Re: gcc feature request / RFC: extra clobbered regs

H. Peter Anvin
2015-07-02T06:17:06Z

On 07/01/2015 10:43 AM, Jakub Jelinek wrote:
> On Wed, Jul 01, 2015 at 01:35:16PM -0400, Vladimir Makarov wrote:
>> Actually it raise a question for me. If we describe that a function
>> clobbers more than calling convention and then use it as a value (assigning
>> a variable or passing as an argument) and loosing a track of it and than
>> call it. How can RA know what the call clobbers actually. So for the
>> function with the attributes we should prohibit use it as a value or make
>> the attributes as a part of the function type, or at least say it is unsafe.
>> So now I see this as a *bigger problem* with this extension. Although I
>> guess it already exists as we have description of different ABI as an
>> extension.
>
> Unfortunately target attribute is function decl attribute rather than
> function type. And having more attributes affect switchable targets will be
> non-fun.
>

How on Earth does that work with existing switchable ABIs? Keep in mind
that we already support multiple ABIs...

-hpa