[LLVMdev] Re: building an ARM backend

Vladimir Prus ghost at cs.msu.su
Tue Apr 25 04:27:43 PDT 2006

Rafael Esp?ndola wrote:

> The company I work for uses quiet some ARM processors and I am trying
> to convince them to let me spend some company time building an llvm
> back end :-)

Funny, I've just got one student for exactly same task -- writing ARM
backend. Of course, the student might well disappear by the time new term
begins and might not produce anything usable for a year ;-)

> I have read the documentation and taken a look on the X86 back end. It
> looks quiet simple to get a very minimal back end working. I am
> considering for a first version:
> 1) only support the 32 bits ABI
> 2) Ignore the shifter (i.e use only 8 bits immediates)
> 3) Ignore the fancier addressing modes
> Without this, the generated code with not be very good but the back
> end will be very simple. The only part that appears to require more
> work is describing the instructions set.
> Am I underestimating how hard it is? How much work do you thing is
> required to have this minimal back end working?

I wrote one backend (private) in a couple of months. I guess it should take
roughly the same time to you if you work full-time on this. 

- Volodya

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