[LLVMdev] Getting Started with LLVM

[Chris Lattner]

On Wed, 15 Mar 2006, Eric Kidd wrote:
> On Mar 14, 2006, at 2:22 PM, Chris Lattner wrote:
>>> Gnome (and many other Unix projects with massively ugly dependencies) can 
>>> be linked trivially using a "foo-config" script. If LLVM had something 
>>> similar, it might save new LLVM developers several hours of digging 
>>> through manuals and Makefiles.
>> 
>> This would be very very cool to have.
>
> OK! Would something like the following interface be a reasonable first 
> approach?
>
>  llvm-config (--cxxflags | --ldflags | --libs) (all | jit)
>    --cxxflags: Flags to use when compiling C++ source code.
>    --ldflags: Linker flags to use when linking against LLVM.
>    --libs: Libraries needed to link the current configuration.
>    all: Link all LLVM libraries for the current platform.
>    jit: Link the libraries needed by the standard JIT/interpreter 
> configuration.

Sounds great.

> This fits nicely into the autoconf/autoconf view of the world, and would only 
> take an evening to get working. If llvm-gcc 4.0 requires a specific subset of 
> libraries, we could add a third hard-coded configuration.

Ok.

> Later on, we could consider adding fine-grained control over which libraries 
> get linked, perhaps based on output from GenLibDeps.pl. But that would 
> require making GenLibDeps.pl more portable (it currently uses some 
> non-portable nm flags). In any case, I'm mostly focused on making things easy 
> for first-time LLVM users.

I would be quite happy to have a hard-coded list of library dependencies, 
even if it means that we need to manually maintain them.  This will force 
us to realize and think about what dependencies there are between 
libraries.

>> For what it's worth, linking is significantly faster for a release build 
>> than a debug build.  Also, if you're on linux, updating to a new binutils 
>> can help things significantly.
>
> Thanks for the tips! I've been writing a (very primitive) llvm-grep program 
> as a warmup exercise, and I was able to JIT good code within a day of getting 
> started.

Cool!

-Chris

-- 
http://nondot.org/sabre/
http://llvm.org/