similar to: [LLVMdev] Chaitin/Briggs register allocator

Hi, We noticed that LLVM has implemented register allocation using PBQP and Briggs as a heuristic for spilling. Is there a direct implementation of the Chaitin-Briggs register allocation algorithm? We intend to modify parts of this algorithm in order to implement a variant of it. It will save us a lot of time if it is already implemented, rather than writing the code from scratch. Thanks and

Hello, I want learn more about register allocation and do some analysis for a current research project. After reading some papers (eg. Chaitin, Briggs) I think its time to get my hands dirty :). First I plan to (re)implement some of the classic approaches to get familiar with the framework. At the beginning the following questions came up: - Is there some documentation about register allocation

Hi, We noticed that LLVM has implemented register allocation using PBQP and Briggs as a heuristic for spilling. Is there a direct implementation of the Chaitin-Briggs register allocation algorithm? We intend to modify parts of this algorithm in order to implement a variant of it. It will save us a lot of time if it is already implemented, rather than writing the code from scratch. Thanks and

On Saturday 01 May 2010 08:34:50 Josef Eisl wrote: > Hello, > > I want learn more about register allocation and do some analysis for a > current research project. After reading some papers (eg. Chaitin, > Briggs) I think its time to get my hands dirty :). Welcome! > First I plan to (re)implement some of the classic approaches to get > familiar with the framework. Before

Hi Jakob, Thanks for a very interesting description of the new register allocation algorithm in LLVM!!! Could you elaborate a bit on the following topics: 1) Do you have any plans to publish something more formal and detailed about this algorithm, e.g. a paper or something similar?  It would be nice to better understand how this algorithm relates to well-known algorithms described in the

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

David Greene wrote: > On Saturday 01 May 2010 08:34:50 Josef Eisl wrote: >> Hello, >> >> I want learn more about register allocation and do some analysis for a >> current research project. After reading some papers (eg. Chaitin, >> Briggs) I think its time to get my hands dirty :). > > Welcome! > >> First I plan to (re)implement some of the classic

On Sep 26, 2011, at 4:22 AM, Leo Romanoff wrote: > Hi Jakob, > > Thanks for a very interesting description of the new register allocation algorithm in LLVM!!! > > Could you elaborate a bit on the following topics: > > 1) Do you have any plans to publish something more formal and detailed about this algorithm, e.g. a paper or something similar? It would be nice to better

Yes, I quite liked the things I've read about the PBQP allocator. Given what the hardware folks have to go through to get 1% improvements in scalar code, spending 20% (or whatever) compile time (under control of a flag) seems like nothing. And falling back on "average code" is a little disingenuous. People looking for performance don't care about average code; they care about

Hi, Using Chaitin's approach, removing a copy via coalescing could expose more opportunities for coalescing. So he would iteratively rebuild the interference graph and check for more opportunities. Chaitin was also careful to make sure that the source and destination of a copy didn't interfere unnecessarily (because of the copy alone); that is, his approach to interference was very

> On Sep 10, 2018, at 5:25 PM, Matthias Braun <mbraun at apple.com> wrote: > > > >> On Sep 10, 2018, at 5:11 PM, Preston Briggs <preston.briggs at gmail.com <mailto:preston.briggs at gmail.com>> wrote: >> >> The phi instruction is irrelevant; just the way I think about things. >> The question is if the allocator believes that t0 and t2

I just uploaded a blog post outlining the new register allocation algorithm in LLVM 3.0. http://blog.llvm.org/2011/09/greedy-register-allocation-in-llvm-30.html Please direct comments here. /jakob

The phi instruction is irrelevant; just the way I think about things. The question is if the allocator believes that t0 and t2 interfere. Perhaps the coalescing example was too simple. In the general case, we can't coalesce without a notion of interference. My worry is that looking at interference by ranges of instruction numbers leads to inaccuracies when a range is introduced by a copy.

> The underlying liveness datastructure is a list of ranges where each vreg is alive > (ranges in terms of instructions numbered). I remember a couple of later linear scan > papers describing the same thing (Traub et.al. being the first if I remember correctly). > That should be as accurate as you can get in terms of liveness information. It depends on the details. For example, given

Hi all, Just wanted to announce that I've implemented a preliminary version of a Chaitin-Briggs graph coloring register allocator for the LLVM x86 back-end. Right now, as it stands, the allocator works correctly for the benchmarks that I tested it on (from the LLVM test suite and some of the SPEC benchmarks). It performs better than the local register allocator in terms of spills and

On 20/09/05, Chris Lattner <sabre at nondot.org> wrote: > > because LiveVariables do not provide an interface to iterate through > > all viritual registers. > > Ok, you could add a method to LiveVariables that returns > VirtRegInfo.size(). The virtual registers are defined by the range: > [MRegisterInfo::FirstVirtualRegister, >

Hi Matthias, Thanks for your hint! It is just for learning and practicing for me, just like migrate DragonEgg http://lists.llvm.org/pipermail/llvm-dev/2017-September/117201.html the motivating is for learning from GCC and LLVM developers. 在 2017年12月19日 10:07, Matthias Braun 写道: > > >> On Dec 18, 2017, at 9:52 AM, Leslie Zhai via llvm-dev >> <llvm-dev at lists.llvm.org

On Tue, 20 Sep 2005, Tzu-Chien Chiu wrote: > On 20/09/05, Chris Lattner <sabre at nondot.org> wrote: >>> because LiveVariables do not provide an interface to iterate through >>> all viritual registers. >> >> Ok, you could add a method to LiveVariables that returns >> VirtRegInfo.size(). The virtual registers are defined by the range: >>

Hi Jakob, Hi Andy, First of all, thanks a lot for very elaborative and interesting answers! > It may be more helpful to explain how LLVM's register allocator came > into existence before debating the high level algorithm. > > When I began working on LLVM last October, Jakob was developing an > infrastructure for global live range splitting. It was just becoming > clear

On Monday 09 July 2007 17:07, David Greene wrote: > On Monday 09 July 2007 16:49, Reid Spencer wrote: > > The only thing that comes to mind is that creating and running the > > coalescer are separate operations so you might want to do the creation > > of it in alias analysis style. Then, the allocator can a) determine if a > > coalescer was created, b) obtain the