[LLVMdev] proposed patch to default to isl-only polly

[Jack Howarth]

On Tue, Nov 19, 2013 at 12:07:18PM +0100, Tobias Grosser wrote:
> On 11/19/2013 08:50 PM, Jack Howarth wrote:
>> Tobias,
>>      Can we add something like the following to polly 3.4?
>>
>> Index: CMakeLists.txt
>> ===================================================================
>> --- CMakeLists.txt	(revision 195142)
>> +++ CMakeLists.txt	(working copy)
>> @@ -81,9 +81,14 @@ set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PAT
>>
>>   FIND_PACKAGE(Isl REQUIRED)
>>   FIND_PACKAGE(Gmp REQUIRED)
>> -FIND_PACKAGE(Cloog)
>>   FIND_PACKAGE(Pluto)
>>
>> +option(POLLY_USE_CLOOG "Build Polly with Cloog support" OFF)
>> +if (POLLY_USE_CLOOG)
>> +  # Build Cloog support in Polly (default is ISL-only).
>> +  FIND_PACKAGE(Cloog)
>> +endif(POLLY_USE_CLOOG)
>
> Hi Jack,
>
> thanks for writing a patch for your feature request. The patch itself  
> looks good the way it is implemented. Though I wonder why it is needed.  
> Polly only uses CLooG if available, so I assume you have a CLooG version  
> installed, but you do not want to use it. What is the reason you do not  
> want to use the installed CLooG version. Is the CLooG version outdated  
> and Polly does not work with it? Or is there another reason for this?
>
> The reason the isl code generation is not yet default is because we do  
> not yet support openmp code generation support for it. Would you be OK  
> with installing Polly without OpenMP generation support?

Tobias,
    The idea is to have some control on whether Polly is built with
cloog outside of crudely deinstalling the cloog headers and libraries
each time Polly is built. If you don't want to default to ISL-only yet,
this change would still be useful even if the default is switched to...

option(POLLY_USE_CLOOG "Build Polly with Cloog support" ON)

since users could still pass cmake...

-DPOLLY_USE_CLOOG=OFF

rather than deinstalling the cloog headers/libraries to achieve an
ISL-only build of Polly.
     I am confused by your comments on OpenMP support. Is this support
parallel and independent of the new OpenMP support from Intel?

http://blog.llvm.org/2013/10/openmp-project.html

My understanding was that this code hadn't been merged in for the
llvm 3.4 release.
          Jack

>
> Cheers,
> Tobias