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From: Richard Henderson <richard.henderson@linaro.org>
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Date: Mon, 26 Nov 2018 11:19:11 -0800
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Subject: Re: [Qemu-devel] [RFC 23/48] translator: add plugin_insn argument
 to translate_insn
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To: =?UTF-8?Q?Alex_Benn=c3=a9e?= <alex.bennee@linaro.org>
Cc: "Emilio G. Cota" <cota@braap.org>, Stefan Hajnoczi <stefanha@gmail.com>, Peter Maydell <peter.maydell@linaro.org>, qemu-devel@nongnu.org, Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>, =?UTF-8?Q?Llu=c3=ads_Vilanova?= <vilanova@ac.upc.edu>

On 11/26/18 10:56 AM, Alex Bennée wrote:
> 
> 
> On Mon, 26 Nov 2018, 18:27 Richard Henderson <richard.henderson@linaro.org
> <mailto:richard.henderson@linaro.org> wrote:
> 
>     On 11/26/18 6:52 AM, Alex Bennée wrote:
>     > I'm not convinced this is the best way to go about it. We end up having
>     > to sprinkle the plugin calls into each decoder rather than keeping all
>     > the infrastructure in the common main loop. However the common loop will
>     > need to know the total number of bytes decoded so we could change the
>     > declaration to:
>     >
>     >   int (*translate_insn)(DisasContextBase *db, CPUState *cpu);
>     >
>     > and return the number of bytes decoded.
> 
>     Returning the number of bytes is more difficult than simply just
> 
>         old_pc = db->pc_next;
>         opc->translate_insn(db, cpu);
>         bytes = db->pc_next - old_pc;
> 
>     requiring no target changes at all.
> 
> 
> If that's always true then great, but what happens with direct branches?

pc_next is still updated by the size of the branch, not it's destination;
db->is_jmp will be != DISAS_NEXT, ending the TB.


r~