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tcg: Use per-temp state data in liveness

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This avoids having to allocate external memory for each temporary.

Backports commit b83eabeac06e38706738bd5e92b1ba117a1b554d from qemu
This commit is contained in:
Richard Henderson 2018-03-05 07:29:27 -05:00 committed by Lioncash
parent 87f2067aac
commit 1f4ac863bf
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GPG key ID: 4E3C3CC1031BA9C7
2 changed files with 129 additions and 120 deletions
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243
qemu/tcg/tcg.c
View file

@ -469,13 +469,6 @@ void tcg_func_start(TCGContext *s)
s->gen_next_op_idx = 1;
}
static inline int temp_idx(TCGContext *s, TCGTemp *ts)
{
ptrdiff_t n = ts - s->temps;
tcg_debug_assert(n >= 0 && n < s->nb_temps);
return n;
}
static inline TCGTemp *tcg_temp_alloc(TCGContext *s)
{
int n = s->nb_temps++;
@ -1674,56 +1667,71 @@ TCGOp *tcg_op_insert_after(TCGContext *s, TCGOp *old_op,
/* liveness analysis: end of function: all temps are dead, and globals
should be in memory. */
static inline void tcg_la_func_end(TCGContext *s, uint8_t *temp_state)
static inline void tcg_la_func_end(TCGContext *s)
{
memset(temp_state, TS_DEAD | TS_MEM, s->nb_globals);
memset(temp_state + s->nb_globals, TS_DEAD, s->nb_temps - s->nb_globals);
int ng = s->nb_globals;
int nt = s->nb_temps;
int i;
for (i = 0; i < ng; ++i) {
s->temps[i].state = TS_DEAD | TS_MEM;
}
for (i = ng; i < nt; ++i) {
s->temps[i].state = TS_DEAD;
}
}
/* liveness analysis: end of basic block: all temps are dead, globals
and local temps should be in memory. */
static inline void tcg_la_bb_end(TCGContext *s, uint8_t *temp_state)
static void tcg_la_bb_end(TCGContext *s)
{
int i, n;
int ng = s->nb_globals;
int nt = s->nb_temps;
int i;
tcg_la_func_end(s, temp_state);
for (i = s->nb_globals, n = s->nb_temps; i < n; i++) {
if (s->temps[i].temp_local) {
temp_state[i] |= TS_MEM;
}
for (i = 0; i < ng; ++i) {
s->temps[i].state = TS_DEAD | TS_MEM;
}
for (i = ng; i < nt; ++i) {
s->temps[i].state = (s->temps[i].temp_local
? TS_DEAD | TS_MEM
: TS_DEAD);
}
}
/*
Unicorn: for brcond, we should refresh liveness states for TCG globals
*/
static inline void tcg_la_br_end(TCGContext *s, uint8_t *temp_state)
static inline void tcg_la_br_end(TCGContext *s)
{
int ng = s->nb_globals;
int nt = s->nb_temps;
int i;
for (i = 0; i < s->nb_globals; i++) {
temp_state[i] |= TS_MEM;
for (i = 0; i < ng; i++) {
s->temps[i].state = TS_MEM;
}
for(i = s->nb_globals; i < s->nb_temps; i++) {
temp_state[i] = s->temps[i].temp_local;
for(i = ng; i < nt; i++) {
s->temps[i].state = s->temps[i].temp_local;
}
}
/* Liveness analysis : update the opc_arg_life array to tell if a
given input arguments is dead. Instructions updating dead
temporaries are removed. */
static void liveness_pass_1(TCGContext *s, uint8_t *temp_state)
static void liveness_pass_1(TCGContext *s)
{
int nb_globals = s->nb_globals;
int oi, oi_prev;
tcg_la_func_end(s, temp_state);
tcg_la_func_end(s);
for (oi = s->gen_op_buf[0].prev; oi != 0; oi = oi_prev) {
int i, nb_iargs, nb_oargs;
TCGOpcode opc_new, opc_new2;
bool have_opc_new2;
TCGLifeData arg_life = 0;
TCGArg arg;
TCGTemp *arg_ts;
TCGOp * const op = &s->gen_op_buf[oi];
TCGOpcode opc = op->opc;
@ -1743,8 +1751,8 @@ static void liveness_pass_1(TCGContext *s, uint8_t *temp_state)
/* pure functions can be removed if their result is unused */
if (call_flags & TCG_CALL_NO_SIDE_EFFECTS) {
for (i = 0; i < nb_oargs; i++) {
arg = op->args[i];
if (temp_state[arg] != TS_DEAD) {
arg_ts = arg_temp(s, op->args[i]);
if (arg_ts->state != TS_DEAD) {
goto do_not_remove_call;
}
}
@ -1754,41 +1762,41 @@ static void liveness_pass_1(TCGContext *s, uint8_t *temp_state)
/* output args are dead */
for (i = 0; i < nb_oargs; i++) {
arg = op->args[i];
if (temp_state[arg] & TS_DEAD) {
arg_ts = arg_temp(s, op->args[i]);
if (arg_ts->state & TS_DEAD) {
arg_life |= DEAD_ARG << i;
}
if (temp_state[arg] & TS_MEM) {
if (arg_ts->state & TS_MEM) {
arg_life |= SYNC_ARG << i;
}
temp_state[arg] = TS_DEAD;
arg_ts->state = TS_DEAD;
}
if (!(call_flags & (TCG_CALL_NO_WRITE_GLOBALS |
TCG_CALL_NO_READ_GLOBALS))) {
/* globals should go back to memory */
memset(temp_state, TS_DEAD | TS_MEM, nb_globals);
for (i = 0; i < nb_globals; i++) {
s->temps[i].state = TS_DEAD | TS_MEM;
}
} else if (!(call_flags & TCG_CALL_NO_READ_GLOBALS)) {
/* globals should be synced to memory */
for (i = 0; i < nb_globals; i++) {
temp_state[i] |= TS_MEM;
s->temps[i].state |= TS_MEM;
}
}
/* record arguments that die in this helper */
for (i = nb_oargs; i < nb_iargs + nb_oargs; i++) {
arg = op->args[i];
if (arg != TCG_CALL_DUMMY_ARG) {
if (temp_state[arg] & TS_DEAD) {
arg_life |= DEAD_ARG << i;
}
arg_ts = arg_temp(s, op->args[i]);
if (arg_ts && arg_ts->state & TS_DEAD) {
arg_life |= DEAD_ARG << i;
}
}
/* input arguments are live for preceding opcodes */
for (i = nb_oargs; i < nb_iargs + nb_oargs; i++) {
arg = op->args[i];
if (arg != TCG_CALL_DUMMY_ARG) {
temp_state[arg] &= ~TS_DEAD;
arg_ts = arg_temp(s, op->args[i]);
if (arg_ts) {
arg_ts->state &= ~TS_DEAD;
}
}
}
@ -1798,7 +1806,7 @@ static void liveness_pass_1(TCGContext *s, uint8_t *temp_state)
break;
case INDEX_op_discard:
/* mark the temporary as dead */
temp_state[op->args[0]] = TS_DEAD;
arg_temp(s, op->args[0])->state = TS_DEAD;
break;
case INDEX_op_add2_i32:
@ -1819,8 +1827,8 @@ static void liveness_pass_1(TCGContext *s, uint8_t *temp_state)
the low part. The result can be optimized to a simple
add or sub. This happens often for x86_64 guest when the
cpu mode is set to 32 bit. */
if (temp_state[op->args[1]] == TS_DEAD) {
if (temp_state[op->args[0]] == TS_DEAD) {
if (arg_temp(s, op->args[1])->state == TS_DEAD) {
if (arg_temp(s, op->args[0])->state == TS_DEAD) {
goto do_remove;
}
/* Replace the opcode and adjust the args in place,
@ -1857,8 +1865,8 @@ static void liveness_pass_1(TCGContext *s, uint8_t *temp_state)
do_mul2:
nb_iargs = 2;
nb_oargs = 2;
if (temp_state[op->args[1]] == TS_DEAD) {
if (temp_state[op->args[0]] == TS_DEAD) {
if (arg_temp(s, op->args[1])->state == TS_DEAD) {
if (arg_temp(s, op->args[0])->state == TS_DEAD) {
/* Both parts of the operation are dead. */
goto do_remove;
}
@ -1866,7 +1874,7 @@ static void liveness_pass_1(TCGContext *s, uint8_t *temp_state)
op->opc = opc = opc_new;
op->args[1] = op->args[2];
op->args[2] = op->args[3];
} else if (temp_state[op->args[0]] == TS_DEAD && have_opc_new2) {
} else if (arg_temp(s, op->args[0])->state == TS_DEAD && have_opc_new2) {
/* The low part of the operation is dead; generate the high. */
op->opc = opc = opc_new2;
op->args[0] = op->args[1];
@ -1889,7 +1897,7 @@ static void liveness_pass_1(TCGContext *s, uint8_t *temp_state)
implies side effects */
if (!(def->flags & TCG_OPF_SIDE_EFFECTS) && nb_oargs != 0) {
for (i = 0; i < nb_oargs; i++) {
if (temp_state[op->args[i]] != TS_DEAD) {
if (arg_temp(s, op->args[i])->state != TS_DEAD) {
goto do_not_remove;
}
}
@ -1899,14 +1907,14 @@ static void liveness_pass_1(TCGContext *s, uint8_t *temp_state)
do_not_remove:
/* output args are dead */
for (i = 0; i < nb_oargs; i++) {
arg = op->args[i];
if (temp_state[arg] & TS_DEAD) {
arg_ts = arg_temp(s, op->args[i]);
if (arg_ts->state & TS_DEAD) {
arg_life |= DEAD_ARG << i;
}
if (temp_state[arg] & TS_MEM) {
if (arg_ts->state & TS_MEM) {
arg_life |= SYNC_ARG << i;
}
temp_state[arg] = TS_DEAD;
arg_ts->state = TS_DEAD;
}
/* if end of basic block, update */
@ -1916,32 +1924,32 @@ static void liveness_pass_1(TCGContext *s, uint8_t *temp_state)
// brcond instruction in the middle of the TB,
// which incorrectly flags end-of-block
if (opc != INDEX_op_brcond_i32) {
tcg_la_bb_end(s, temp_state);
tcg_la_bb_end(s);
} else {
// Unicorn: we do not touch dead temps for brcond,
// but we should refresh TCG globals In-Memory states,
// otherwise, important CPU states(especially conditional flags) might be forgotten,
// result in wrongly generated host code that run into wrong branch.
// Refer to https://github.com/unicorn-engine/unicorn/issues/287 for further information
tcg_la_br_end(s, temp_state);
tcg_la_br_end(s);
}
} else if (def->flags & TCG_OPF_SIDE_EFFECTS) {
/* globals should be synced to memory */
for (i = 0; i < nb_globals; i++) {
temp_state[i] |= TS_MEM;
s->temps[i].state |= TS_MEM;
}
}
/* record arguments that die in this opcode */
for (i = nb_oargs; i < nb_oargs + nb_iargs; i++) {
arg = op->args[i];
if (temp_state[arg] & TS_DEAD) {
arg_ts = arg_temp(s, op->args[i]);
if (arg_ts->state & TS_DEAD) {
arg_life |= DEAD_ARG << i;
}
}
/* input arguments are live for preceding opcodes */
for (i = nb_oargs; i < nb_oargs + nb_iargs; i++) {
temp_state[op->args[i]] &= ~TS_DEAD;
arg_temp(s, op->args[i])->state &= ~TS_DEAD;
}
}
break;
@ -1951,16 +1959,12 @@ static void liveness_pass_1(TCGContext *s, uint8_t *temp_state)
}
/* Liveness analysis: Convert indirect regs to direct temporaries. */
static bool liveness_pass_2(TCGContext *s, uint8_t *temp_state)
static bool liveness_pass_2(TCGContext *s)
{
int nb_globals = s->nb_globals;
int16_t *dir_temps;
int i, oi, oi_next;
int nb_temps, i, oi, oi_next;
bool changes = false;
dir_temps = tcg_malloc(s, nb_globals * sizeof(int16_t));
memset(dir_temps, 0, nb_globals * sizeof(int16_t));
/* Create a temporary for each indirect global. */
for (i = 0; i < nb_globals; ++i) {
TCGTemp *its = &s->temps[i];
@ -1968,11 +1972,18 @@ static bool liveness_pass_2(TCGContext *s, uint8_t *temp_state)
TCGTemp *dts = tcg_temp_alloc(s);
dts->type = its->type;
dts->base_type = its->base_type;
dir_temps[i] = temp_idx(s, dts);
its->state_ptr = dts;
} else {
its->state_ptr = NULL;
}
/* All globals begin dead. */
its->state = TS_DEAD;
}
for (nb_temps = s->nb_temps; i < nb_temps; ++i) {
TCGTemp *its = &s->temps[i];
its->state_ptr = NULL;
its->state = TS_DEAD;
}
memset(temp_state, TS_DEAD, nb_globals);
for (oi = s->gen_op_buf[0].next; oi != 0; oi = oi_next) {
TCGOp *op = &s->gen_op_buf[oi];
@ -1980,7 +1991,7 @@ static bool liveness_pass_2(TCGContext *s, uint8_t *temp_state)
const TCGOpDef *def = &s->tcg_op_defs[opc];
TCGLifeData arg_life = op->life;
int nb_iargs, nb_oargs, call_flags;
TCGArg arg, dir;
TCGTemp *arg_ts, *dir_ts;
oi_next = op->next;
@ -2008,23 +2019,21 @@ static bool liveness_pass_2(TCGContext *s, uint8_t *temp_state)
/* Make sure that input arguments are available. */
for (i = nb_oargs; i < nb_iargs + nb_oargs; i++) {
arg = op->args[i];
/* Note this unsigned test catches TCG_CALL_ARG_DUMMY too. */
if (arg < nb_globals) {
dir = dir_temps[arg];
if (dir != 0 && temp_state[arg] == TS_DEAD) {
TCGTemp *its = arg_temp(s, arg);
TCGOpcode lopc = (its->type == TCG_TYPE_I32
arg_ts = arg_temp(s, op->args[i]);
if (arg_ts) {
dir_ts = arg_ts->state_ptr;
if (dir_ts && arg_ts->state == TS_DEAD) {
TCGOpcode lopc = (arg_ts->type == TCG_TYPE_I32
? INDEX_op_ld_i32
: INDEX_op_ld_i64);
TCGOp *lop = tcg_op_insert_before(s, op, lopc, 3);
lop->args[0] = dir;
lop->args[1] = temp_idx(s, its->mem_base);
lop->args[2] = its->mem_offset;
lop->args[0] = temp_arg(s, dir_ts);
lop->args[1] = temp_arg(s, arg_ts->mem_base);
lop->args[2] = arg_ts->mem_offset;
/* Loaded, but synced with memory. */
temp_state[arg] = TS_MEM;
arg_ts->state = TS_MEM;
}
}
}
@ -2033,14 +2042,14 @@ static bool liveness_pass_2(TCGContext *s, uint8_t *temp_state)
No action is required except keeping temp_state up to date
so that we reload when needed. */
for (i = nb_oargs; i < nb_iargs + nb_oargs; i++) {
arg = op->args[i];
if (arg < nb_globals) {
dir = dir_temps[arg];
if (dir != 0) {
op->args[i] = dir;
arg_ts = arg_temp(s, op->args[i]);
if (arg_ts) {
dir_ts = arg_ts->state_ptr;
if (dir_ts) {
op->args[i] = temp_arg(s, dir_ts);
changes = true;
if (IS_DEAD_ARG(i)) {
temp_state[arg] = TS_DEAD;
arg_ts->state = TS_DEAD;
}
}
}
@ -2054,51 +2063,49 @@ static bool liveness_pass_2(TCGContext *s, uint8_t *temp_state)
for (i = 0; i < nb_globals; ++i) {
/* Liveness should see that globals are synced back,
that is, either TS_DEAD or TS_MEM. */
tcg_debug_assert(dir_temps[i] == 0
|| temp_state[i] != 0);
arg_ts = &s->temps[i];
tcg_debug_assert(arg_ts->state_ptr == 0
|| arg_ts->state != 0);
}
} else {
for (i = 0; i < nb_globals; ++i) {
/* Liveness should see that globals are saved back,
that is, TS_DEAD, waiting to be reloaded. */
tcg_debug_assert(dir_temps[i] == 0
|| temp_state[i] == TS_DEAD);
arg_ts = &s->temps[i];
tcg_debug_assert(arg_ts->state_ptr == 0
|| arg_ts->state == TS_DEAD);
}
}
/* Outputs become available. */
for (i = 0; i < nb_oargs; i++) {
arg = op->args[i];
if (arg >= nb_globals) {
arg_ts = arg_temp(s, op->args[i]);
dir_ts = arg_ts->state_ptr;
if (!dir_ts) {
continue;
}
dir = dir_temps[arg];
if (dir == 0) {
continue;
}
op->args[i] = dir;
op->args[i] = temp_arg(s, dir_ts);
changes = true;
/* The output is now live and modified. */
temp_state[arg] = 0;
arg_ts->state = 0;
/* Sync outputs upon their last write. */
if (NEED_SYNC_ARG(i)) {
TCGTemp *its = arg_temp(s, arg);
TCGOpcode sopc = (its->type == TCG_TYPE_I32
TCGOpcode sopc = (arg_ts->type == TCG_TYPE_I32
? INDEX_op_st_i32
: INDEX_op_st_i64);
TCGOp *sop = tcg_op_insert_after(s, op, sopc, 3);
sop->args[0] = dir;
sop->args[1] = temp_idx(s, its->mem_base);
sop->args[2] = its->mem_offset;
sop->args[0] = temp_arg(s, dir_ts);
sop->args[1] = temp_arg(s, arg_ts->mem_base);
sop->args[2] = arg_ts->mem_offset;
temp_state[arg] = TS_MEM;
arg_ts->state = TS_MEM;
}
/* Drop outputs that are dead. */
if (IS_DEAD_ARG(i)) {
temp_state[arg] = TS_DEAD;
arg_ts->state = TS_DEAD;
}
}
}
@ -2860,25 +2867,21 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
s->la_time -= profile_getclock();
#endif
{
uint8_t *temp_state = tcg_malloc(s, s->nb_temps + s->nb_indirects);
liveness_pass_1(s);
liveness_pass_1(s, temp_state);
if (s->nb_indirects > 0) {
if (s->nb_indirects > 0) {
#ifdef DEBUG_DISAS
if (unlikely(qemu_loglevel_mask(CPU_LOG_TB_OP_IND)
&& qemu_log_in_addr_range(tb->pc))) {
qemu_log("OP before indirect lowering:\n");
tcg_dump_ops(s);
qemu_log("\n");
}
if (unlikely(qemu_loglevel_mask(CPU_LOG_TB_OP_IND)
&& qemu_log_in_addr_range(tb->pc))) {
qemu_log("OP before indirect lowering:\n");
tcg_dump_ops(s);
qemu_log("\n");
}
#endif
/* Replace indirect temps with direct temps. */
if (liveness_pass_2(s, temp_state)) {
/* If changes were made, re-run liveness. */
liveness_pass_1(s, temp_state);
}
/* Replace indirect temps with direct temps. */
if (liveness_pass_2(s)) {
/* If changes were made, re-run liveness. */
liveness_pass_1(s);
}
}

6
qemu/tcg/tcg.h
View file

@ -595,6 +595,12 @@ typedef struct TCGTemp {
intptr_t mem_offset;
struct TCGTemp *mem_base;
const char *name;
/* Pass-specific information that can be stored for a temporary.
One word worth of integer data, and one pointer to data
allocated separately. */
uintptr_t state;
void *state_ptr;
} TCGTemp;
typedef struct TCGContext TCGContext;