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...as <sanjoy at playingwithpointers.com> wrote: > > [+CC Andy] > >> Can anyone familiar with ScalarRevolution tell me whether this is an >> expected behavior or a bug? > > Assuming you're talking about 2*k, this is a bug. ScalarEvolution > should be able to prove that {0,+,4} is <nsw> and <nuw>. I also find it surprising that the inbounds gep does not allow us to prove nuw of the pointer here. LAA has logic for this. Not to mention that we’re trying to figure out the distance of x[2*k] against *itself* which should be zero regardless of wrapp...

I am testing vectorization on the following test case: float x[1024], y[1024]; void myloop1() { for (long int k = 0; k < 512; k++) { x[2*k] = x[2*k]+y[k]; } } Vectorization failed due to "unsafe dependent memory operation". I traced the LoopAccessAnalysis.cpp and found the reason is the NoWrapFlag for SCEVAddRecExpr is not set and consequently the

From: Maxime Rey <maximejeanrey at gmail.com> Hello, I've discovered an issue with sshd when it's configured to use the SSH agent alongside multiple host keys. Specifically, this problem happens during the hostkeys-prove-00 at openssh.com request, when the server attempts to demonstrate ownership of the host keys by calling the agent. The issue occurs because, while processing the hostkeys-prove-00 at openssh.com request, sshd does not specify the signature algorithm in its call to the agent. As a result, when ssh...

...------------------- Pre-treatment Post-treatment Pat1 25 28 Pat2 19 15 Pat3 94 89 ... Pat32 49 23 ------------------------------------------------ How can we prove that the treatment did not make any difference in the amount of protein A. In another word, Pre- and post- are the same. 1) I assume that a paired t-test can work, but can I prove a null hypothesis by not-rejecting it? 2) If I use correlation test, the best I can get is to reject a null hypothesis...

...express C rules in llvm IR. For > signed types "nsw" flag on arithmetic seems close, if I understand the > description of trap values. Right; this is the second of the two approaches Eli originally suggested. For this approach, the IR is already sufficient to allow the optimizer to prove that i >=0 and to subsequently prove that the relevant pointers don't alias. BasicAA doesn't have any logic related to proving either i >= 0, or that _length and _data don't alias even if it somehow knew i >= 0. It could be taught both of those things, if someone were interest...

...orrectness of all the instcombine transformations for "free". > Moreover, instcombine has also suffered from infinite loops in the past > (because canonicalization did not make progress for some inputs), which is > also your concern with legalization of MI. We have algorithms to prove > termination of rewriting systems, so I believe we could also prove progress > for both instcombine and MI legalization. > > I'm mixing MI legalization and instcombine, since I think that the > correctness and progress checking technology that we would need is the > exactly t...

Dear List, I'm now working on MLE and OSL estimators.I just noticed that the textbook argues they are joint normal distributed.But how to prove the conclusion? Thanks for your time in advance! Best, Ning

> On Jun 10, 2015, at 6:17 PM, Sanjoy Das <sanjoy at playingwithpointers.com> wrote: > > I'm not sure if inbounds can be used to prove <nuw>. If an object > %OBJ is allocated at address -1 then "gep inbounds %OBJ 1" is not > poison, but the underlying computation unsigned-overflows. I think that this should yield poison per langref because the signed arithmetic implied by the indices should be performed wit...

...instcombine transformations for "free". >> Moreover, instcombine has also suffered from infinite loops in the past >> (because canonicalization did not make progress for some inputs), which >> is >> also your concern with legalization of MI. We have algorithms to prove >> termination of rewriting systems, so I believe we could also prove >> progress >> for both instcombine and MI legalization. >> >> I'm mixing MI legalization and instcombine, since I think that the >> correctness and progress checking technology that we wo...

...cs.ndsu.nodak.edu> wrote: > Unix and ntp handle leap seconds a bit differently. > Unix time increases during the leap second and drops back a second after. > Ntp freezes time during the leap second. > OS kernels may do either or neither. Does anyone have a succinct summary of how to prove to management-types that a given linux box won't have a problem with the leap second? Like kernel > some_version, tzdata > some_version, tzdata-java > some_version? -- Les Mikesell lesmikesell at gmail.com

Colleagues, I am trying to learn to use uniroot to solve a simple linear equation. I define the function, prove the function and a call to the function works. When I try to use uniroot to solve the equation I get an error message, Error in yfu n(x,10,20) : object 'x' not found. I hope someone can tell we how I can fix the problem if(!require(rootSolve)){install.packages("rootSolve")}...

Hello, I've found that when using the ssh agent and sshd together, there is an issue when using multiple host keys. Specifically, after the key exchange phase, when a client requests proof of ownership for the host keys via the "hostkeys-prove-00 at openssh.com" request, the server prepares the response without specifying the signature algoorithm in case of non-RSA keys. This leads to "SSH_ERR_INVALID_ARGUMENT" when verifying the signature in : openssh-portable/authfd.c line if ((r = sshkey_check_sigtype(sig, len, alg))...

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> only if the compiler can prove that the called function has > no side effects (such as modifying some global variables or > causing the program to exit). can it prove if the function resides in a shared library? -- View this message in context: http://old.nabble.com/DCE-and-external-function-tp29932485p29942236.html Sent...

...ely rare”, why all the effort to delete it ? > And why make deleting it the default rather than warning about it ? > > There seems to be some confusion/misunderstanding here. My best understanding is that when David said this: > > "The cases where the compiler can statically prove that undefined behaviour is present are comparatively rare." > > What he was referring to/describing was a contrast with the optimizations described prior to that. > > It's something like this: > > UB-based optimizations don't prove UB is present - they optimize on...

...a counter-example to any definition. It's just maybe hard to construct. Just a bit of speculation about option 3 (not sure how often this case is): we can have dependency between SCEVs which is not represented in use-list. For example: if ({100,+,1} > -1) { x = a / {1,+,1} } If we prove nsw for the first addrec, it will also imply nsw for the second addrec (because the number of iterations in this loop is provably less than MAX_INT - 99). But there is no clear use-chain dependency between them. So I would rather belive in option 1 as in the most reliable. I'll try to experime...

...I am interested in the formalization is that I find the current RegionInfo implementation very helpful in defining regions in between barriers in the OpenCL implementation on CPU. I haven't found a test case that breaks it. I got the right intuition, just could not figure out a way to formally prove it, neither did I find one in your regioninfo draft. Thanks, Paul On Fri, Jun 27, 2014 at 3:25 PM, Tobias Grosser <tobias at grosser.es> wrote: > On 27/06/2014 22:04, Paul Vario wrote: > >> Hi Tobi, >> >> I have one additional question about the RegionInfo:...

...c like {1,+,1} and cached its range as [MIN_INT, MAX_INT+1), and then later found out that this recurrency provably has <nsw>, its cached range doesn't get updated. As well as ranges of all other SCEVs that depend on that. As result, we have a very weird behavior of SCEV that is unable to prove that sext({1,+,1}<nsw>) is a positive value just because it has outdated cached ranges. In fact, I don't see any point in having <nsw>/<nuw> for AddRecs if they are not used to prove useful facts about these recs (such as non-negativeness or positiveness). We will only be abl...

...check the correctness of all the instcombine transformations for "free". Moreover, instcombine has also suffered from infinite loops in the past (because canonicalization did not make progress for some inputs), which is also your concern with legalization of MI. We have algorithms to prove termination of rewriting systems, so I believe we could also prove progress for both instcombine and MI legalization. I'm mixing MI legalization and instcombine, since I think that the correctness and progress checking technology that we would need is the exactly the same. I wouldn't m...

...and cached its range as [MIN_INT, MAX_INT+1), and then later found out that > this recurrency provably has <nsw>, its cached range doesn't get updated. As > well as ranges of all other SCEVs that depend on that. As result, we have a > very weird behavior of SCEV that is unable to prove that sext({1,+,1}<nsw>) > is a positive value just because it has outdated cached ranges. Yes, this problem has come up several times and it is counter-intuitive. Part of the problem is (I'm guessing, I wasn't there when SCEV was written) that SCEV is tuned for C/C++ and for C/C+...