similar to: [LLVMdev] Re: [open-analysis] Alias Analysis Design & Implementation and LLVM

On Thu, 6 Nov 2003, Michelle Strout wrote: > I think some clarifications and examples would be helpful. No problem. :) > - LLVM is in SSA. It is in SSA before alias analysis has been > >>>> performed. With OA, it has been mentioned that the SSA generation > >>>> is > >>>> incorrect because it doesn't take alias analysis information into

Chris and everyone else, Below I summarize my understanding of what llvm does when converting to SSA and a clarification on why backward dataflow analyses can not be performed on "just" SSA. >> Scalar variables still have a stack location associated with them, >> don't they? > > No, they don't. All scalar values in LLVM represent "virtual >

Chris, I think some clarifications and examples would be helpful. - LLVM is in SSA. It is in SSA before alias analysis has been >>>> performed. With OA, it has been mentioned that the SSA generation >>>> is >>>> incorrect because it doesn't take alias analysis information into >>>> account. This seems logical, because the definition of

On Thu, Jul 6, 2017 at 7:00 AM, Davide Italiano <davide at freebsd.org> wrote: > On Wed, Jul 5, 2017 at 3:59 PM, Johan Engelen via llvm-dev > <llvm-dev at lists.llvm.org> wrote: > > Hi all, > > I just found an optimization regression regarding simple > > dataflow/constprop analysis: > > https://godbolt.org/g/Uz8P7t > > > > This code >

Hello. Thank you very much for the research paper. I will try to make use of the algorithms it presents. I just want to add that I found a 3rd party project doing dataflow analysis for LLVM IR at https://github.com/rohitjha/cse231-proj2. As written at http://cseweb.ucsd.edu/~r1jha/#five , the project's description is: "Dataflow Analysis Framework for LLVM This is an

I am working on implementing an algorithm that needs one of the standard Data Flow Analysis as its precondition (VeryBusyExpression to be precise). Thus I take a look into LLVM (2.8) and check their availability. I do expect to see all of the following standard ones: - Reaching Definition (RD) - Live Variable (LV) - Available Expression (AE) - Very Busy Expression (VBE) To my surprise, I

Hello. Could you please tell me how can I implement best a live interval analysis on LLVM IR (not on Machine instructions, which is already available in http://llvm.org/docs/doxygen/html/LiveIntervalAnalysis_8cpp_source.html)? I need to analyze the standard LLVM IR (list of Instruction *) and decide for each SSA variable what is it's live(ness) interval. My problem is that I

Is there a traditional dataflow algorithm buried in LLVM somewhere? I need to be able to do some very late transformations (after regalloc) and we aren't in SSA anymore. I will need a dataflow analysis to ensure correctness. At one point I thought I remembered seeing a generic fixed-point dataflow analysis engine but now I can't find it. Does it still exist or did it ever exist? If

Mingxing Tan wrote: > > Hi, all; > > How can I get the number of variables in a function/module (both the > number of variables in original source program and the number of > temporal variables for ssa-form)? > Do you want the SSA values *created* by a function, those used by a function, or both? For SSA values, simply iterate over all of the instructions within the

> You can solve andersens and steengaards and everything else using > standard dataflow solvers, and that's an implementation strategy, but > it will be really slow. > > Part of the tradeoff is how fast something runs, and approaches that > are orders of magnitude faster often change the calculus of what > people do. For example, before hardekopf's work, andersens

You can use: http://www.rw.cdl.uni-saarland.de/~grund/papers/cgo08-liveness.pdf -----Original Message----- From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of Alex Susu via llvm-dev Sent: Saturday, May 21, 2016 9:39 PM To: llvm-dev <llvm-dev at lists.llvm.org> Subject: [llvm-dev] Live interval analysis on LLVM IR (not on Machine instructions) Hello. Could you

On 4/16/13 11:30 AM, dag at cray.com wrote: > Is there a traditional dataflow algorithm buried in LLVM somewhere? I > need to be able to do some very late transformations (after regalloc) > and we aren't in SSA anymore. I will need a dataflow analysis to ensure > correctness. > > At one point I thought I remembered seeing a generic fixed-point > dataflow analysis engine

Hi all, I just found an optimization regression regarding simple dataflow/constprop analysis: https://godbolt.org/g/Uz8P7t This code ``` int dataflow(int b) { int a; if (b==4) a = 3*b; // fully optimized when changed to a = 3; else a = 5; if (a == 4) return 0; else return 1; } ``` is no longer optimized to just a "return 1". The regression happened in LLVM

> > > > Also as a side note, I think in the original MachineOutliner RFC thread > there was some confusion as to whether it was possible to solve the code > folding outlining problem exactly as a graph problem on SSA using standard > value numbering algorithms in polynomial time. > > I can elaborate further, but > 1. it is easy to see that you can map an arbitrary

Hi debuginfo cabal, tl;dr: I'd like to know what people think about an alternative to DBG_VALUE instructions describing variable locations in registers, virtual or real. Before instruction selection in LLVM-IR we identify the _values_ of variables [0] by the instruction that computes the value; I believe we should be able to do the same post-isel, and it would avoid having to analyse register

Hi, all; How can I get the number of variables in a function/module (both the number of variables in original source program and the number of temporal variables for ssa-form)? I’m dealing with some dataflow analysis problem and need the information of variables. Appreciate any help. Thanks. Star.Tan -------------- next part -------------- An HTML attachment was scrubbed... URL:

On May 11, 2005, at 3:03 PM, Chris Lattner wrote: > On Wed, 11 May 2005, Alkis Evlogimenos wrote: >> On Wed, 2005-05-11 at 13:17 -0500, Chris Lattner wrote: >>> On Wed, 11 May 2005, Vladimir Prus wrote: >>>> Say I want to find all LLVM Value*-es that a live on exit from a >>>> basic block. >>>> What's the best way? >>>>

Hello, I'm looking to learn more about what is available for memory versioning or inducing some kind of SSA for memory objects. I found this page: http://llvm.org/docs/tutorial/OCamlLangImpl7.html#memory-in-llvm Which says: "[LLVM] does not require (or permit) memory objects to be in SSA form.... In LLVM, instead of encoding dataflow analysis of memory into the LLVM IR, it

Hi debuginfo-cabal, tl;dr: Let's please consider using a new implementation of LiveDebugValues that produces richer information, might be slightly faster, but mostly will support the instruction referencing and value tracking paradigm from my RFC [0] rather than the location tracking that LiveDebugValues does today. In that RFC, the main motivator is to treat variable locations a bit more

>>>>> "Jakob" == Jakob Praher <jp at hapra.at> writes: Jakob> I would definitely like to look into it. I'll send it in private email. Jakob> Yes very much! How did you find writing it directly in Jakob> SSA-form. Actually I used what Chris called "the alloca trick"... the JIT doesn't really generate SSA form but instead uses alloca to