search for: chaitin

I seem to recall that LLVM had a Chaitin/Briggs register allocator, but looking at today's source, I only see a Linear Scan and some basic block allocators. Does anyone know if a Chaitin/Briggs allocator for LLVM exists and is available? Peter

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 Regards, Prajish

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 Regards, Prajish

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 in LLVM? - As far as I understand it, reg...

Last Friday, Gregory Chaitin (http://www.umcs.maine.edu/~chaitin/lm.html) mentioned that there can be no proof that a given code is the shortest for a problem, even within a language. Still, the script below, a replacement of the "TDT", one of the most frequently used tests in genetics (http://mustat.rockefeller....

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...

...n't this problem solved ages ago? Preston On Tue, Sep 11, 2018 at 11:00 AM, Quentin Colombet < quentin.colombet at gmail.com> wrote: > Le mar. 11 sept. 2018 à 10:23, Preston Briggs > <preston.briggs at gmail.com> a écrit : > > > > 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. > > I am not sure Chaitin's approach would lead to a better coalescing > than what...

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 doing that, can you describe your research a bit? A number of people (include me!) have done graph-coloring style r...

...really > would like it, I would have no problem promoting it to be a public > interface. Let me know what you'd like. A public interface. the interface of LiveIntervals is more convenient than LiveVariables when building build the interference graph, which is necessary for the family of Chaitin style register allocators. Actually I am surprised that some common graph like the interference graph and the data dependence graph (a.k.a. data precedence graph or scheduling graph) is not available in CodeGen, except the control flow graph. Though they are not difficult to construct, it's te...

...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 literature, e.g. linear scan, graph coloring, iterated register coalescing by Chaitin-Briggs, register allocation by priority-based coloring by Chow and Hennesey and if it represents an extension of one of those algorithms or if it is a totally new algorithm. And of course it would be nice if the terminology used by this description would follow the one published in the literature,...

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

...it, I would have no problem promoting it to be a public >> interface. Let me know what you'd like. > > A public interface. the interface of LiveIntervals is more convenient > than LiveVariables when building build the interference graph, which > is necessary for the family of Chaitin style register allocators. Ok. > Actually I am surprised that some common graph like the interference > graph and the data dependence graph (a.k.a. data precedence graph or > scheduling graph) is not available in CodeGen, except the control flow > graph. Though they are not difficult...

...Sep 11, 2018 at 11:00 AM, Quentin Colombet <quentin.colombet at gmail.com> wrote: >>> >>> Le mar. 11 sept. 2018 à 10:23, Preston Briggs >>> <preston.briggs at gmail.com> a écrit : >>>> >>>> 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. >>> >>> I am not sure Chaitin's approach would lead to a better coalescing...

...the details. For example, given t0 = mumble if (something) { t2 = 3 } else { t3 = t0 + 3 print t0 } t4 = phi(t2, t3) it's clear that t2 and t0 shouldn't interfere, but some folks might say the ranges overlap. Similarly, t6 = mumble t7 = t6 t8 = t6 + 5 t9 = t7 + 10 print t8, t9 Chaitin points out that t6 and t7 shouldn't interfere, even though the live ranges overlap. Anyway, I'll look at the links. Thanks, Preston > > We have separate aggressive coalescing pass before allocation. The > register allocator will later perform live range splitting inside the...

...that t2 and t0 shouldn't interfere, >>> but some folks might say the ranges overlap. >>> >>> Similarly, >>> >>> t6 = mumble >>> t7 = t6 >>> t8 = t6 + 5 >>> t9 = t7 + 10 >>> print t8, t9 >>> >>> Chaitin points out that t6 and t7 shouldn't interfere, >>> even though the live ranges overlap. >> >> - We go out of SSA form before allocating registers so you won't see phi instruction. >> - In the second case the copy coalesceing pass should have coalesced t6 and t7....

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 approaches to get >> familiar with the framework. > > Before doing that, can you describe your research a bit? A number of > people (inc...

...rg/course/cs232/papers/HackGoos-ipl06.pdf A lot of the earlier literature regarding the register allocation problem describes the general graph colouring problem as NP-complete, however previous research in Register Allocation has been in the context of programs that were not in SSA form. i.e. the Chaitin-Briggs paper states that register allocation is NP-complete and proposes an iterative algorithm. If one reads Hack Goos, there is the discovery that programs that are in SSA form have chordal graphs, and the colouring algorithm for chordal graphs can be completed in polynomial time. After the cost...

...0 + 3 > print t0 > } > t4 = phi(t2, t3) > > > it's clear that t2 and t0 shouldn't interfere, > but some folks might say the ranges overlap. > > > Similarly, > > t6 = mumble > t7 = t6 > t8 = t6 + 5 > t9 = t7 + 10 > print t8, t9 > > > Chaitin points out that t6 and t7 shouldn't interfere, > even though the live ranges overlap. > > - We go out of SSA form before allocating registers so you won't see phi > instruction. > - In the second case the copy coalesceing pass should have coalesced t6 > and t7. > > I...

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

...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 literature, e.g. linear scan, graph coloring, iterated register coalescing by Chaitin-Briggs, register allocation by priority-based coloring by Chow and Hennesey and if it represents an extension of one of those algorithms or if it is a totally new algorithm. And of course it would be nice if the terminology used by this description would follow the one published in the literature,...