Numba installation and "make check-all" - makefile

Question

I have been trying to install numba in a virtual environment. Numba requires llvm and what seems to be a Python wrapper of llvmpy. I successfully installed it using the following steps:
wget http://llvm.org/releases/3.2/llvm-3.2.src.tar.gz
tar zxvf llvm-3.2.src.tar.gz
cd llvm-3.2.src
./configure --enable-optimized --prefix=/opt
REQUIRES_RTTI=1 make
make check-all
sudo REQUIRES_RTTI=1 make install
git clone git://github.com/llvmpy/llvmpy.git
cd llvmpy
sudo LLVM_CONFIG_PATH=/opt/bin/llvm-config /path/to/environment/bin/python setup.py install
python -c "import llvm; llvm.test()"
However, I would like to know what is the correct procedure. For example, in the line REQUIRES_RTTI=1 make and sudo REQUIRES_RTTI=1 make install, the variable REQUIRES_RTTI is repeated. Is it necessary?
According to the documentation of numba, it recommends to execute REQUIRES_RTTI=1 make install and llvmpy recommends REQUIRES_RTTI=1 make, so there are slight differences. I don't really know what each step is doing so I would appreciate a general explanation of what is going on and if all these steps are strictly necessary.
Furthermore, what is make check-all? I have seen it is particularly relevant in questions related to llvm but I don't know what is its purpose.
Another suggestion from llvmpy's documentation is to install using a different directory (--prefix) Why is that the recommended approach?
Thanks a lot

Answer 1

The following lines
REQUIRES_RTTI=1 make
sudo REQUIRES_RTTI=1 make install
use the way of setting up environment of the called process without modifying the environment of the calee (like in case of export REQUIRES_RTTI=1); from bash manual:
The environment for any simple command or function may be augmented
temporarily by prefixing it with parameter assignments. These assignment statements affect only the
environment seen by that command.
This setting is recommended because from LLVM docs:
Add REQUIRES_RTTI=1 to your environment
while running make to re-enable it. This will allow users to build
with RTTI enabled and still inherit from LLVM classes.
and according to llvmpy docs, RTTI is required.
So, forgetting this "complication" and standard requirement to use "sudo" for installing, the steps are standard:
### generating makefile:
./configure --enable-optimized --prefix=/opt
### building core libraries (make without target is the same as "make all")
make
### check-all is a makefile target that is used to run regression tests (according to LLVM docs)
make check-all
### installing the libraries to the place where other tools / libraries can find them:
make install