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tcg: Drop gen_io_end()

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Now we have removed all the uses of gen_io_end() from target frontends,
the only callsite is inside gen_tb_start(). Inline the code there,
and remove the reference to it from the documentation.

While we are inlining the code, switch it to use tcg_constant_i32()
so we don't have to manually create and destroy a TCG temporary.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210724134902.7785-3-peter.maydell@linaro.org>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
This commit is contained in:
Peter Maydell 2021-07-24 14:49:02 +01:00 committed by Mark Cave-Ayland
parent b5328172a9
commit f383eb80f6
2 changed files with 10 additions and 20 deletions
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3
docs/devel/tcg-icount.rst
View File

@ -92,6 +92,3 @@ When the translator is handling an instruction of this kind:
} }
* it must end the TB immediately after this instruction * it must end the TB immediately after this instruction
Note that some older front-ends call a "gen_io_end()" function:
this is obsolete and should not be used.

27
include/exec/gen-icount.h
View File

@ -17,22 +17,6 @@ static inline void gen_io_start(void)
tcg_temp_free_i32(tmp); tcg_temp_free_i32(tmp);
} }
/*
* cpu->can_do_io is cleared automatically 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. Therefore, backends only need to call
* gen_io_start.
*/
static inline void gen_io_end(void)
{
TCGv_i32 tmp = tcg_const_i32(0);
tcg_gen_st_i32(tmp, cpu_env,
offsetof(ArchCPU, parent_obj.can_do_io) -
offsetof(ArchCPU, env));
tcg_temp_free_i32(tmp);
}
static inline void gen_tb_start(const TranslationBlock *tb) static inline void gen_tb_start(const TranslationBlock *tb)
{ {
TCGv_i32 count; TCGv_i32 count;
@ -64,7 +48,16 @@ static inline void gen_tb_start(const TranslationBlock *tb)
tcg_gen_st16_i32(count, cpu_env, tcg_gen_st16_i32(count, cpu_env,
offsetof(ArchCPU, neg.icount_decr.u16.low) - offsetof(ArchCPU, neg.icount_decr.u16.low) -
offsetof(ArchCPU, env)); offsetof(ArchCPU, env));
gen_io_end(); /*
* 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().
*/
tcg_gen_st_i32(tcg_constant_i32(0), cpu_env,
offsetof(ArchCPU, parent_obj.can_do_io) -
offsetof(ArchCPU, env));
} }
tcg_temp_free_i32(count); tcg_temp_free_i32(count);