similar to: How to find the root causes of compiler bugs in practice?

In general, finding the root cause in LLVM is not really a big difference than debugging a normal software: Depending on the scenario, if it’s a crash then putting it on a gdb is probably the first step you wanna do. And this usually can tell you the answer pretty fast. More tricky scenarios usually involving developers to leverage various of LLVM-specific diagnosing features, the

## TL;DR We introduce bcov, an open-source binary-level coverage analysis tool [1]. The details are discussed in our paper [2], which is accepted to ESEC/FSE'20. bcov statically instruments x86-64 ELF binaries without compiler support. It features several techniques that allow it to achieve high performance, transparency, and flexibility. For example, running "make

I was wondering, is there any way to express in the IR that an instruction/instruction sequence/basic block/region/function/module/whatever is an alternate version of another? e.g. let's keep things simple and say that I have an instruction I. An optimization pass reads it and could be able to produce one or more functionally-equivalent instructions I1, ..., In without being really able

http://dl.acm.org/citation.cfm?id=2843863 Luke Jones, Ryan Whelan, Jeremy Blackthorne, and Graham Baker. 2015. Flowtables: Program Skeletal Inversion for Defeat of Interprocedural Analysis with Unique Metamorphism. In Proceedings of the 5th Program Protection and Reverse Engineering Workshop (PPREW-5). ACM, New York, NY, USA, , Article 6 , 11 pages. DOI=http://dx.doi.org/10.1145/2843859.2843863

Hi Chris, Thanks. I will see what I can do for this. Junjie On Wed, May 19, 2010 at 3:45 PM, Chris Lattner <clattner at apple.com> wrote: > > On May 19, 2010, at 2:38 PM, Junjie Gu wrote: > >> Many compilers support per-loop pragma, such as loop unrolling (ie >> #pragma unroll=2).  Is there any LLVM project/effort going on >> in this area ? What is the expected

A more pressing need is a pre-regalloc scheduler that can switch modes to balance reducing latency vs. reducing register pressure. The problem is the current approach is the scheduler is locked into one mode or the other. For x86, it generally makes sense to schedule for low register pressure. That is, until you are dealing with a block that are explicitly SSE code in 64-bit mode. In that case,

Hi Fangrui, Many thanks for providing such detailed feedback! Please find my comments inlined below. - Ammar On Sun, Jun 28, 2020 at 5:59 AM Fangrui Song <maskray at google.com> wrote: > On 2020-06-26, Ammar Ben Khadra via llvm-dev wrote: > >## TL;DR > > > >We introduce bcov, an open-source binary-level coverage analysis tool [1]. > >The details are discussed

Instant Rails is a one-stop Rails runtime solution containing Ruby, Rails, Apache, and MySQL, all preconfigured and ready to run. No installer, you simply drop it into the directory of your choice and run it. It does not modify your system environment. This release of Instant Rails is for Windows, but there are plans for ports to Linux, BSD, and OSX. This release upgrades Rails to 1.1 and the

I'd like to add a pragma support in llvm. I am thinking about using a llvm intrinsic to represent each pragma, such as llvm.pragma (metadata, ...) where metadata describes a pragma. So if an application has: #pragma p1 .. #pragma p2... for (...) The llvm IR would be llvm.pragma (metadata..) // for p1 llvm.pragma (metadata..) // for p2 llvm IR for "for

Thank you very much for your suggestions. That's very helpful. However, since I'm trying to compile several somewhat large projects, I assume generating bitcode for each single file and linking them together might be painful (I don't want to modify too much the project makefiles). So I hope my pass can be used just with simple compilation command like "llvm-gcc

I think you can also avoid the RDF computation using a more directed form of control dependence testing such as described in Keshav Pingali and Gianfranco Bilardi. 1997. Optimal control dependence computation and the Roman chariots problem. ACM Trans. Program. Lang. Syst. 19, 3 (May 1997), 462-491. DOI=http://dx.doi.org/10.1145/256167.256217 However one challenge seems to be fixing the SSA graph

On Tue, Jun 1, 2010 at 5:42 PM, Junjie Gu <jgu222 at gmail.com> wrote: > Any suggestions/ideas ? IIUC, Chris suggested something like following ... header: br i1 %x, label %then, %label endif then: ... br i1 %y, label %loop_exit, label %header, !loop_pragma !1 endif: ... br i1 %z, label %loop_exit, label %header, !loop_pragma !2 loop_exit: ret i32 1 Where !1 and !2 are the

Can you describe quickly (or point to references for the inclined) what this pass will do and what other stuff it might enable for LLVM? I'm just curious. -- Christopher Lamb -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20080324/46829334/attachment.html>

>> As part of the advanced compilers course semester project (at >> UIUC), we >> are starting to implement array dependence analysis for LLVM. Great! This is something we've needed for a long time. > I'm currently working on a similar project and hoping to finish it in > about two weeks. Cool! I think the most critical part of this is to get a good

Many compilers support per-loop pragma, such as loop unrolling (ie #pragma unroll=2). Is there any LLVM project/effort going on in this area ? What is the expected way for implementing per-loop pragma, or general pragma ? Suggestions/comments ? Thanks Junjie

I have a MDNode, and one of its operand is an int. I'd like to assign a new int value to that operand during the llvm optimization. What is the right way to do this ? (There is no setOperand() with MDNode class.) Junjie

I have TOT of llvm and it builds 64-bit without issues on my 64-bit ubuntu. My question is how to build 32-bit llvm on my 64-bit ubuntu ? I've not found any configure options to specify that. Thanks Junjie

Hi there, I'd like to plot some maps. Is it possible for me to use SAS map data in R? Thank you. Best, Junjie _________________________________________________________________ your life. [[alternative HTML version deleted]]

What is the difference between WeakAnyLinkage and ExternalWeakLinkage ? They are defined in GlobalValue.h. Thanks Junjie

Thanks for comments/suggestions. Yes, attaching metadata to instructions will be good choices for many cases. But for loops, attaching metadata to back-edges requires that the front end to build loops, which is an additional task for the front end. And this task is really a backend's job, not the front end's. If the only concern is that it is hard for pragma intrinsics to stay with their