Messages in this thread | | | Date | Wed, 01 Jul 2015 14:12:26 -0400 | From | Vladimir Makarov <> | Subject | Re: gcc feature request / RFC: extra clobbered regs |
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On 07/01/2015 01:43 PM, 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. > > Making attributes a part of type probably creates a lot issues too.
Although I am not a front-end developer, still I think it is hard to implement in front-end. Sticking fully to this approach, it would be logical to describe this as a debug info (I am not sure it is even possible).
Portability would be an issue too. It is hard to prevent for a regular C developer to assign such function to variable because it is ok on his system while the compilation of such code may fail on another system.
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