similar to: undef value

Hello, I want to know, if I can always assume that when I do unsigned operations like udiv, urem I will get the both operands converted to unsigned values? with under optimized version of code I sometimes receive these lines: unsigned a = 123; int b = -2; int c = a / b; -> %1 = udiv i32 123, -2 and get the result 0. Will it always be zero? or is it undefined?

I call this function and it returns only "i" in my example. Are there any ways to return "j" also? 2017-07-25 19:11 GMT+02:00 Michael Kruse <llvmdev at meinersbur.de>: > There is Loop::getCanonicalInductionVariable() > > You may need to run the "-indvars" (IndVarSimplify) pass before it > returns a value. I am not sure it normalizes the step size

Hello, I need to perform the analysis of loop induction variables. However, as I understood, directly it is possible to extract only a canonical induction variable which is only one. If I have multiple induction variables with the step not one, are there any methods to extract their phi node? int a[10]; int b[10]; for (int i = 0, j = 1; i < 10, j < 10; i++, j+=2) {

Thank you for your answer! I tested your example, yes, perhaps I should preserve some kind of tree to parse this start and end expressions for induction variable... I was surprised, that SCEV cannot compute the tripcount here. I thought, that all linear and maybe expressions with multiplication are suitable for analysis. 2017-08-10 19:30 GMT+02:00 Sanjoy Das <sanjoy at google.com>: > Hi

To continue this topic: sometimes SCEV's behavior is rather controversial : for loops with i changing as i \=2 for example, he can't figure what the type of expressions is, but surprisingly can determine max trip count. Shouldn't it be able to detect or not detect these parameters at the same time? 2017-08-11 15:56 GMT+02:00 Anastasiya Ruzhanskaya < anastasiya.ruzhanskaya at

This support was removed years ago from indvars. We don't need canonical induction variables any more as all analysis are done on SCEVs. The SCEV generator can transform them even without the need for explicit canonical induction variables. Best, Tobias On Wed, Aug 9, 2017, at 14:23, Anastasiya Ruzhanskaya via llvm-dev wrote: > The files of this strange pass are described here >

Ok, thank you. I have also one question about getelementptr. In different versions of clang I see that sometimes array[i][i] is preceded by two getelementptr instructions and sometimes only by one - with an already complex index. 2017-09-01 12:50 GMT+02:00 David Chisnall <David.Chisnall at cl.cam.ac.uk>: > On 1 Sep 2017, at 11:44, Anastasiya Ruzhanskaya via llvm-dev < > llvm-dev

I am primarily interested in phi nodes and their induction variables, in ValueTracking file there is an analysis of them, but if the upper bound is inf, it is not working? 2017-08-07 11:41 GMT+02:00 Anastasiya Ruzhanskaya < anastasiya.ruzhanskaya at frtk.ru>: > So, it is not supported to determine by this instruction : %cmp = icmp slt > i32 %i.03, 99, > that %i.03 = phi i32 [ 0,

No. It would be helpful to understand what you are trying to accomplish overall, which may help people give you details about the best way to accomplish it. For example, if you are trying to understand or recover array indexes from GEP's, that is non-trivial. On Sat, Sep 2, 2017 at 3:53 AM, Anastasiya Ruzhanskaya via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Is there a way

Hello, I wonder if llvm has pure range propagation pass. Is correlated value propagation that one? It seems that it is not directly deals with ranges. Maybe there any passes that simply contain some information about value ranges? Will symbolic value range propagation be done in some time? -------------- next part -------------- An HTML attachment was scrubbed... URL:

Hi! By only two cases I mean , that in exiting block when computing the condition related to PHI node I can expect only icmp on one of incoming values or on phi node itself... I tried to come up with some more complex examples but I always receive only these two cases, that is why I am asking. This problem still relates to the problem of all induction, cumulative and so on variables in loop. SCEV

Hi Anastasiya, If it fits you use case, you can consider walking the loop header and calling getSCEV() on all of the PHI nodes in the header. This will give you a SCEV* which should be easier to analyze than manually inspecting PHI cycles. Thanks! -- Sanjoy On Tue, Jul 25, 2017 at 11:42 AM, Michael Kruse via llvm-dev <llvm-dev at lists.llvm.org> wrote: > 2017-07-25 19:32 GMT+02:00

Hello, this is a question, concerning cmake lists configuration. I am trying to link together two llvm passes, but they still should be as two modules. So: passA - A.so passB - B.so passB should use passA , so I sould use target_link_libraries ( and of course, I have included useAnalysis in passB) . But I can't link libraries that are build as Modules, so I tried to create two libraries at

Hello! Does libvirt uses certificate pinning in tls? I want to setup a transparent proxy (mitmproxy) and can't do this even after I added mitmproxy ca certificate to the trusted certificates in ubuntu.

Hello, is there a possibility to redirect the output of dump() function in llvm? -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20170808/9c3b234a/attachment.html>

Hello, I have already asked how to receive unoptimized IR. This way: clang -S -emit-llvm -O3 -mllvm -disable-llvm-optzns memset.c -o memset.s I have noticed, that in any case, when I use O1, O2, O3 and disable optimizations, I still get llvm intrinsics functions inserted. when I put O0, I have no intrinsics, but have noopt attribute. Is there a way to receive purely unoptimizaed IR without any

Hello, I have this piece of code: int main() { int m = 0; // int i, j, k; // int N = f()%10; for (int l = 0; l < 1000; l+=4) printf("%d", l); I am sure, that llvm is capable to convert this into canonical induction variable, but even with O3 define i32 @main() #0 { br label %2 ; <label>:1 ; preds

Thank you! I wanted to use the right part of the instruction , %a = alloca i32, align 4 - %a here , but I don't quite understand the difference between Instruction object and Value object of a, which is used further , and in this case : %1 = alloca i32, align 4 - I also wanted to use %1 and in this case the only possibility is Instruction object. 2017-07-20 15:32 GMT+02:00 Evgeny Astigeevich

Hi, On Sun, Aug 13, 2017 at 5:58 AM, Anastasiya Ruzhanskaya via llvm-dev <llvm-dev at lists.llvm.org> wrote: > And still, aren't there any possibilities to find that phi node, that led > SCEV to compute max trip count? So there is no good answer to your question since in most cases SCEV does not directly look at PHI nodes (or expressions based off of the PHI node). It converts

Thank you for the answer. So, as I understood, to get the type of the "or" instruction (which I cannot access further as Value , because it is actually a dead instruction), I should get the type of one of its' operands, yes? because the example with ret is quite understandable, but it seems really strange that such instructions as add, and , which define the actual values can have