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accel/tcg: Track current value of can_do_io in the TB

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Simplify translator_io_start by recording the current
known value of can_do_io within DisasContextBase.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2023-09-14 08:06:14 -07:00
parent 5d97e94638
commit 0ca41ccf1c
2 changed files with 16 additions and 17 deletions
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31
accel/tcg/translator.c
View File

@ -16,11 +16,14 @@
#include "tcg/tcg-op-common.h"
#include "internal.h"
static void gen_io_start(void)
static void set_can_do_io(DisasContextBase *db, bool val)
{
tcg_gen_st_i32(tcg_constant_i32(1), cpu_env,
offsetof(ArchCPU, parent_obj.can_do_io) -
offsetof(ArchCPU, env));
if (db->saved_can_do_io != val) {
db->saved_can_do_io = val;
tcg_gen_st_i32(tcg_constant_i32(val), cpu_env,
offsetof(ArchCPU, parent_obj.can_do_io) -
offsetof(ArchCPU, env));
}
}
bool translator_io_start(DisasContextBase *db)
@ -30,12 +33,8 @@ bool translator_io_start(DisasContextBase *db)
if (!(cflags & CF_USE_ICOUNT)) {
return false;
}
if (db->num_insns == db->max_insns && (cflags & CF_LAST_IO)) {
/* Already started in translator_loop. */
return true;
}
gen_io_start();
set_can_do_io(db, true);
/*
* Ensure that this instruction will be the last in the TB.
@ -47,7 +46,7 @@ bool translator_io_start(DisasContextBase *db)
return true;
}
static TCGOp *gen_tb_start(uint32_t cflags)
static TCGOp *gen_tb_start(DisasContextBase *db, uint32_t cflags)
{
TCGv_i32 count = NULL;
TCGOp *icount_start_insn = NULL;
@ -91,12 +90,9 @@ static TCGOp *gen_tb_start(uint32_t cflags)
* cpu->can_do_io is cleared automatically here at the beginning of
* each translation block. The cost is minimal and only paid for
* -icount, plus it would be very easy to forget doing it in the
* translator. Doing it here means we don't need a gen_io_end() to
* go with gen_io_start().
* translator.
*/
tcg_gen_st_i32(tcg_constant_i32(0), cpu_env,
offsetof(ArchCPU, parent_obj.can_do_io) -
offsetof(ArchCPU, env));
set_can_do_io(db, false);
}
return icount_start_insn;
@ -147,6 +143,7 @@ void translator_loop(CPUState *cpu, TranslationBlock *tb, int *max_insns,
db->num_insns = 0;
db->max_insns = *max_insns;
db->singlestep_enabled = cflags & CF_SINGLE_STEP;
db->saved_can_do_io = -1;
db->host_addr[0] = host_pc;
db->host_addr[1] = NULL;
@ -154,7 +151,7 @@ void translator_loop(CPUState *cpu, TranslationBlock *tb, int *max_insns,
tcg_debug_assert(db->is_jmp == DISAS_NEXT); /* no early exit */
/* Start translating. */
icount_start_insn = gen_tb_start(cflags);
icount_start_insn = gen_tb_start(db, cflags);
ops->tb_start(db, cpu);
tcg_debug_assert(db->is_jmp == DISAS_NEXT); /* no early exit */
@ -181,7 +178,7 @@ void translator_loop(CPUState *cpu, TranslationBlock *tb, int *max_insns,
the next instruction. */
if (db->num_insns == db->max_insns && (cflags & CF_LAST_IO)) {
/* Accept I/O on the last instruction. */
gen_io_start();
set_can_do_io(db, true);
}
ops->translate_insn(db, cpu);

2
include/exec/translator.h
View File

@ -72,6 +72,7 @@ typedef enum DisasJumpType {
* @num_insns: Number of translated instructions (including current).
* @max_insns: Maximum number of instructions to be translated in this TB.
* @singlestep_enabled: "Hardware" single stepping enabled.
* @saved_can_do_io: Known value of cpu->neg.can_do_io, or -1 for unknown.
*
* Architecture-agnostic disassembly context.
*/
@ -83,6 +84,7 @@ typedef struct DisasContextBase {
int num_insns;
int max_insns;
bool singlestep_enabled;
int8_t saved_can_do_io;
void *host_addr[2];
} DisasContextBase;