Commit a0522c7a authored by Sergey Fedorov's avatar Sergey Fedorov Committed by Richard Henderson
Browse files

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: default avatarAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: default avatarSergey Fedorov <serge.fdrv@gmail.com>
Signed-off-by: default avatarSergey Fedorov <sergey.fedorov@linaro.org>
Signed-off-by: default avatarRichard Henderson <rth@twiddle.net>
[rth: Fixed rebase typo in nochain test.]
parent 6f789be5

cpu-exec.c

+19 −16
Original line number Diff line number Diff line
@@ -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);