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cpu-exec: Move TB chaining into tb_find_fast() 

Move tb_add_jump() call and surrounding code from cpu_exec() into
tb_find_fast(). That simplifies cpu_exec() a little by hiding the direct
chaining optimization details into tb_find_fast(). It also allows to
move tb_lock()/tb_unlock() pair into tb_find_fast(), putting it closer
to tb_find_slow() which also manipulates the lock.

Suggested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sergey Fedorov <serge.fdrv@gmail.com>
Signed-off-by: Sergey Fedorov <sergey.fedorov@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
[rth: Fixed rebase typo in nochain test.]
This commit is contained in:
Sergey Fedorov 2016-04-25 18:17:30 +03:00 committed by Richard Henderson
parent 6f789be56d
commit a0522c7a55
1 changed files with 19 additions and 16 deletions
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35
cpu-exec.c
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@ -320,7 +320,9 @@ found:
return tb;
}
static inline TranslationBlock *tb_find_fast(CPUState *cpu)
static inline TranslationBlock *tb_find_fast(CPUState *cpu,
TranslationBlock **last_tb,
int tb_exit)
{
CPUArchState *env = (CPUArchState *)cpu->env_ptr;
TranslationBlock *tb;
@ -331,11 +333,24 @@ static inline TranslationBlock *tb_find_fast(CPUState *cpu)
always be the same before a given translated block
is executed. */
cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags);
tb_lock();
tb = cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)];
if (unlikely(!tb || tb->pc != pc || tb->cs_base != cs_base ||
tb->flags != flags)) {
tb = tb_find_slow(cpu, pc, cs_base, flags);
}
if (cpu->tb_flushed) {
/* Ensure that no TB jump will be modified as the
* translation buffer has been flushed.
*/
*last_tb = NULL;
cpu->tb_flushed = false;
}
/* See if we can patch the calling TB. */
if (*last_tb && !qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) {
tb_add_jump(*last_tb, tb_exit, tb);
}
tb_unlock();
return tb;
}
@ -441,7 +456,8 @@ int cpu_exec(CPUState *cpu)
} else if (replay_has_exception()
&& cpu->icount_decr.u16.low + cpu->icount_extra == 0) {
/* try to cause an exception pending in the log */
cpu_exec_nocache(cpu, 1, tb_find_fast(cpu), true);
last_tb = NULL; /* Avoid chaining TBs */
cpu_exec_nocache(cpu, 1, tb_find_fast(cpu, &last_tb, 0), true);
ret = -1;
break;
#endif
@ -511,20 +527,7 @@ int cpu_exec(CPUState *cpu)
cpu->exception_index = EXCP_INTERRUPT;
cpu_loop_exit(cpu);
}
tb_lock();
tb = tb_find_fast(cpu);
if (cpu->tb_flushed) {
/* Ensure that no TB jump will be modified as the
* translation buffer has been flushed.
*/
last_tb = NULL;
cpu->tb_flushed = false;
}
/* See if we can patch the calling TB. */
if (last_tb && !qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) {
tb_add_jump(last_tb, tb_exit, tb);
}
tb_unlock();
tb = tb_find_fast(cpu, &last_tb, tb_exit);
if (likely(!cpu->exit_request)) {
uintptr_t ret;
trace_exec_tb(tb, tb->pc);