[LLVMdev] Named register variables GNU-style

[Krzysztof Parzyszek]

On 3/27/2014 5:36 PM, Renato Golin wrote:
> On 27 March 2014 21:20, Krzysztof Parzyszek <kparzysz at codeaurora.org> wrote:
>> That's all fine, but I'm not sure how this supports having named register
>> builtins. The problem is that once we implement a feature, it may be
>> impossible to get rid of it, should it turn out to be a flop.  Do we
>> understand all intended and unintended consequences of implementing this?
>
> I think you're misunderstanding... I'm not proposing named register
> builtins, just named registers, like GCC.
>

Well, my main point is that as long as users can access individual 
registers, the code won't be much closer to C, regardless what mechanism 
they will use.  Since we have to have working inline asm, I'm not sure 
if having an extra set of builtins will really help a lot.  By inserting 
uses of physical registers in the code the user may impede register 
allocation and scheduling.  The user already has means to accomplish all 
that and more.

-K


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