "machmode.h"
#include "hard-reg-set.h"
#include "rtl.h"
#include "tm_p.h"
#include "flags.h"
#include "regs.h"
#include "function.h"
#include "insn-config.h"
#include "recog.h"
#include "reload.h"
#include "output.h"
#include "toplev.h"
#include "tree-pass.h"
#include "timevar.h"
#include "vecprim.h"
/* This pass of the compiler performs global register allocation.
It assigns hard register numbers to all the pseudo registers
that were not handled in local_alloc. Assignments are recorded
in the vector reg_renumber, not by changing the rtl code.
(Such changes are made by final). The entry point is
the function global_alloc.
After allocation is complete, the reload pass is run as a subroutine
of this pass, so that when a pseudo reg loses its hard reg due to
spilling it is possible to make a second attempt to find a hard
reg for it. The reload pass is independent in other respects
and it is run even when stupid register allocation is in use.
1. Assign allocation-numbers (allocnos) to the pseudo-registers
still needing allocations and to the pseudo-registers currently
allocated by local-alloc which may be spilled by reload.
Set up tables reg_allocno and allocno_reg to map
reg numbers to allocnos and vice versa.
max_allocno gets the number of allocnos in use.
2. Allocate a max_allocno by max_allocno conflict bit matrix and clear it.
Allocate a max_allocno by FIRST_PSEUDO_REGISTER conflict matrix
for conflicts between allocnos and explicit hard register use
(which includes use of pseudo-registers allocated by local_alloc).
3. For each basic block
walk forward through the block, recording which
pseudo-registers and which hardware registers are live.
Build the conflict matrix between the pseudo-registers
and another of pseudo-registers versus hardware registers.
Also record the preferred hardware registers
for each pseudo-register.
4. Sort a table of the allocnos into order of
desirability of the variables.
5. Allocate the variables in that order; each if possible into
a preferred register, else into another register. */
/* Number of pseudo-registers which are candidates for allocation. */
static int max_allocno;
/* Indexed by (pseudo) reg number, gives the allocno, or -1
for pseudo registers which are not to be allocated. */
static int *reg_allocno;
struct allocno
{
int reg;
/* Gives the number of consecutive hard registers needed by that
pseudo reg. */
int size;
/* Number of calls crossed by each allocno. */
int calls_crossed;
/* Number of calls that might throw crossed by each allocno. */
int throwing_calls_crossed;
/* Number of refs to each allocno. */
int n_refs;
/* Frequency of uses of each allocno. */
int freq;
/* Guess at live length of each allocno.
This is actually the max of the live lengths of the regs. */
int live_length;
/* Set of hard regs conflicting with allocno N. */
HARD_REG_SET hard_reg_conflicts;
/* Set of hard regs preferred by allocno N.
This is used to make allocnos go into regs that are copied to or from them,
when possible, to reduce register shuffling. */
HARD_REG_SET hard_reg_preferences;
/* Similar, but just counts register preferences made in simple copy
operations, rather than arithmetic. These are given priority because
we can always eliminate an insn by using these, but using a register
in the above list won't always eliminate an insn. */
HARD_REG_SET hard_reg_copy_preferences;
/* Similar to hard_reg_preferences, but includes bits for subsequent
registers when an allocno is multi-word. The above variable is used for
allocation while this is used to build reg_someone_prefers, below. */
HARD_REG_SET hard_reg_full_preferences;
/* Set of hard registers that some later allocno has a preference for. */
HARD_REG_SET regs_someone_prefers;
#ifdef STACK_REGS
/* Set to true if allocno can't be allocated in the stack register. */
bool no_stack_reg;
#endif
};
static struct allocno *allocno;
/* A vector of the integers from 0 to max_allocno-1,
sorted in the order of first-to-be-allocated first. */
static int *allocno_order;
/* Indexed by (pseudo) reg number, gives the number of another
lower-numbered pseudo reg which can share a hard reg with this pseudo
*even if the two pseudos would otherwise appear to conflict*. */
static int *reg_may_share;
/* Define the number of bits in each element of `conflicts' and what
type that element has. We use the largest integer format on the
host machine. */
#define INT_BITS HOST_BITS_PER_WIDE_INT
#define INT_TYPE HOST_WIDE_INT
/* max_allocno by max_allocno array of bits,
recording whether two allocno's conflict (can't go in the same
hardware register).
`conflicts' is symmetric after the call to mirror_conflicts. */
static INT_TYPE *conflicts;
/* Number of ints required to hold max_allocno bits.
This is the length of a row in `conflicts'. */
static int allocno_row_words;
/* Two macros to test or store 1 in an element of `conflicts'. */
#define CONFLICTP(I, J) \
(conflicts[(I) * allocno_row_words + (unsigned) (J) / INT_BITS] \
& ((INT_TYPE) 1 << ((unsigned) (J) % INT_BITS)))
/* For any allocno set in ALLOCNO_SET, set ALLOCNO to that allocno,
and execute CODE. */
#define EXECUTE_IF_SET_IN_ALLOCNO_SET(ALLOCNO_SET, ALLOCNO, CODE) \
do { \
int i_; \
int allocno_; \
INT_TYPE *p_ = (ALLOCNO_SET); \
\
for (i_ = allocno_row_words - 1, allocno_ = 0; i_ >= 0; \
i_--, allocno_ += INT_BITS) \
{ \
unsigned INT_TYPE word_ = (unsigned INT_TYPE) *p_++; \
\
for ((ALLOCNO) = allocno_; word_; word_ >>= 1, (ALLOCNO)++) \
{ \
if (word_ & 1) \
{CODE;} \
} \
} \
} while (0)
/* This doesn't work for non-GNU C due to the way CODE is macro expanded. */
#if 0
/* For any allocno that conflicts with IN_ALLOCNO, set OUT_ALLOCNO to
the conflicting allocno, and execute CODE. This macro assumes that
mirror_conflicts has been run. */
#define EXECUTE_IF_CONFLICT(IN_ALLOCNO, OUT_ALLOCNO, CODE)\
EXECUTE_IF_SET_IN_ALLOCNO_SET (conflicts + (IN_ALLOCNO) * allocno_row_words,\
OUT_ALLOCNO, (CODE))
#endif
/* Set of hard regs currently live (during scan of all insns). */
static HARD_REG_SET hard_regs_live;
/* Set of registers that global-alloc isn't supposed to use. */
static HARD_REG_SET no_global_alloc_regs;
/* Set of registers used so far. */
static HARD_REG_SET regs_used_so_far;
/* Number of refs to each hard reg, as used by local alloc.
It is zero for a reg that contains global pseudos or is explicitly used. */
static int local_reg_n_refs[FIRST_PSEUDO_REGISTER];
/* Frequency of uses of given hard reg. */
static int local_reg_freq[FIRST_PSEUDO_REGISTER];
/* Guess at live length of each hard reg, as used by local alloc.
This is actually the sum of the live lengths of the specific regs. */
static int local_reg_live_length[FIRST_PSEUDO_REGISTER];
/* Set to 1 a bit in a vector TABLE of HARD_REG_SETs, for vector
element I, and hard register number J. */
#define SET_REGBIT(TABLE, I, J) SET_HARD_REG_BIT (allocno[I].TABLE, J)
/* Bit mask for allocnos live at current point in the scan. */
static INT_TYPE *allocnos_live;
/* Test, set or clear bit number I in allocnos_live,
a bit vector indexed by allocno. */
#define SET_ALLOCNO_LIVE(I) \
(allocnos_live[(unsigned) (I) / INT_BITS] \
|= ((INT_TYPE) 1 << ((unsigned) (I) % INT_BITS)))
#define CLEAR_ALLOCNO_LIVE(I) \
(allocnos_live[(unsigned) (I) / INT_BITS] \
&= ~((INT_TYPE) 1 << ((unsigned) (I) % INT_BITS)))
/* This is turned off because it doesn't work right for DImode.
(And it is only used for DImode, so the other cases are worthless.)
The problem is that it isn't true that there is NO possibility of conflict;
only that there is no conflict if the two pseudos get the exact same regs.
If they were allocated with a partial overlap, there would be a conflict.
We can't safely turn off the conflict unless we have another way to
prevent the partial overlap.
Idea: change hard_reg_conflicts so that instead of recording which
hard regs the allocno may not overlap, it records where the allocno
may not start. Change both where it is used and where it is updated.
Then there is a way to record that (reg:DI 108) may start at 10
but not at 9 or 11. There is still the question of how to record
this semi-conflict between two pseudos. */
#if 0
/* Reg pairs for which conflict after the current insn
is inhibited by a REG_NO_CONFLICT note.
If the table gets full, we ignore any other notes--that is conservative. */
#define NUM_NO_CONFLICT_PAIRS 4
/* Number of pairs in use in this insn. */
int n_no_conflict_pairs;
static struct { int allocno1, allocno2;}
no_conflict_pairs[NUM_NO_CONFLICT_PAIRS];
#endif /* 0 */
/* Record all regs that are set in any one insn.
Communication from mark_reg_{store,clobber} and global_conflicts. */
static rtx *regs_set;
static int n_regs_set;
/* All registers that can be eliminated. */
static HARD_REG_SET eliminable_regset;
static int allocno_compare (const void *, const void *);
static void global_conflicts (void);
static void mirror_conflicts (void);
static void expand_preferences (void);
static void prune_preferences (void);
static void find_reg (int, HARD_REG_SET, int, int, int);
static void record_one_conflict (int);
static void record_conflicts (int *, int);
static void mark_reg_store (rtx, rtx, void *);
static void mark_reg_clobber (rtx, rtx, void *);
static void mark_reg_conflicts (rtx);
static void mark_reg_death (rtx);
static void mark_reg_live_nc (int, enum machine_mode);
static void set_preference (rtx, rtx);
static void dump_conflicts (FILE *);
static void reg_becomes_live (rtx, rtx, void *);
static void reg_dies (int, enum machine_mode, struct insn_chain *);
static void allocate_bb_info (void);
static void free_bb_info (void);
static bool check_earlyclobber (rtx);
static void mark_reg_use_for_earlyclobber_1 (rtx *, void *);
static int mark_reg_use_for_earlyclobber (rtx *, void *);
static void calculate_local_reg_bb_info (void);
static void set_up_bb_rts_numbers (void);
static int rpost_cmp (const void *, const void *);
static void calculate_reg_pav (void);
static void modify_reg_pav (void);
static void make_accurate_live_analysis (void);
/* Perform allocation of pseudo-registers not allocated by local_alloc.
Return value is nonzero if reload failed
and we must not do any more for this function. */
static int
global_alloc (void)
{
int retval;
#ifdef ELIMINABLE_REGS
static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS;
#endif
int need_fp
= (! flag_omit_frame_pointer
|| (current_function_calls_alloca && EXIT_IGNORE_STACK)
|| FRAME_POINTER_REQUIRED);
size_t i;
rtx x;
make_accurate_live_analysis ();
max_allocno = 0;
/* A machine may have certain hard registers that
are safe to use only within a basic block. */
CLEAR_HARD_REG_SET (no_global_alloc_regs);
/* Build the regset of all eliminable registers and show we can't use those
that we already know won't be eliminated. */
#ifdef ELIMINABLE_REGS
for (i = 0; i < ARRAY_SIZE (eliminables); i++)
{
bool cannot_elim
= (! CAN_ELIMINATE (eliminables[i].from, eliminables[i].to)
|| (eliminables[i].to == STACK_POINTER_REGNUM && need_fp));
if (!regs_asm_clobbered[eliminables[i].from])
{
SET_HARD_REG_BIT (eliminable_regset, eliminables[i].from);
if (cannot_elim)
SET_HARD_REG_BIT (no_global_alloc_regs, eliminables[i].from);
}
else if (cannot_elim)
error ("%s cannot be used in asm here",
reg_names[eliminables[i].from]);
else
regs_ever_live[eliminables[i].from] = 1;
}
#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
if (!regs_asm_clobbered[HARD_FRAME_POINTER_REGNUM])
{
SET_HARD_REG_BIT (eliminable_regset, HARD_FRAME_POINTER_REGNUM);
if (need_fp)
SET_HARD_REG_BIT (no_global_alloc_regs, HARD_FRAME_POINTER_REGNUM);
}
else if (need_fp)
error ("%s cannot be used in asm here",
reg_names[HARD_FRAME_POINTER_REGNUM]);
else
regs_ever_live[HARD_FRAME_POINTER_REGNUM] = 1;
#endif
#else
if (!regs_asm_clobbered[FRAME_POINTER_REGNUM])
{
SET_HARD_REG_BIT (eliminable_regset, FRAME_POINTER_REGNUM);
if (need_fp)
SET_HARD_REG_BIT (no_global_alloc_regs, FRAME_POINTER_REGNUM);
}
else if (need_fp)
error ("%s cannot be used in asm here", reg_names[FRAME_POINTER_REGNUM]);
else
regs_ever_live[FRAME_POINTER_REGNUM] = 1;
#endif
/* Track which registers have already been used. Start with registers
explicitly in the rtl, then registers allocated by local register
allocation. */
CLEAR_HARD_REG_SET (regs_used_so_far);
#ifdef LEAF_REGISTERS
/* If we are doing the leaf function optimization, and this is a leaf
function, it means that the registers that take work to save are those
that need a register window. So prefer the ones that can be used in
a leaf function. */
{
const char *cheap_regs;
const char *const leaf_regs = LEAF_REGISTERS;
if (only_leaf_regs_used () && leaf_function_p ())
cheap_regs = leaf_regs;
else
cheap_regs = call_used_regs;
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
if (regs_ever_live[i] || cheap_regs[i])
SET_HARD_REG_BIT (regs_used_so_far, i);
}
#else
/* We consider registers that do not have to be saved over calls as if
they were already used since there is no cost in using them. */
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
if (regs_ever_live[i] || call_used_regs[i])
SET_HARD_REG_BIT (regs_used_so_far, i);
#endif
for (i = FIRST_PSEUDO_REGISTER; i < (size_t) max_regno; i++)
if (reg_renumber[i] >= 0)
SET_HARD_REG_BIT (regs_used_so_far, reg_renumber[i]);
/* Establish mappings from register number to allocation number
and vice versa. In the process, count the allocnos. */
reg_allocno = XNEWVEC (int, max_regno);
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
reg_allocno[i] = -1;
/* Initialize the shared-hard-reg mapping
from the list of pairs that may share. */
reg_may_share = XCNEWVEC (int, max_regno);
for (x = regs_may_share; x; x = XEXP (XEXP (x, 1), 1))
{
int r1 = REGNO (XEXP (x, 0));
int r2 = REGNO (XEXP (XEXP (x, 1), 0));
if (r1 > r2)
reg_may_share[r1] = r2;
else
reg_may_share[r2] = r1;
}
for (i = FIRST_PSEUDO_REGISTER; i < (size_t) max_regno; i++)
/* Note that reg_live_length[i] < 0 indicates a "constant" reg
that we are supposed to refrain from putting in a hard reg.
-2 means do make an allocno but don't allocate it. */
if (REG_N_REFS (i) != 0 && REG_LIVE_LENGTH (i) != -1
/* Don't allocate pseudos that cross calls,
if this function receives a nonlocal goto. */
&& (! current_function_has_nonlocal_label
|| REG_N_CALLS_CROSSED (i) == 0))
{
if (reg_renumber[i] < 0
&& reg_may_share[i] && reg_allocno[reg_may_share[i]] >= 0)
reg_allocno[i] = reg_allocno[reg_may_share[i]];
else
reg_allocno[i] = max_allocno++;
gcc_assert (REG_LIVE_LENGTH (i));
}
else
reg_allocno[i] = -1;
allocno = XCNEWVEC (struct allocno, max_allocno);
for (i = FIRST_PSEUDO_REGISTER; i < (size_t) max_regno; i++)
if (reg_allocno[i] >= 0)
{
int num = reg_allocno[i];
allocno[num].reg = i;
allocno[num].size = PSEUDO_REGNO_SIZE (i);
allocno[num].calls_crossed += REG_N_CALLS_CROSSED (i);
allocno[num].throwing_calls_crossed
+= REG_N_THROWING_CALLS_CROSSED (i);
allocno[num].n_refs += REG_N_REFS (i);
allocno[num].freq += REG_FREQ (i);
if (allocno[num].live_length < REG_LIVE_LENGTH (i))
allocno[num].live_length = REG_LIVE_LENGTH (i);
}
/* Calculate amount of usage of each hard reg by pseudos
allocated by local-alloc. This is to see if we want to
override it. */
memset (local_reg_live_length, 0, sizeof local_reg_live_length);
memset (local_reg_n_refs, 0, sizeof local_reg_n_refs);
memset (local_reg_freq, 0, sizeof local_reg_freq);
for (i = FIRST_PSEUDO_REGISTER; i < (size_t) max_regno; i++)
if (reg_renumber[i] >= 0)
{
int regno = reg_renumber[i];
int endregno = regno + hard_regno_nregs[regno][PSEUDO_REGNO_MODE (i)];
int j;
for (j = regno; j < endregno; j++)
{
local_reg_n_refs[j] += REG_N_REFS (i);
local_reg_freq[j] += REG_FREQ (i);
local_reg_live_length[j] += REG_LIVE_LENGTH (i);
}
}
/* We can't override local-alloc for a reg used not just by local-alloc. */
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
if (regs_ever_live[i])
local_reg_n_refs[i] = 0, local_reg_freq[i] = 0;
allocno_row_words = (max_allocno + INT_BITS - 1) / INT_BITS;
/* We used to use alloca here, but the size of what it would try to
allocate would occasionally cause it to exceed the stack limit and
cause unpredictable core dumps. Some examples were > 2Mb in size. */
conflicts = XCNEWVEC (INT_TYPE, max_allocno * allocno_row_words);
allocnos_live = XNEWVEC (INT_TYPE, allocno_row_words);
/* If there is work to be done (at least one reg to allocate),
perform global conflict analysis and allocate the regs. */
if (max_allocno > 0)
{
/* Scan all the insns and compute the conflicts among allocnos
and between allocnos and hard regs. */
global_conflicts ();
mirror_conflicts ();
/* Eliminate conflicts between pseudos and eliminable registers. If
the register is not eliminated, the pseudo won't really be able to
live in the eliminable register, so the conflict doesn't matter.
If we do eliminate the register, the conflict will no longer exist.
So in either case, we can ignore the conflict. Likewise for
preferences. */
for (i = 0; i < (size_t) max_allocno; i++)
{
AND_COMPL_HARD_REG_SET (allocno[i].hard_reg_conflicts,
eliminable_regset);
AND_COMPL_HARD_REG_SET (allocno[i].hard_reg_copy_preferences,
eliminable_regset);
AND_COMPL_HARD_REG_SET (allocno[i].hard_reg_preferences,
eliminable_regset);
}
/* Try to expand the preferences by merging them between allocnos. */
expand_preferences ();
/* Determine the order to allocate the remaining pseudo registers. */
allocno_order = XNEWVEC (int, max_allocno);
for (i = 0; i < (size_t) max_allocno; i++)
allocno_order[i] = i;
/* Default the size to 1, since allocno_compare uses it to divide by.
Also convert allocno_live_length of zero to -1. A length of zero
can occur when all the registers for that allocno have reg_live_length
equal to -2. In this case, we want to make an allocno, but not
allocate it. So avoid the divide-by-zero and set it to a low
priority. */
for (i = 0; i < (size_t) max_allocno; i++)
{
if (allocno[i].size == 0)
allocno[i].size = 1;
if (allocno[i].live_length == 0)
allocno[i].live_length = -1;
}
qsort (allocno_order, max_allocno, sizeof (int), allocno_compare);
prune_preferences ();
if (dump_file)
dump_conflicts (dump_file);
/* Try allocating them, one by one, in that order,
except for parameters marked with reg_live_length[regno] == -2. */
for (i = 0; i < (size_t) max_allocno; i++)
if (reg_renumber[allocno[allocno_order[i]].reg] < 0
&& REG_LIVE_LENGTH (allocno[allocno_order[i]].reg) >= 0)
{
/* If we have more than one register class,
first try allocating in the class that is cheapest
for this pseudo-reg. If that fails, try any reg. */
if (N_REG_CLASSES > 1)
{
find_reg (allocno_order[i], 0, 0, 0, 0);
if (reg_renumber[allocno[allocno_order[i]].reg] >= 0)
continue;
}
if (reg_alternate_class (allocno[allocno_order[i]].reg) != NO_REGS)
find_reg (allocno_order[i], 0, 1, 0, 0);
}
free (allocno_order);
}
/* Do the reloads now while the allocno data still exists, so that we can
try to assign new hard regs to any pseudo regs that are spilled. */
#if 0 /* We need to eliminate regs even if there is no rtl code,
for the sake of debugging information. */
if (n_basic_blocks > NUM_FIXED_BLOCKS)
#endif
{
build_insn_chain (get_insns ());
retval = reload (get_insns (), 1);
}
/* Clean up. */
free (reg_allocno);
free (reg_may_share);
free (allocno);
free (conflicts);
free (allocnos_live);
return retval;
}
/* Sort predicate for ordering the allocnos.
Returns -1 (1) if *v1 should be allocated before (after) *v2. */
static int
allocno_compare (const void *v1p, const void *v2p)
{
int v1 = *(const int *)v1p, v2 = *(const int *)v2p;
/* Note that the quotient will never be bigger than
the value of floor_log2 times the maximum number of
times a register can occur in one insn (surely less than 100)
weighted by the frequency (maximally REG_FREQ_MAX).
Multiplying this by 10000/REG_FREQ_MAX can't overflow. */
int pri1
= (((double) (floor_log2 (allocno[v1].n_refs) * allocno[v1].freq)
/ allocno[v1].live_length)
* (10000 / REG_FREQ_MAX) * allocno[v1].size);
int pri2
= (((double) (floor_log2 (allocno[v2].n_refs) * allocno[v2].freq)
/ allocno[v2].live_length)
* (10000 / REG_FREQ_MAX) * allocno[v2].size);
if (pri2 - pri1)
return pri2 - pri1;
/* If regs are equally good, sort by allocno,
so that the results of qsort leave nothing to chance. */
return v1 - v2;
}
/* Scan the rtl code and record all conflicts and register preferences in the
conflict matrices and preference tables. */
static void
global_conflicts (void)
{
unsigned i;
basic_block b;
rtx insn;
int *block_start_allocnos;
/* Make a vector that mark_reg_{store,clobber} will store in. */
regs_set = XNEWVEC (rtx, max_parallel * 2);
block_start_allocnos = XNEWVEC (int, max_allocno);
FOR_EACH_BB (b)
{
memset (allocnos_live, 0, allocno_row_words * sizeof (INT_TYPE));
/* Initialize table of registers currently live
to the state at the beginning of this basic block.
This also marks the conflicts among hard registers
and any allocnos that are live.
For pseudo-regs, there is only one bit for each one
no matter how many hard regs it occupies.
This is ok; we know the size from PSEUDO_REGNO_SIZE.
For explicit hard regs, we cannot know the size that way
since one hard reg can be used with various sizes.
Therefore, we must require that all the hard regs
implicitly live as part of a multi-word hard reg
be explicitly marked in basic_block_live_at_start. */
{
regset old = b->il.rtl->global_live_at_start;
int ax = 0;
reg_set_iterator rsi;
REG_SET_TO_HARD_REG_SET (hard_regs_live, old);
EXECUTE_IF_SET_IN_REG_SET (old, FIRST_PSEUDO_REGISTER, i, rsi)
{
int a = reg_allocno[i];
if (a >= 0)
{
SET_ALLOCNO_LIVE (a);
block_start_allocnos[ax++] = a;
}
else if ((a = reg_renumber[i]) >= 0)
mark_reg_live_nc (a, PSEUDO_REGNO_MODE (i));
}
/* Record that each allocno now live conflicts with each hard reg
now live.
It is not necessary to mark any conflicts between pseudos at
this point, even for pseudos which are live at the start of
the basic block.
Given two pseudos X and Y and any point in the CFG P.
On any path to point P where X and Y are live one of the
following conditions must be true:
1. X is live at some instruction on the path that
evaluates Y.
2. Y is live at some instruction on the path that
evaluates X.
3. Either X or Y is not evaluated on the path to P
(i.e. it is used uninitialized) and thus the
conflict can be ignored.
In cases #1 and #2 the conflict will be recorded when we
scan the instruction that makes either X or Y become live. */
record_conflicts (block_start_allocnos, ax);
#ifdef EH_RETURN_DATA_REGNO
if (bb_has_eh_pred (b))
{
unsigned int i;
for (i = 0; ; ++i)
{
unsigned int regno = EH_RETURN_DATA_REGNO (i);
if (regno == INVALID_REGNUM)
break;
record_one_conflict (regno);
}
}
#endif
/* Pseudos can't go in stack regs at the start of a basic block that
is reached by an abnormal edge. Likewise for call clobbered regs,
because caller-save, fixup_abnormal_edges and possibly the table
driven EH machinery are not quite ready to handle such regs live
across such edges. */
{
edge e;
edge_iterator ei;
FOR_EACH_EDGE (e, ei, b->preds)
if (e->flags & EDGE_ABNORMAL)
break;
if (e != NULL)
{
#ifdef STACK_REGS
EXECUTE_IF_SET_IN_ALLOCNO_SET (allocnos_live, ax,
{
allocno[ax].no_stack_reg = 1;
});
for (ax = FIRST_STACK_REG; ax <= LAST_STACK_REG; ax++)
record_one_conflict (ax);
#endif
/* No need to record conflicts for call clobbered regs if we have
nonlocal labels around, as we don't ever try to allocate such
regs in this case. */
if (! current_function_has_nonlocal_label)
for (ax = 0; ax < FIRST_PSEUDO_REGISTER; ax++)
if (call_used_regs [ax])
record_one_conflict (ax);
}
}
}
insn = BB_HEAD (b);
/* Scan the code of this basic block, noting which allocnos
and hard regs are born or die. When one is born,
record a conflict with all others currently live. */
while (1)
{
RTX_CODE code = GET_CODE (insn);
rtx link;
/* Make regs_set an empty set. */
n_regs_set = 0;
if (code == INSN || code == CALL_INSN || code == JUMP_INSN)
{
#if 0
int i = 0;
for (link = REG_NOTES (insn);
link && i < NUM_NO_CONFLICT_PAIRS;
link = XEXP (link, 1))
if (REG_NOTE_KIND (link) == REG_NO_CONFLICT)
{
no_conflict_pairs[i].allocno1
= reg_allocno[REGNO (SET_DEST (PATTERN (insn)))];
no_conflict_pairs[i].allocno2
= reg_allocno[REGNO (XEXP (link, 0))];
i++;
}
#endif /* 0 */
/* Mark any registers clobbered by INSN as live,
so they conflict with the inputs. */
note_stores (PATTERN (insn), mark_reg_clobber, NULL);
/* Mark any registers dead after INSN as dead now. */
for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
if (REG_NOTE_KIND (link) == REG_DEAD)
mark_reg_death (XEXP (link, 0));
/* Mark any registers set in INSN as live,
and mark them as conflicting with all other live regs.
Clobbers are processed again, so they conflict with
the registers that are set. */
note_stores (PATTERN (insn), mark_reg_store, NULL);
#ifdef AUTO_INC_DEC
for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
if (REG_NOTE_KIND (link) == REG_INC)
mark_reg_store (XEXP (link, 0), NULL_RTX, NULL);
#endif
/* If INSN has multiple outputs, then any reg that dies here
and is used inside of an output
must conflict with the other outputs.
It is unsafe to use !single_set here since it will ignore an
unused output. Just because an output is unused does not mean
the compiler can assume the side effect will not occur.
Consider if REG appears in the address of an output and we
reload the output. If we allocate REG to the same hard
register as an unused output we could set the hard register
before the output reload insn. */
if (GET_CODE (PATTERN (insn)) == PARALLEL && multiple_sets (insn))
for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
if (REG_NOTE_KIND (link) == REG_DEAD)
{
int used_in_output = 0;
int i;
rtx reg = XEXP (link, 0);
for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--)
{
rtx set = XVECEXP (PATTERN (insn), 0, i);
if (GET_CODE (set) == SET
&& !REG_P (SET_DEST (set))
&& !rtx_equal_p (reg, SET_DEST (set))
&& reg_overlap_mentioned_p (reg, SET_DEST (set)))
used_in_output = 1;
}
if (used_in_output)
mark_reg_conflicts (reg);
}
/* Mark any registers set in INSN and then never used. */
while (n_regs_set-- > 0)
{
rtx note = find_regno_note (insn, REG_UNUSED,
REGNO (regs_set[n_regs_set]));
if (note)
mark_reg_death (XEXP (note, 0));
}
}
if (insn == BB_END (b))
break;
insn = NEXT_INSN (insn);
}
}
/* Clean up. */
free (block_start_allocnos);
free (regs_set);
}
/* Expand the preference information by looking for cases where one allocno
dies in an insn that sets an allocno. If those two allocnos don't conflict,
merge any preferences between those allocnos. */
static void
expand_preferences (void)
{
rtx insn;
rtx link;
rtx set;
/* We only try to handle the most common cases here. Most of the cases
where this wins are reg-reg copies. */
for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
if (INSN_P (insn)
&& (set = single_set (insn)) != 0
&& REG_P (SET_DEST (set))
&& reg_allocno[REGNO (SET_DEST (set))] >= 0)
for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
if (REG_NOTE_KIND (link) == REG_DEAD
&& REG_P (XEXP (link, 0))
&& reg_allocno[REGNO (XEXP (link, 0))] >= 0
&& ! CONFLICTP (reg_allocno[REGNO (SET_DEST (set))],
reg_allocno[REGNO (XEXP (link, 0))]))
{
int a1 = reg_allocno[REGNO (SET_DEST (set))];
int a2 = reg_allocno[REGNO (XEXP (link, 0))];
if (XEXP (link, 0) == SET_SRC (set))
{
IOR_HARD_REG_SET (allocno[a1].hard_reg_copy_preferences,
allocno[a2].hard_reg_copy_preferences);
IOR_HARD_REG_SET (allocno[a2].hard_reg_copy_preferences,
allocno[a1].hard_reg_copy_preferences);
}
IOR_HARD_REG_SET (allocno[a1].hard_reg_preferences,
allocno[a2].hard_reg_preferences);
IOR_HARD_REG_SET (allocno[a2].hard_reg_preferences,
allocno[a1].hard_reg_preferences);
IOR_HARD_REG_SET (allocno[a1].hard_reg_full_preferences,
allocno[a2].hard_reg_full_preferences);
IOR_HARD_REG_SET (allocno[a2].hard_reg_full_preferences,
allocno[a1].hard_reg_full_preferences);
}
}
/* Prune the preferences for global registers to exclude registers that cannot
be used.
Compute `regs_someone_prefers', which is a bitmask of the hard registers
that are preferred by conflicting registers of lower priority. If possible,
we will avoid using these registers. */
static void
prune_preferences (void)
{
int i;
int num;
int *allocno_to_order = XNEWVEC (int, max_allocno);
/* Scan least most important to most important.
For each allocno, remove from preferences registers that cannot be used,
either because of conflicts or register type. Then compute all registers
preferred by each lower-priority register that conflicts. */
for (i = max_allocno - 1; i >= 0; i--)
{
HARD_REG_SET temp;
num = allocno_order[i];
allocno_to_order[num] = i;
COPY_HARD_REG_SET (temp, allocno[num].hard_reg_conflicts);
if (allocno[num].calls_crossed == 0)
IOR_HARD_REG_SET (temp, fixed_reg_set);
else
IOR_HARD_REG_SET (temp, call_used_reg_set);
IOR_COMPL_HARD_REG_SET
(temp,
reg_class_contents[(int) reg_preferred_class (allocno[num].reg)]);
AND_COMPL_HARD_REG_SET (allocno[num].hard_reg_preferences, temp);
AND_COMPL_HARD_REG_SET (allocno[num].hard_reg_copy_preferences, temp);
AND_COMPL_HARD_REG_SET (allocno[num].hard_reg_full_preferences, temp);
}
for (i = max_allocno - 1; i >= 0; i--)
{
/* Merge in the preferences of lower-priority registers (they have
already been pruned). If we also prefer some of those registers,
don't exclude them unless we are of a smaller size (in which case
we want to give the lower-priority allocno the first chance for
these registers). */