llvm dev - May 2009 - [LLVMdev] [PATCH] llvm-config: add svn revision to --version

Frits van Bommel skrev:
> Benjamin Kramer wrote:
>   
>> At the moment llvm-config outputs "2.6svn" if llvm is build
from trunk
>>
>> $ llvm-config --version
>> 2.6svn
>>
>> Some external projects (built out-of-tree) need to know which revision 
>> of llvm is installed. LDC currently asks llvm-config --src-root for the
>> source directory and then parses svn info's output to get the
revision
>> number. This requires the user to keep the llvm source tree around even
>> if it is not needed to build ldc.
>>     
>
> Not technically true; it's not *required*. However, if this isn't
done you need
> to set it manually in the cmake configuration...
>
>   
>> The attached patch modifies the llvm build system (both autotools and 
>> cmake) to write the revision into PACKAGE_VERSION:
>>
>> $ llvm-config --version
>> 2.6-71981
>>     
>
> I don't think that's enough for LDC; we want to be able to compare
the version
> with #if, so we need it to produce something like '#define LLVM_REV
71981' (i.e.
> a raw integer, not a string).
>   
When we build Icedtea shark JIT we use the llvm-config version to make 
the icedtea code compatible with api changes in llvm.
I belive you are trying to do something similarwith LDC. This can be 
done without changing the llvm codebase.

I suggest the following:
add to the LDC configure.

LLVM_CFLAGS="$LLVM_CFLAGS -DLLVM_VERSION=`$LLVM_CONFIG --version | sed
's/\.//;s/svn.*//'`"

this will take the llvm-config --version output and truncates the versionnumber
from

2.6svn to 26

now the LLVM_VERSION can be used in your source code like this:

#if LLVM_VERSION >= 26
/*llvm 2.6 and above compatible code*/
#endif

#if LLVM_VERSION >= 25
// etc...
#endif

cheers
Xerxes

Xerxes Rånby wrote:
> Frits van Bommel skrev:
>> Benjamin Kramer wrote:
>>> The attached patch modifies the llvm build system (both autotools
and
>>> cmake) to write the revision into PACKAGE_VERSION:
>>>
>>> $ llvm-config --version
>>> 2.6-71981
>>>     
>> I don't think that's enough for LDC; we want to be able to
compare the version
>> with #if, so we need it to produce something like '#define LLVM_REV
71981' (i.e.
>> a raw integer, not a string).
>>   
> When we build Icedtea shark JIT we use the llvm-config version to make 
> the icedtea code compatible with api changes in llvm.
> I belive you are trying to do something similarwith LDC. This can be 
> done without changing the llvm codebase.
> 
> I suggest the following:
> add to the LDC configure.
> 
> LLVM_CFLAGS="$LLVM_CFLAGS -DLLVM_VERSION=`$LLVM_CONFIG --version | sed
's/\.//;s/svn.*//'`"
> 
> this will take the llvm-config --version output and truncates the
versionnumber from
> 
> 2.6svn to 26
> 
> now the LLVM_VERSION can be used in your source code like this:
> 
> #if LLVM_VERSION >= 26
> /*llvm 2.6 and above compatible code*/
> #endif
> 
> #if LLVM_VERSION >= 25
> // etc...
> #endif
That's not precise enough. API changes are introduced in svn all the time,
and
bugs are fixed (obsoleting workarounds). We currently test for 5 different trunk
revisions after 2.5.

Though I suppose a similar technique could be used with the original version of 
the patch, sed'ing out the revision nr. It'd certainly be less
error-prone than
the current approach.

On 2009-05-18 20:06, Frits van Bommel wrote:
> Xerxes Rånby wrote:
>   
>> Frits van Bommel skrev:
>>     
>>> Benjamin Kramer wrote:
>>>       
>>>> The attached patch modifies the llvm build system (both
autotools and
>>>> cmake) to write the revision into PACKAGE_VERSION:
>>>>
>>>> $ llvm-config --version
>>>> 2.6-71981
>>>>     
>>>>         
>>> I don't think that's enough for LDC; we want to be able to
compare the version
>>> with #if, so we need it to produce something like '#define
LLVM_REV 71981' (i.e.
>>> a raw integer, not a string).
>>>   
>>>       
>> When we build Icedtea shark JIT we use the llvm-config version to make 
>> the icedtea code compatible with api changes in llvm.
>> I belive you are trying to do something similarwith LDC. This can be 
>> done without changing the llvm codebase.
>>
>> I suggest the following:
>> add to the LDC configure.
>>
>> LLVM_CFLAGS="$LLVM_CFLAGS -DLLVM_VERSION=`$LLVM_CONFIG --version |
sed 's/\.//;s/svn.*//'`"
>>
>> this will take the llvm-config --version output and truncates the
versionnumber from
>>
>> 2.6svn to 26
>>
>> now the LLVM_VERSION can be used in your source code like this:
>>
>> #if LLVM_VERSION >= 26
>> /*llvm 2.6 and above compatible code*/
>> #endif
>>
>> #if LLVM_VERSION >= 25
>> // etc...
>> #endif
>>     
>
> That's not precise enough. API changes are introduced in svn all the
time, and
> bugs are fixed (obsoleting workarounds). We currently test for 5 different
trunk
> revisions after 2.5.
>
> Though I suppose a similar technique could be used with the original
version of
> the patch, sed'ing out the revision nr. It'd certainly be less
error-prone than
> the current approach.
I think you don't need to support all trunk revisions.
People using trunk could be told to either update to a certain revision,
or stick to a released version.

This should suffice:

#if LLVM_VERSION >= 25
....
#endif

#if LLVM_VERSION == 26
#if LLVM_REVISION < MINIMUM_THAT_CONTAINS_ALLYOUNEED
#error "Please update to SVN rXYZ"
#else
//code for SVN API
#endif

Best regards,
--Edwin