On May 2, 2012, at 2:41 PM, Chad Rosier <[email protected]> wrote: > > On May 2, 2012, at 2:29 PM, Eric Christopher wrote: > >> >> On May 2, 2012, at 2:23 PM, Eli Friedman <[email protected]> wrote: >> >>> On Wed, May 2, 2012 at 2:07 PM, Chad Rosier <[email protected]> wrote: >>>> The attached patch allows inline assembly to inherit the readnone/readonly >>>> function attribute from the caller. This allows the attributes to be >>>> retained after function inlining. In turn, CSE is able to do it's magic >>>> on inline assembly statements. >>>> >>>> An orthogonal solution would be to add support for the const keyword for >>>> inline assembly (e.g., asm const("mov $0x12345678, %0" : "=r" (ptr)); ). >>> >>> It's not obvious to me that this is safe... __attribute((const)) means >>> that a function doesn't cause expose any side-effects, not that it >>> doesn't have any internal state. >>> >> >> Perhaps a way to give a statement an attribute then? > > I think this is what I proposed as the orthogonal approach. However, > assuming what Eli suggest below is correct, then this is not necessary. We > can detect constness. > >> >> In this case it's a read from memory so it'd be readonly... but the point is >> good.
*nod* but at that point you're parsing the inline asm to look around and see if it does anything you don't want - I worry about people lying (or making a mistake) and not marking something as clobber that is, etc. That said, it's probably no worse than any other solution :) -eric _______________________________________________ cfe-commits mailing list [email protected] http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
