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Re: [Qemu-devel] [PATCH 8/8] tcg: Clean up tb_jmp_unlink()
From: |
Alex Bennée |
Subject: |
Re: [Qemu-devel] [PATCH 8/8] tcg: Clean up tb_jmp_unlink() |
Date: |
Thu, 24 Mar 2016 15:36:14 +0000 |
User-agent: |
mu4e 0.9.17; emacs 25.0.92.7 |
address@hidden writes:
> From: Sergey Fedorov <address@hidden>
>
> Unify the code of this function with tb_jmp_remove_from_list(). Making
> these functions similar improves their readability. Also this could be a
> step towards making this function thread-safe.
>
> Signed-off-by: Sergey Fedorov <address@hidden>
> Signed-off-by: Sergey Fedorov <address@hidden>
> ---
> translate-all.c | 20 ++++++++------------
> 1 file changed, 8 insertions(+), 12 deletions(-)
>
> diff --git a/translate-all.c b/translate-all.c
> index 8b4bfa713bf7..56c77a72773d 100644
> --- a/translate-all.c
> +++ b/translate-all.c
> @@ -962,25 +962,21 @@ static inline void tb_reset_jump(TranslationBlock *tb,
> int n)
> /* remove any jumps to the TB */
> static inline void tb_jmp_unlink(TranslationBlock *tb)
> {
> - uintptr_t tb1, tb2;
> + TranslationBlock *tb1;
> + uintptr_t *ptb;
> unsigned int n1;
>
> - tb1 = tb->jmp_list_first;
> + ptb = &tb->jmp_list_first;
> for (;;) {
> - TranslationBlock *tmp_tb;
> - n1 = tb1 & 3;
> + n1 = *ptb & 3;
> + tb1 = (TranslationBlock *)(*ptb & ~3);
I would hope the compiler saw through the duplicate indirect accesses
but maybe:
uintptr_t *ptb, ntb;
and
ntb = *ptb;
n1 = ntb & 3;
tb1 = (TranslationBlock *)(ntb & ~3);
would be clearer?
> if (n1 == 2) {
> break;
> }
> - tmp_tb = (TranslationBlock *)(tb1 & ~3);
> - tb2 = tmp_tb->jmp_list_next[n1];
> - tb_reset_jump(tmp_tb, n1);
> - tmp_tb->jmp_list_next[n1] = (uintptr_t)NULL;
> - tb1 = tb2;
> + tb_reset_jump(tb1, n1);
> + *ptb = tb1->jmp_list_next[n1];
> + tb1->jmp_list_next[n1] = (uintptr_t)NULL;
> }
> -
> - assert(((uintptr_t)tb & 3) == 0);
> - tb->jmp_list_first = (uintptr_t)tb | 2; /* fail safe */
> }
>
> /* invalidate one TB */
Otherwise:
Reviewed-by: Alex Bennée <address@hidden>
--
Alex Bennée
[Qemu-devel] [PATCH 7/8] tcg: Extract removing of jumps to TB from tb_phys_invalidate(), sergey . fedorov, 2016/03/24
Re: [Qemu-devel] [PATCH 0/8] tcg: Direct block chaining clean-up, Paolo Bonzini, 2016/03/24