/* RTL dead store elimination.
- Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc.
+ Copyright (C) 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
Contributed by Richard Sandiford <rsandifor@codesourcery.com>
and Kenneth Zadeck <zadeck@naturalbridge.com>
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
-Software Foundation; either version 2, or (at your option) any later
+Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
for more details.
You should have received a copy of the GNU General Public License
-along with GCC; see the file COPYING. If not, write to the Free
-Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
-02110-1301, USA. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
#undef BASELINE
#include "tm.h"
#include "rtl.h"
#include "tree.h"
+#include "tm_p.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "flags.h"
#include "expr.h"
#include "recog.h"
#include "dse.h"
+#include "optabs.h"
#include "dbgcnt.h"
+#include "target.h"
/* This file contains three techniques for performing Dead Store
Elimination (dse).
5) Delete the insns that the global analysis has indicated are
unnecessary.
- 6) Cleanup.
+ 6) Delete insns that store the same value as preceeding store
+ where the earlier store couldn't be eliminated.
+
+ 7) Cleanup.
This step uses cselib and canon_rtx to build the largest expression
possible for each address. This pass is a forwards pass through
... <- A
flow would replace the right hand side of the second insn with a
- reference to r100. Most of the infomation is available to add this
+ reference to r100. Most of the information is available to add this
to this pass. It has not done it because it is a lot of work in
the case that either r100 is assigned to between the first and
second insn and/or the second insn is a load of part of the value
/* False means this is a clobber. */
bool is_set;
+ /* False if a single HOST_WIDE_INT bitmap is used for positions_needed. */
+ bool is_large;
+
/* The id of the mem group of the base address. If rtx_varies_p is
true, this is -1. Otherwise, it is the index into the group
table. */
/* This canonized mem. */
rtx mem;
- /* The result of get_addr on mem. */
+ /* Canonized MEM address for use by canon_true_dependence. */
rtx mem_addr;
/* If this is non-zero, it is the alias set of a spill location. */
- HOST_WIDE_INT alias_set;
+ alias_set_type alias_set;
/* The offset of the first and byte before the last byte associated
with the operation. */
- int begin, end;
+ HOST_WIDE_INT begin, end;
+
+ union
+ {
+ /* A bitmask as wide as the number of bytes in the word that
+ contains a 1 if the byte may be needed. The store is unused if
+ all of the bits are 0. This is used if IS_LARGE is false. */
+ unsigned HOST_WIDE_INT small_bitmask;
+
+ struct
+ {
+ /* A bitmap with one bit per byte. Cleared bit means the position
+ is needed. Used if IS_LARGE is false. */
+ bitmap bmap;
- /* An bitmask as wide as the number of bytes in the word that
- contains a 1 if the byte may be needed. The store is unused if
- all of the bits are 0. */
- long positions_needed;
+ /* Number of set bits (i.e. unneeded bytes) in BITMAP. If it is
+ equal to END - BEGIN, the whole store is unused. */
+ int count;
+ } large;
+ } positions_needed;
/* The next store info for this insn. */
struct store_info *next;
/* The right hand side of the store. This is used if there is a
subsequent reload of the mems address somewhere later in the
basic block. */
- rtx rhs;
+ rtx rhs;
+
+ /* If rhs is or holds a constant, this contains that constant,
+ otherwise NULL. */
+ rtx const_rhs;
+
+ /* Set if this store stores the same constant value as REDUNDANT_REASON
+ insn stored. These aren't eliminated early, because doing that
+ might prevent the earlier larger store to be eliminated. */
+ struct insn_info *redundant_reason;
};
+/* Return a bitmask with the first N low bits set. */
+
+static unsigned HOST_WIDE_INT
+lowpart_bitmask (int n)
+{
+ unsigned HOST_WIDE_INT mask = ~(unsigned HOST_WIDE_INT) 0;
+ return mask >> (HOST_BITS_PER_WIDE_INT - n);
+}
+
typedef struct store_info *store_info_t;
static alloc_pool cse_store_info_pool;
static alloc_pool rtx_store_info_pool;
int group_id;
/* If this is non-zero, it is the alias set of a spill location. */
- HOST_WIDE_INT alias_set;
+ alias_set_type alias_set;
/* The offset of the first and byte after the last byte associated
with the operation. If begin == end == 0, the read did not have
contains a wild read, the use_rec will be null. */
bool wild_read;
- /* This field is set for const function calls. Const functions
- cannot read memory, but they can read the stack because that is
- where they may get their parms. So having this set is less
- severe than a wild read, it just means that all of the stores to
- the stack are killed rather than all stores. */
- bool stack_read;
+ /* This field is only used for the processing of const functions.
+ These functions cannot read memory, but they can read the stack
+ because that is where they may get their parms. We need to be
+ this conservative because, like the store motion pass, we don't
+ consider CALL_INSN_FUNCTION_USAGE when processing call insns.
+ Moreover, we need to distinguish two cases:
+ 1. Before reload (register elimination), the stores related to
+ outgoing arguments are stack pointer based and thus deemed
+ of non-constant base in this pass. This requires special
+ handling but also means that the frame pointer based stores
+ need not be killed upon encountering a const function call.
+ 2. After reload, the stores related to outgoing arguments can be
+ either stack pointer or hard frame pointer based. This means
+ that we have no other choice than also killing all the frame
+ pointer based stores upon encountering a const function call.
+ This field is set after reload for const function calls. Having
+ this set is less severe than a wild read, it just means that all
+ the frame related stores are killed rather than all the stores. */
+ bool frame_read;
+
+ /* This field is only used for the processing of const functions.
+ It is set if the insn may contain a stack pointer based store. */
+ bool stack_pointer_based;
/* This is true if any of the sets within the store contains a
cselib base. Such stores can only be deleted by the local
insn. If the insn is deletable, it contains only one mem set.
But it could also contain clobbers. Insns that contain more than
one mem set are not deletable, but each of those mems are here in
- order to provied info to delete other insns. */
+ order to provide info to delete other insns. */
store_info_t store_rec;
/* The linked list of mem uses in this insn. Only the reads from
/* The linked list of insns that are in consideration for removal in
the forwards pass thru the basic block. This pointer may be
trash as it is not cleared when a wild read occurs. The only
- time it is guaranteed to be correct is when the traveral starts
+ time it is guaranteed to be correct is when the traversal starts
at active_local_stores. */
struct insn_info * next_local_store;
};
operations. */
bool apply_wild_read;
+ /* The following 4 bitvectors hold information about which positions
+ of which stores are live or dead. They are indexed by
+ get_bitmap_index. */
+
/* The set of store positions that exist in this block before a wild read. */
bitmap gen;
just initializes the vector from one of the out sets of the
successors of the block. */
bitmap out;
+
+ /* The following bitvector is indexed by the reg number. It
+ contains the set of regs that are live at the current instruction
+ being processed. While it contains info for all of the
+ registers, only the pseudos are actually examined. It is used to
+ assure that shift sequences that are inserted do not accidently
+ clobber live hard regs. */
+ bitmap regs_live;
};
typedef struct bb_info *bb_info_t;
canonical ordering of these that is not based on addresses. */
int id;
+ /* True if there are any positions that are to be processed
+ globally. */
+ bool process_globally;
+
+ /* True if the base of this group is either the frame_pointer or
+ hard_frame_pointer. */
+ bool frame_related;
+
/* A mem wrapped around the base pointer for the group in order to
do read dependency. */
rtx base_mem;
- /* Canonized version of base_mem, most likely the same thing. */
- rtx canon_base_mem;
+ /* Canonized version of base_mem's address. */
+ rtx canon_base_addr;
/* These two sets of two bitmaps are used to keep track of how many
- stores are actually referencing that postion from this base. We
+ stores are actually referencing that position from this base. We
only do this for rtx bases as this will be used to assign
- postions in the bitmaps for the global problem. Bit N is set in
+ positions in the bitmaps for the global problem. Bit N is set in
store1 on the first store for offset N. Bit N is set in store2
for the second store to offset N. This is all we need since we
only care about offsets that have two or more stores for them.
deleted. */
bitmap store1_n, store1_p, store2_n, store2_p;
- /* The postions in this bitmap have the same assignments as the in,
+ /* The positions in this bitmap have the same assignments as the in,
out, gen and kill bitmaps. This bitmap is all zeros except for
- the postions that are occupied by stores for this group. */
+ the positions that are occupied by stores for this group. */
bitmap group_kill;
- /* True if there are any positions that are to be processed
- globally. */
- bool process_globally;
-
- /* True if the base of this group is either the frame_pointer or
- hard_frame_pointer. */
- bool frame_related;
-
/* The offset_map is used to map the offsets from this base into
- postions in the global bitmaps. It is only created after all of
+ positions in the global bitmaps. It is only created after all of
the all of stores have been scanned and we know which ones we
care about. */
int *offset_map_n, *offset_map_p;
int offset_map_size_n, offset_map_size_p;
};
typedef struct group_info *group_info_t;
+typedef const struct group_info *const_group_info_t;
static alloc_pool rtx_group_info_pool;
/* Tables of group_info structures, hashed by base value. */
/* Hash table element to look up the mode for an alias set. */
struct clear_alias_mode_holder
{
- HOST_WIDE_INT alias_set;
+ alias_set_type alias_set;
enum machine_mode mode;
};
static alloc_pool clear_alias_mode_pool;
-/* This is true except for two cases:
- (1) current_function_stdarg -- i.e. we cannot do this
- for vararg functions because they play games with the frame.
- (2) In ada, it is sometimes not safe to do assume that any stores
- based off the stack frame go dead at the exit to a function. */
+/* This is true except if cfun->stdarg -- i.e. we cannot do
+ this for vararg functions because they play games with the frame. */
static bool stores_off_frame_dead_at_return;
/* Counter for stats. */
static bool gate_dse (void);
+static bool gate_dse1 (void);
+static bool gate_dse2 (void);
\f
/*----------------------------------------------------------------------------
/* Find the entry associated with ALIAS_SET. */
static struct clear_alias_mode_holder *
-clear_alias_set_lookup (HOST_WIDE_INT alias_set)
+clear_alias_set_lookup (alias_set_type alias_set)
{
struct clear_alias_mode_holder tmp_holder;
void **slot;
slot = htab_find_slot (clear_alias_mode_table, &tmp_holder, NO_INSERT);
gcc_assert (*slot);
- return *slot;
+ return (struct clear_alias_mode_holder *) *slot;
}
static int
invariant_group_base_eq (const void *p1, const void *p2)
{
- const group_info_t gi1 = (const group_info_t) p1;
- const group_info_t gi2 = (const group_info_t) p2;
+ const_group_info_t gi1 = (const_group_info_t) p1;
+ const_group_info_t gi2 = (const_group_info_t) p2;
return rtx_equal_p (gi1->rtx_base, gi2->rtx_base);
}
static hashval_t
invariant_group_base_hash (const void *p)
{
- const group_info_t gi = (const group_info_t) p;
+ const_group_info_t gi = (const_group_info_t) p;
int do_not_record;
return hash_rtx (gi->rtx_base, Pmode, &do_not_record, NULL, false);
}
{
if (!clear_alias_group)
{
- clear_alias_group = gi = pool_alloc (rtx_group_info_pool);
+ clear_alias_group = gi =
+ (group_info_t) pool_alloc (rtx_group_info_pool);
memset (gi, 0, sizeof (struct group_info));
gi->id = rtx_group_next_id++;
gi->store1_n = BITMAP_ALLOC (NULL);
if (gi == NULL)
{
- *slot = gi = pool_alloc (rtx_group_info_pool);
+ *slot = gi = (group_info_t) pool_alloc (rtx_group_info_pool);
gi->rtx_base = base;
gi->id = rtx_group_next_id++;
gi->base_mem = gen_rtx_MEM (QImode, base);
- gi->canon_base_mem = canon_rtx (gi->base_mem);
+ gi->canon_base_addr = canon_rtx (base);
gi->store1_n = BITMAP_ALLOC (NULL);
gi->store1_p = BITMAP_ALLOC (NULL);
gi->store2_n = BITMAP_ALLOC (NULL);
bb_table = XCNEWVEC (bb_info_t, last_basic_block);
rtx_group_next_id = 0;
- stores_off_frame_dead_at_return =
- (!(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
- && (TYPE_RETURNS_STACK_DEPRESSED (TREE_TYPE (current_function_decl)))))
- && (!current_function_stdarg);
+ stores_off_frame_dead_at_return = !cfun->stdarg;
init_alias_analysis ();
while (store_info)
{
store_info_t next = store_info->next;
+ if (store_info->is_large)
+ BITMAP_FREE (store_info->positions_needed.large.bmap);
if (store_info->cse_base)
pool_free (cse_store_info_pool, store_info);
else
case POST_INC:
{
rtx r1 = XEXP (x, 0);
- rtx c = gen_int_mode (Pmode, data->size);
- add_insn_before (data->insn,
- gen_rtx_SET (Pmode, r1,
- gen_rtx_PLUS (Pmode, r1, c)),
- NULL);
+ rtx c = gen_int_mode (data->size, Pmode);
+ emit_insn_before (gen_rtx_SET (Pmode, r1,
+ gen_rtx_PLUS (Pmode, r1, c)),
+ data->insn);
return -1;
}
case POST_DEC:
{
rtx r1 = XEXP (x, 0);
- rtx c = gen_int_mode (Pmode, -data->size);
- add_insn_before (data->insn,
- gen_rtx_SET (Pmode, r1,
- gen_rtx_PLUS (Pmode, r1, c)),
- NULL);
+ rtx c = gen_int_mode (-data->size, Pmode);
+ emit_insn_before (gen_rtx_SET (Pmode, r1,
+ gen_rtx_PLUS (Pmode, r1, c)),
+ data->insn);
return -1;
}
insn that contained it. */
rtx add = XEXP (x, 0);
rtx r1 = XEXP (add, 0);
- add_insn_before (data->insn,
- gen_rtx_SET (Pmode, r1, add), NULL);
+ emit_insn_before (gen_rtx_SET (Pmode, r1, add), data->insn);
return -1;
}
replace_inc_dec_mem (rtx *r, void *d)
{
rtx x = *r;
- if (GET_CODE (x) == MEM)
+ if (x != NULL_RTX && MEM_P (x))
{
struct insn_size data;
data.size = GET_MODE_SIZE (GET_MODE (x));
- data.insn = (rtx)d;
+ data.insn = (rtx) d;
for_each_rtx (&XEXP (x, 0), replace_inc_dec, &data);
INSN_UID (insn_info->insn));
if (insn_info->store_rec->alias_set)
fprintf (dump_file, "alias set %d\n",
- (int)insn_info->store_rec->alias_set);
+ (int) insn_info->store_rec->alias_set);
else
fprintf (dump_file, "\n");
}
{
HOST_WIDE_INT i;
- if ((offset > -MAX_OFFSET) && (offset < MAX_OFFSET))
+ if (offset > -MAX_OFFSET && offset + width < MAX_OFFSET)
for (i=offset; i<offset+width; i++)
{
bitmap store1;
while (*ptr)
{
read_info_t next = (*ptr)->next;
- if ( (*ptr)->alias_set == 0 )
+ if ((*ptr)->alias_set == 0)
{
pool_free (read_info_pool, *ptr);
*ptr = next;
}
-/* Return true if X is a constant or one of the registers that behaves
- as a constant over the life of a function. */
+/* Return true if X is a constant or one of the registers that behave
+ as a constant over the life of a function. This is equivalent to
+ !rtx_varies_p for memory addresses. */
static bool
const_or_frame_p (rtx x)
static bool
canon_address (rtx mem,
- HOST_WIDE_INT *alias_set_out,
+ alias_set_type *alias_set_out,
int *group_id,
HOST_WIDE_INT *offset,
cselib_val **base)
if (clear_alias_sets)
{
/* If this is a spill, do not do any further processing. */
- HOST_WIDE_INT alias_set = MEM_ALIAS_SET (mem);
+ alias_set_type alias_set = MEM_ALIAS_SET (mem);
if (dump_file)
- fprintf (dump_file, "found alias set %d\n", (int)alias_set);
+ fprintf (dump_file, "found alias set %d\n", (int) alias_set);
if (bitmap_bit_p (clear_alias_sets, alias_set))
{
struct clear_alias_mode_holder *entry
if (dump_file)
fprintf (dump_file,
"disqualifying alias set %d, (%s) != (%s)\n",
- (int)alias_set, GET_MODE_NAME (entry->mode),
+ (int) alias_set, GET_MODE_NAME (entry->mode),
GET_MODE_NAME (GET_MODE (mem)));
bitmap_set_bit (disqualified_clear_alias_sets, alias_set);
if (GET_CODE (address) == CONST)
address = XEXP (address, 0);
- if (GET_CODE (address) == PLUS && GET_CODE (XEXP (address, 1)) == CONST_INT)
+ if (GET_CODE (address) == PLUS && CONST_INT_P (XEXP (address, 1)))
{
*offset = INTVAL (XEXP (address, 1));
address = XEXP (address, 0);
store_info = store_info->next;
store_info->rhs = NULL;
+ store_info->const_rhs = NULL;
ptr = ptr->next_local_store;
}
}
+/* Mark byte POS bytes from the beginning of store S_INFO as unneeded. */
+
+static inline void
+set_position_unneeded (store_info_t s_info, int pos)
+{
+ if (__builtin_expect (s_info->is_large, false))
+ {
+ if (!bitmap_bit_p (s_info->positions_needed.large.bmap, pos))
+ {
+ s_info->positions_needed.large.count++;
+ bitmap_set_bit (s_info->positions_needed.large.bmap, pos);
+ }
+ }
+ else
+ s_info->positions_needed.small_bitmask
+ &= ~(((unsigned HOST_WIDE_INT) 1) << pos);
+}
+
+/* Mark the whole store S_INFO as unneeded. */
+
+static inline void
+set_all_positions_unneeded (store_info_t s_info)
+{
+ if (__builtin_expect (s_info->is_large, false))
+ {
+ int pos, end = s_info->end - s_info->begin;
+ for (pos = 0; pos < end; pos++)
+ bitmap_set_bit (s_info->positions_needed.large.bmap, pos);
+ s_info->positions_needed.large.count = end;
+ }
+ else
+ s_info->positions_needed.small_bitmask = (unsigned HOST_WIDE_INT) 0;
+}
+
+/* Return TRUE if any bytes from S_INFO store are needed. */
+
+static inline bool
+any_positions_needed_p (store_info_t s_info)
+{
+ if (__builtin_expect (s_info->is_large, false))
+ return (s_info->positions_needed.large.count
+ < s_info->end - s_info->begin);
+ else
+ return (s_info->positions_needed.small_bitmask
+ != (unsigned HOST_WIDE_INT) 0);
+}
+
+/* Return TRUE if all bytes START through START+WIDTH-1 from S_INFO
+ store are needed. */
+
+static inline bool
+all_positions_needed_p (store_info_t s_info, int start, int width)
+{
+ if (__builtin_expect (s_info->is_large, false))
+ {
+ int end = start + width;
+ while (start < end)
+ if (bitmap_bit_p (s_info->positions_needed.large.bmap, start++))
+ return false;
+ return true;
+ }
+ else
+ {
+ unsigned HOST_WIDE_INT mask = lowpart_bitmask (width) << start;
+ return (s_info->positions_needed.small_bitmask & mask) == mask;
+ }
+}
+
+
+static rtx get_stored_val (store_info_t, enum machine_mode, HOST_WIDE_INT,
+ HOST_WIDE_INT, basic_block, bool);
+
+
/* BODY is an instruction pattern that belongs to INSN. Return 1 if
there is a candidate store, after adding it to the appropriate
local store group if so. */
static int
record_store (rtx body, bb_info_t bb_info)
{
- rtx mem;
+ rtx mem, rhs, const_rhs, mem_addr;
HOST_WIDE_INT offset = 0;
HOST_WIDE_INT width = 0;
- HOST_WIDE_INT spill_alias_set;
+ alias_set_type spill_alias_set;
insn_info_t insn_info = bb_info->last_insn;
store_info_t store_info = NULL;
int group_id;
cselib_val *base = NULL;
- insn_info_t ptr, last;
+ insn_info_t ptr, last, redundant_reason;
bool store_is_unused;
if (GET_CODE (body) != SET && GET_CODE (body) != CLOBBER)
return 0;
+ mem = SET_DEST (body);
+
/* If this is not used, then this cannot be used to keep the insn
from being deleted. On the other hand, it does provide something
that can be used to prove that another store is dead. */
store_is_unused
- = (find_reg_note (insn_info->insn, REG_UNUSED, body) != NULL);
+ = (find_reg_note (insn_info->insn, REG_UNUSED, mem) != NULL);
/* Check whether that value is a suitable memory location. */
- mem = SET_DEST (body);
if (!MEM_P (mem))
{
/* If the set or clobber is unused, then it does not effect our
fprintf (dump_file, " adding wild read for (clobber (mem:BLK (scratch))\n");
add_wild_read (bb_info);
insn_info->cannot_delete = true;
+ return 0;
}
- else if (!store_is_unused)
+ /* Handle (set (mem:BLK (addr) [... S36 ...]) (const_int 0))
+ as memset (addr, 0, 36); */
+ else if (!MEM_SIZE (mem)
+ || !CONST_INT_P (MEM_SIZE (mem))
+ || GET_CODE (body) != SET
+ || INTVAL (MEM_SIZE (mem)) <= 0
+ || INTVAL (MEM_SIZE (mem)) > MAX_OFFSET
+ || !CONST_INT_P (SET_SRC (body)))
{
- /* If the set or clobber is unused, then it does not effect our
- ability to get rid of the entire insn. */
- insn_info->cannot_delete = true;
- clear_rhs_from_active_local_stores ();
+ if (!store_is_unused)
+ {
+ /* If the set or clobber is unused, then it does not effect our
+ ability to get rid of the entire insn. */
+ insn_info->cannot_delete = true;
+ clear_rhs_from_active_local_stores ();
+ }
+ return 0;
}
- return 0;
}
/* We can still process a volatile mem, we just cannot delete it. */
if (MEM_VOLATILE_P (mem))
- insn_info->cannot_delete = true;
+ insn_info->cannot_delete = true;
if (!canon_address (mem, &spill_alias_set, &group_id, &offset, &base))
{
return 0;
}
- width = GET_MODE_SIZE (GET_MODE (mem));
+ if (GET_MODE (mem) == BLKmode)
+ width = INTVAL (MEM_SIZE (mem));
+ else
+ {
+ width = GET_MODE_SIZE (GET_MODE (mem));
+ gcc_assert ((unsigned) width <= HOST_BITS_PER_WIDE_INT);
+ }
if (spill_alias_set)
{
bitmap store1 = clear_alias_group->store1_p;
bitmap store2 = clear_alias_group->store2_p;
+
+ gcc_assert (GET_MODE (mem) != BLKmode);
if (bitmap_bit_p (store1, spill_alias_set))
bitmap_set_bit (store2, spill_alias_set);
if (clear_alias_group->offset_map_size_p < spill_alias_set)
clear_alias_group->offset_map_size_p = spill_alias_set;
- store_info = pool_alloc (rtx_store_info_pool);
+ store_info = (store_info_t) pool_alloc (rtx_store_info_pool);
if (dump_file)
fprintf (dump_file, " processing spill store %d(%s)\n",
- (int)spill_alias_set, GET_MODE_NAME (GET_MODE (mem)));
+ (int) spill_alias_set, GET_MODE_NAME (GET_MODE (mem)));
}
else if (group_id >= 0)
{
group_info_t group
= VEC_index (group_info_t, rtx_group_vec, group_id);
- store_info = pool_alloc (rtx_store_info_pool);
+ store_info = (store_info_t) pool_alloc (rtx_store_info_pool);
set_usage_bits (group, offset, width);
if (dump_file)
}
else
{
- store_info = pool_alloc (cse_store_info_pool);
+ rtx base_term = find_base_term (XEXP (mem, 0));
+ if (!base_term
+ || (GET_CODE (base_term) == ADDRESS
+ && GET_MODE (base_term) == Pmode
+ && XEXP (base_term, 0) == stack_pointer_rtx))
+ insn_info->stack_pointer_based = true;
insn_info->contains_cselib_groups = true;
+
+ store_info = (store_info_t) pool_alloc (cse_store_info_pool);
group_id = -1;
if (dump_file)
(int)offset, (int)(offset+width));
}
+ const_rhs = rhs = NULL_RTX;
+ if (GET_CODE (body) == SET
+ /* No place to keep the value after ra. */
+ && !reload_completed
+ && (REG_P (SET_SRC (body))
+ || GET_CODE (SET_SRC (body)) == SUBREG
+ || CONSTANT_P (SET_SRC (body)))
+ && !MEM_VOLATILE_P (mem)
+ /* Sometimes the store and reload is used for truncation and
+ rounding. */
+ && !(FLOAT_MODE_P (GET_MODE (mem)) && (flag_float_store)))
+ {
+ rhs = SET_SRC (body);
+ if (CONSTANT_P (rhs))
+ const_rhs = rhs;
+ else if (body == PATTERN (insn_info->insn))
+ {
+ rtx tem = find_reg_note (insn_info->insn, REG_EQUAL, NULL_RTX);
+ if (tem && CONSTANT_P (XEXP (tem, 0)))
+ const_rhs = XEXP (tem, 0);
+ }
+ if (const_rhs == NULL_RTX && REG_P (rhs))
+ {
+ rtx tem = cselib_expand_value_rtx (rhs, scratch, 5);
+
+ if (tem && CONSTANT_P (tem))
+ const_rhs = tem;
+ }
+ }
+
/* Check to see if this stores causes some other stores to be
dead. */
ptr = active_local_stores;
last = NULL;
+ redundant_reason = NULL;
+ mem = canon_rtx (mem);
+ /* For alias_set != 0 canon_true_dependence should be never called. */
+ if (spill_alias_set)
+ mem_addr = NULL_RTX;
+ else
+ {
+ if (group_id < 0)
+ mem_addr = base->val_rtx;
+ else
+ {
+ group_info_t group
+ = VEC_index (group_info_t, rtx_group_vec, group_id);
+ mem_addr = group->canon_base_addr;
+ }
+ if (offset)
+ mem_addr = plus_constant (mem_addr, offset);
+ }
while (ptr)
{
insn_info_t next = ptr->next_local_store;
store_info_t s_info = ptr->store_rec;
- bool delete = true;
+ bool del = true;
/* Skip the clobbers. We delete the active insn if this insn
- shaddows the set. To have been put on the active list, it
+ shadows the set. To have been put on the active list, it
has exactly on set. */
while (!s_info->is_set)
s_info = s_info->next;
if (s_info->alias_set != spill_alias_set)
- delete = false;
+ del = false;
else if (s_info->alias_set)
{
struct clear_alias_mode_holder *entry
if ((GET_MODE (mem) == GET_MODE (s_info->mem))
&& (GET_MODE (mem) == entry->mode))
{
- delete = true;
- s_info->positions_needed = 0;
+ del = true;
+ set_all_positions_unneeded (s_info);
}
if (dump_file)
fprintf (dump_file, " trying spill store in insn=%d alias_set=%d\n",
- INSN_UID (ptr->insn), (int)s_info->alias_set);
+ INSN_UID (ptr->insn), (int) s_info->alias_set);
}
else if ((s_info->group_id == group_id)
&& (s_info->cse_base == base))
fprintf (dump_file, " trying store in insn=%d gid=%d[%d..%d)\n",
INSN_UID (ptr->insn), s_info->group_id,
(int)s_info->begin, (int)s_info->end);
- for (i = offset; i < offset+width; i++)
- if (i >= s_info->begin && i < s_info->end)
- s_info->positions_needed &= ~(1L << (i - s_info->begin));
+
+ /* Even if PTR won't be eliminated as unneeded, if both
+ PTR and this insn store the same constant value, we might
+ eliminate this insn instead. */
+ if (s_info->const_rhs
+ && const_rhs
+ && offset >= s_info->begin
+ && offset + width <= s_info->end
+ && all_positions_needed_p (s_info, offset - s_info->begin,
+ width))
+ {
+ if (GET_MODE (mem) == BLKmode)
+ {
+ if (GET_MODE (s_info->mem) == BLKmode
+ && s_info->const_rhs == const_rhs)
+ redundant_reason = ptr;
+ }
+ else if (s_info->const_rhs == const0_rtx
+ && const_rhs == const0_rtx)
+ redundant_reason = ptr;
+ else
+ {
+ rtx val;
+ start_sequence ();
+ val = get_stored_val (s_info, GET_MODE (mem),
+ offset, offset + width,
+ BLOCK_FOR_INSN (insn_info->insn),
+ true);
+ if (get_insns () != NULL)
+ val = NULL_RTX;
+ end_sequence ();
+ if (val && rtx_equal_p (val, const_rhs))
+ redundant_reason = ptr;
+ }
+ }
+
+ for (i = MAX (offset, s_info->begin);
+ i < offset + width && i < s_info->end;
+ i++)
+ set_position_unneeded (s_info, i - s_info->begin);
}
else if (s_info->rhs)
/* Need to see if it is possible for this store to overwrite
if (canon_true_dependence (s_info->mem,
GET_MODE (s_info->mem),
s_info->mem_addr,
- mem, rtx_varies_p))
- s_info->rhs = NULL;
+ mem, mem_addr, rtx_varies_p))
+ {
+ s_info->rhs = NULL;
+ s_info->const_rhs = NULL;
+ }
}
-
+
/* An insn can be deleted if every position of every one of
its s_infos is zero. */
- if (s_info->positions_needed != 0)
- delete = false;
-
- if (delete)
+ if (any_positions_needed_p (s_info)
+ || ptr->cannot_delete)
+ del = false;
+
+ if (del)
{
insn_info_t insn_to_delete = ptr;
ptr = next;
}
- gcc_assert ((unsigned) width < sizeof (store_info->positions_needed) * CHAR_BIT);
-
/* Finish filling in the store_info. */
store_info->next = insn_info->store_rec;
insn_info->store_rec = store_info;
- store_info->mem = canon_rtx (mem);
+ store_info->mem = mem;
store_info->alias_set = spill_alias_set;
- store_info->mem_addr = get_addr (XEXP (mem, 0));
+ store_info->mem_addr = mem_addr;
store_info->cse_base = base;
- store_info->positions_needed = (1L << width) - 1;
+ if (width > HOST_BITS_PER_WIDE_INT)
+ {
+ store_info->is_large = true;
+ store_info->positions_needed.large.count = 0;
+ store_info->positions_needed.large.bmap = BITMAP_ALLOC (NULL);
+ }
+ else
+ {
+ store_info->is_large = false;
+ store_info->positions_needed.small_bitmask = lowpart_bitmask (width);
+ }
store_info->group_id = group_id;
store_info->begin = offset;
store_info->end = offset + width;
store_info->is_set = GET_CODE (body) == SET;
+ store_info->rhs = rhs;
+ store_info->const_rhs = const_rhs;
+ store_info->redundant_reason = redundant_reason;
- if (store_info->is_set
- /* No place to keep the value after ra. */
- && !reload_completed
- /* The careful reviewer may wish to comment my checking that the
- rhs of a store is always a reg. */
- && REG_P (SET_SRC (body))
- /* Sometimes the store and reload is used for truncation and
- rounding. */
- && !(FLOAT_MODE_P (GET_MODE (mem)) && (flag_float_store)))
- store_info->rhs = SET_SRC (body);
- else
- store_info->rhs = NULL;
-
/* If this is a clobber, we return 0. We will only be able to
delete this insn if there is only one store USED store, but we
can use the clobber to delete other stores earlier. */
}
+/* If the modes are different and the value's source and target do not
+ line up, we need to extract the value from lower part of the rhs of
+ the store, shift it, and then put it into a form that can be shoved
+ into the read_insn. This function generates a right SHIFT of a
+ value that is at least ACCESS_SIZE bytes wide of READ_MODE. The
+ shift sequence is returned or NULL if we failed to find a
+ shift. */
+
+static rtx
+find_shift_sequence (int access_size,
+ store_info_t store_info,
+ enum machine_mode read_mode,
+ int shift, bool speed, bool require_cst)
+{
+ enum machine_mode store_mode = GET_MODE (store_info->mem);
+ enum machine_mode new_mode;
+ rtx read_reg = NULL;
+
+ /* Some machines like the x86 have shift insns for each size of
+ operand. Other machines like the ppc or the ia-64 may only have
+ shift insns that shift values within 32 or 64 bit registers.
+ This loop tries to find the smallest shift insn that will right
+ justify the value we want to read but is available in one insn on
+ the machine. */
+
+ for (new_mode = smallest_mode_for_size (access_size * BITS_PER_UNIT,
+ MODE_INT);
+ GET_MODE_BITSIZE (new_mode) <= BITS_PER_WORD;
+ new_mode = GET_MODE_WIDER_MODE (new_mode))
+ {
+ rtx target, new_reg, shift_seq, insn, new_lhs;
+ int cost;
+
+ /* If a constant was stored into memory, try to simplify it here,
+ otherwise the cost of the shift might preclude this optimization
+ e.g. at -Os, even when no actual shift will be needed. */
+ if (store_info->const_rhs)
+ {
+ unsigned int byte = subreg_lowpart_offset (new_mode, store_mode);
+ rtx ret = simplify_subreg (new_mode, store_info->const_rhs,
+ store_mode, byte);
+ if (ret && CONSTANT_P (ret))
+ {
+ ret = simplify_const_binary_operation (LSHIFTRT, new_mode,
+ ret, GEN_INT (shift));
+ if (ret && CONSTANT_P (ret))
+ {
+ byte = subreg_lowpart_offset (read_mode, new_mode);
+ ret = simplify_subreg (read_mode, ret, new_mode, byte);
+ if (ret && CONSTANT_P (ret)
+ && rtx_cost (ret, SET, speed) <= COSTS_N_INSNS (1))
+ return ret;
+ }
+ }
+ }
+
+ if (require_cst)
+ return NULL_RTX;
+
+ /* Try a wider mode if truncating the store mode to NEW_MODE
+ requires a real instruction. */
+ if (GET_MODE_BITSIZE (new_mode) < GET_MODE_BITSIZE (store_mode)
+ && !TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (new_mode),
+ GET_MODE_BITSIZE (store_mode)))
+ continue;
+
+ /* Also try a wider mode if the necessary punning is either not
+ desirable or not possible. */
+ if (!CONSTANT_P (store_info->rhs)
+ && !MODES_TIEABLE_P (new_mode, store_mode))
+ continue;
+
+ new_reg = gen_reg_rtx (new_mode);
+
+ start_sequence ();
+
+ /* In theory we could also check for an ashr. Ian Taylor knows
+ of one dsp where the cost of these two was not the same. But
+ this really is a rare case anyway. */
+ target = expand_binop (new_mode, lshr_optab, new_reg,
+ GEN_INT (shift), new_reg, 1, OPTAB_DIRECT);
+
+ shift_seq = get_insns ();
+ end_sequence ();
+
+ if (target != new_reg || shift_seq == NULL)
+ continue;
+
+ cost = 0;
+ for (insn = shift_seq; insn != NULL_RTX; insn = NEXT_INSN (insn))
+ if (INSN_P (insn))
+ cost += insn_rtx_cost (PATTERN (insn), speed);
+
+ /* The computation up to here is essentially independent
+ of the arguments and could be precomputed. It may
+ not be worth doing so. We could precompute if
+ worthwhile or at least cache the results. The result
+ technically depends on both SHIFT and ACCESS_SIZE,
+ but in practice the answer will depend only on ACCESS_SIZE. */
+
+ if (cost > COSTS_N_INSNS (1))
+ continue;
+
+ new_lhs = extract_low_bits (new_mode, store_mode,
+ copy_rtx (store_info->rhs));
+ if (new_lhs == NULL_RTX)
+ continue;
+
+ /* We found an acceptable shift. Generate a move to
+ take the value from the store and put it into the
+ shift pseudo, then shift it, then generate another
+ move to put in into the target of the read. */
+ emit_move_insn (new_reg, new_lhs);
+ emit_insn (shift_seq);
+ read_reg = extract_low_bits (read_mode, new_mode, new_reg);
+ break;
+ }
+
+ return read_reg;
+}
+
+
+/* Call back for note_stores to find the hard regs set or clobbered by
+ insn. Data is a bitmap of the hardregs set so far. */
+
+static void
+look_for_hardregs (rtx x, const_rtx pat ATTRIBUTE_UNUSED, void *data)
+{
+ bitmap regs_set = (bitmap) data;
+
+ if (REG_P (x)
+ && REGNO (x) < FIRST_PSEUDO_REGISTER)
+ {
+ int regno = REGNO (x);
+ int n = hard_regno_nregs[regno][GET_MODE (x)];
+ while (--n >= 0)
+ bitmap_set_bit (regs_set, regno + n);
+ }
+}
+
+/* Helper function for replace_read and record_store.
+ Attempt to return a value stored in STORE_INFO, from READ_BEGIN
+ to one before READ_END bytes read in READ_MODE. Return NULL
+ if not successful. If REQUIRE_CST is true, return always constant. */
+
+static rtx
+get_stored_val (store_info_t store_info, enum machine_mode read_mode,
+ HOST_WIDE_INT read_begin, HOST_WIDE_INT read_end,
+ basic_block bb, bool require_cst)
+{
+ enum machine_mode store_mode = GET_MODE (store_info->mem);
+ int shift;
+ int access_size; /* In bytes. */
+ rtx read_reg;
+
+ /* To get here the read is within the boundaries of the write so
+ shift will never be negative. Start out with the shift being in
+ bytes. */
+ if (store_mode == BLKmode)
+ shift = 0;
+ else if (BYTES_BIG_ENDIAN)
+ shift = store_info->end - read_end;
+ else
+ shift = read_begin - store_info->begin;
+
+ access_size = shift + GET_MODE_SIZE (read_mode);
+
+ /* From now on it is bits. */
+ shift *= BITS_PER_UNIT;
+
+ if (shift)
+ read_reg = find_shift_sequence (access_size, store_info, read_mode, shift,
+ optimize_bb_for_speed_p (bb),
+ require_cst);
+ else if (store_mode == BLKmode)
+ {
+ /* The store is a memset (addr, const_val, const_size). */
+ gcc_assert (CONST_INT_P (store_info->rhs));
+ store_mode = int_mode_for_mode (read_mode);
+ if (store_mode == BLKmode)
+ read_reg = NULL_RTX;
+ else if (store_info->rhs == const0_rtx)
+ read_reg = extract_low_bits (read_mode, store_mode, const0_rtx);
+ else if (GET_MODE_BITSIZE (store_mode) > HOST_BITS_PER_WIDE_INT
+ || BITS_PER_UNIT >= HOST_BITS_PER_WIDE_INT)
+ read_reg = NULL_RTX;
+ else
+ {
+ unsigned HOST_WIDE_INT c
+ = INTVAL (store_info->rhs)
+ & (((HOST_WIDE_INT) 1 << BITS_PER_UNIT) - 1);
+ int shift = BITS_PER_UNIT;
+ while (shift < HOST_BITS_PER_WIDE_INT)
+ {
+ c |= (c << shift);
+ shift <<= 1;
+ }
+ read_reg = GEN_INT (trunc_int_for_mode (c, store_mode));
+ read_reg = extract_low_bits (read_mode, store_mode, read_reg);
+ }
+ }
+ else if (store_info->const_rhs
+ && (require_cst
+ || GET_MODE_CLASS (read_mode) != GET_MODE_CLASS (store_mode)))
+ read_reg = extract_low_bits (read_mode, store_mode,
+ copy_rtx (store_info->const_rhs));
+ else
+ read_reg = extract_low_bits (read_mode, store_mode,
+ copy_rtx (store_info->rhs));
+ if (require_cst && read_reg && !CONSTANT_P (read_reg))
+ read_reg = NULL_RTX;
+ return read_reg;
+}
+
/* Take a sequence of:
A <- r1
...
...
... <- r2
- The STORE_INFO and STORE_INFO are for the store and the READ_INFO
+ or
+
+ r3 <- extract (r1)
+ r3 <- r3 >> shift
+ r2 <- extract (r3)
+ ... <- r2
+
+ or
+
+ r2 <- extract (r1)
+ ... <- r2
+
+ Depending on the alignment and the mode of the store and
+ subsequent load.
+
+
+ The STORE_INFO and STORE_INSN are for the store and READ_INFO
and READ_INSN are for the read. Return true if the replacement
went ok. */
static bool
replace_read (store_info_t store_info, insn_info_t store_insn,
- read_info_t read_info, insn_info_t read_insn, rtx *loc)
+ read_info_t read_info, insn_info_t read_insn, rtx *loc,
+ bitmap regs_live)
{
+ enum machine_mode store_mode = GET_MODE (store_info->mem);
+ enum machine_mode read_mode = GET_MODE (read_info->mem);
+ rtx insns, this_insn, read_reg;
+ basic_block bb;
+
if (!dbg_cnt (dse))
return false;
+ /* Create a sequence of instructions to set up the read register.
+ This sequence goes immediately before the store and its result
+ is read by the load.
+
+ We need to keep this in perspective. We are replacing a read
+ with a sequence of insns, but the read will almost certainly be
+ in cache, so it is not going to be an expensive one. Thus, we
+ are not willing to do a multi insn shift or worse a subroutine
+ call to get rid of the read. */
if (dump_file)
- fprintf (dump_file, "generating move to replace load at %d from store at %d\n",
- INSN_UID (read_insn->insn), INSN_UID (store_insn->insn));
- if (GET_MODE (store_info->mem) == GET_MODE (read_info->mem))
- {
- rtx new_reg = gen_reg_rtx (GET_MODE (store_info->mem));
- if (validate_change (read_insn->insn, loc, new_reg, 0))
- {
- rtx insns;
- deferred_change_t deferred_change = pool_alloc (deferred_change_pool);
+ fprintf (dump_file, "trying to replace %smode load in insn %d"
+ " from %smode store in insn %d\n",
+ GET_MODE_NAME (read_mode), INSN_UID (read_insn->insn),
+ GET_MODE_NAME (store_mode), INSN_UID (store_insn->insn));
+ start_sequence ();
+ bb = BLOCK_FOR_INSN (read_insn->insn);
+ read_reg = get_stored_val (store_info,
+ read_mode, read_info->begin, read_info->end,
+ bb, false);
+ if (read_reg == NULL_RTX)
+ {
+ end_sequence ();
+ if (dump_file)
+ fprintf (dump_file, " -- could not extract bits of stored value\n");
+ return false;
+ }
+ /* Force the value into a new register so that it won't be clobbered
+ between the store and the load. */
+ read_reg = copy_to_mode_reg (read_mode, read_reg);
+ insns = get_insns ();
+ end_sequence ();
- start_sequence ();
- emit_move_insn (new_reg, store_info->rhs);
- insns = get_insns ();
- end_sequence ();
- emit_insn_before (insns, store_insn->insn);
+ if (insns != NULL_RTX)
+ {
+ /* Now we have to scan the set of new instructions to see if the
+ sequence contains and sets of hardregs that happened to be
+ live at this point. For instance, this can happen if one of
+ the insns sets the CC and the CC happened to be live at that
+ point. This does occasionally happen, see PR 37922. */
+ bitmap regs_set = BITMAP_ALLOC (NULL);
- if (dump_file)
- fprintf (dump_file, " -- adding move insn %d: r%d = r%d\n",
- INSN_UID (insns), REGNO (new_reg), REGNO (store_info->rhs));
-
- /* And now for the cludge part: cselib croaks if you just
- return at this point. There are two reasons for this:
-
- 1) Cselib has an idea of how many pseudos there are and
- that does not include the new one we just added.
-
- 2) Cselib does not know about the move insn we added
- above the store_info, and there is no way to tell it
- about it, because it has "moved on".
-
- So we are just going to have to lie. The move insn is
- not really an issue, cselib did not see it. But the use
- of the new pseudo read_insn is a real problem. The way
- that we solve this problem is that we are just going to
- put the mem back keep a table of mems to get rid of. At
- the end of the basic block we can put it back. */
-
- *loc = read_info->mem;
- deferred_change->next = deferred_change_list;
- deferred_change_list = deferred_change;
- deferred_change->loc = loc;
- deferred_change->reg = new_reg;
-
- /* Get rid of the read_info, from the point of view of the
- rest of dse, play like this read never happened. */
- read_insn->read_rec = read_info->next;
- pool_free (read_info_pool, read_info);
- return true;
- }
- else
+ for (this_insn = insns; this_insn != NULL_RTX; this_insn = NEXT_INSN (this_insn))
+ note_stores (PATTERN (this_insn), look_for_hardregs, regs_set);
+
+ bitmap_and_into (regs_set, regs_live);
+ if (!bitmap_empty_p (regs_set))
{
if (dump_file)
- fprintf (dump_file, " -- validation failure\n");
+ {
+ fprintf (dump_file,
+ "abandoning replacement because sequence clobbers live hardregs:");
+ df_print_regset (dump_file, regs_set);
+ }
+
+ BITMAP_FREE (regs_set);
return false;
}
+ BITMAP_FREE (regs_set);
}
- else
+
+ if (validate_change (read_insn->insn, loc, read_reg, 0))
+ {
+ deferred_change_t deferred_change =
+ (deferred_change_t) pool_alloc (deferred_change_pool);
+
+ /* Insert this right before the store insn where it will be safe
+ from later insns that might change it before the read. */
+ emit_insn_before (insns, store_insn->insn);
+
+ /* And now for the kludge part: cselib croaks if you just
+ return at this point. There are two reasons for this:
+
+ 1) Cselib has an idea of how many pseudos there are and
+ that does not include the new ones we just added.
+
+ 2) Cselib does not know about the move insn we added
+ above the store_info, and there is no way to tell it
+ about it, because it has "moved on".
+
+ Problem (1) is fixable with a certain amount of engineering.
+ Problem (2) is requires starting the bb from scratch. This
+ could be expensive.
+
+ So we are just going to have to lie. The move/extraction
+ insns are not really an issue, cselib did not see them. But
+ the use of the new pseudo read_insn is a real problem because
+ cselib has not scanned this insn. The way that we solve this
+ problem is that we are just going to put the mem back for now
+ and when we are finished with the block, we undo this. We
+ keep a table of mems to get rid of. At the end of the basic
+ block we can put them back. */
+
+ *loc = read_info->mem;
+ deferred_change->next = deferred_change_list;
+ deferred_change_list = deferred_change;
+ deferred_change->loc = loc;
+ deferred_change->reg = read_reg;
+
+ /* Get rid of the read_info, from the point of view of the
+ rest of dse, play like this read never happened. */
+ read_insn->read_rec = read_info->next;
+ pool_free (read_info_pool, read_info);
+ if (dump_file)
+ {
+ fprintf (dump_file, " -- replaced the loaded MEM with ");
+ print_simple_rtl (dump_file, read_reg);
+ fprintf (dump_file, "\n");
+ }
+ return true;
+ }
+ else
{
- /* Someone with excellent rtl skills needs to fill this in. You
- are guaranteed that the read is of the same size or smaller
- than the store, and that the read does not hang off one of
- the ends of the store. But the offsets of each must be
- checked because the read does not have to line up on either
- end of the store so the begin fields need to be examined in
- both the store_info and read_info. */
if (dump_file)
- fprintf (dump_file, " -- complex load, currently unsupported.\n");
+ {
+ fprintf (dump_file, " -- replacing the loaded MEM with ");
+ print_simple_rtl (dump_file, read_reg);
+ fprintf (dump_file, " led to an invalid instruction\n");
+ }
return false;
}
}
-
/* A for_each_rtx callback in which DATA is the bb_info. Check to see
if LOC is a mem and if it is look at the address and kill any
appropriate stores that may be active. */
static int
check_mem_read_rtx (rtx *loc, void *data)
{
- rtx mem = *loc;
+ rtx mem = *loc, mem_addr;
bb_info_t bb_info;
insn_info_t insn_info;
HOST_WIDE_INT offset = 0;
HOST_WIDE_INT width = 0;
- HOST_WIDE_INT spill_alias_set = 0;
+ alias_set_type spill_alias_set = 0;
cselib_val *base = NULL;
int group_id;
read_info_t read_info;
else
width = GET_MODE_SIZE (GET_MODE (mem));
- read_info = pool_alloc (read_info_pool);
+ read_info = (read_info_t) pool_alloc (read_info_pool);
read_info->group_id = group_id;
read_info->mem = mem;
read_info->alias_set = spill_alias_set;
read_info->end = offset + width;
read_info->next = insn_info->read_rec;
insn_info->read_rec = read_info;
+ /* For alias_set != 0 canon_true_dependence should be never called. */
+ if (spill_alias_set)
+ mem_addr = NULL_RTX;
+ else
+ {
+ if (group_id < 0)
+ mem_addr = base->val_rtx;
+ else
+ {
+ group_info_t group
+ = VEC_index (group_info_t, rtx_group_vec, group_id);
+ mem_addr = group->canon_base_addr;
+ }
+ if (offset)
+ mem_addr = plus_constant (mem_addr, offset);
+ }
/* We ignore the clobbers in store_info. The is mildly aggressive,
but there really should not be a clobber followed by a read. */
if (dump_file)
fprintf (dump_file, " processing spill load %d\n",
- (int)spill_alias_set);
+ (int) spill_alias_set);
while (i_ptr)
{
= canon_true_dependence (store_info->mem,
GET_MODE (store_info->mem),
store_info->mem_addr,
- mem, rtx_varies_p);
+ mem, mem_addr, rtx_varies_p);
else if (group_id == store_info->group_id)
{
= canon_true_dependence (store_info->mem,
GET_MODE (store_info->mem),
store_info->mem_addr,
- mem, rtx_varies_p);
+ mem, mem_addr, rtx_varies_p);
/* If this read is just reading back something that we just
stored, rewrite the read. */
else
{
if (store_info->rhs
- && (offset >= store_info->begin)
- && (offset + width <= store_info->end))
- {
- int mask = ((1L << width) - 1) << (offset - store_info->begin);
-
- if ((store_info->positions_needed & mask) == mask
- && replace_read (store_info, i_ptr,
- read_info, insn_info, loc))
- return 0;
- }
+ && offset >= store_info->begin
+ && offset + width <= store_info->end
+ && all_positions_needed_p (store_info,
+ offset - store_info->begin,
+ width)
+ && replace_read (store_info, i_ptr, read_info,
+ insn_info, loc, bb_info->regs_live))
+ return 0;
+
/* The bases are the same, just see if the offsets
overlap. */
if ((offset < store_info->end)
if (store_info->rhs
&& store_info->group_id == -1
&& store_info->cse_base == base
- && (offset >= store_info->begin)
- && (offset + width <= store_info->end))
- {
- int mask = ((1L << width) - 1) << (offset - store_info->begin);
-
- if ((store_info->positions_needed & mask) == mask
- && replace_read (store_info, i_ptr,
- read_info, insn_info, loc))
- return 0;
- }
+ && width != -1
+ && offset >= store_info->begin
+ && offset + width <= store_info->end
+ && all_positions_needed_p (store_info,
+ offset - store_info->begin, width)
+ && replace_read (store_info, i_ptr, read_info, insn_info, loc,
+ bb_info->regs_live))
+ return 0;
if (!store_info->alias_set)
remove = canon_true_dependence (store_info->mem,
GET_MODE (store_info->mem),
store_info->mem_addr,
- mem, rtx_varies_p);
+ mem, mem_addr, rtx_varies_p);
if (remove)
{
for_each_rtx (loc, check_mem_read_rtx, data);
}
+
+/* Get arguments passed to CALL_INSN. Return TRUE if successful.
+ So far it only handles arguments passed in registers. */
+
+static bool
+get_call_args (rtx call_insn, tree fn, rtx *args, int nargs)
+{
+ CUMULATIVE_ARGS args_so_far;
+ tree arg;
+ int idx;
+
+ INIT_CUMULATIVE_ARGS (args_so_far, TREE_TYPE (fn), NULL_RTX, 0, 3);
+
+ arg = TYPE_ARG_TYPES (TREE_TYPE (fn));
+ for (idx = 0;
+ arg != void_list_node && idx < nargs;
+ arg = TREE_CHAIN (arg), idx++)
+ {
+ enum machine_mode mode = TYPE_MODE (TREE_VALUE (arg));
+ rtx reg = FUNCTION_ARG (args_so_far, mode, NULL_TREE, 1), link, tmp;
+ if (!reg || !REG_P (reg) || GET_MODE (reg) != mode
+ || GET_MODE_CLASS (mode) != MODE_INT)
+ return false;
+
+ for (link = CALL_INSN_FUNCTION_USAGE (call_insn);
+ link;
+ link = XEXP (link, 1))
+ if (GET_CODE (XEXP (link, 0)) == USE)
+ {
+ args[idx] = XEXP (XEXP (link, 0), 0);
+ if (REG_P (args[idx])
+ && REGNO (args[idx]) == REGNO (reg)
+ && (GET_MODE (args[idx]) == mode
+ || (GET_MODE_CLASS (GET_MODE (args[idx])) == MODE_INT
+ && (GET_MODE_SIZE (GET_MODE (args[idx]))
+ <= UNITS_PER_WORD)
+ && (GET_MODE_SIZE (GET_MODE (args[idx]))
+ > GET_MODE_SIZE (mode)))))
+ break;
+ }
+ if (!link)
+ return false;
+
+ tmp = cselib_expand_value_rtx (args[idx], scratch, 5);
+ if (GET_MODE (args[idx]) != mode)
+ {
+ if (!tmp || !CONST_INT_P (tmp))
+ return false;
+ tmp = GEN_INT (trunc_int_for_mode (INTVAL (tmp), mode));
+ }
+ if (tmp)
+ args[idx] = tmp;
+
+ FUNCTION_ARG_ADVANCE (args_so_far, mode, NULL_TREE, 1);
+ }
+ if (arg != void_list_node || idx != nargs)
+ return false;
+ return true;
+}
+
+
/* Apply record_store to all candidate stores in INSN. Mark INSN
if some part of it is not a candidate store and assigns to a
non-register target. */
scan_insn (bb_info_t bb_info, rtx insn)
{
rtx body;
- insn_info_t insn_info = pool_alloc (insn_info_pool);
+ insn_info_t insn_info = (insn_info_t) pool_alloc (insn_info_pool);
int mems_found = 0;
memset (insn_info, 0, sizeof (struct insn_info));
if (CALL_P (insn))
{
+ bool const_call;
+ tree memset_call = NULL_TREE;
+
insn_info->cannot_delete = true;
+
/* Const functions cannot do anything bad i.e. read memory,
- however, they can read their parameters which may have been
- pushed onto the stack. */
- if (CONST_OR_PURE_CALL_P (insn) && !pure_call_p (insn))
+ however, they can read their parameters which may have
+ been pushed onto the stack.
+ memset and bzero don't read memory either. */
+ const_call = RTL_CONST_CALL_P (insn);
+ if (!const_call)
+ {
+ rtx call = PATTERN (insn);
+ if (GET_CODE (call) == PARALLEL)
+ call = XVECEXP (call, 0, 0);
+ if (GET_CODE (call) == SET)
+ call = SET_SRC (call);
+ if (GET_CODE (call) == CALL
+ && MEM_P (XEXP (call, 0))
+ && GET_CODE (XEXP (XEXP (call, 0), 0)) == SYMBOL_REF)
+ {
+ rtx symbol = XEXP (XEXP (call, 0), 0);
+ if (SYMBOL_REF_DECL (symbol)
+ && TREE_CODE (SYMBOL_REF_DECL (symbol)) == FUNCTION_DECL)
+ {
+ if ((DECL_BUILT_IN_CLASS (SYMBOL_REF_DECL (symbol))
+ == BUILT_IN_NORMAL
+ && (DECL_FUNCTION_CODE (SYMBOL_REF_DECL (symbol))
+ == BUILT_IN_MEMSET))
+ || SYMBOL_REF_DECL (symbol) == block_clear_fn)
+ memset_call = SYMBOL_REF_DECL (symbol);
+ }
+ }
+ }
+ if (const_call || memset_call)
{
insn_info_t i_ptr = active_local_stores;
insn_info_t last = NULL;
if (dump_file)
- fprintf (dump_file, "const call %d\n", INSN_UID (insn));
+ fprintf (dump_file, "%s call %d\n",
+ const_call ? "const" : "memset", INSN_UID (insn));
+ /* See the head comment of the frame_read field. */
+ if (reload_completed)
+ insn_info->frame_read = true;
+
+ /* Loop over the active stores and remove those which are
+ killed by the const function call. */
while (i_ptr)
{
- store_info_t store_info = i_ptr->store_rec;
+ bool remove_store = false;
- /* Skip the clobbers. */
- while (!store_info->is_set)
- store_info = store_info->next;
+ /* The stack pointer based stores are always killed. */
+ if (i_ptr->stack_pointer_based)
+ remove_store = true;
- /* Remove the frame related stores. */
- if (store_info->group_id >= 0
- && VEC_index (group_info_t, rtx_group_vec, store_info->group_id)->frame_related)
+ /* If the frame is read, the frame related stores are killed. */
+ else if (insn_info->frame_read)
+ {
+ store_info_t store_info = i_ptr->store_rec;
+
+ /* Skip the clobbers. */
+ while (!store_info->is_set)
+ store_info = store_info->next;
+
+ if (store_info->group_id >= 0
+ && VEC_index (group_info_t, rtx_group_vec,
+ store_info->group_id)->frame_related)
+ remove_store = true;
+ }
+
+ if (remove_store)
{
if (dump_file)
dump_insn_info ("removing from active", i_ptr);
}
else
last = i_ptr;
+
i_ptr = i_ptr->next_local_store;
}
- insn_info->stack_read = true;
-
- return;
+ if (memset_call)
+ {
+ rtx args[3];
+ if (get_call_args (insn, memset_call, args, 3)
+ && CONST_INT_P (args[1])
+ && CONST_INT_P (args[2])
+ && INTVAL (args[2]) > 0)
+ {
+ rtx mem = gen_rtx_MEM (BLKmode, args[0]);
+ set_mem_size (mem, args[2]);
+ body = gen_rtx_SET (VOIDmode, mem, args[1]);
+ mems_found += record_store (body, bb_info);
+ if (dump_file)
+ fprintf (dump_file, "handling memset as BLKmode store\n");
+ if (mems_found == 1)
+ {
+ insn_info->next_local_store = active_local_stores;
+ active_local_stores = insn_info;
+ }
+ }
+ }
}
- /* Every other call, including pure functions may read memory. */
- add_wild_read (bb_info);
+ else
+ /* Every other call, including pure functions, may read memory. */
+ add_wild_read (bb_info);
+
return;
}
/* Assuming that there are sets in these insns, we cannot delete
them. */
if ((GET_CODE (PATTERN (insn)) == CLOBBER)
- || volatile_insn_p (PATTERN (insn))
+ || volatile_refs_p (PATTERN (insn))
|| (flag_non_call_exceptions && may_trap_p (PATTERN (insn)))
|| (RTX_FRAME_RELATED_P (insn))
|| find_reg_note (insn, REG_FRAME_RELATED_EXPR, NULL_RTX))
fprintf (dump_file, "mems_found = %d, cannot_delete = %s\n",
mems_found, insn_info->cannot_delete ? "true" : "false");
- /* If we found some sets of mems, and the insn has not been marked
- cannot delete, add it into the active_local_stores so that it can
- be locally deleted if found dead. Otherwise mark it as cannot
- delete. This simplifies the processing later. */
- if (mems_found == 1 && !insn_info->cannot_delete)
+ /* If we found some sets of mems, add it into the active_local_stores so
+ that it can be locally deleted if found dead or used for
+ replace_read and redundant constant store elimination. Otherwise mark
+ it as cannot delete. This simplifies the processing later. */
+ if (mems_found == 1)
{
insn_info->next_local_store = active_local_stores;
active_local_stores = insn_info;
while (insn_info)
{
store_info_t store_info = insn_info->store_rec;
- bool delete = false;
+ bool del = false;
/* If ANY of the store_infos match the cselib group that is
being deleted, then the insn can not be deleted. */
if ((store_info->group_id == -1)
&& (store_info->cse_base == base))
{
- delete = true;
+ del = true;
break;
}
store_info = store_info->next;
}
- if (delete)
+ if (del)
{
if (last)
last->next_local_store = insn_info->next_local_store;
dse_step1 (void)
{
basic_block bb;
-
+ bitmap regs_live = BITMAP_ALLOC (NULL);
+
cselib_init (false);
all_blocks = BITMAP_ALLOC (NULL);
bitmap_set_bit (all_blocks, ENTRY_BLOCK);
FOR_ALL_BB (bb)
{
insn_info_t ptr;
- bb_info_t bb_info = pool_alloc (bb_info_pool);
+ bb_info_t bb_info = (bb_info_t) pool_alloc (bb_info_pool);
memset (bb_info, 0, sizeof (struct bb_info));
bitmap_set_bit (all_blocks, bb->index);
+ bb_info->regs_live = regs_live;
+
+ bitmap_copy (regs_live, DF_LR_IN (bb));
+ df_simulate_initialize_forwards (bb, regs_live);
bb_table[bb->index] = bb_info;
cselib_discard_hook = remove_useless_values;
if (INSN_P (insn))
scan_insn (bb_info, insn);
cselib_process_insn (insn);
+ if (INSN_P (insn))
+ df_simulate_one_insn_forwards (bb, insn, regs_live);
}
/* This is something of a hack, because the global algorithm
&& (EDGE_COUNT (bb->succs) == 0
|| (single_succ_p (bb)
&& single_succ (bb) == EXIT_BLOCK_PTR
- && ! current_function_calls_eh_return)))
+ && ! crtl->calls_eh_return)))
{
insn_info_t i_ptr = active_local_stores;
while (i_ptr)
/* Skip the clobbers. */
while (!store_info->is_set)
store_info = store_info->next;
- if (store_info->alias_set)
+ if (store_info->alias_set && !i_ptr->cannot_delete)
delete_dead_store_insn (i_ptr);
else
if (store_info->group_id >= 0)
{
group_info_t group
= VEC_index (group_info_t, rtx_group_vec, store_info->group_id);
- if (group->frame_related)
+ if (group->frame_related && !i_ptr->cannot_delete)
delete_dead_store_insn (i_ptr);
}
while (ptr)
{
if (ptr->contains_cselib_groups)
- free_store_info (ptr);
+ {
+ store_info_t s_info = ptr->store_rec;
+ while (s_info && !s_info->is_set)
+ s_info = s_info->next;
+ if (s_info
+ && s_info->redundant_reason
+ && s_info->redundant_reason->insn
+ && !ptr->cannot_delete)
+ {
+ if (dump_file)
+ fprintf (dump_file, "Locally deleting insn %d "
+ "because insn %d stores the "
+ "same value and couldn't be "
+ "eliminated\n",
+ INSN_UID (ptr->insn),
+ INSN_UID (s_info->redundant_reason->insn));
+ delete_dead_store_insn (ptr);
+ }
+ if (s_info)
+ s_info->redundant_reason = NULL;
+ free_store_info (ptr);
+ }
+ else
+ {
+ store_info_t s_info;
+
+ /* Free at least positions_needed bitmaps. */
+ for (s_info = ptr->store_rec; s_info; s_info = s_info->next)
+ if (s_info->is_large)
+ {
+ BITMAP_FREE (s_info->positions_needed.large.bmap);
+ s_info->is_large = false;
+ }
+ }
ptr = ptr->prev_insn;
}
free_alloc_pool (cse_store_info_pool);
}
+ bb_info->regs_live = NULL;
}
+ BITMAP_FREE (regs_live);
cselib_finish ();
htab_empty (rtx_group_table);
}
Assign each byte position in the stores that we are going to
analyze globally to a position in the bitmaps. Returns true if
- there are any bit postions assigned.
+ there are any bit positions assigned.
----------------------------------------------------------------------------*/
static void
void
-dse_record_singleton_alias_set (HOST_WIDE_INT alias_set,
+dse_record_singleton_alias_set (alias_set_type alias_set,
enum machine_mode mode)
{
struct clear_alias_mode_holder tmp_holder;
slot = htab_find_slot (clear_alias_mode_table, &tmp_holder, INSERT);
gcc_assert (*slot == NULL);
- *slot = entry = pool_alloc (clear_alias_mode_pool);
+ *slot = entry =
+ (struct clear_alias_mode_holder *) pool_alloc (clear_alias_mode_pool);
entry->alias_set = alias_set;
entry->mode = mode;
}
/* Remove ALIAS_SET from the sets of stack slots being considered. */
void
-dse_invalidate_singleton_alias_set (HOST_WIDE_INT alias_set)
+dse_invalidate_singleton_alias_set (alias_set_type alias_set)
{
if ((!gate_dse()) || !alias_set)
return;
int i;
group_info_t group;
- /* For const function calls kill the stack related stores. */
- if (insn_info->stack_read)
+ /* If this insn reads the frame, kill all the frame related stores. */
+ if (insn_info->frame_read)
{
for (i = 0; VEC_iterate (group_info_t, rtx_group_vec, i, group); i++)
if (group->process_globally && group->frame_related)
if ((read_info->group_id < 0)
&& canon_true_dependence (group->base_mem,
QImode,
- group->canon_base_mem,
- read_info->mem, rtx_varies_p))
+ group->canon_base_addr,
+ read_info->mem, NULL_RTX,
+ rtx_varies_p))
{
if (kill)
bitmap_ior_into (kill, group->group_kill);
}
}
/* We do want to process the local info if the insn was
- deleted. For insntance, if the insn did a wild read, we
+ deleted. For instance, if the insn did a wild read, we
no longer need to trash the info. */
if (insn_info->insn
&& INSN_P (insn_info->insn)
/*----------------------------------------------------------------------------
Sixth step.
- Destroy everything left standing.
+ Delete stores made redundant by earlier stores (which store the same
+ value) that couldn't be eliminated.
----------------------------------------------------------------------------*/
-static void
-dse_step6 (bool global_done)
+static void
+dse_step6 (void)
{
- unsigned int i;
- group_info_t group;
basic_block bb;
-
- if (global_done)
+
+ FOR_ALL_BB (bb)
{
- for (i = 0; VEC_iterate (group_info_t, rtx_group_vec, i, group); i++)
- {
- free (group->offset_map_n);
- free (group->offset_map_p);
- BITMAP_FREE (group->store1_n);
- BITMAP_FREE (group->store1_p);
- BITMAP_FREE (group->store2_n);
- BITMAP_FREE (group->store2_p);
- BITMAP_FREE (group->group_kill);
- }
+ bb_info_t bb_info = bb_table[bb->index];
+ insn_info_t insn_info = bb_info->last_insn;
- FOR_ALL_BB (bb)
+ while (insn_info)
{
- bb_info_t bb_info = bb_table[bb->index];
- BITMAP_FREE (bb_info->gen);
- if (bb_info->kill)
- BITMAP_FREE (bb_info->kill);
- if (bb_info->in)
- BITMAP_FREE (bb_info->in);
- if (bb_info->out)
- BITMAP_FREE (bb_info->out);
+ /* There may have been code deleted by the dce pass run before
+ this phase. */
+ if (insn_info->insn
+ && INSN_P (insn_info->insn)
+ && !insn_info->cannot_delete)
+ {
+ store_info_t s_info = insn_info->store_rec;
+
+ while (s_info && !s_info->is_set)
+ s_info = s_info->next;
+ if (s_info
+ && s_info->redundant_reason
+ && s_info->redundant_reason->insn
+ && INSN_P (s_info->redundant_reason->insn))
+ {
+ rtx rinsn = s_info->redundant_reason->insn;
+ if (dump_file)
+ fprintf (dump_file, "Locally deleting insn %d "
+ "because insn %d stores the "
+ "same value and couldn't be "
+ "eliminated\n",
+ INSN_UID (insn_info->insn),
+ INSN_UID (rinsn));
+ delete_dead_store_insn (insn_info);
+ }
+ }
+ insn_info = insn_info->prev_insn;
}
}
- else
+}
+\f
+/*----------------------------------------------------------------------------
+ Seventh step.
+
+ Destroy everything left standing.
+----------------------------------------------------------------------------*/
+
+static void
+dse_step7 (bool global_done)
+{
+ unsigned int i;
+ group_info_t group;
+ basic_block bb;
+
+ for (i = 0; VEC_iterate (group_info_t, rtx_group_vec, i, group); i++)
{
- for (i = 0; VEC_iterate (group_info_t, rtx_group_vec, i, group); i++)
- {
- BITMAP_FREE (group->store1_n);
- BITMAP_FREE (group->store1_p);
- BITMAP_FREE (group->store2_n);
- BITMAP_FREE (group->store2_p);
- BITMAP_FREE (group->group_kill);
- }
+ free (group->offset_map_n);
+ free (group->offset_map_p);
+ BITMAP_FREE (group->store1_n);
+ BITMAP_FREE (group->store1_p);
+ BITMAP_FREE (group->store2_n);
+ BITMAP_FREE (group->store2_p);
+ BITMAP_FREE (group->group_kill);
}
+ if (global_done)
+ FOR_ALL_BB (bb)
+ {
+ bb_info_t bb_info = bb_table[bb->index];
+ BITMAP_FREE (bb_info->gen);
+ if (bb_info->kill)
+ BITMAP_FREE (bb_info->kill);
+ if (bb_info->in)
+ BITMAP_FREE (bb_info->in);
+ if (bb_info->out)
+ BITMAP_FREE (bb_info->out);
+ }
+
if (clear_alias_sets)
{
BITMAP_FREE (clear_alias_sets);
}
-
/* -------------------------------------------------------------------------
DSE
------------------------------------------------------------------------- */
df_set_flags (DF_DEFER_INSN_RESCAN);
+ /* Need the notes since we must track live hardregs in the forwards
+ direction. */
+ df_note_add_problem ();
+ df_analyze ();
+
dse_step0 ();
dse_step1 ();
dse_step2_init ();
dse_step4 ();
dse_step5_spill ();
}
-
- dse_step6 (did_global);
+
+ dse_step6 ();
+ dse_step7 (did_global);
if (dump_file)
fprintf (dump_file, "dse: local deletions = %d, global deletions = %d, spill deletions = %d\n",
static bool
gate_dse (void)
{
- return optimize > 0 && flag_dse;
+ return gate_dse1 () || gate_dse2 ();
}
-struct tree_opt_pass pass_rtl_dse1 =
+static bool
+gate_dse1 (void)
{
+ return optimize > 0 && flag_dse
+ && dbg_cnt (dse1);
+}
+
+static bool
+gate_dse2 (void)
+{
+ return optimize > 0 && flag_dse
+ && dbg_cnt (dse2);
+}
+
+struct rtl_opt_pass pass_rtl_dse1 =
+{
+ {
+ RTL_PASS,
"dse1", /* name */
- gate_dse, /* gate */
+ gate_dse1, /* gate */
rest_of_handle_dse, /* execute */
NULL, /* sub */
NULL, /* next */
0, /* properties_destroyed */
0, /* todo_flags_start */
TODO_dump_func |
- TODO_df_finish |
- TODO_ggc_collect, /* todo_flags_finish */
- 'w' /* letter */
+ TODO_df_finish | TODO_verify_rtl_sharing |
+ TODO_ggc_collect /* todo_flags_finish */
+ }
};
-struct tree_opt_pass pass_rtl_dse2 =
+struct rtl_opt_pass pass_rtl_dse2 =
{
+ {
+ RTL_PASS,
"dse2", /* name */
- gate_dse, /* gate */
+ gate_dse2, /* gate */
rest_of_handle_dse, /* execute */
NULL, /* sub */
NULL, /* next */
0, /* properties_destroyed */
0, /* todo_flags_start */
TODO_dump_func |
- TODO_df_finish |
- TODO_ggc_collect, /* todo_flags_finish */
- 'w' /* letter */
+ TODO_df_finish | TODO_verify_rtl_sharing |
+ TODO_ggc_collect /* todo_flags_finish */
+ }
};
-
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