434 lines
13 KiB
C
434 lines
13 KiB
C
/* Web construction code for GNU compiler.
|
||
Contributed by Jan Hubicka.
|
||
Copyright (C) 2001-2017 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 "backend.h"
|
||
#include "rtl.h"
|
||
#include "df.h"
|
||
#include "insn-config.h"
|
||
#include "recog.h"
|
||
|
||
#include "tree-pass.h"
|
||
|
||
|
||
/* Find the root of unionfind tree (the representative of set). */
|
||
|
||
web_entry_base *
|
||
web_entry_base::unionfind_root ()
|
||
{
|
||
web_entry_base *element = this, *element1 = this, *element2;
|
||
|
||
while (element->pred ())
|
||
element = element->pred ();
|
||
while (element1->pred ())
|
||
{
|
||
element2 = element1->pred ();
|
||
element1->set_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 (web_entry_base *first, web_entry_base *second)
|
||
{
|
||
first = first->unionfind_root ();
|
||
second = second->unionfind_root ();
|
||
if (first == second)
|
||
return true;
|
||
second->set_pred (first);
|
||
return false;
|
||
}
|
||
|
||
class web_entry : public web_entry_base
|
||
{
|
||
private:
|
||
rtx reg_pvt;
|
||
|
||
public:
|
||
rtx reg () { return reg_pvt; }
|
||
void set_reg (rtx r) { reg_pvt = r; }
|
||
};
|
||
|
||
/* 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 *insn, web_entry *def_entry, web_entry *use_entry,
|
||
bool (*fun) (web_entry_base *, web_entry_base *))
|
||
{
|
||
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);
|
||
struct web_entry *dup_entry;
|
||
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;
|
||
|
||
dup_entry = use_entry;
|
||
for (dupref = use_link; dupref; dupref = DF_REF_NEXT_LOC (dupref))
|
||
if (DF_REF_LOC (dupref) == recog_data.dup_loc[i])
|
||
break;
|
||
|
||
if (dupref == NULL && type == OP_INOUT)
|
||
{
|
||
dup_entry = def_entry;
|
||
for (dupref = def_link; dupref; dupref = DF_REF_NEXT_LOC (dupref))
|
||
if (DF_REF_LOC (dupref) == recog_data.dup_loc[i])
|
||
break;
|
||
}
|
||
/* ??? *DUPREF can still be zero, because when an operand matches
|
||
a memory, DF_REF_LOC (use_link[n]) points to the register part
|
||
of the address, whereas recog_data.dup_loc[m] points to the
|
||
entire memory ref, thus we fail to find the duplicate entry,
|
||
even though it is there.
|
||
Example: i686-pc-linux-gnu gcc.c-torture/compile/950607-1.c
|
||
-O3 -fomit-frame-pointer -funroll-loops */
|
||
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 = DF_REF_NEXT_LOC (ref))
|
||
{
|
||
rtx *l = DF_REF_LOC (ref);
|
||
if (l == recog_data.operand_loc[op])
|
||
break;
|
||
if (l && DF_REF_REAL_LOC (ref) == recog_data.operand_loc[op])
|
||
break;
|
||
}
|
||
|
||
if (!ref && type == OP_INOUT)
|
||
{
|
||
entry = use_entry;
|
||
for (ref = use_link; ref; ref = DF_REF_NEXT_LOC (ref))
|
||
{
|
||
rtx *l = DF_REF_LOC (ref);
|
||
if (l == recog_data.operand_loc[op])
|
||
break;
|
||
if (l && DF_REF_REAL_LOC (ref) == recog_data.operand_loc[op])
|
||
break;
|
||
}
|
||
}
|
||
|
||
gcc_assert (ref);
|
||
(*fun) (dup_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, web_entry *def_entry,
|
||
unsigned int *used, web_entry *use_entry,
|
||
bool (*fun) (web_entry_base *, web_entry_base *))
|
||
{
|
||
struct df_insn_info *insn_info = DF_REF_INSN_INFO (use);
|
||
struct df_link *link = DF_REF_CHAIN (use);
|
||
rtx set;
|
||
|
||
if (insn_info)
|
||
{
|
||
df_ref eq_use;
|
||
|
||
set = single_set (insn_info->insn);
|
||
FOR_EACH_INSN_INFO_EQ_USE (eq_use, insn_info)
|
||
if (use != eq_use
|
||
&& DF_REF_REAL_REG (use) == DF_REF_REAL_REG (eq_use))
|
||
(*fun) (use_entry + DF_REF_ID (use), use_entry + DF_REF_ID (eq_use));
|
||
}
|
||
else
|
||
set = NULL;
|
||
|
||
/* Union all occurrences of the same register in reg notes. */
|
||
|
||
/* 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))
|
||
{
|
||
df_ref def;
|
||
|
||
FOR_EACH_INSN_INFO_DEF (def, insn_info)
|
||
if (DF_REF_REAL_REG (use) == DF_REF_REAL_REG (def))
|
||
(*fun) (use_entry + DF_REF_ID (use), def_entry + DF_REF_ID (def));
|
||
}
|
||
|
||
/* 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)
|
||
if (insn_info)
|
||
{
|
||
df_ref def;
|
||
|
||
FOR_EACH_INSN_INFO_DEF (def, insn_info)
|
||
if (DF_REF_REAL_REG (use) == DF_REF_REAL_REG (def))
|
||
(*fun) (use_entry + DF_REF_ID (use), def_entry + DF_REF_ID (def));
|
||
}
|
||
}
|
||
|
||
/* Find the corresponding register for the given entry. */
|
||
|
||
static rtx
|
||
entry_register (web_entry *entry, df_ref ref, unsigned int *used)
|
||
{
|
||
web_entry *root;
|
||
rtx reg, newreg;
|
||
|
||
/* Find the corresponding web and see if it has been visited. */
|
||
root = (web_entry *)entry->unionfind_root ();
|
||
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->set_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));
|
||
}
|
||
|
||
|
||
namespace {
|
||
|
||
const pass_data pass_data_web =
|
||
{
|
||
RTL_PASS, /* type */
|
||
"web", /* name */
|
||
OPTGROUP_NONE, /* optinfo_flags */
|
||
TV_WEB, /* tv_id */
|
||
0, /* properties_required */
|
||
0, /* properties_provided */
|
||
0, /* properties_destroyed */
|
||
0, /* todo_flags_start */
|
||
TODO_df_finish, /* todo_flags_finish */
|
||
};
|
||
|
||
class pass_web : public rtl_opt_pass
|
||
{
|
||
public:
|
||
pass_web (gcc::context *ctxt)
|
||
: rtl_opt_pass (pass_data_web, ctxt)
|
||
{}
|
||
|
||
/* opt_pass methods: */
|
||
virtual bool gate (function *) { return (optimize > 0 && flag_web); }
|
||
virtual unsigned int execute (function *);
|
||
|
||
}; // class pass_web
|
||
|
||
unsigned int
|
||
pass_web::execute (function *fun)
|
||
{
|
||
web_entry *def_entry;
|
||
web_entry *use_entry;
|
||
unsigned int max = max_reg_num ();
|
||
unsigned int *used;
|
||
basic_block bb;
|
||
unsigned int uses_num = 0;
|
||
rtx_insn *insn;
|
||
|
||
df_set_flags (DF_NO_HARD_REGS + DF_EQ_NOTES);
|
||
df_set_flags (DF_RD_PRUNE_DEAD_DEFS);
|
||
df_chain_add_problem (DF_UD_CHAIN);
|
||
df_analyze ();
|
||
df_set_flags (DF_DEFER_INSN_RESCAN);
|
||
|
||
/* Assign ids to the uses. */
|
||
FOR_ALL_BB_FN (bb, fun)
|
||
FOR_BB_INSNS (bb, insn)
|
||
{
|
||
if (NONDEBUG_INSN_P (insn))
|
||
{
|
||
struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn);
|
||
df_ref use;
|
||
FOR_EACH_INSN_INFO_USE (use, insn_info)
|
||
if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER)
|
||
DF_REF_ID (use) = uses_num++;
|
||
FOR_EACH_INSN_INFO_EQ_USE (use, insn_info)
|
||
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 (web_entry, DF_DEFS_TABLE_SIZE ());
|
||
used = XCNEWVEC (unsigned, max);
|
||
use_entry = XCNEWVEC (web_entry, uses_num);
|
||
|
||
/* Produce the web. */
|
||
FOR_ALL_BB_FN (bb, fun)
|
||
FOR_BB_INSNS (bb, insn)
|
||
if (NONDEBUG_INSN_P (insn))
|
||
{
|
||
struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn);
|
||
df_ref use;
|
||
union_match_dups (insn, def_entry, use_entry, unionfind_union);
|
||
FOR_EACH_INSN_INFO_USE (use, insn_info)
|
||
if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER)
|
||
union_defs (use, def_entry, used, use_entry, unionfind_union);
|
||
FOR_EACH_INSN_INFO_EQ_USE (use, insn_info)
|
||
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_FN (bb, fun)
|
||
FOR_BB_INSNS (bb, 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)
|
||
{
|
||
struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn);
|
||
df_ref def, use;
|
||
FOR_EACH_INSN_INFO_USE (use, insn_info)
|
||
if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER)
|
||
replace_ref (use, entry_register (use_entry + DF_REF_ID (use),
|
||
use, used));
|
||
FOR_EACH_INSN_INFO_EQ_USE (use, insn_info)
|
||
if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER)
|
||
replace_ref (use, entry_register (use_entry + DF_REF_ID (use),
|
||
use, used));
|
||
FOR_EACH_INSN_INFO_DEF (def, insn_info)
|
||
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;
|
||
}
|
||
|
||
} // anon namespace
|
||
|
||
rtl_opt_pass *
|
||
make_pass_web (gcc::context *ctxt)
|
||
{
|
||
return new pass_web (ctxt);
|
||
}
|