On Thu, Mar 8, 2018 at 2:22 PM, Richard Biener <richard.guent...@gmail.com> wrote: > On Thu, Mar 8, 2018 at 1:54 PM, Michael Matz <m...@suse.de> wrote: >> Hi, >> >> On Wed, 7 Mar 2018, Peter Bergner wrote: >> >>> On 3/7/18 12:01 AM, Jeff Law wrote: >>> > I believe so by nature that the setjmp dominates the longjmp sites and >>> > thus also dominates the dispatcher. But it's something I want to >>> > explicitly check before resubmitting. >>> >>> Are we sure a setjmp has to dominate its longjmp sites? >> >> No, they don't have to dominate. For lack of better term I used something >> like "ordered after" in my mails :) >> >>> Couldn't you have something like: >> >> Yeah, exactly. > > So given all the discussion _iff_ we want to change the CFG we generate then > let's invent a general __builtin_receiver () and lower setjmp to > > setjmp (); > res = __builtin_receiver (); > > and construct a CFG around that. Remember that IIRC I added the abnormal > edges to and from setjmp to inhibit code-motion across it so whatever CFG > we'll end up with should ensure that there can't be any code-motion > optimization > across the above pair nor "inbetween" it. The straight-forward > CFG of, apart from the fallthru from setjmp to the receiver, a abnormal edge > to the dispatcher from setjmp and an abnormal edge from the dispatcher to > the receiver would do that trick I think. > > I'd rather not do that for GCC 8 though. So to fix the warning can't we do > sth else "good" and move the strange warning code from RTL to GIMPLE? > > Or re-do the warning? Since in the other thread about setjmp side-effects > we concluded that setjmp has to preserve all call-saved regs? I don't see > that reflected in regno_clobbered_at_setjmp or its caller -- that is, > we should only warn for call clobbered and thus caller-saved regs because > normal return may clobber the spilled values. > > Not sure if the PR testcase is amongst the cases fixed by such change.
Ah, slight complication is we warn from IRA but _before_ RA. Not sure if there's a place where hardregs are assigned but not yet spilled (and those hardreg assignments hold in the end) where we can move the warning to. Richard. > Richard. > >> >> Ciao, >> Michael.
