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tcg: Compress liveness data to 16 bits

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This reduces both memory usage and per-insn cacheline usage
during code generation.

Backports commit a1b3c48d2b23d6eaeb4529d3e1183d2648731bf8 from qemu
This commit is contained in:
Richard Henderson 2018-02-25 21:27:00 -05:00 committed by Lioncash
parent 30cbcafc05
commit b2e6e351c2
No known key found for this signature in database
GPG key ID: 4E3C3CC1031BA9C7
2 changed files with 30 additions and 40 deletions
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56
qemu/tcg/tcg.c
View file

@ -1401,7 +1401,7 @@ static inline void tcg_la_br_end(TCGContext *s, uint8_t *mem_temps)
}
}
/* Liveness analysis : update the opc_dead_args array to tell if a
/* 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 tcg_liveness_analysis(TCGContext *s)
@ -1411,8 +1411,7 @@ static void tcg_liveness_analysis(TCGContext *s)
nb_ops = s->gen_next_op_idx;
s->op_dead_args = tcg_malloc(s, nb_ops * sizeof(uint16_t));
s->op_sync_args = tcg_malloc(s, nb_ops * sizeof(uint8_t));
s->op_arg_life = tcg_malloc(s, nb_ops * sizeof(TCGLifeData));
dead_temps = tcg_malloc(s, s->nb_temps);
mem_temps = tcg_malloc(s, s->nb_temps);
@ -1422,8 +1421,7 @@ static void tcg_liveness_analysis(TCGContext *s)
int i, nb_iargs, nb_oargs;
TCGOpcode opc_new, opc_new2;
bool have_opc_new2;
uint16_t dead_args;
uint8_t sync_args;
TCGLifeData arg_life = 0;
TCGArg arg;
TCGOp * const op = &s->gen_op_buf[oi];
@ -1455,15 +1453,13 @@ static void tcg_liveness_analysis(TCGContext *s)
do_not_remove_call:
/* output args are dead */
dead_args = 0;
sync_args = 0;
for (i = 0; i < nb_oargs; i++) {
arg = args[i];
if (dead_temps[arg]) {
dead_args |= (1 << i);
arg_life |= DEAD_ARG << i;
}
if (mem_temps[arg]) {
sync_args |= (1 << i);
arg_life |= SYNC_ARG << i;
}
dead_temps[arg] = 1;
mem_temps[arg] = 0;
@ -1484,13 +1480,11 @@ static void tcg_liveness_analysis(TCGContext *s)
arg = args[i];
if (arg != TCG_CALL_DUMMY_ARG) {
if (dead_temps[arg]) {
dead_args |= (1 << i);
arg_life |= DEAD_ARG << i;
}
dead_temps[arg] = 0;
}
}
s->op_dead_args[oi] = dead_args;
s->op_sync_args[oi] = sync_args;
}
}
break;
@ -1601,15 +1595,13 @@ static void tcg_liveness_analysis(TCGContext *s)
} else {
do_not_remove:
/* output args are dead */
dead_args = 0;
sync_args = 0;
for (i = 0; i < nb_oargs; i++) {
arg = args[i];
if (dead_temps[arg]) {
dead_args |= (1 << i);
arg_life |= DEAD_ARG << i;
}
if (mem_temps[arg]) {
sync_args |= (1 << i);
arg_life |= SYNC_ARG << i;
}
dead_temps[arg] = 1;
mem_temps[arg] = 0;
@ -1639,15 +1631,14 @@ static void tcg_liveness_analysis(TCGContext *s)
for (i = nb_oargs; i < nb_oargs + nb_iargs; i++) {
arg = args[i];
if (dead_temps[arg]) {
dead_args |= (1 << i);
arg_life |= DEAD_ARG << i;
}
dead_temps[arg] = 0;
}
s->op_dead_args[oi] = dead_args;
s->op_sync_args[oi] = sync_args;
}
break;
}
s->op_arg_life[oi] = arg_life;
}
}
#else
@ -1986,11 +1977,11 @@ static void tcg_reg_alloc_bb_end(TCGContext *s, TCGRegSet allocated_regs)
save_globals(s, allocated_regs);
}
#define IS_DEAD_ARG(n) ((dead_args >> (n)) & 1)
#define NEED_SYNC_ARG(n) ((sync_args >> (n)) & 1)
#define IS_DEAD_ARG(n) (arg_life & (DEAD_ARG << (n)))
#define NEED_SYNC_ARG(n) (arg_life & (SYNC_ARG << (n)))
static void tcg_reg_alloc_movi(TCGContext *s, const TCGArg *args,
uint16_t dead_args, uint8_t sync_args)
TCGLifeData arg_life)
{
TCGTemp *ots;
tcg_target_ulong val;
@ -2018,8 +2009,7 @@ static void tcg_reg_alloc_movi(TCGContext *s, const TCGArg *args,
}
static void tcg_reg_alloc_mov(TCGContext *s, const TCGOpDef *def,
const TCGArg *args, uint16_t dead_args,
uint8_t sync_args)
const TCGArg *args, TCGLifeData arg_life)
{
TCGRegSet allocated_regs;
TCGTemp *ts, *ots;
@ -2101,8 +2091,7 @@ static void tcg_reg_alloc_mov(TCGContext *s, const TCGOpDef *def,
static void tcg_reg_alloc_op(TCGContext *s,
const TCGOpDef *def, TCGOpcode opc,
const TCGArg *args, uint16_t dead_args,
uint8_t sync_args)
const TCGArg *args, TCGLifeData arg_life)
{
TCGRegSet allocated_regs;
int i, k, nb_iargs, nb_oargs;
@ -2258,8 +2247,7 @@ static void tcg_reg_alloc_op(TCGContext *s,
#endif
static void tcg_reg_alloc_call(TCGContext *s, int nb_oargs, int nb_iargs,
const TCGArg * const args, uint16_t dead_args,
uint8_t sync_args)
const TCGArg * const args, TCGLifeData arg_life)
{
int flags, nb_regs, i;
TCGReg reg;
@ -2475,8 +2463,7 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
TCGArg * const args = &s->gen_opparam_buf[op->args];
TCGOpcode opc = op->opc;
const TCGOpDef *def = &s->tcg_op_defs[opc];
uint16_t dead_args = s->op_dead_args[oi];
uint8_t sync_args = s->op_sync_args[oi];
TCGLifeData arg_life = s->op_arg_life[oi];
oi_next = op->next;
#ifdef CONFIG_PROFILER
@ -2485,11 +2472,11 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
switch (opc) {
case INDEX_op_mov_i32:
case INDEX_op_mov_i64:
tcg_reg_alloc_mov(s, def, args, dead_args, sync_args);
tcg_reg_alloc_mov(s, def, args, arg_life);
break;
case INDEX_op_movi_i32:
case INDEX_op_movi_i64:
tcg_reg_alloc_movi(s, args, dead_args, sync_args);
tcg_reg_alloc_movi(s, args, arg_life);
break;
case INDEX_op_insn_start:
if (num_insns >= 0) {
@ -2514,8 +2501,7 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
tcg_out_label(s, arg_label(s, args[0]), s->code_ptr);
break;
case INDEX_op_call:
tcg_reg_alloc_call(s, op->callo, op->calli, args,
dead_args, sync_args);
tcg_reg_alloc_call(s, op->callo, op->calli, args, arg_life);
break;
default:
/* Sanity check that we've not introduced any unhandled opcodes. */
@ -2525,7 +2511,7 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
/* Note: in order to speed up the code, it would be much
faster to have specialized register allocator functions for
some common argument patterns */
tcg_reg_alloc_op(s, def, opc, args, dead_args, sync_args);
tcg_reg_alloc_op(s, def, opc, args, arg_life);
break;
}
#ifdef CONFIG_DEBUG_TCG

14
qemu/tcg/tcg.h
View file

@ -577,6 +577,14 @@ typedef struct TCGTempSet {
unsigned long l[BITS_TO_LONGS(TCG_MAX_TEMPS)];
} TCGTempSet;
/* While we limit helpers to 6 arguments, for 32-bit hosts, with padding,
this imples a max of 6*2 (64-bit in) + 2 (64-bit out) = 14 operands.
There are never more than 2 outputs, which means that we can store all
dead + sync data within 16 bits. */
#define DEAD_ARG 4
#define SYNC_ARG 1
typedef uint16_t TCGLifeData;
typedef struct TCGOp {
TCGOpcode opc : 8;
@ -735,11 +743,7 @@ struct TCGContext {
uintptr_t *tb_jmp_target_addr; /* tb->jmp_target_addr if !USE_DIRECT_JUMP */
/* liveness analysis */
uint16_t *op_dead_args; /* for each operation, each bit tells if the
corresponding argument is dead */
uint8_t *op_sync_args; /* for each operation, each bit tells if the
corresponding output argument needs to be
sync to memory. */
TCGLifeData *op_arg_life;
TCGRegSet reserved_regs;
intptr_t current_frame_offset;