search for: ubs

Hi Johannes, >> Not sure the semantics of "used" you propose is sufficient. AFAIU the >> proposal, "used" could only be used in cases where the function will >> always trigger UB if poison is passed as argument. The semantics of >> attributes is usually the other way around, since function calls need >> to have UB as strong as the worst

I think calling the attribute "used" is confusing. I'd suggest the following: "not_poison": If an argument is marked not_poison, and the argument is poison at runtime, the call is instant UB. Whether an argument is poison is checked after the rules for other attributes like "nonnull" and "align" are applied. This makes it clear that the IR semantics

Hi, I've stumbled upon a case where I think gvn does a bad (wrong) optimization. It's a bit messy to debug though so I'm not sure if I should just write a PR about it a let someone who knows the code look at it instead. Anyway, for the bug to trigger I need to run the following passes in the same opt invocation: -sroa -instcombine -simplifycfg -instcombine -gvn The problem

...mmer has any UB inside. >> >> This is exactly the example that Hal gave. >> >> This can't be used to expose any meaningful information to the programmer, because it would be full of false positive. Basically a program could be clean of any static analyzer error, of any UBSAN error, and totally UB-free, and still exhibit tons and tons of such issues. >> >> -- >> Mehdi > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20170724/98006c76/attachment-0001...

...en by the programmer has any UB inside. > > This is exactly the example that Hal gave. > > This can't be used to expose any meaningful information to the programmer, because it would be full of false positive. Basically a program could be clean of any static analyzer error, of any UBSAN error, and totally UB-free, and still exhibit tons and tons of such issues. > > -- > Mehdi -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20170721/3be0562f/attachment-0001.html>

...s relies on UB - instead the optimizations rely on the IR definitions to make valid transformations, and it's a separate pass in the frontend (clang) that can add extra checks to avoid UB (& diagnose it as such, if that's the best thing to do). > > One could make an IR version of UBSan, that could take some IR and add null checks around every load/store, all the other things UBSan does. But I wouldn't expect that would be a priority for anyone to build (as it's more a compiler developer tool at that point - smaller audience, etc). > > For your debugging situation...

...on UB - instead the optimizations rely on the IR definitions to make valid transformations, and it's a separate pass in the frontend (clang) that can add extra checks to avoid UB (& diagnose it as such, if that's the best thing to do). >> >> One could make an IR version of UBSan, that could take some IR and add null checks around every load/store, all the other things UBSan does. But I wouldn't expect that would be a priority for anyone to build (as it's more a compiler developer tool at that point - smaller audience, etc). >> >> For your debugging s...

Hello all, LangRef says it is undefined behavior to pass null to a nonnull argument (`call f(nonnull null);`), but the semantics is too strong for a few existing optimizations. To support these, we can relax the semantics so `f(nonnull null)` is equivalent to `f(poison)`, but (A) it again blocks another set of optimizations, and (B) this makes the semantics of nonnull deviate from other

Not sure the semantics of "used" you propose is sufficient. AFAIU the proposal, "used" could only be used in cases where the function will always trigger UB if poison is passed as argument. The semantics of attributes is usually the other way around, since function calls need to have UB as strong as the worst behavior of the function. If a function may for some reason trigger

...inside. >>> >>> This is exactly the example that Hal gave. >>> >>> This can't be used to expose any meaningful information to the programmer, because it would be full of false positive. Basically a program could be clean of any static analyzer error, of any UBSAN error, and totally UB-free, and still exhibit tons and tons of such issues. >>> >>> -- >>> Mehdi -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20170726/5e3d1f4a/attachment-0001...

...izations >> rely on the IR definitions to make valid transformations, and it's a >> separate pass in the frontend (clang) that can add extra checks to avoid UB >> (& diagnose it as such, if that's the best thing to do). >> >> One could make an IR version of UBSan, that could take some IR and add >> null checks around every load/store, all the other things UBSan does. But I >> wouldn't expect that would be a priority for anyone to build (as it's more >> a compiler developer tool at that point - smaller audience, etc). >> &gt...

John, I finally decided to go for it and kick off our NT-PDC (UB-SERVER). I want to transfer our domain (UB) to Samba 3.0.1 with OpenLDAP (2.1.23-1) as backend on Debian Woody (this machine's netbios-name in my test environment is UB-KIOSK). I read all documentation I could get a hold on and followed these procedures you suggested, but I am stuck... > * From: John H Terpstra >

...instead the optimizations rely on the IR definitions to make valid transformations, and it's a separate pass in the frontend (clang) that can add extra checks to avoid UB (& diagnose it as such, if that's the best thing to do). >>> >>> One could make an IR version of UBSan, that could take some IR and add null checks around every load/store, all the other things UBSan does. But I wouldn't expect that would be a priority for anyone to build (as it's more a compiler developer tool at that point - smaller audience, etc). >>> >>> For your deb...

...trip.white = TRUE) but no matter what I do the strings are turned into factors. I believe it's the "n=2" parameter that causes the problem as it seems to work without this. Am I missing something? Thanks in advance, David Jessop -------------- next part -------------- Issued by UBS AG or affiliates to professional investors for information only and its accuracy/completeness is not guaranteed. All opinions may change without notice and may differ to opinions/recommendations expressed by other business areas of UBS. UBS may maintain long/short positions and trade in instrum...

Sean, Let me re-phrase a couple words to make it perfectly clear > On Jul 21, 2017, at 6:29 PM, Peter Lawrence <peterl95124 at sbcglobal.net> wrote: > > Sean, > > Dan Gohman’s “transform” changes a loop induction variable, but does not change the CFG, > > Hal’s “transform” deletes blocks out of the CFG, fundamentally altering it. > > These are two totally

Sean, Dan Gohman’s “transform” changes a loop induction variable, but does not change the CFG, Hal’s “transform” deletes blocks out of the CFG, fundamentally altering it. These are two totally different transforms. And even the analysis is different, The first is based on an *assumption* of non-UB (actually there is no analysis to perform) the second Is based on a *proof* of existence of UB

Yeah, there's a lot of things this could be. On the memdep side: Note that memdep is not actually properly updated in all cases by most passes that claim to not invalidate it (they don't invalidate dependent pointers, only pointers they directly touch). There's already a bug filed about this. So far we've only seen missed-opt, not wrong code from this. But it should be possible

...d B C D 2008-08-02 5 8 11 2008-08-03 6 9 12 And > t2 [both.dates, both.cols] gives B C D 2008-08-02 1 4 7 2008-08-03 2 5 8 But > t1 [both.dates, both.cols] <- t2 [both.dates, both.cols] gives Error in t1[both.dates, both.cols] <- t2[both.dates, both.cols] : subscript out of bounds I've tried various varieties of as.matrix, coredata but always get this error. It's something to do with the first part of the expression as > t1 [as.Date (both.dates), both.cols] = matrix (1, nrow = 2, ncol = 3) Error in t1[as.Date(both.dates), both.cols] = matrix(...

> > > Message: 5 > Date: Tue, 25 Jul 2017 00:12:35 -0700 > From: Sean Silva via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> > To: Peter Lawrence <peterl95124 at sbcglobal.net <mailto:peterl95124 at sbcglobal.net>> > Cc: llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>>, John Regehr >

> On Jul 20, 2017, at 11:22 AM, David Blaikie <dblaikie at gmail.com> wrote: > > > > On Wed, Jul 19, 2017 at 10:17 AM Peter Lawrence via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote: > Chandler, > The only thing David made clear that wasn’t already clear > is that he believes UB to be “comparatively