Christophe de Dinechin
2010-Feb-03 16:34 UTC
[LLVMdev] Changes in FunctionPassManager constructor
What guarantees does LLVM try to provide regarding source code compatibility? Case in point: rev 94686 (http://llvm.org/viewvc/llvm-project?view=rev&revision=94686) breaks any code that creates a JIT. For example, we used to construct a FunctionPassManager with a ModuleProvider, it's now to be done with a Module. I cannot ship source code for my own project that is compatible with both pre-94686 and post-94686. This seems to be relatively frequent in LLVM. My project is not very active, and it's relatively young, but I think this is the third time it hits us. At some point i had to add InitializeNativeTarget(). At some other point, I had to add "context" everywhere. And then there was another issue with globals that eludes me right now. Anyway, I have to assume that preserving source-code compatibility is a non-objective. I could not find any documentation about what the "policy" for C++ is. The check-in for 94686 seems to suggest that the C bindings are somewhat preserved, but doesn't it make sense to provide some guarantees regarding the most frequently used C++ code? Also note that the documentation is unintentionally misleading. It's very confusing for http://llvm.org/docs/tutorial/LangImpl4.html to show "Last modified: $Date: 2007-10-17 11:05:13 -0700 (Wed, 17 Oct 2007) $" at the bottom, as if nothing had changed since then, when the code it displays is actually less than a week old... I guess the source code snippets are updated automagically. As a result, the code shown there as an example will NOT compile on anything but a most recent LLVM, i.e. it will not work if you install LLVM with apt-get or MacPorts. I don't think that's desirable. Opinions? Christophe de Dinechin
On Wed, Feb 3, 2010 at 8:34 AM, Christophe de Dinechin <christophe at taodyne.com> wrote:> What guarantees does LLVM try to provide regarding source code compatibility?None.> Also note that the documentation is unintentionally misleading. It's very confusing for http://llvm.org/docs/tutorial/LangImpl4.html to show "Last modified: $Date: 2007-10-17 11:05:13 -0700 (Wed, 17 Oct 2007) $" at the bottom, as if nothing had changed since then, when the code it displays is actually less than a week old... I guess the source code snippets are updated automagically. As a result, the code shown there as an example will NOT compile on anything but a most recent LLVM, i.e. it will not work if you install LLVM with apt-get or MacPorts. I don't think that's desirable.That's the docs for trunk; to get docs for a specific release, try, for example, http://llvm.org/releases/2.6/docs/tutorial/LangImpl4.html . -Eli
Hi Christophe, So this is a pain, but we are dealing with a pre-release. Until the 2.7 freeze the source should continue to churn. Regards Garrison On Feb 3, 2010, at 11:34, Christophe de Dinechin wrote:> What guarantees does LLVM try to provide regarding source code compatibility? > > Case in point: rev 94686 (http://llvm.org/viewvc/llvm-project?view=rev&revision=94686) breaks any code that creates a JIT. For example, we used to construct a FunctionPassManager with a ModuleProvider, it's now to be done with a Module. I cannot ship source code for my own project that is compatible with both pre-94686 and post-94686. > > This seems to be relatively frequent in LLVM. My project is not very active, and it's relatively young, but I think this is the third time it hits us. At some point i had to add InitializeNativeTarget(). At some other point, I had to add "context" everywhere. And then there was another issue with globals that eludes me right now. Anyway, I have to assume that preserving source-code compatibility is a non-objective. > > I could not find any documentation about what the "policy" for C++ is. The check-in for 94686 seems to suggest that the C bindings are somewhat preserved, but doesn't it make sense to provide some guarantees regarding the most frequently used C++ code? > > Also note that the documentation is unintentionally misleading. It's very confusing for http://llvm.org/docs/tutorial/LangImpl4.html to show "Last modified: $Date: 2007-10-17 11:05:13 -0700 (Wed, 17 Oct 2007) $" at the bottom, as if nothing had changed since then, when the code it displays is actually less than a week old... I guess the source code snippets are updated automagically. As a result, the code shown there as an example will NOT compile on anything but a most recent LLVM, i.e. it will not work if you install LLVM with apt-get or MacPorts. I don't think that's desirable. > > Opinions? > > > Christophe de Dinechin > > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
So, it looks like I mis-read this. You were referring to backward compatibility. Garrison On Feb 3, 2010, at 12:11, Garrison Venn wrote:> Hi Christophe, > > So this is a pain, but we are dealing with a pre-release. Until the 2.7 freeze the source should continue to churn. > > Regards > > Garrison > > On Feb 3, 2010, at 11:34, Christophe de Dinechin wrote: > >> What guarantees does LLVM try to provide regarding source code compatibility? >> >> Case in point: rev 94686 (http://llvm.org/viewvc/llvm-project?view=rev&revision=94686) breaks any code that creates a JIT. For example, we used to construct a FunctionPassManager with a ModuleProvider, it's now to be done with a Module. I cannot ship source code for my own project that is compatible with both pre-94686 and post-94686. >> >> This seems to be relatively frequent in LLVM. My project is not very active, and it's relatively young, but I think this is the third time it hits us. At some point i had to add InitializeNativeTarget(). At some other point, I had to add "context" everywhere. And then there was another issue with globals that eludes me right now. Anyway, I have to assume that preserving source-code compatibility is a non-objective. >> >> I could not find any documentation about what the "policy" for C++ is. The check-in for 94686 seems to suggest that the C bindings are somewhat preserved, but doesn't it make sense to provide some guarantees regarding the most frequently used C++ code? >> >> Also note that the documentation is unintentionally misleading. It's very confusing for http://llvm.org/docs/tutorial/LangImpl4.html to show "Last modified: $Date: 2007-10-17 11:05:13 -0700 (Wed, 17 Oct 2007) $" at the bottom, as if nothing had changed since then, when the code it displays is actually less than a week old... I guess the source code snippets are updated automagically. As a result, the code shown there as an example will NOT compile on anything but a most recent LLVM, i.e. it will not work if you install LLVM with apt-get or MacPorts. I don't think that's desirable. >> >> Opinions? >> >> >> Christophe de Dinechin >> >> >> _______________________________________________ >> LLVM Developers mailing list >> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu >> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >
Christophe de Dinechin
2010-Feb-03 17:26 UTC
[LLVMdev] Changes in FunctionPassManager constructor
On 3 févr. 2010, at 17:54, Eli Friedman wrote:> On Wed, Feb 3, 2010 at 8:34 AM, Christophe de Dinechin > <christophe at taodyne.com> wrote: >> What guarantees does LLVM try to provide regarding source code compatibility? > > None.And this is a good thing because... ? Christophe
Christophe de Dinechin
2010-Feb-03 17:34 UTC
[LLVMdev] Changes in FunctionPassManager constructor
>> Also note that the documentation is unintentionally misleading. It's very confusing for http://llvm.org/docs/tutorial/LangImpl4.html to show "Last modified: $Date: 2007-10-17 11:05:13 -0700 (Wed, 17 Oct 2007) $" at the bottom, as if nothing had changed since then, when the code it displays is actually less than a week old... I guess the source code snippets are updated automagically. As a result, the code shown there as an example will NOT compile on anything but a most recent LLVM, i.e. it will not work if you install LLVM with apt-get or MacPorts. I don't think that's desirable. > > That's the docs for trunk; to get docs for a specific release, try, > for example, http://llvm.org/releases/2.6/docs/tutorial/LangImpl4.htmlThese are the docs I get by default if I click on "documentation" then "Tutorial" then ... or if I use Google. How is a poor schmuck trying to build his first LLVM tool supposed to figure out that the documentation is not "the right one"? Christophe
On Feb 3, 2010, at 8:34 AM, Christophe de Dinechin wrote:> Also note that the documentation is unintentionally misleading. It's very confusing for http://llvm.org/docs/tutorial/LangImpl4.html to show "Last modified: $Date: 2007-10-17 11:05:13 -0700 (Wed, 17 Oct 2007) $" at the bottom, as if nothing had changed since then, when the code it displays is actually less than a week old... I guess the source code snippets are updated automagically. As a result, the code shown there as an example will NOT compile on anything but a most recent LLVM, i.e. it will not work if you install LLVM with apt-get or MacPorts. I don't think that's desirable.This particular issue is now fixed. Unfortunately it means that all the "Last modified" dates on those pages are now today rather than their last real modification, but theoretically they should now stay current with future changes. Dan
Christophe de Dinechin
2010-Feb-03 18:41 UTC
[LLVMdev] Changes in FunctionPassManager constructor
That's much better. Thanks a lot. Christophe On 3 févr. 2010, at 19:37, Dan Gohman wrote:> > On Feb 3, 2010, at 8:34 AM, Christophe de Dinechin wrote: >> Also note that the documentation is unintentionally misleading. It's very confusing for http://llvm.org/docs/tutorial/LangImpl4.html to show "Last modified: $Date: 2007-10-17 11:05:13 -0700 (Wed, 17 Oct 2007) $" at the bottom, as if nothing had changed since then, when the code it displays is actually less than a week old... I guess the source code snippets are updated automagically. As a result, the code shown there as an example will NOT compile on anything but a most recent LLVM, i.e. it will not work if you install LLVM with apt-get or MacPorts. I don't think that's desirable. > > This particular issue is now fixed. Unfortunately it means that all the > "Last modified" dates on those pages are now today rather than their last > real modification, but theoretically they should now stay current with > future changes. > > Dan >
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