[LLVMdev] micro mips/mips32

Jim Grosbach grosbach at apple.com
Wed Sep 5 20:28:36 PDT 2012


The instructions are defined by their encodings, not the assembly syntax. You want separate instruction definitions for the different encodings and select. Between them in the assembler via sub target features. See ARM handling of thumb vs thumb2 vs arm for examples of how to do this.

On Sep 5, 2012, at 6:59 PM, reed kotler <rkotler at mips.com> wrote:

> The micro mips processor assembly language is basically 100% the same as mips32/mips64.
> There are some assembler directives you add but for a base port, but that is all you need to do.
> 
> However, the binary instruction encoding is entirely different. There are a combination of 16 and 32 bit instruction encodings.
> 
> The question is, what's the best way to handle this?
> 
> Extending tablegen ?
> 
> You would want a single instruction to have multiple encodings dependent on the current mode we are compiler for.
> 
> Thoughts?
> 
> reed
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