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Re: [Qemu-devel] implementation of Vmul instruction in QEMU that seems t
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From: |
Paul Brook |
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Subject: |
Re: [Qemu-devel] implementation of Vmul instruction in QEMU that seems to be illogical |
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Date: |
Mon, 6 Dec 2010 09:22:19 +0000 |
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User-agent: |
KMail/1.13.5 (Linux/2.6.36-trunk-amd64; KDE/4.4.5; x86_64; ; ) |
> Logically, implementation of Vmull.s32 and vmul.u32 is just similar to the
> 8 and 16 bit cases. For example:
> case 4: gen_helper_neon_mull_s32(dest, a, b); break;
> case 5: gen_helper_neon_mull_u32(dest, a, b); break;
> I implemented in this way and tested. It is OK. So I can't understand why
> Vmull.s32 and vmul.u32 were implemented like this in QEMU 0.12.5. Please
> explain for me !
I think you're asking the wrong question. Instead ask yourself why should we
add a new helper when we already know how to do 32x32->64 multiplies.
Paul