-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 03/09/11 09:24, Xinliang David Li wrote: > On Wed, Mar 9, 2011 at 6:03 AM, Jeff Law <l...@redhat.com> wrote: > On 03/09/11 02:45, Richard Guenther wrote: >>>> On Tue, Mar 8, 2011 at 11:04 PM, Jeff Law <l...@redhat.com> wrote: > >>>> True. I've been repeatedly thinking of building some on-the-side CFG >>>> with value-numbered predicates to also catch the CFG vs. scalar-code >>>> predicate combinations we have. On such on-the-side data structure >>>> we could do very aggressive jump-threading just for analysis purposes >>>> (experiments when working on separating conditions shows that >>>> a PRE-like algorithm could drive this). > I'm pondering the same kind of thing. PRE on the predicates with a more > structured approach to block copying to isolate the paths seems to be > the way to go. > > >> Any simple examples to show how your idea would work? Our current jump threading is just a special case of path isolation; the biggest problem with path isolation is exploding codesize.
I'd like to see that code generalized in a few ways based on well known algorithms rather than the ad-hoc stuff we've got now keeping a reasonable knob on the codesize bloat. In cases where we want more accurate warnings, but aren't willing to accept the size bloat, on the side structures might be the way to go. I'm still looking a literature on the subject, but there's clearly things we can do to improve the path sensitivity of the optimizers and warning analysis. jeff -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJNenzuAAoJEBRtltQi2kC78csH/iBQvJ7UC8NQSgyYg6VRs0zZ PeQtFOkEmZ5cmnBSswl6y82hXmBERXrvqx2/jkQa5AkM7m1gOwh8ieI40hDdsDZi 6253orEdlsWxnXJ7LOm/pmGD5JexSPNq2bbPD+fQZ6W+Xtoh4ckoyCA/f3PMQpXG gugkRMKjwAoMHplEOZHDCQpdgssPQjsa226UwyEcvEb5mi01Atfq4PtvchYF8rnY P2FisaYgHIbi9Ct7infXZVkPyvh0tVbbCwS/s/OPBkf+Ez6mHmEOx9dwOIkJdQEv 8uV7hXQmGbI9wLh+0Q1ZQ36o918mL4h4zYXQ8TGlqY4kVg1WEWRr1Pt+iNs7heA= =2zgD -----END PGP SIGNATURE-----
