similar to: [LLVMdev] RFC: Garbage collection infrastructure

On Feb 27, 2009, at 12:56, Mark Shannon wrote: > Gordon Henriksen wrote: > >> The ultimate endgoal is to support schemes with still-lower >> execution overhead. The next step for LLVM GC would be elimination >> of the reload penalty for using GC intrinsics with a copying >> collector. This, again, requires that the code generator perform >> bookkeeping

Gordon Henriksen wrote: > Hi Mark, > > I don't think anyone will dispute that it's easier to hack up a shadow > stack (or plug into a conservative collector) to get up and running > with GC. That is absolutely the route to go if portability trumps > performance. Why? LLVM is all about portability AND performance. > > If you review the mailing list history,

I've written a reference-counting garbage collector for LLVM, but I'm still unclear on a few things. The following piece of code that appears on http://llvm.cs.uiuc.edu/docs/GarbageCollection.html is unclear: ;; As the pointer goes out of scope, store a null value into ;; it, to indicate that the value is no longer live. store %Object* null, %Object** %X ... How exactly does

Gordon Henriksen wrote: > > The "runtime interface" is a historical artifact. LLVM does not impose > a runtime library on its users. I wouldn't have a problem deleting all > mention of it, since LLVM does not impose a contract on the runtime. > Excellent, I found it somewhat unhelpful! >> The semantics of llvm.gcroot are vague: >> "At

On 2009-03-01, at 05:41, Mark Shannon wrote: > Gordon Henriksen wrote: > >>> The semantics of llvm.gcroot are vague: "At compile-time, the code >>> generator generates information to allow the runtime to find the >>> pointer at GC safe points." >>> >>> Vague, ill-specified interfaces are worse than none. >> >>

Hi Mark, I don't think anyone will dispute that it's easier to hack up a shadow stack (or plug into a conservative collector) to get up and running with GC. That is absolutely the route to go if portability trumps performance. If you review the mailing list history, I think you'll also find that developers who do care about performance have been disappointed with the impact

Hello, i want to implement a common lisp subset using llvm for fun. This requires the use of a garbage collector. I read the docs, but many things are still unclear to me. 1. how are collectors supposed to find all living objects? there is llvm.gcroot for marking objects on the stack,but how do collectors crawl heap objects? I did not see a way to provide custom mark functions. Are

This is a template that takes care of managing plugin registries. I wrote it because I got the distinct feeling I was needlessly reinventing the wheel as I wrote a collector registry. I haven't converted anything else to use it, though. Still, it's orthogonal and has become stable in my usage, so I thought I'd submit it in advance. To get my collector registry going, all I

Hi, I realise this might be a bit controversial ;) Suppose I am writing a VM (such as VMKit), or a VM toolkit, and I want to add a generational GC. If I want to use the llvm.gcwrite intrinsic for my write barrier then I need to write a GC and then implement for each and *every* backend the gcwrite intrinsic for my write barrier. Now, if I don't use the intrinsic, I need to write my write

Again, sorry for the delay. :( On Thu, 9 Mar 2006, Sandro Magi wrote: > I've written a reference-counting garbage collector for LLVM, but I'm > still unclear on a few things. Cool! > The following piece of code that appears on > http://llvm.cs.uiuc.edu/docs/GarbageCollection.html is unclear: > > ;; As the pointer goes out of scope, store a null value into > ;;

Hi, I'm thinking out loud, please give me some feedback. Regarding llvm.gcread and llvm.gcwrite, wouldn't it be nicer if they are implemented as: llvm.gcread(sbyte** object, uint offset) llvm.gcwrite(sbyte* data, sbyte** object, uint offset) Where you also have the offset into the object. In this way the GC would know where the header of the object we are reading/writing to is. Also

On 2007-09-15, at 18:01, Talin wrote: > I'm still (slowly) working on the project of creating a concurrent > garbage collector that works with LLVM. I want to ask a little bit > more about object tags and write barriers and so on. > > Let's start with the assumption that a particular language does not > use per-object type tags. The code generator knows the types

Ok, here's the new patch. (Please tell me if I shouldn't mail patches directly on the mailing list.) While I was editing LowerGC.cpp I made a little test (not part of this patch, but the diff with LowerGC.cpp in cvs is attached). I've added a new intrinsic called llvm.gcroot_value(sbyte*, sbyte*), which takes a pointer directly instead and transforms it into an alloca. The idea is the

On 2007-09-15, at 23:55, Talin wrote: > Gordon Henriksen wrote: > >> Can you be more specific the algorithm for which you need type >> metadata in a write barrier? No algorithms I am aware of perform >> any tracing from a write barrier. > > This one does: > > http://citeseer.ist.psu.edu/cache/papers/cs2/442/ >

On Fri, 2010-09-17 at 12:16 +0100, David Given wrote: > On 17/09/10 09:55, Pedro Ferreira wrote: > > As I understand it, LLVM simply gives you support for garbage collectors > > that you have to implement yourself and link into the final binary, > > similar to what C's malloc does (it's a library call). The issue with > > GC's is that they need to be provided

On Wed, 21 Jul 2004, Chris Lattner wrote: > > Yes, this makes a tremendous amount of sense. Do you think you could > prepare some patches to make this happen? If you have any questions, feel > free to ask :) Ok, a patch[1] is attached. I didn't care to coerce the offset, since I assume that it is an uint, but maybe I should? Hopefully I've understood the llvm source

Gordon Henriksen wrote: > Can you be more specific the algorithm for which you need type > metadata in a write barrier? No algorithms I am aware of perform any > tracing from a write barrier. > This one does: http://citeseer.ist.psu.edu/cache/papers/cs2/442/http:zSzzSzwww.cs.technion.ac.ilzSz~erezzSzPaperszSzms-sliding-views.pdf/an-on-the-fly.pdf > Write barriers are

As I understand it, LLVM simply gives you support for garbage collectors that you have to implement yourself and link into the final binary, similar to what C's malloc does (it's a library call). The issue with GC's is that they need to be provided info about the stack, thats where LLVM's support comes in. As far as I know, the garbage collector is linked into the final binary

On Apr 28, 2008, at 10:50, Jonathan S. Shapiro wrote: > On Sun, 2008-04-27 at 22:34 -0400, Gordon Henriksen wrote: >> On 2008-04-27, at 21:29, Lane Schwartz wrote: >>> Since this is a simple copying collector, the functions >>> llvm_gc_read and llvm_gc_write won't really do much: >>> void *llvm_gc_read(void *ObjPtr, void **FieldPtr) { return

Browsing http://llvm.org/releases/2.5/docs/GarbageCollection.html#ocaml I stumbled across the sentence "...The ocaml collector does not use read or write barriers, so the user program may use load and store instead of llvm.gcread and llvm.gcwrite..." Which I believe is wrong as the ocaml collector does indeed use a write barrier (caml_modify). But maybe I misunderstood? Thanks,