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Re: [Qemu-devel] [PATCH 0/2] tcg: Fix launchpad 1824853
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From: |
Richard Henderson |
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Subject: |
Re: [Qemu-devel] [PATCH 0/2] tcg: Fix launchpad 1824853 |
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Date: |
Fri, 19 Apr 2019 15:38:59 -1000 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 |
On 4/19/19 1:07 PM, Alex Bennée wrote:
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> Richard Henderson <address@hidden> writes:
>
>> This is a case where we generate more than 64k code for a mere 231
>> guest instructions.
>
> I would like to know more! Are these unrolled vector ops or something else?
Yes. E.g.
ld4 { v0.16b - v3.16b }, [x0]
will generate 64 guest byte loads. Given the size of the code
generated for each guest memory operation, we should probably
change this to use 64-bit loads and dole out the bytes manually.
Even for linux-user, with direct host memory ops this converts
to 1k code.
r~