From: Richard Henderson <richard.henderson@linaro.org>
To: Nicholas Piggin <npiggin@gmail.com>, qemu-ppc@nongnu.org
Cc: qemu-devel@nongnu.org
Subject: Re: [RFC PATCH 2/4] tcg/ppc: ST_ST memory ordering is not provided with eieio
Date: Tue, 3 May 2022 08:01:44 -0700 [thread overview]
Message-ID: <e22f73a0-4763-e256-3f06-33ca858f8fe1@linaro.org> (raw)
In-Reply-To: <20220503103334.2046414-2-npiggin@gmail.com>
On 5/3/22 03:33, Nicholas Piggin wrote:
> eieio does not provide ordering between stores to CI memory and stores
> to cacheable memory so it can't be used as a general ST_ST barrier.
>
> Signed-of-by: Nicholas Piggin <npiggin@gmail.com>
> ---
> tcg/ppc/tcg-target.c.inc | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/tcg/ppc/tcg-target.c.inc b/tcg/ppc/tcg-target.c.inc
> index cfcd121f9c..3ff845d063 100644
> --- a/tcg/ppc/tcg-target.c.inc
> +++ b/tcg/ppc/tcg-target.c.inc
> @@ -1836,8 +1836,6 @@ static void tcg_out_mb(TCGContext *s, TCGArg a0)
> a0 &= TCG_MO_ALL;
> if (a0 == TCG_MO_LD_LD) {
> insn = LWSYNC;
> - } else if (a0 == TCG_MO_ST_ST) {
> - insn = EIEIO;
> }
> tcg_out32(s, insn);
> }
Certainly matches the comment from patch 1.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
r~
next prev parent reply other threads:[~2022-05-03 15:03 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-03 10:33 [RFC PATCH 1/4] target/ppc: Fix eieio memory ordering semantics Nicholas Piggin
2022-05-03 10:33 ` [RFC PATCH 2/4] tcg/ppc: ST_ST memory ordering is not provided with eieio Nicholas Piggin
2022-05-03 15:01 ` Richard Henderson [this message]
2022-05-03 10:33 ` [RFC PATCH 3/4] tcg/ppc: Optimize memory ordering generation with lwsync Nicholas Piggin
2022-05-03 14:53 ` Richard Henderson
2022-05-03 10:33 ` [RFC PATCH 4/4] target/ppc: Implement lwsync with weaker memory ordering Nicholas Piggin
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