On Tue, 13 Sep 2016, kugan wrote: > Hi Richard, > > > On 19/08/16 18:00, Richard Biener wrote: > > On Fri, 19 Aug 2016, Kugan Vivekanandarajah wrote: > > > > > On 19 August 2016 at 12:09, Kugan Vivekanandarajah > > > <kugan.vivekanandara...@linaro.org> wrote: > > > > The testcase pr33738.C for warning fails with early-vrp patch. The > > > > reason is, with early-vrp ccp2 is folding the comparison that used to > > > > be folded in simplify_stmt_for_jump_threading. Since early-vrp does > > > > not perform jump-threading is not optimized there. > > > > > > > > Attached patch adds this warning to tree-ssa-ccp.c. We might also run > > > > into some other similar issues in the future. > > > > > > Sorry, I attached the wrong patch (with typo). Here is the correct one. > > > > I think emitting this warning from GIMPLE optimizations is fundamentally > > flawed and the warning should be removed there and put next to > > the cases we alrady handle in c/c-common.c:shorten_compare (or in > > FE specific code). I see no reason why only VRP or CCP would > > do the simplification for -fstrict-enums enums (thus it seems to be > > missing from the generic comparison folders). > > > But, If I understand this correctly, I think we will not be able to fold all > the cases we handle in FE. Therefore we will not be able to warn there. For > very simple cases yes, but not for others.
Sure. But I do not see an issue with that. With GIMPLE level warnings you have the general issue that the warning may be only exposed by optimization (like cross-unit inlining with LTO) and thus would be considered a false positive. Richard. > > Thanks, > Kugan > > > Richard. > > > > > Thanks, > > > Kugan > > > > > > > > > > > Bootstrapped and regression tested on x86_64-linux-gnu with no new > > > > regressions. > > > > > > > > Is this OK for trunk? > > > > > > > > Thanks, > > > > Kugan > > > > > > > > gcc/ChangeLog: > > > > > > > > 2016-08-18 Kugan Vivekanandarajah <kug...@linaro.org> > > > > > > > > * tree-ssa-ccp.c (ccp_fold_stmt): If the comparison is being folded > > > > and the operand on the LHS is being compared against a constant > > > > value that is outside of type limit, issue warning. > > > > > k > > > > -- Richard Biener <rguent...@suse.de> SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)
