On Mon, 17 Dec 2018 at 12:47, Richard Sandiford <richard.sandif...@arm.com> wrote: > > Dimitar Dimitrov <dimi...@dinux.eu> writes: > > On Sun, Dec 16 2018 at 14:36:26 EET Bernd Edlinger wrote: > >> Hi, > >> > >> if I understood that right, then clobbering sp is and has always been > >> ignored. > > PR77904 was about the clobber not being ignored, so the behaviour > hasn't been consistent. > > I'm also not sure it was always ignored in recent sources. The clobber > does get added to the associated rtl insn, and it'd be surprising if > that never had an effect. > > >> If that is right, then I would much prefer a warning, that says exactly > >> that, because that would also help to understand why removing that clobber > >> statement is safe even for old gcc versions. > > If the asm does leave sp with a different value, then it's never been safe, > regardless of the gcc version. That's why an error seems more appropriate. > > > Thank you. Looks like general consensus is to have a warning. See attached > > patch that switches the error to a warning. > > I don't think there's a good reason to treat this differently from the > preexisting PIC register error. If the argument for making it a warning > rather than an error is that the asm might happen to work by accident, > then the same is true for the PIC register. >
If we leave the error, maybe a more explanatory message would be helpful? (along the lines of what I posted earlier in this thread, which may be too verbose) Christophe > Thanks, > Richard
