[llvm-commits] [PATCH] TableGen: reduce the size of ContextDecision tables in X86GenDisassemblerTables

[Craig Topper]

Far as I can tell there's no reason you can't just change the existing
index to 16-bits. The largest index is 43459. I'd rather to see effort
spent uniquifying the ModRM decision table which will provide a much larger
bang.

On Mon, Sep 10, 2012 at 12:28 PM, Manman Ren <mren at apple.com> wrote:

>
> TableGen: reduce the size of ContextDecision tables in
> X86GenDisassemblerTables
> by adding an encoder for instructionIDs. The main motivation is that in
> 83% of
> the cases, the value is zero, so we should be able to use a 16-bit index
> into the encoder and the encoder will translate the index into the actual
> 32-bit value.
>
> Later on, we may combine the modrm_type with instructionIDs to fit into a
> single
> 16-bit number.
>
> The size of libLTO in a Release build is reduced by 200k. The downside is
> one
> more memory access to the encoder when decoding the instruction ID.
>
> Thanks for reviewing the patch! Comments are greatly appreciated.
>
> Manman
>
>
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>


-- 
~Craig
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