similar to: A couple ideas for possible GSoC projects

Hi Philip, > On Mar 22, 2016, at 4:43 PM, Philip Reames via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > If there are any students looking for ideas, here a couple of projects you might consider. > > p.s. Anyone know where in the repo the OpenProjects page is? I'd expected it to be the docs/ folder of the LLVM repo, but it wasn't. Is it what you're

Is there any particular reason that CaptureTracking.h isn't folded into ValueTracking.h? I was looking for the method to check whether a pointer would be captured and looked in ValueTracking.h, unaware that a new header had been created for that one method. Would anyone mind if I folded CaptureTracking into ValueTracking? Nick -------------- next part -------------- An HTML attachment was

Hal, Thanks for your suggestion. I think that makes sense. Currently, non-zero alloca address space is already represented by data layout, e.g., the last component of the data layout of amdgcn---amdgiz target is -A5, which means alloca is in address space 5. How about adding a letter z to -A5 to indicate alloca may have zero value? i.e. -A5 means alloca is in address space 5 and always has

Eric Christopher wrote: > How are you trying to call it? Do you have a DataLayout? In test/Analysis/ValueTracking/memory-dereferenceable.ll, just change byval to dereferenceable(8), and %dparam won't match (see lib/IR/Value.cpp:521 for the logic that is supposed to fire). How do I get it to pass? I tried introducing a target-triple and target-datalayout, but it didn't help.

Given a pointer, does any addrspacecast affect the pointer's dereferenceablity ? For example, %pm = addrspaacecast float addrspacecast(n)* %pn to float addrspacecast(m)* %r = load float addrspace(m)* %pm In another word. the question is whether the following is true ? isDereferenceablePointer(pn) == isDereferenceablePointer(pm) [Note that the function is defined as

Working on a downstream optimization which uses CaptureTracking (CT) I came across a coupling problem. It looks like optimizations and analyses which use CT often need to be in sync with CT implementation. Analyzing the uses of the given pointer CT handles three kinds of uses: * Simple non-capturing use. When one is encountered, CT just moves on. * Non-capturing, but produces another value,

Aaron, On Thu, Jun 02, 2005 at 10:38:58PM +0100, Aaron Gray wrote: > http://www.st.cs.uni-sb.de/~lindig/src/quest/ I don't know about Tanu, but we can certainly use this in finding bugs in LLVM! This has been listed as an "open project" for a long time [1], but someone already implemented it, saving us the time and effort. Thanks for the link! [1]

Right now, we have Value::getPointerDereferenceableBytes() and Value::getPointerAlignment() that allow to query these properties for a value. However, neither does any "reasoning" that would require looking at other values, e.g., they do pure local lookups. To do actual reasoning we have the "isDereferenceableAndAlignedPointer()"-family of functions in Loads.h. Additionally,

Tanu, You've seen ? :- http://www.st.cs.uni-sb.de/~lindig/src/quest/ Don't know whether it is applicable to what you are trying to achieve but I thought I should point it out in case it is useful to you and you have not seen it. Aaron ----- Original Message ----- From: Tanu Sharma To: LLVM Developers Mailing List Sent: Thursday, June 02, 2005 9:53 PM Subject:

Dear prospective LLVM GSoC Mentors, The organization application period for GSoC 2020 will open on January, 14. This means that we're having some time to prepare the list of project ideas for the next year. When proposing the project please keep in mind the following criteria: 1. The project should serve both LLVM as a project and provide the relevant LLVM knowledge to the student. 2. The

Hi, I'm looking to do a semester-long course project involving LLVM. To avoid duplicating efforts, I wanted to know if the following projects (lifted off http://llvm.org/OpenProjects.html) are done with or are currently worked upon. Atleast I couldn't find evidence of these in the 1.9 sources. 1. Implement GVN-PRE, a powerful and simple Partial Redundancy Elimination

Hi there lowering experts, Can the llvm.mem* intrinsics ever turn into a library call? Or do they invariably turn into inline code? This comes up because there was a patch to StackProtector to use CaptureTracking instead of a home-grown analysis, which changes the treatment of calls to intrinsics. (The old code treated them as normal calls, the new code decides intrinsics can never capture.)

Chandler Carruth wrote: > This seems fine to me, but I'd like to make sure it looks OK to Nick as > well. I strongly prefer baking in knowledge about the intrinsics themselves into the passes if possible. Metadata will always be secondary. Separately, should value tracking look use range metadata when it's available? Absolutely. I think it should apply to all CallInst not just

Hi, The range metadata can only be attached to LoadInst for now. I am considering extending its usage to IntrinsicInst so that the frontend can annotate the range of the return value of an intrinsic call. e.g., %a = call i32 @llvm.xxx(), !range !0 !0 = metadata !{ i32 0, i23 1024 } The motivation behind this extension is some optimizations we are working on for CUDA programs. Some special

On the subject of undefined behavior and known bits, as I'm sure some of you are aware, code in ValueTracking.cpp is exploiting poison value rules to get a bit of extra precision in the known bits. These rules fire on examples like the ones below. Do we have a set of rules that clients of known bits need to follow to avoid unsoundness? I remember Nuno and/or David Majnemer saying

Hi, I've noticed that for a while, the instruction combiner would convert certain arithmetic operations (like + or *) into bit-manipulation operations. Specific example I have in mind is converting "2*x+1" into "(x<<1)|1". What is the intention of doing this? The reason I ask is that this kind of transformation makes it harder for later code to analyze it. In

On 17 June 2014 06:41, Eli Bendersky <eliben at google.com> wrote: > On Tue, Jun 17, 2014 at 1:38 AM, Nick Lewycky <nicholas at mxc.ca> wrote: > >> Chandler Carruth wrote: >> >>> This seems fine to me, but I'd like to make sure it looks OK to Nick as >>> well. >>> >> >> I strongly prefer baking in knowledge about the

Hi All, I have faced a problem with TargetLowering::SimplifyDemandedBits with AND. Here is a example as following: /* C source code */ struct A { unsigned int a; unsigned char c1, c2; bool b1 : 1; bool b2 : 1; bool b3 : 1; }; int main () { struct A x[1]; x[0].b1 = false; int s = 0; s = x[0].b1 ? 1 : 0; <--- Here is problem. if (s != 0) __builtin_abort

Some optimizations depend on whether alloca instruction always has non-zero value. Currently, this checking is done by isKnownNonZero() in ValueTracking, and it assumes alloca in address space 0 always has non-zero value but alloca in non-zero address spaces does not always have non-zero value. However, this assumption is incorrect for certain targets. For example, amdgcn---amdgiz target has

Dean, Please add this to OpenProjects page. On Tue, Feb 20, 2018 at 6:49 AM, Dean Michael Berris via cfe-dev <cfe-dev at lists.llvm.org> wrote: > Hi Tanya, > > Is it too late to get some smaller projects for XRay in there? > > Here's two: > > XRay Function Coverage Mode: Implementing an XRay mode to gather function > call coverage information. This will be