[PATCH 0/2] Require that constraints are used to reference global regs

[Michael Matz]

Hi,

On Tue, 1 May 2018, Jeff Law wrote:

> The very nature of a traditional asm implies that it can read or write 
> anything visible to compiler.  We can't realistically peek inside to see 
> what's happening and the user hasn't provided appropriate dataflow 
> information.  One could make the argument that traditional asms should 
> go the way of the dodo bird.  I think we looked at that not terribly 
> long ago, but didn't really get anywhere.

Yeah, with traditional asms we have to assume dependencies to everything 
(right now, i.e. if we don't want to enter the rathole of deprecating 
them).  But we were also talking about non-traditional asms, i.e. with 
operands, where I think Alexander made the case that those should have 
explicit dependencies if they access the same registers as global reg 
vars.


Ciao,
Michael.