similar to: [LLVMdev] Code instruction selection based on SSA-graphs

> > What do you think about this approach? Whould it be interesting to > implement something like that for LLVM? May be you already have > considered something like that? Are there any plans to it? We have talked about whole function instruction selection but does not have immediate plan to implement it. If we were to implement it today, it would probably be done on DAGs with

Hello, we are currently working on my project that aims at improving the register allocation scheme by identifying if the interference graphs are chordal or not. we are working on the llvm compiler .we are forcing the compiler to use PBQP register allocation scheme by an option of ' ' regalloc=pbqp ' during the execution of prgm. we have been succesfull in accessing the interference

Hi Prasad, The comments at the beginning of RegAllocPBQP.cpp list the two most relevant papers for PBQP register allocation. // (1) Hames, L. and Scholz, B. 2006. Nearly optimal register allocation with // PBQP. In Proceedings of the 7th Joint Modular Languages Conference // (JMLC'06). LNCS, vol. 4228. Springer, New York, NY, USA. 346-361. // // (2) Scholz, B., Eckstein, E.

Chris, Chris Lattner wrote: > I would love to see any progress in this area. It is clearly an > important thing to tackle, and it is blocking other interesting > improvements in the code generator. It would also allow us to > eliminate a significant amount of weirdness that exists to hack around > this (e.g. switch lowering). we've been working on a whole-function

On Mar 25, 2008, at 9:40 AM, Dietmar Ebner wrote: > Chris, > > Chris Lattner wrote: >> I would love to see any progress in this area. It is clearly an >> important thing to tackle, and it is blocking other interesting >> improvements in the code generator. It would also allow us to >> eliminate a significant amount of weirdness that exists to hack >>

Hello to all LLVM Developers. The LLVM IR is in strict SSA form (i.e. every variable is defined before it is used along every path from the entry to exit point)? According to the documentation, currently the LLVM IR is in the SSA form, but I don't see additional information about *strict* SSA form. The strict SSA form provide opportunities of optimization in register allocation, because is

> (1) Spill cost metrics. I think this one cannot be dissociated from some kind of live range pre-splitting. Cheers, Arnaud From: Lang Hames [mailto:lhames at gmail.com] Sent: 03 June 2016 23:15 To: James Molloy Cc: Arnaud De Grandmaison; llvm-dev at lists.llvm.org; Sebastian Buchwald; Bernhard Scholz Subject: Re: [llvm-dev] PBQP register allocation and copy propagation Hi James, Arnaud,

Hi everyone, This is a quick status update regarding the PBQP (Partitioned Boolean Quadratic Programming) register allocator. A quick overview of the project: PBQP is a heavyweight allocation technique intended for native code compilation, and compilation of performance critical sections. It works by modeling register allocation problems as PBQP problems, solving these using a generic solver, and

Hi Duncan, >> New PBQP solver. > > nice! Any chance of a quick summary of the state of the pbqp allocator and > who might want to use it? Sure. Here's an update, broken into three handy sections: Summary for LLVM users: --- PBQP is a heavyweight register allocator. A quick, not-at-all scientific look at SPEC2006 shows that compiling with -regalloc=pbqp increased runtime

Hi, > > I think one idea to improve the situation is to consider the cost vector of adjacent nodes during RN. Let's say you decided to do a RN for node A and want to compute the costs for choosing register %Ri. The current implementation does this by computing min(row/column i of edge A <--> B) but you can do better by adding B's cost vector to the row/column before computing

Hi All, I've just committed some changes to the PBQP allocator which are designed to make it easier to implement custom register allocation constraints. This is a quick summary of those changes, and of the status of the PBQP allocator in general. First a quick bit of background: The PBQP allocator is based on ideas described in [1]. I implemented this algorithm (with the improved heuristic

Hi Leslie, I suggest adding these 3 papers to your reading list. Register allocation for programs in SSA-form Sebastian Hack, Daniel Grund, and Gerhard Goos http://www.rw.cdl.uni-saarland.de/~grund/papers/cc06-ra_ssa.pdf Simple and Efficient Construction of Static Single Assignment Form Matthias Braun , Sebastian Buchwald , Sebastian Hack , Roland Leißa , Christoph Mallon , and Andreas

Hello, I have worked on LLVM for my project related to Register Allocation. Bernhard Scholz suggested that Implementing Branch and Bound Heuristic for Reduce N in PBQP register Allocation for LLVM would be to great project to work on. I'm looking forward to implement it in LLVM system. How should i get start about it ? I would also like to know about some of the other projects in LLVM.

Hi Lang, Thanks for your inputs on the problem. I was just curious to know if you got any opportunity to work on the solution for this. Regards Sachin > -----Original Message----- > From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On > Behalf Of Sachin.Punyani at microchip.com > Sent: Tuesday, November 17, 2009 12:00 PM > Subject: Re: [LLVMdev] Crash

Hello Lang, thanks for the suggestion :) it's very interesting. I'll take a read to the email you've pointed out there to understand how it works. Btw, does this mean that only your allocator is able to handle or support this type of constraint? As a follow up to my previous email, the following code is a real example of what i was explaining, Lang this example is exactly why i need

Hi Sachin, llvm-dev, I've just committed a new PBQP solver which, among other things, should take care of this bug. Please let me know how it works out for you. Cheers, Lang. On Tue, Dec 15, 2009 at 5:54 PM, Lang Hames <lhames at gmail.com> wrote: > Hi Sachin, > > Yes. Bernhard Scholz and I have just discussed a fix for this. I hope to > commit it in the next few days. I

Hello, I am working on developing register allocator for irregular architectures (with register pair, and banks) and plan to base my work on graph coloring register allocator. I wonder if LLVM already has basic graph coloring register allocator, or somebody is working on it? Also, I'm not sure what is the best way to even describe the register constraints in tablegen: - How can I

Hi Sachin, Yes. Bernhard Scholz and I have just discussed a fix for this. I hope to commit it in the next few days. I will let you know as soon as it goes in to the mainline. Regards, Lang. On Tue, Dec 15, 2009 at 5:34 PM, <Sachin.Punyani at microchip.com> wrote: > Hi Lang, > > Thanks for your inputs on the problem. I was just curious to know if you > got any opportunity to

Hello, all, I want to implement the register allocation algorithm described in the paper "Register Allocation via Coloring of Chordal Graphs, APLAS'05" in LLVM. This is a graph coloring algorithm that can find an optimal coloring of the interference graph in most of the cases. I've downloaded LLVM last week, and started studying the code. Basically, I have to implement: 1) A

Hi all. I’ve heard a couple of times that some of the problems solved by various passes in the optimizer are indeed NP-hard, even though the instances are small enough to be tractable (and very quickly). Is this true? If so, which are these problems? Register allocation? Instruction scheduling? Are they solved exactly or by approximations? Or not solved at all (the need of solving them is