similar to: Precise meaning of must alias?

Hello all, I've read the documentation on alias analysis, and I think I understand it literally, but I just want to be sure, because it seems a bit strange. As it says on this web page <http://llvm.org/docs/AliasAnalysis.html>, The MayAlias response is used whenever the two pointers might refer to the > same object. > > The PartialAlias response is used when the two memory

Thanks Daniel! I think you've cleared up some of my misconceptions, but I still am a bit confused about some of the corner cases. Suppose we had something like this std::vector<int> A(100); > int* x,y; > x=&A[0]; > for(int i=0; i<100; i++) { > y=&A[i]; > *y=*x; > x=&A[i+1]; > } > Would the load and store instructions be MustAlias? I

On Sun, Jul 16, 2017 at 2:34 PM, Nuno Lopes <nunoplopes at sapo.pt> wrote: > On Sun, Jul 16, 2017, 12:45 PM Nuno Lopes wrote: >>> >>>> On 07/15/2017 04:51 AM, Nuno Lopes wrote: >>>> >>>>> On 07/14/2017 04:37 PM, Nuno Lopes wrote: >>>>>> >>>>>>> Thank you all for your replies.

Hey Daniel, Thanks again for the help. I'm still a bit confused about the interface to the alias analysis. It seems like we are talking about different interfaces. Has it changed from what the documentation says? As far as I can tell, the documentation takes a specific Value*, and no information about which dynamic execution it is talking about. When you say "Right. It's a

On Sun, Jul 16, 2017, 12:45 PM Nuno Lopes <nunoplopes at sapo.pt> wrote: > >On 07/15/2017 04:51 AM, Nuno Lopes wrote: > >>> On 07/14/2017 04:37 PM, Nuno Lopes wrote: > >>>> Thank you all for your replies. > >>>> So here seems to be an agreement that the documentation for > >>>> PartialAlias is incorrect. > >>>>

On Sat, Jul 15, 2017 at 5:35 AM, Hal Finkel <hfinkel at anl.gov> wrote: > > On 07/15/2017 04:51 AM, Nuno Lopes wrote: > >> On 07/14/2017 04:37 PM, Nuno Lopes wrote: >>> >>>> Thank you all for your replies. >>>> So here seems to be an agreement that the documentation for >>>> PartialAlias is incorrect. >>>>

Thank you all for your replies. So here seems to be an agreement that the documentation for PartialAlias is incorrect. Daniel: now you got me wondering about MustAlias. This is what the docs say: "The MustAlias response may only be returned if the two memory objects are *guaranteed to always start at exactly the same location*" This statement is regardless of the access sizes. For

> On 07/14/2017 04:37 PM, Nuno Lopes wrote: >> Thank you all for your replies. >> So here seems to be an agreement that the documentation for PartialAlias >> is incorrect. >> >> Daniel: now you got me wondering about MustAlias. This is what the docs >> say: >> "The MustAlias response may only be returned if the two memory objects >> are

Hello everyone, I am trying to find the alias between a store instruction's pointer operand and function arguments. This is the code, virtual void getAnalysisUsage(AnalysisUsage &AU) const { AU.addRequiredTransitive<AliasAnalysis>(); AU.addPreserved<AliasAnalysis>(); } virtual bool runOnFunction(Function &F) { AliasAnalysis &AA =

(sorry for the wide distribution, but this impacts Clang users quite a bit) It's come up a few times in reviews of CFL-AA (a new alias analysis for LLVM), so I wanted to write down what I think the current state actually is for AA pass ordering, why, and how it should look eventually. I may have some bugs here, so please correct me if I miss anything. And I'd love thoughts about the end

Hi! On 7/10/2020 07:17, Shuai Wang wrote: > Hello! > > Thank you very much! Yes, that makes a lot of sense to me. However, just > want to point out two things that are still unclear: > > 1. The output contains a alias set of only one element, for instance: > "must alias, Mod       Pointers: (i32* %y, LocationSize::precise(4))" > > This one really confused

On Thu, Aug 14, 2014 at 6:37 AM, Daniel Berlin <dberlin at dberlin.org> wrote: > On Wed, Aug 13, 2014 at 8:35 PM, Jeremy Salwen <jeremysalwen at gmail.com> wrote: >> Hey Daniel, >> >> Thanks again for the help. I'm still a bit confused about the interface to >> the alias analysis. It seems like we are talking about different >> interfaces. >

On 07/14/2017 03:00 PM, Davide Italiano via llvm-dev wrote: > On Fri, Jul 14, 2017 at 12:50 PM, Nuno Lopes via llvm-dev > <llvm-dev at lists.llvm.org> wrote: >> Hi, >> >> I going through the alias analysis documentation >> (http://llvm.org/docs/AliasAnalysis.html) and noticed the following in the >> definition of PartialAlias: >> " >> The

Hello all, I observed that BasicAA alias query returns PartialAlias between different fields of a structure. Following is the test program and -print–all-alias-modref-info output: --- ; test.ll target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" target triple = "x86_64-unknown-linux-gnu" %"type" = type { [10 x i32], i64 } define void

Hi again! Replying in chronological order: > On Thu, Jul 9, 2020 at 6:51 PM Shuai Wang <wangshuai901 at gmail.com > <mailto:wangshuai901 at gmail.com>> wrote: > > Hey Matt, > > That's awesome. Thank you very much for all the information and > clarification! Just a few follow up questions. Could you kindly shed > some lights on it? Thank

Updated testcases to have MayAlias/note issues as FIXME. On Tue Jan 20 2015 at 3:54:10 PM Hal Finkel <hfinkel at anl.gov> wrote: > ----- Original Message ----- > > From: "Daniel Berlin" <dberlin at dberlin.org> > > To: "Hal Finkel" <hfinkel at anl.gov> > > Cc: "Jiangning Liu" <Jiangning.Liu at arm.com>, "George

Hi Daniel, Sorry for taking so long to respond. I spoke with a colleague more familiar with llvm who thought he could clear up my confusion, but we both came out of the conversation confused. I will try my best to explain the ambiguity. In an DAG, alias queries would be completely unambiguous. Every instruction would only be executed once, and every SSA value really would have a single static

On Wed Jan 21 2015 at 12:30:50 PM Hal Finkel <hfinkel at anl.gov> wrote: > ----- Original Message ----- > > From: "Daniel Berlin" <dberlin at dberlin.org> > > To: "Hal Finkel" <hfinkel at anl.gov> > > Cc: "Jiangning Liu" <Jiangning.Liu at arm.com>, "George Burgess IV" < > george.burgess.iv at gmail.com>,

Hello, I'm trying to get the whole picture of what we are doing in terms of alias analysis in LLVM. Being new to this I may be missing some well known things so my apologies if I seem to ask obvious things. There are lots of questions arise in my head as I read related bug reports, sources and documentation, of which looks to be the most simple is, Why the current TBAA implementation

Hi, We've seen a similar case recently, where BasicAA returns PartialAlias for the access of two different fields of a structure. We noticed this since Lint complained about it when checking for aliasing beteen "noalias" attributed parameters: opt -S -lint ./alias.ll gave Unusual: noalias argument aliases another argument on the (silly) function: %rec7 = type { i16, i16, i16