Re: LLVM as a gcc plugin?
On Mon, Jun 8, 2009 at 3:10 AM, Rafael Espindolaespind...@google.com wrote: GMP and MPFR are required components of GCC, and every developer has to deal with them. For interfacing between GCC and LLVM, the experts who'll be able to answer the questions are generally going to be found on the LLVM lists, not the gcc list, and those (like you) who participate on both lists, well, you're on both lists. That is not the case here. There is already a version of gcc that uses llvm. I'd turn that around: There is already a version of LLVM that uses GCC. I don't see any way in which the FSF GCC benefits from this. And since this list concerns the FSF GCC... Ciao! Steven
Re: LLVM as a gcc plugin?
I'd turn that around: There is already a version of LLVM that uses GCC. I don't see any way in which the FSF GCC benefits from this. And since this list concerns the FSF GCC... That is not a valid turn around. We know that the existing LLVM can handle this. We are not sure if the existing plugin infrastructure can. That also goes to the more general question should plugin development be discussed on this list?. One of the main uses of plugins will probably be adding features that are not of interest to GCC in general. Ciao! Steven Cheers, -- Rafael Avila de Espindola Google | Gordon House | Barrow Street | Dublin 4 | Ireland Registered in Dublin, Ireland | Registration Number: 368047
Re: LLVM as a gcc plugin?
GMP and MPFR are required components of GCC, and every developer has to deal with them. For interfacing between GCC and LLVM, the experts who'll be able to answer the questions are generally going to be found on the LLVM lists, not the gcc list, and those (like you) who participate on both lists, well, you're on both lists. That is not the case here. There is already a version of gcc that uses llvm. What we are trying to find is if the GCC plugin infrastructure is generic enough to support similar use cases. In a previous mail I raised some issues in GCC that illustrate this. So as a practical matter, it seems that LLVM lists are more suitable. If it's ever decided that LLVM becomes a required piece of GCC, like GMP and MPFR, that would change. Cheers, -- Rafael Avila de Espindola Google | Gordon House | Barrow Street | Dublin 4 | Ireland Registered in Dublin, Ireland | Registration Number: 368047
Re: LLVM as a gcc plugin?
Hi guys, Just saw this discussion so wanted to mention that we at HiPEAC are now interested to use both GCC as static compiler and LLVM as run-time infrastructure for research and several colleagues wanted to port ICI framework (the recent release is based on the official gcc plugin branch) to LLVM. We want to have both official gcc plugins and ICI addition on top of it since we have a relatively large community already around those tools and ICI plugins, and additional tools for automatic program optimization. I will unlikely be involved in that now because I just don't have time so I CCed this email to Andy Nisbet who has been interested to provide plugin system for LLVM, Zbigniew Chamski who supports ICI for GCC and also Albert Cohen and Ayal Zaks who are also coordinating those activities within HiPEAC. The idea is to make GCC and LLVM more attractive to the researchers (i.e. that it's easy to use compilers without knowing internals much) so that research ideas could go back to the compilers much faster improving GCC and LLVM ... Cheers, Grigori On Jun 3, 2009, at 11:30 PM, Uros Bizjak wrote: Hello! Some time ago, there was a discussion about integrating LLVM and GCC [1]. However, with plugin infrastructure in place, could LLVM be plugged into GCC as an additional optimization plugin? [1] http://gcc.gnu.org/ml/gcc/2005-11/msg00888.html Hi Uros, I'd love to see this, but I can't contribute to it directly. I think the plugin interfaces would need small extensions, but there are no specific technical issues preventing it from happening. LLVM has certainly progressed a lot since that (really old) email went out :) -Chris
Re: LLVM as a gcc plugin?
Hello, I am interested in developing LLVM functionality to support the interfaces in GCC ICI. I plan to spend some time to investigate feasibility in a couple of weeks time once all exam boards are finished. My initial goal would be to enable LLVM to be used for iterative compilation using the HiPEAC ICI framework, either as a drop in replacement for GCC, or as a plugin. I'd welcome focussed discussion and collaboration with this goal in mind. My previous work in LLVM was in trying to develop a backend for a soft-core processor written in HandelC. I am also interested in developing/extending teaching resources to support compiler based undergraduate/postgraduate courses and projects. One of my long term research goals is to investigate (implement) iterative feedback directed compilation and design space exploration tools/techniques for hybrid multicore processor architectures comprised of hard and reconfigurable logic. Thanks, Andy Dr. Andy Nisbet: URL http://www.docm.mmu.ac.uk/STAFF/A.Nisbet Department of Computing and Mathematics, John Dalton Building, Manchester Metropolitan University, Chester Street, Manchester M1 5GD, UK. Email: a.nis...@mmu.ac.uk, Phone:(+44)-161-247-1556; Fax:(+44)-161-247-6840. Before acting on this email or opening any attachments you should read the Manchester Metropolitan University's email disclaimer available on its website http://www.mmu.ac.uk/emaildisclaimer Dr. Andy Nisbet: URL http://www.docm.mmu.ac.uk/STAFF/A.Nisbet Department of Computing and Mathematics, John Dalton Building, Manchester Metropolitan University, Chester Street, Manchester M1 5GD, UK. Email: a.nis...@mmu.ac.uk, Phone:(+44)-161-247-1556; Fax:(+44)-161-247-6840. Before acting on this email or opening any attachments you should read the Manchester Metropolitan University's email disclaimer available on its website http://www.mmu.ac.uk/emaildisclaimer
Re: LLVM as a gcc plugin?
On Fri, Jun 5, 2009 at 12:40 PM, Andrew Nisbeta.nis...@mmu.ac.uk wrote: Hello, I am interested in developing LLVM functionality to support the interfaces in GCC ICI. *sigh* GCC != LLVM. And this is a GCC list. Can LLVM topics please be discussed on an LLVM mailing list? Ciao! Steven
Re: LLVM as a gcc plugin?
On Jun 5, 2009, at 3:43 AM, Steven Bosscher wrote: On Fri, Jun 5, 2009 at 12:40 PM, Andrew Nisbeta.nis...@mmu.ac.uk wrote: Hello, I am interested in developing LLVM functionality to support the interfaces in GCC ICI. *sigh* GCC != LLVM. And this is a GCC list. Can LLVM topics please be discussed on an LLVM mailing list? How is LLVM any different than another external imported library (like GMP or MPFR) in this context? -Chris
Re: LLVM as a gcc plugin?
On Fri, Jun 5, 2009 at 12:40 PM, Andrew Nisbeta.nis...@mmu.ac.uk wrote: Hello, I am interested in developing LLVM functionality to support the interfaces in GCC ICI. On Jun 5, 2009, at 3:43 AM, Steven Bosscher wrote: GCC != LLVM. And this is a GCC list. Can LLVM topics please be discussed on an LLVM mailing list? On Fri, Jun 05, 2009 at 09:48:52AM -0700, Chris Lattner wrote: How is LLVM any different than another external imported library (like GMP or MPFR) in this context? GMP and MPFR are required components of GCC, and every developer has to deal with them. For interfacing between GCC and LLVM, the experts who'll be able to answer the questions are generally going to be found on the LLVM lists, not the gcc list, and those (like you) who participate on both lists, well, you're on both lists. So as a practical matter, it seems that LLVM lists are more suitable. If it's ever decided that LLVM becomes a required piece of GCC, like GMP and MPFR, that would change.
Re: LLVM as a gcc plugin?
On Jun 3, 2009, at 11:30 PM, Uros Bizjak wrote: Hello! Some time ago, there was a discussion about integrating LLVM and GCC [1]. However, with plugin infrastructure in place, could LLVM be plugged into GCC as an additional optimization plugin? [1] http://gcc.gnu.org/ml/gcc/2005-11/msg00888.html Hi Uros, I'd love to see this, but I can't contribute to it directly. I think the plugin interfaces would need small extensions, but there are no specific technical issues preventing it from happening. LLVM has certainly progressed a lot since that (really old) email went out :) -Chris
Re: LLVM as a gcc plugin?
Chris Lattner clatt...@apple.com writes: Some time ago, there was a discussion about integrating LLVM and GCC [1]. However, with plugin infrastructure in place, could LLVM be plugged into GCC as an additional optimization plugin? I'd love to see this, but I can't contribute to it directly. I think the plugin interfaces would need small extensions, but there are no specific technical issues preventing it from happening. LLVM has certainly progressed a lot since that (really old) email went out :) Is there a description somewhere of areas where llvm is thought to do well compared to gcc, and maybe future plans for improvement? In the (limited) tests I've done, gcc [4.4, but 4.2 yields similar results] seems to do a lot better than llvm [2.5], but those were C++ code and I wonder if llvm is currently concentrating on C? -Miles -- Quotation, n. The act of repeating erroneously the words of another. The words erroneously repeated.
Re: LLVM as a gcc plugin?
Hi, Some time ago, there was a discussion about integrating LLVM and GCC [1]. However, with plugin infrastructure in place, could LLVM be plugged into GCC as an additional optimization plugin? I plan to start working on an llvm plugin any day now. Ciao, Duncan.
Re: LLVM as a gcc plugin?
I'd love to see this, but I can't contribute to it directly. I think the plugin interfaces would need small extensions, but there are no specific technical issues preventing it from happening. LLVM has certainly progressed a lot since that (really old) email went out :) I can help a bit. There was some talk about it on #gcc. A plugin should be able to see all the GCC IL, so it should be able to convert it to LLVM. Keeping the current llvm-gcc interface would require some hacks *) The plugin will have to call exit to keep gcc's code generation from running. *) It will have to remove and recreate the .s file that is being output. Not sure if this will work. *) Gcc always produces .o files by calling the assembler, so -c -emit-llvm will not work. *) The plugis options will be of the form -fplugin-arg-llvm-emit-llvm One way to avoid these problems is to make llvm-gcc a gcc wrapper that runs gcc with the llvm plugin, converts command line options and in the case of -c -emit-llvm calls llvm-as. Another source of problem will be the early transformations that gcc does and that are normally disabled in llvm-gcc. The one that I remember right now is c++ thunk generation. -Chris Cheers, -- Rafael Avila de Espindola Google | Gordon House | Barrow Street | Dublin 4 | Ireland Registered in Dublin, Ireland | Registration Number: 368047
Re: LLVM as a gcc plugin?
On Thu, Jun 4, 2009 at 12:14 PM, Rafael Espindola espind...@google.com wrote: I'd love to see this, but I can't contribute to it directly. I think the plugin interfaces would need small extensions, but there are no specific technical issues preventing it from happening. LLVM has certainly progressed a lot since that (really old) email went out :) I can help a bit. Excuse me if this is a stupid question, but eh -- why would you want to make an LLVM plugin? Aren't LLVM and GCC doing just fine as competing compilers? Ciao! Steven
Re: LLVM as a gcc plugin?
Excuse me if this is a stupid question, but eh -- why would you want to make an LLVM plugin? Aren't LLVM and GCC doing just fine as competing compilers? LLVM is a toolkit. There is a patched version of GCC that uses LLVM (llvm-gcc). This is particularly important for fortran and ada since clang supports only c like languages. The hope is that a plugin will be easier to maintain than llvm-gcc. Ciao! Steven Cheers, -- Rafael Avila de Espindola Google | Gordon House | Barrow Street | Dublin 4 | Ireland Registered in Dublin, Ireland | Registration Number: 368047
Re: LLVM as a gcc plugin?
On Jun 3, 2009, at 11:59 PM, Miles Bader wrote: Chris Lattner clatt...@apple.com writes: Some time ago, there was a discussion about integrating LLVM and GCC [1]. However, with plugin infrastructure in place, could LLVM be plugged into GCC as an additional optimization plugin? I'd love to see this, but I can't contribute to it directly. I think the plugin interfaces would need small extensions, but there are no specific technical issues preventing it from happening. LLVM has certainly progressed a lot since that (really old) email went out :) Is there a description somewhere of areas where llvm is thought to do well compared to gcc, and maybe future plans for improvement? In the (limited) tests I've done, gcc [4.4, but 4.2 yields similar results] seems to do a lot better than llvm [2.5], but those were C++ code and I wonder if llvm is currently concentrating on C? LLVM has many capabilities and advantages that GCC doesn't (and is also missing some features and capabilities that GCC has), but it is also common to misconfigure it so that it isn't optimizing like it should. It is pretty off topic for this list though, please ask on the llvmdev mailing list for more information. Please send information about how you built llvm and what your machine configuration is, Thanks, -Chris
Re: LLVM as a gcc plugin?
On Jun 4, 2009, at 3:20 AM, Steven Bosscher wrote: On Thu, Jun 4, 2009 at 12:14 PM, Rafael Espindola espind...@google.com wrote: I'd love to see this, but I can't contribute to it directly. I think the plugin interfaces would need small extensions, but there are no specific technical issues preventing it from happening. LLVM has certainly progressed a lot since that (really old) email went out :) I can help a bit. Aren't LLVM and GCC doing just fine as competing compilers? I'm not sure what you mean, LLVM and GCC are two completely different things. LLVM is an infrastructure for building compilers, GCC is an instance of a compiler. Combining LLVM with GCC gives LLVM-GCC (another instance of a compiler), which adds new capabilities to GCC that many users find useful. These include things such as cross- language LTO support (for C, c++, fortran, etc), JIT compilation, better performance in some scenarios, etc. Excuse me if this is a stupid question, but eh -- why would you want to make an LLVM plugin? There are multiple answers to this question. The most obvious one is that the current version of llvm-gcc is stuck on GCC 4.2, and 4.2 lacks a number of improvements the fortran and ada front-ends and runtimes. It would be straight-forward to forward port the patches to gcc mainline, but presumably implementing llvm-gcc in terms of plugins would result in something that has easier maintenance (this remains to be seen of course). -Chris
Re: LLVM as a gcc plugin?
Hi Rafael, There was some talk about it on #gcc. A plugin should be able to see all the GCC IL, so it should be able to convert it to LLVM. Keeping the current llvm-gcc interface would require some hacks *) The plugin will have to call exit to keep gcc's code generation from running. this would work when doing unit-at-a-time, but not when doing function-at-a-time. Does gcc still do function-at-a-time? Another source of problem will be the early transformations that gcc does and that are normally disabled in llvm-gcc. The one that I remember right now is c++ thunk generation. Good point. Ciao, Duncan.
Re: LLVM as a gcc plugin?
Duncan Sands baldr...@free.fr writes: this would work when doing unit-at-a-time, but not when doing function-at-a-time. Does gcc still do function-at-a-time? No. Ian
