[LLVMdev] building clang when present

[Mike Stump]

On Jan 19, 2009, at 12:35 PM, Dan Villiom Podlaski Christiansen wrote:
> On 19 Jan 2009, at 21:16, Mike Stump wrote:
>
>> On Jan 19, 2009, at 11:55 AM, Dan Villiom Podlaski Christiansen  
>> wrote:
>>> In my humble opinion, using OPTIONAL_DIRS would be better and
>>> cleaner.
>>> It may require some changes to ‘Makefile.rules’ to work as
>>> intended, though. If there's interest in such a change, I can  
>>> prepare
>>> a patch?
>>
>> Are OPTIONAL_DIRS parallel?  For some reason, I was assuming not.
>
> Well, from my recollection, PARALLEL_DIRS and the other *_DIRS don't
> interact terribly well with each other with the current LLVM build
> system. It may or may not actually be executed parallel with other
> directories, but I wouldn't consider that a problem, as Clang itself
> contains quite a lot of source files, libraries and directories.
> Parallelism within the Clang source should be Good Enough™ ;)

If there are bugs in the parallel aspects of llvm, I've never hit  
them.  I only ever build 8-way, and I expect it to just work; if it  
doesn't, I'd rather just fix it.  Avoiding parallel isn't the way to  
get a build system that just works in parallel.  Lastly, I'm more  
demanding than, good enough.

I'll add OPTIONAL_PARALLEL_DIRS, if people would rather it be done  
that way.  :-)