Re: Inline assembly clobbered registers

[Christian Hildner <christian dot hildner at hob dot de>]

Falk Hueffner schrieb:

> Christian Hildner <christian.hildner@hob.de> writes:
>
>  
>
> > Falk Hueffner schrieb:
> >    
> >
> > > Christian Hildner <christian.hildner@hob.de> writes:
> > >      
> > >
> > > > I need a temporary general register inside the inline assembly
> > > > code. The definition for a particular register is possible by for
> > > > example "eax". But how to define a general register that the
> > > > compiler is allowed to choose as it is possible with input/output
> > > > registers who are referenced by %0, %1, ... ? So simply to allow "r"
> > > > in the clobbered list and reference it by %x in the assembly code.
> > > >        
> > > Why can't you just make it an output variable?
> > >
> > >      
> > I made it an input one instead.
> >    
>
> That will lead to wrong code, since gcc thinks you won't change it.
Inspecting the output I found that there will be no corruption of 
registers. But since it may not be 100% save I will switch to the usage 
of output registers (as you suggested).

> > This is possible, but it would be nicer to allow an unspecified
> > general register in the clobbered list.
> >    
>
> But since the functioinality is trivially available by another way, I
> don't think it's worth adding complexity to the compiler for this.
I am just wondering to be at least the only one that would need that 
feature.

Thanks

Christian