[Mono-dev] Building Mono on Linux/Alpha

Zoltan Varga vargaz at gmail.com
Wed Aug 2 13:46:28 EDT 2006


> I have a question:
> Alpha arch doesn't have unassigned compare for floats, but IR seems to
> require it. What would be the best place to
> implement taking abs values for arguments to compare and do comparition?
> I was thinking of using inssel-alpha.brg file to add instruction like
> "stmt: OP_COND_BRANCH (OP_COMPARE(freg, freg)) { ... }"
> (I found usage like this in inssel-arm.brg) to implement abs of fregs
> and do compare, but I read documentation that this would limit
> optimization and register allocation logic.

I don't know how that would limit optimization, so I think it is fine for now.

> Another thing - Alpha doesn't have special flag register to hold
> comparition result and uses some of common registers. Right now I am using
> one predefined register, but this limit its usage for other ops. I would
> like to use local register allocation to allocate register to hold
> compare results and use it in conditional branch instruction.

This is not currently possible, ia64 has the same problem and uses a dedicated
predicate register.


> Thank you,
> --
> Sergey Tikhonov
> Solvo Ltd.
> Saint-Petersburg, Russia
> tsv at solvo.ru

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