mirrors/qemu
0
0
Fork 0
mirror of https://github.com/qemu/qemu.git synced 2024-11-26 04:13:39 +08:00
Code Issues Packages Projects Releases Wiki Activity
9a152519a9
qemu/tcg/optimize.c
Richard Henderson 5d8f536300 tcg: Optimize two-address commutative operations 
While swapping constants to the second operand, swap
sources matching destinations to the first operand.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
2012-09-21 19:53:17 +02:00

719 lines
23 KiB
C
Raw Blame History

/*
* Optimizations for Tiny Code Generator for QEMU
*
* Copyright (c) 2010 Samsung Electronics.
* Contributed by Kirill Batuzov <batuzovk@ispras.ru>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "config.h"
#include <stdlib.h>
#include <stdio.h>
#include "qemu-common.h"
#include "tcg-op.h"
#define CASE_OP_32_64(x) \
glue(glue(case INDEX_op_, x), _i32): \
glue(glue(case INDEX_op_, x), _i64)
typedef enum {
TCG_TEMP_UNDEF = 0,
TCG_TEMP_CONST,
TCG_TEMP_COPY,
TCG_TEMP_HAS_COPY,
TCG_TEMP_ANY
} tcg_temp_state;
struct tcg_temp_info {
tcg_temp_state state;
uint16_t prev_copy;
uint16_t next_copy;
tcg_target_ulong val;
};
static struct tcg_temp_info temps[TCG_MAX_TEMPS];
/* Reset TEMP's state to TCG_TEMP_ANY. If TEMP was a representative of some
class of equivalent temp's, a new representative should be chosen in this
class. */
static void reset_temp(TCGArg temp, int nb_temps, int nb_globals)
{
int i;
TCGArg new_base = (TCGArg)-1;
if (temps[temp].state == TCG_TEMP_HAS_COPY) {
for (i = temps[temp].next_copy; i != temp; i = temps[i].next_copy) {
if (i >= nb_globals) {
temps[i].state = TCG_TEMP_HAS_COPY;
new_base = i;
break;
}
}
for (i = temps[temp].next_copy; i != temp; i = temps[i].next_copy) {
if (new_base == (TCGArg)-1) {
temps[i].state = TCG_TEMP_ANY;
} else {
temps[i].val = new_base;
}
}
temps[temps[temp].next_copy].prev_copy = temps[temp].prev_copy;
temps[temps[temp].prev_copy].next_copy = temps[temp].next_copy;
} else if (temps[temp].state == TCG_TEMP_COPY) {
temps[temps[temp].next_copy].prev_copy = temps[temp].prev_copy;
temps[temps[temp].prev_copy].next_copy = temps[temp].next_copy;
new_base = temps[temp].val;
}
temps[temp].state = TCG_TEMP_ANY;
if (new_base != (TCGArg)-1 && temps[new_base].next_copy == new_base) {
temps[new_base].state = TCG_TEMP_ANY;
}
}
static int op_bits(TCGOpcode op)
{
const TCGOpDef *def = &tcg_op_defs[op];
return def->flags & TCG_OPF_64BIT ? 64 : 32;
}
static TCGOpcode op_to_movi(TCGOpcode op)
{
switch (op_bits(op)) {
case 32:
return INDEX_op_movi_i32;
case 64:
return INDEX_op_movi_i64;
default:
fprintf(stderr, "op_to_movi: unexpected return value of "
"function op_bits.\n");
tcg_abort();
}
}
static void tcg_opt_gen_mov(TCGArg *gen_args, TCGArg dst, TCGArg src,
int nb_temps, int nb_globals)
{
reset_temp(dst, nb_temps, nb_globals);
assert(temps[src].state != TCG_TEMP_COPY);
if (src >= nb_globals) {
assert(temps[src].state != TCG_TEMP_CONST);
if (temps[src].state != TCG_TEMP_HAS_COPY) {
temps[src].state = TCG_TEMP_HAS_COPY;
temps[src].next_copy = src;
temps[src].prev_copy = src;
}
temps[dst].state = TCG_TEMP_COPY;
temps[dst].val = src;
temps[dst].next_copy = temps[src].next_copy;
temps[dst].prev_copy = src;
temps[temps[dst].next_copy].prev_copy = dst;
temps[src].next_copy = dst;
}
gen_args[0] = dst;
gen_args[1] = src;
}
static void tcg_opt_gen_movi(TCGArg *gen_args, TCGArg dst, TCGArg val,
int nb_temps, int nb_globals)
{
reset_temp(dst, nb_temps, nb_globals);
temps[dst].state = TCG_TEMP_CONST;
temps[dst].val = val;
gen_args[0] = dst;
gen_args[1] = val;
}
static TCGOpcode op_to_mov(TCGOpcode op)
{
switch (op_bits(op)) {
case 32:
return INDEX_op_mov_i32;
case 64:
return INDEX_op_mov_i64;
default:
fprintf(stderr, "op_to_mov: unexpected return value of "
"function op_bits.\n");
tcg_abort();
}
}
static TCGArg do_constant_folding_2(TCGOpcode op, TCGArg x, TCGArg y)
{
switch (op) {
CASE_OP_32_64(add):
return x + y;
CASE_OP_32_64(sub):
return x - y;
CASE_OP_32_64(mul):
return x * y;
CASE_OP_32_64(and):
return x & y;
CASE_OP_32_64(or):
return x | y;
CASE_OP_32_64(xor):
return x ^ y;
case INDEX_op_shl_i32:
return (uint32_t)x << (uint32_t)y;
case INDEX_op_shl_i64:
return (uint64_t)x << (uint64_t)y;
case INDEX_op_shr_i32:
return (uint32_t)x >> (uint32_t)y;
case INDEX_op_shr_i64:
return (uint64_t)x >> (uint64_t)y;
case INDEX_op_sar_i32:
return (int32_t)x >> (int32_t)y;
case INDEX_op_sar_i64:
return (int64_t)x >> (int64_t)y;
case INDEX_op_rotr_i32:
x = ((uint32_t)x << (32 - y)) | ((uint32_t)x >> y);
return x;
case INDEX_op_rotr_i64:
x = ((uint64_t)x << (64 - y)) | ((uint64_t)x >> y);
return x;
case INDEX_op_rotl_i32:
x = ((uint32_t)x << y) | ((uint32_t)x >> (32 - y));
return x;
case INDEX_op_rotl_i64:
x = ((uint64_t)x << y) | ((uint64_t)x >> (64 - y));
return x;
CASE_OP_32_64(not):
return ~x;
CASE_OP_32_64(neg):
return -x;
CASE_OP_32_64(andc):
return x & ~y;
CASE_OP_32_64(orc):
return x | ~y;
CASE_OP_32_64(eqv):
return ~(x ^ y);
CASE_OP_32_64(nand):
return ~(x & y);
CASE_OP_32_64(nor):
return ~(x | y);
CASE_OP_32_64(ext8s):
return (int8_t)x;
CASE_OP_32_64(ext16s):
return (int16_t)x;
CASE_OP_32_64(ext8u):
return (uint8_t)x;
CASE_OP_32_64(ext16u):
return (uint16_t)x;
case INDEX_op_ext32s_i64:
return (int32_t)x;
case INDEX_op_ext32u_i64:
return (uint32_t)x;
default:
fprintf(stderr,
"Unrecognized operation %d in do_constant_folding.\n", op);
tcg_abort();
}
}
static TCGArg do_constant_folding(TCGOpcode op, TCGArg x, TCGArg y)
{
TCGArg res = do_constant_folding_2(op, x, y);
if (op_bits(op) == 32) {
res &= 0xffffffff;
}
return res;
}
static TCGArg do_constant_folding_cond(TCGOpcode op, TCGArg x,
TCGArg y, TCGCond c)
{
switch (op_bits(op)) {
case 32:
switch (c) {
case TCG_COND_EQ:
return (uint32_t)x == (uint32_t)y;
case TCG_COND_NE:
return (uint32_t)x != (uint32_t)y;
case TCG_COND_LT:
return (int32_t)x < (int32_t)y;
case TCG_COND_GE:
return (int32_t)x >= (int32_t)y;
case TCG_COND_LE:
return (int32_t)x <= (int32_t)y;
case TCG_COND_GT:
return (int32_t)x > (int32_t)y;
case TCG_COND_LTU:
return (uint32_t)x < (uint32_t)y;
case TCG_COND_GEU:
return (uint32_t)x >= (uint32_t)y;
case TCG_COND_LEU:
return (uint32_t)x <= (uint32_t)y;
case TCG_COND_GTU:
return (uint32_t)x > (uint32_t)y;
}
break;
case 64:
switch (c) {
case TCG_COND_EQ:
return (uint64_t)x == (uint64_t)y;
case TCG_COND_NE:
return (uint64_t)x != (uint64_t)y;
case TCG_COND_LT:
return (int64_t)x < (int64_t)y;
case TCG_COND_GE:
return (int64_t)x >= (int64_t)y;
case TCG_COND_LE:
return (int64_t)x <= (int64_t)y;
case TCG_COND_GT:
return (int64_t)x > (int64_t)y;
case TCG_COND_LTU:
return (uint64_t)x < (uint64_t)y;
case TCG_COND_GEU:
return (uint64_t)x >= (uint64_t)y;
case TCG_COND_LEU:
return (uint64_t)x <= (uint64_t)y;
case TCG_COND_GTU:
return (uint64_t)x > (uint64_t)y;
}
break;
}
fprintf(stderr,
"Unrecognized bitness %d or condition %d in "
"do_constant_folding_cond.\n", op_bits(op), c);
tcg_abort();
}
/* Propagate constants and copies, fold constant expressions. */
static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
TCGArg *args, TCGOpDef *tcg_op_defs)
{
int i, nb_ops, op_index, nb_temps, nb_globals, nb_call_args;
TCGOpcode op;
const TCGOpDef *def;
TCGArg *gen_args;
TCGArg tmp;
TCGCond cond;
/* Array VALS has an element for each temp.
If this temp holds a constant then its value is kept in VALS' element.
If this temp is a copy of other ones then this equivalence class'
representative is kept in VALS' element.
If this temp is neither copy nor constant then corresponding VALS'
element is unused. */
nb_temps = s->nb_temps;
nb_globals = s->nb_globals;
memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
nb_ops = tcg_opc_ptr - gen_opc_buf;
gen_args = args;
for (op_index = 0; op_index < nb_ops; op_index++) {
op = gen_opc_buf[op_index];
def = &tcg_op_defs[op];
/* Do copy propagation */
if (!(def->flags & (TCG_OPF_CALL_CLOBBER | TCG_OPF_SIDE_EFFECTS))) {
assert(op != INDEX_op_call);
for (i = def->nb_oargs; i < def->nb_oargs + def->nb_iargs; i++) {
if (temps[args[i]].state == TCG_TEMP_COPY) {
args[i] = temps[args[i]].val;
}
}
}
/* For commutative operations make constant second argument */
switch (op) {
CASE_OP_32_64(add):
CASE_OP_32_64(mul):
CASE_OP_32_64(and):
CASE_OP_32_64(or):
CASE_OP_32_64(xor):
CASE_OP_32_64(eqv):
CASE_OP_32_64(nand):
CASE_OP_32_64(nor):
if (temps[args[1]].state == TCG_TEMP_CONST) {
tmp = args[1];
args[1] = args[2];
args[2] = tmp;
}
break;
CASE_OP_32_64(brcond):
if (temps[args[0]].state == TCG_TEMP_CONST
&& temps[args[1]].state != TCG_TEMP_CONST) {
tmp = args[0];
args[0] = args[1];
args[1] = tmp;
args[2] = tcg_swap_cond(args[2]);
}
break;
CASE_OP_32_64(setcond):
if (temps[args[1]].state == TCG_TEMP_CONST
&& temps[args[2]].state != TCG_TEMP_CONST) {
tmp = args[1];
args[1] = args[2];
args[2] = tmp;
args[3] = tcg_swap_cond(args[3]);
}
break;
CASE_OP_32_64(movcond):
cond = args[5];
if (temps[args[1]].state == TCG_TEMP_CONST
&& temps[args[2]].state != TCG_TEMP_CONST) {
tmp = args[1];
args[1] = args[2];
args[2] = tmp;
cond = tcg_swap_cond(cond);
}
/* For movcond, we canonicalize the "false" input reg to match
the destination reg so that the tcg backend can implement
a "move if true" operation. */
if (args[0] == args[3]) {
tmp = args[3];
args[3] = args[4];
args[4] = tmp;
cond = tcg_invert_cond(cond);
}
args[5] = cond;
default:
break;
}
/* Simplify expressions for "shift/rot r, 0, a => movi r, 0" */
switch (op) {
CASE_OP_32_64(shl):
CASE_OP_32_64(shr):
CASE_OP_32_64(sar):
CASE_OP_32_64(rotl):
CASE_OP_32_64(rotr):
if (temps[args[1]].state == TCG_TEMP_CONST
&& temps[args[1]].val == 0) {
gen_opc_buf[op_index] = op_to_movi(op);
tcg_opt_gen_movi(gen_args, args[0], 0, nb_temps, nb_globals);
args += 3;
gen_args += 2;
continue;
}
break;
default:
break;
}
/* Simplify expression for "op r, a, 0 => mov r, a" cases */
switch (op) {
CASE_OP_32_64(add):
CASE_OP_32_64(sub):
CASE_OP_32_64(shl):
CASE_OP_32_64(shr):
CASE_OP_32_64(sar):
CASE_OP_32_64(rotl):
CASE_OP_32_64(rotr):
CASE_OP_32_64(or):
CASE_OP_32_64(xor):
if (temps[args[1]].state == TCG_TEMP_CONST) {
/* Proceed with possible constant folding. */
break;
}
if (temps[args[2]].state == TCG_TEMP_CONST
&& temps[args[2]].val == 0) {
if ((temps[args[0]].state == TCG_TEMP_COPY
&& temps[args[0]].val == args[1])
|| args[0] == args[1]) {
gen_opc_buf[op_index] = INDEX_op_nop;
} else {
gen_opc_buf[op_index] = op_to_mov(op);
tcg_opt_gen_mov(gen_args, args[0], args[1],
nb_temps, nb_globals);
gen_args += 2;
}
args += 3;
continue;
}
break;
default:
break;
}
/* Simplify expression for "op r, a, 0 => movi r, 0" cases */
switch (op) {
CASE_OP_32_64(and):
CASE_OP_32_64(mul):
if ((temps[args[2]].state == TCG_TEMP_CONST
&& temps[args[2]].val == 0)) {
gen_opc_buf[op_index] = op_to_movi(op);
tcg_opt_gen_movi(gen_args, args[0], 0, nb_temps, nb_globals);
args += 3;
gen_args += 2;
continue;
}
break;
default:
break;
}
/* Simplify expression for "op r, a, a => mov r, a" cases */
switch (op) {
CASE_OP_32_64(or):
CASE_OP_32_64(and):
if (args[1] == args[2]) {
if (args[1] == args[0]) {
gen_opc_buf[op_index] = INDEX_op_nop;
} else {
gen_opc_buf[op_index] = op_to_mov(op);
tcg_opt_gen_mov(gen_args, args[0], args[1], nb_temps,
nb_globals);
gen_args += 2;
}
args += 3;
continue;
}
break;
default:
break;
}
/* Propagate constants through copy operations and do constant
folding. Constants will be substituted to arguments by register
allocator where needed and possible. Also detect copies. */
switch (op) {
CASE_OP_32_64(mov):
if ((temps[args[1]].state == TCG_TEMP_COPY
&& temps[args[1]].val == args[0])
|| args[0] == args[1]) {
args += 2;
gen_opc_buf[op_index] = INDEX_op_nop;
break;
}
if (temps[args[1]].state != TCG_TEMP_CONST) {
tcg_opt_gen_mov(gen_args, args[0], args[1],
nb_temps, nb_globals);
gen_args += 2;
args += 2;
break;
}
/* Source argument is constant. Rewrite the operation and
let movi case handle it. */
op = op_to_movi(op);
gen_opc_buf[op_index] = op;
args[1] = temps[args[1]].val;
/* fallthrough */
CASE_OP_32_64(movi):
tcg_opt_gen_movi(gen_args, args[0], args[1], nb_temps, nb_globals);
gen_args += 2;
args += 2;
break;
CASE_OP_32_64(not):
CASE_OP_32_64(neg):
CASE_OP_32_64(ext8s):
CASE_OP_32_64(ext8u):
CASE_OP_32_64(ext16s):
CASE_OP_32_64(ext16u):
case INDEX_op_ext32s_i64:
case INDEX_op_ext32u_i64:
if (temps[args[1]].state == TCG_TEMP_CONST) {
gen_opc_buf[op_index] = op_to_movi(op);
tmp = do_constant_folding(op, temps[args[1]].val, 0);
tcg_opt_gen_movi(gen_args, args[0], tmp, nb_temps, nb_globals);
} else {
reset_temp(args[0], nb_temps, nb_globals);
gen_args[0] = args[0];
gen_args[1] = args[1];
}
gen_args += 2;
args += 2;
break;
CASE_OP_32_64(add):
CASE_OP_32_64(sub):
CASE_OP_32_64(mul):
CASE_OP_32_64(or):
CASE_OP_32_64(and):
CASE_OP_32_64(xor):
CASE_OP_32_64(shl):
CASE_OP_32_64(shr):
CASE_OP_32_64(sar):
CASE_OP_32_64(rotl):
CASE_OP_32_64(rotr):
CASE_OP_32_64(andc):
CASE_OP_32_64(orc):
CASE_OP_32_64(eqv):
CASE_OP_32_64(nand):
CASE_OP_32_64(nor):
if (temps[args[1]].state == TCG_TEMP_CONST
&& temps[args[2]].state == TCG_TEMP_CONST) {
gen_opc_buf[op_index] = op_to_movi(op);
tmp = do_constant_folding(op, temps[args[1]].val,
temps[args[2]].val);
tcg_opt_gen_movi(gen_args, args[0], tmp, nb_temps, nb_globals);
gen_args += 2;
} else {
reset_temp(args[0], nb_temps, nb_globals);
gen_args[0] = args[0];
gen_args[1] = args[1];
gen_args[2] = args[2];
gen_args += 3;
}
args += 3;
break;
CASE_OP_32_64(setcond):
if (temps[args[1]].state == TCG_TEMP_CONST
&& temps[args[2]].state == TCG_TEMP_CONST) {
gen_opc_buf[op_index] = op_to_movi(op);
tmp = do_constant_folding_cond(op, temps[args[1]].val,
temps[args[2]].val, args[3]);
tcg_opt_gen_movi(gen_args, args[0], tmp, nb_temps, nb_globals);
gen_args += 2;
} else {
reset_temp(args[0], nb_temps, nb_globals);
gen_args[0] = args[0];
gen_args[1] = args[1];
gen_args[2] = args[2];
gen_args[3] = args[3];
gen_args += 4;
}
args += 4;
break;
CASE_OP_32_64(brcond):
if (temps[args[0]].state == TCG_TEMP_CONST
&& temps[args[1]].state == TCG_TEMP_CONST) {
if (do_constant_folding_cond(op, temps[args[0]].val,
temps[args[1]].val, args[2])) {
memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
gen_opc_buf[op_index] = INDEX_op_br;
gen_args[0] = args[3];
gen_args += 1;
} else {
gen_opc_buf[op_index] = INDEX_op_nop;
}
} else {
memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
reset_temp(args[0], nb_temps, nb_globals);
gen_args[0] = args[0];
gen_args[1] = args[1];
gen_args[2] = args[2];
gen_args[3] = args[3];
gen_args += 4;
}
args += 4;
break;
CASE_OP_32_64(movcond):
if (temps[args[1]].state == TCG_TEMP_CONST
&& temps[args[2]].state == TCG_TEMP_CONST) {
tmp = do_constant_folding_cond(op, temps[args[1]].val,
temps[args[2]].val, args[5]);
if (args[0] == args[4-tmp]
|| (temps[args[4-tmp]].state == TCG_TEMP_COPY
&& temps[args[4-tmp]].val == args[0])) {
gen_opc_buf[op_index] = INDEX_op_nop;
} else if (temps[args[4-tmp]].state == TCG_TEMP_CONST) {
gen_opc_buf[op_index] = op_to_movi(op);
tcg_opt_gen_movi(gen_args, args[0], temps[args[4-tmp]].val,
nb_temps, nb_globals);
gen_args += 2;
} else {
gen_opc_buf[op_index] = op_to_mov(op);
tcg_opt_gen_mov(gen_args, args[0], args[4-tmp],
nb_temps, nb_globals);
gen_args += 2;
}
} else {
reset_temp(args[0], nb_temps, nb_globals);
gen_args[0] = args[0];
gen_args[1] = args[1];
gen_args[2] = args[2];
gen_args[3] = args[3];
gen_args[4] = args[4];
gen_args[5] = args[5];
gen_args += 6;
}
args += 6;
break;
case INDEX_op_call:
nb_call_args = (args[0] >> 16) + (args[0] & 0xffff);
if (!(args[nb_call_args + 1] & (TCG_CALL_CONST | TCG_CALL_PURE))) {
for (i = 0; i < nb_globals; i++) {
reset_temp(i, nb_temps, nb_globals);
}
}
for (i = 0; i < (args[0] >> 16); i++) {
reset_temp(args[i + 1], nb_temps, nb_globals);
}
i = nb_call_args + 3;
while (i) {
*gen_args = *args;
args++;
gen_args++;
i--;
}
break;
default:
/* Default case: we do know nothing about operation so no
propagation is done. We trash everything if the operation
is the end of a basic block, otherwise we only trash the
output args. */
if (def->flags & TCG_OPF_BB_END) {
memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
} else {
for (i = 0; i < def->nb_oargs; i++) {
reset_temp(args[i], nb_temps, nb_globals);
}
}
for (i = 0; i < def->nb_args; i++) {
gen_args[i] = args[i];
}
args += def->nb_args;
gen_args += def->nb_args;
break;
}
}
return gen_args;
}
TCGArg *tcg_optimize(TCGContext *s, uint16_t *tcg_opc_ptr,
TCGArg *args, TCGOpDef *tcg_op_defs)
{
TCGArg *res;
res = tcg_constant_folding(s, tcg_opc_ptr, args, tcg_op_defs);
return res;
}
Reference in New Issue View Git Blame Copy Permalink