[LLVMdev] building an ARM backend

Andrew Lenharth alenhar2 at uiuc.edu
Mon Apr 24 08:10:55 PDT 2006

On Mon, 2006-04-24 at 08:50, Rafael EspĂ­ndola wrote:
> 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:

One of the RISC backends will make the work look a lot simpler :)

> 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.

Actually, I think the most work goes into the calling conventions and
ABI.  Describing the instruction set is just a lot of typing things from

Well, you will also likely need a CFE, which is a bit of work in itself.

> Am I underestimating how hard it is? How much work do you thing is
> required to have this minimal back end working?

So, if you've done one before, you could get one up in a couple weeks if
you had fast enough available hardware.

Andrew (aka crazy guy who did the Alpha backend and uses it!)

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