439 lines
12 KiB
C
439 lines
12 KiB
C
/* Web construction code for GNU compiler.
|
||
Contributed by Jan Hubicka.
|
||
Copyright (C) 2001, 2002, 2004, 2006, 2007, 2008, 2010
|
||
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/>. */
|
||
|
||
/* Simple optimization pass that splits independent uses of each pseudo,
|
||
increasing effectiveness of other optimizations. The optimization can
|
||
serve as an example of use for the dataflow module.
|
||
|
||
We don't split registers with REG_USERVAR set unless -fmessy-debugging
|
||
is specified, because debugging information about such split variables
|
||
is almost unusable.
|
||
|
||
TODO
|
||
- We may use profile information and ignore infrequent use for the
|
||
purpose of web unifying, inserting the compensation code later to
|
||
implement full induction variable expansion for loops (currently
|
||
we expand only if the induction variable is dead afterward, which
|
||
is often the case). */
|
||
|
||
#include "config.h"
|
||
#include "system.h"
|
||
#include "coretypes.h"
|
||
#include "tm.h"
|
||
#include "diagnostic-core.h"
|
||
|
||
#include "rtl.h"
|
||
#include "hard-reg-set.h"
|
||
#include "flags.h"
|
||
#include "obstack.h"
|
||
#include "basic-block.h"
|
||
#include "output.h"
|
||
#include "df.h"
|
||
#include "function.h"
|
||
#include "insn-config.h"
|
||
#include "recog.h"
|
||
#include "timevar.h"
|
||
#include "tree-pass.h"
|
||
|
||
|
||
/* Find the root of unionfind tree (the representative of set). */
|
||
|
||
struct web_entry *
|
||
unionfind_root (struct web_entry *element)
|
||
{
|
||
struct web_entry *element1 = element, *element2;
|
||
|
||
while (element->pred)
|
||
element = element->pred;
|
||
while (element1->pred)
|
||
{
|
||
element2 = element1->pred;
|
||
element1->pred = element;
|
||
element1 = element2;
|
||
}
|
||
return element;
|
||
}
|
||
|
||
/* Union sets.
|
||
Return true if FIRST and SECOND points to the same web entry structure and
|
||
nothing is done. Otherwise, return false. */
|
||
|
||
bool
|
||
unionfind_union (struct web_entry *first, struct web_entry *second)
|
||
{
|
||
first = unionfind_root (first);
|
||
second = unionfind_root (second);
|
||
if (first == second)
|
||
return true;
|
||
second->pred = first;
|
||
return false;
|
||
}
|
||
|
||
/* For INSN, union all defs and uses that are linked by match_dup.
|
||
FUN is the function that does the union. */
|
||
|
||
static void
|
||
union_match_dups (rtx insn, struct web_entry *def_entry,
|
||
struct web_entry *use_entry,
|
||
bool (*fun) (struct web_entry *, struct web_entry *))
|
||
{
|
||
struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn);
|
||
df_ref *use_link = DF_INSN_INFO_USES (insn_info);
|
||
df_ref *def_link = DF_INSN_INFO_DEFS (insn_info);
|
||
int i;
|
||
|
||
extract_insn (insn);
|
||
|
||
for (i = 0; i < recog_data.n_dups; i++)
|
||
{
|
||
int op = recog_data.dup_num[i];
|
||
enum op_type type = recog_data.operand_type[op];
|
||
df_ref *ref, *dupref;
|
||
struct web_entry *entry;
|
||
|
||
for (dupref = use_link; *dupref; dupref++)
|
||
if (DF_REF_LOC (*dupref) == recog_data.dup_loc[i])
|
||
break;
|
||
|
||
if (*dupref == NULL
|
||
|| DF_REF_REGNO (*dupref) < FIRST_PSEUDO_REGISTER)
|
||
continue;
|
||
|
||
ref = type == OP_IN ? use_link : def_link;
|
||
entry = type == OP_IN ? use_entry : def_entry;
|
||
for (; *ref; ref++)
|
||
if (DF_REF_LOC (*ref) == recog_data.operand_loc[op])
|
||
break;
|
||
|
||
(*fun) (use_entry + DF_REF_ID (*dupref), entry + DF_REF_ID (*ref));
|
||
}
|
||
}
|
||
|
||
/* For each use, all possible defs reaching it must come in the same
|
||
register, union them.
|
||
FUN is the function that does the union.
|
||
|
||
In USED, we keep the DF_REF_ID of the first uninitialized uses of a
|
||
register, so that all uninitialized uses of the register can be
|
||
combined into a single web. We actually offset it by 2, because
|
||
the values 0 and 1 are reserved for use by entry_register. */
|
||
|
||
void
|
||
union_defs (df_ref use, struct web_entry *def_entry,
|
||
unsigned int *used, struct web_entry *use_entry,
|
||
bool (*fun) (struct web_entry *, struct web_entry *))
|
||
{
|
||
struct df_insn_info *insn_info = DF_REF_INSN_INFO (use);
|
||
struct df_link *link = DF_REF_CHAIN (use);
|
||
df_ref *eq_use_link;
|
||
df_ref *def_link;
|
||
rtx set;
|
||
|
||
if (insn_info)
|
||
{
|
||
rtx insn = insn_info->insn;
|
||
eq_use_link = DF_INSN_INFO_EQ_USES (insn_info);
|
||
def_link = DF_INSN_INFO_DEFS (insn_info);
|
||
set = single_set (insn);
|
||
}
|
||
else
|
||
{
|
||
/* An artificial use. It links up with nothing. */
|
||
eq_use_link = NULL;
|
||
def_link = NULL;
|
||
set = NULL;
|
||
}
|
||
|
||
/* Union all occurrences of the same register in reg notes. */
|
||
|
||
if (eq_use_link)
|
||
while (*eq_use_link)
|
||
{
|
||
if (use != *eq_use_link
|
||
&& DF_REF_REAL_REG (use) == DF_REF_REAL_REG (*eq_use_link))
|
||
(*fun) (use_entry + DF_REF_ID (use),
|
||
use_entry + DF_REF_ID (*eq_use_link));
|
||
eq_use_link++;
|
||
}
|
||
|
||
/* Recognize trivial noop moves and attempt to keep them as noop. */
|
||
|
||
if (set
|
||
&& SET_SRC (set) == DF_REF_REG (use)
|
||
&& SET_SRC (set) == SET_DEST (set))
|
||
{
|
||
if (def_link)
|
||
while (*def_link)
|
||
{
|
||
if (DF_REF_REAL_REG (use) == DF_REF_REAL_REG (*def_link))
|
||
(*fun) (use_entry + DF_REF_ID (use),
|
||
def_entry + DF_REF_ID (*def_link));
|
||
def_link++;
|
||
}
|
||
}
|
||
|
||
/* UD chains of uninitialized REGs are empty. Keeping all uses of
|
||
the same uninitialized REG in a single web is not necessary for
|
||
correctness, since the uses are undefined, but it's wasteful to
|
||
allocate one register or slot for each reference. Furthermore,
|
||
creating new pseudos for uninitialized references in debug insns
|
||
(see PR 42631) causes -fcompare-debug failures. We record the
|
||
number of the first uninitialized reference we found, and merge
|
||
with it any other uninitialized references to the same
|
||
register. */
|
||
if (!link)
|
||
{
|
||
int regno = REGNO (DF_REF_REAL_REG (use));
|
||
if (used[regno])
|
||
(*fun) (use_entry + DF_REF_ID (use), use_entry + used[regno] - 2);
|
||
else
|
||
used[regno] = DF_REF_ID (use) + 2;
|
||
}
|
||
|
||
while (link)
|
||
{
|
||
(*fun) (use_entry + DF_REF_ID (use),
|
||
def_entry + DF_REF_ID (link->ref));
|
||
link = link->next;
|
||
}
|
||
|
||
/* A READ_WRITE use requires the corresponding def to be in the same
|
||
register. Find it and union. */
|
||
if (DF_REF_FLAGS (use) & DF_REF_READ_WRITE)
|
||
{
|
||
df_ref *link;
|
||
|
||
if (insn_info)
|
||
link = DF_INSN_INFO_DEFS (insn_info);
|
||
else
|
||
link = NULL;
|
||
|
||
if (link)
|
||
while (*link)
|
||
{
|
||
if (DF_REF_REAL_REG (*link) == DF_REF_REAL_REG (use))
|
||
(*fun) (use_entry + DF_REF_ID (use),
|
||
def_entry + DF_REF_ID (*link));
|
||
link++;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Find the corresponding register for the given entry. */
|
||
|
||
static rtx
|
||
entry_register (struct web_entry *entry, df_ref ref, unsigned int *used)
|
||
{
|
||
struct web_entry *root;
|
||
rtx reg, newreg;
|
||
|
||
/* Find the corresponding web and see if it has been visited. */
|
||
root = unionfind_root (entry);
|
||
if (root->reg)
|
||
return root->reg;
|
||
|
||
/* We are seeing this web for the first time, do the assignment. */
|
||
reg = DF_REF_REAL_REG (ref);
|
||
|
||
/* In case the original register is already assigned, generate new
|
||
one. Since we use USED to merge uninitialized refs into a single
|
||
web, we might found an element to be nonzero without our having
|
||
used it. Test for 1, because union_defs saves it for our use,
|
||
and there won't be any use for the other values when we get to
|
||
this point. */
|
||
if (used[REGNO (reg)] != 1)
|
||
newreg = reg, used[REGNO (reg)] = 1;
|
||
else
|
||
{
|
||
newreg = gen_reg_rtx (GET_MODE (reg));
|
||
REG_USERVAR_P (newreg) = REG_USERVAR_P (reg);
|
||
REG_POINTER (newreg) = REG_POINTER (reg);
|
||
REG_ATTRS (newreg) = REG_ATTRS (reg);
|
||
if (dump_file)
|
||
fprintf (dump_file, "Web oldreg=%i newreg=%i\n", REGNO (reg),
|
||
REGNO (newreg));
|
||
}
|
||
|
||
root->reg = newreg;
|
||
return newreg;
|
||
}
|
||
|
||
/* Replace the reference by REG. */
|
||
|
||
static void
|
||
replace_ref (df_ref ref, rtx reg)
|
||
{
|
||
rtx oldreg = DF_REF_REAL_REG (ref);
|
||
rtx *loc = DF_REF_REAL_LOC (ref);
|
||
unsigned int uid = DF_REF_INSN_UID (ref);
|
||
|
||
if (oldreg == reg)
|
||
return;
|
||
if (dump_file)
|
||
fprintf (dump_file, "Updating insn %i (%i->%i)\n",
|
||
uid, REGNO (oldreg), REGNO (reg));
|
||
*loc = reg;
|
||
df_insn_rescan (DF_REF_INSN (ref));
|
||
}
|
||
|
||
|
||
static bool
|
||
gate_handle_web (void)
|
||
{
|
||
return (optimize > 0 && flag_web);
|
||
}
|
||
|
||
/* Main entry point. */
|
||
|
||
static unsigned int
|
||
web_main (void)
|
||
{
|
||
struct web_entry *def_entry;
|
||
struct web_entry *use_entry;
|
||
unsigned int max = max_reg_num ();
|
||
unsigned int *used;
|
||
basic_block bb;
|
||
unsigned int uses_num = 0;
|
||
rtx insn;
|
||
|
||
df_set_flags (DF_NO_HARD_REGS + DF_EQ_NOTES);
|
||
df_chain_add_problem (DF_UD_CHAIN);
|
||
df_analyze ();
|
||
df_set_flags (DF_DEFER_INSN_RESCAN);
|
||
|
||
/* Assign ids to the uses. */
|
||
FOR_ALL_BB (bb)
|
||
FOR_BB_INSNS (bb, insn)
|
||
{
|
||
unsigned int uid = INSN_UID (insn);
|
||
if (NONDEBUG_INSN_P (insn))
|
||
{
|
||
df_ref *use_rec;
|
||
for (use_rec = DF_INSN_UID_USES (uid); *use_rec; use_rec++)
|
||
{
|
||
df_ref use = *use_rec;
|
||
if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER)
|
||
DF_REF_ID (use) = uses_num++;
|
||
}
|
||
for (use_rec = DF_INSN_UID_EQ_USES (uid); *use_rec; use_rec++)
|
||
{
|
||
df_ref use = *use_rec;
|
||
if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER)
|
||
DF_REF_ID (use) = uses_num++;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Record the number of uses and defs at the beginning of the optimization. */
|
||
def_entry = XCNEWVEC (struct web_entry, DF_DEFS_TABLE_SIZE());
|
||
used = XCNEWVEC (unsigned, max);
|
||
use_entry = XCNEWVEC (struct web_entry, uses_num);
|
||
|
||
/* Produce the web. */
|
||
FOR_ALL_BB (bb)
|
||
FOR_BB_INSNS (bb, insn)
|
||
{
|
||
unsigned int uid = INSN_UID (insn);
|
||
if (NONDEBUG_INSN_P (insn))
|
||
{
|
||
df_ref *use_rec;
|
||
union_match_dups (insn, def_entry, use_entry, unionfind_union);
|
||
for (use_rec = DF_INSN_UID_USES (uid); *use_rec; use_rec++)
|
||
{
|
||
df_ref use = *use_rec;
|
||
if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER)
|
||
union_defs (use, def_entry, used, use_entry, unionfind_union);
|
||
}
|
||
for (use_rec = DF_INSN_UID_EQ_USES (uid); *use_rec; use_rec++)
|
||
{
|
||
df_ref use = *use_rec;
|
||
if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER)
|
||
union_defs (use, def_entry, used, use_entry, unionfind_union);
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Update the instruction stream, allocating new registers for split pseudos
|
||
in progress. */
|
||
FOR_ALL_BB (bb)
|
||
FOR_BB_INSNS (bb, insn)
|
||
{
|
||
unsigned int uid = INSN_UID (insn);
|
||
|
||
if (NONDEBUG_INSN_P (insn)
|
||
/* Ignore naked clobber. For example, reg 134 in the second insn
|
||
of the following sequence will not be replaced.
|
||
|
||
(insn (clobber (reg:SI 134)))
|
||
|
||
(insn (set (reg:SI 0 r0) (reg:SI 134)))
|
||
|
||
Thus the later passes can optimize them away. */
|
||
&& GET_CODE (PATTERN (insn)) != CLOBBER)
|
||
{
|
||
df_ref *use_rec;
|
||
df_ref *def_rec;
|
||
for (use_rec = DF_INSN_UID_USES (uid); *use_rec; use_rec++)
|
||
{
|
||
df_ref use = *use_rec;
|
||
if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER)
|
||
replace_ref (use, entry_register (use_entry + DF_REF_ID (use), use, used));
|
||
}
|
||
for (use_rec = DF_INSN_UID_EQ_USES (uid); *use_rec; use_rec++)
|
||
{
|
||
df_ref use = *use_rec;
|
||
if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER)
|
||
replace_ref (use, entry_register (use_entry + DF_REF_ID (use), use, used));
|
||
}
|
||
for (def_rec = DF_INSN_UID_DEFS (uid); *def_rec; def_rec++)
|
||
{
|
||
df_ref def = *def_rec;
|
||
if (DF_REF_REGNO (def) >= FIRST_PSEUDO_REGISTER)
|
||
replace_ref (def, entry_register (def_entry + DF_REF_ID (def), def, used));
|
||
}
|
||
}
|
||
}
|
||
|
||
free (def_entry);
|
||
free (use_entry);
|
||
free (used);
|
||
return 0;
|
||
}
|
||
|
||
struct rtl_opt_pass pass_web =
|
||
{
|
||
{
|
||
RTL_PASS,
|
||
"web", /* name */
|
||
gate_handle_web, /* gate */
|
||
web_main, /* execute */
|
||
NULL, /* sub */
|
||
NULL, /* next */
|
||
0, /* static_pass_number */
|
||
TV_WEB, /* tv_id */
|
||
0, /* properties_required */
|
||
0, /* properties_provided */
|
||
0, /* properties_destroyed */
|
||
0, /* todo_flags_start */
|
||
TODO_df_finish | TODO_verify_rtl_sharing /* todo_flags_finish */
|
||
}
|
||
};
|