On 26/04/2017 12:29, Alex Bennée wrote:
>
> Emilio G. Cota <c...@braap.org> writes:
>
>> This paves the way for upcoming work.
>>
>> Reviewed-by: Richard Henderson <r...@twiddle.net>
>> Signed-off-by: Emilio G. Cota <c...@braap.org>
>> ---
>> tcg-runtime.c | 21 +++++++++++++++++++++
>> tcg/tcg-runtime.h | 2 ++
>> tcg/tcg.h | 1 +
>> 3 files changed, 24 insertions(+)
>>
>> diff --git a/tcg-runtime.c b/tcg-runtime.c
>> index 4c60c96..90d2d4b 100644
>> --- a/tcg-runtime.c
>> +++ b/tcg-runtime.c
>> @@ -27,6 +27,7 @@
>> #include "exec/helper-proto.h"
>> #include "exec/cpu_ldst.h"
>> #include "exec/exec-all.h"
>> +#include "exec/tb-hash.h"
>>
>> /* 32-bit helpers */
>>
>> @@ -141,6 +142,26 @@ uint64_t HELPER(ctpop_i64)(uint64_t arg)
>> return ctpop64(arg);
>> }
>>
>> +void *HELPER(lookup_tb_ptr)(CPUArchState *env, target_ulong addr)
>> +{
>> + CPUState *cpu = ENV_GET_CPU(env);
>> + TranslationBlock *tb;
>> + target_ulong cs_base, pc;
>> + uint32_t flags;
>> +
>> + if (unlikely(atomic_read(&cpu->exit_request))) {
>> + goto out_epilogue;
>> + }
>> + cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags);
>> + tb = atomic_rcu_read(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(addr)]);
>> + if (likely(tb && tb->pc == addr && tb->cs_base == cs_base &&
>> + tb->flags == flags)) {
>
> Should we also not be checking the TB hasn't been invalidated: tb->invalid?
It's not needed because this lookup is (if I understand it right) once
only and is not reused later. This is why tb_find doesn't check
tb->invalid, but uses it to avoid adding the TB to the chain.
Good:
tb_find tb_phys_invalidate
tb_lock
tb->invalid = true
lookup cache
cache hit
tb_unlock
tb_lock
tb->invalid?
yes, skip tb_add_jump
tb_unlock
execute tb once
Bad (doesn't happen):
tb_find tb_phys_invalidate
tb_lock
tb->invalid = true
lookup cache
cache hit
tb_unlock
tb_lock
tb_add_jump
tb_unlock
execute tb many times
Paolo
>> + return tb->tc_ptr;
>> + }
>> + out_epilogue:
>> + return tcg_ctx.code_gen_epilogue;
>> +}
>> +
>> void HELPER(exit_atomic)(CPUArchState *env)
>> {
>> cpu_loop_exit_atomic(ENV_GET_CPU(env), GETPC());
>> diff --git a/tcg/tcg-runtime.h b/tcg/tcg-runtime.h
>> index 114ea6f..c41d38a 100644
>> --- a/tcg/tcg-runtime.h
>> +++ b/tcg/tcg-runtime.h
>> @@ -24,6 +24,8 @@ DEF_HELPER_FLAGS_1(clrsb_i64, TCG_CALL_NO_RWG_SE, i64, i64)
>> DEF_HELPER_FLAGS_1(ctpop_i32, TCG_CALL_NO_RWG_SE, i32, i32)
>> DEF_HELPER_FLAGS_1(ctpop_i64, TCG_CALL_NO_RWG_SE, i64, i64)
>>
>> +DEF_HELPER_FLAGS_2(lookup_tb_ptr, TCG_CALL_NO_WG_SE, ptr, env, tl)
>> +
>> DEF_HELPER_FLAGS_1(exit_atomic, TCG_CALL_NO_WG, noreturn, env)
>>
>> #ifdef CONFIG_SOFTMMU
>> diff --git a/tcg/tcg.h b/tcg/tcg.h
>> index 6c216bb..5ec48d1 100644
>> --- a/tcg/tcg.h
>> +++ b/tcg/tcg.h
>> @@ -699,6 +699,7 @@ struct TCGContext {
>> extension that allows arithmetic on void*. */
>> int code_gen_max_blocks;
>> void *code_gen_prologue;
>> + void *code_gen_epilogue;
>> void *code_gen_buffer;
>> size_t code_gen_buffer_size;
>> void *code_gen_ptr;
>
>
> --
> Alex Bennée
>
