[LLVMdev] include's are not being located

[Joseph]

Hi Dan,


Thank you for your advice on the build/install.


On Jun 11, 2014, at 7:06 PM, Dan Liew <dan at su-root.co.uk> wrote:

> Well on many Linux distributions LLVM and Clang are installable as
> packages (along with the header files) so for something like the
> Kaleidoscope tutorial it isn't necessary to build LLVM and Clang from
> source. However you are running OSX which I'm not familiar with so I
> don't know what the situation is there. I know clang is now the
> default compiler but I don't know if LLVM header files and libraries
> are shipped with OSX or can be installed as the OSX equivalent of a
> package.

It doesn’t appear to be installed on mac osx by default (it’s not on either of my two machines).

> You are doing what is called an "out of source build". This is where
> all the generated binary files and some build system files go in a
> different directory to the source code directory. This is the opposite
> of an "in source build" where binary files and some build system files
> go in the same directory as the source code directory. The advantage
> of doing an "out of source build" is that
> 
> - you can have multiple build configurations all building from the
> same source directory
> - Prevents you from accidently committing files generated by the build system
> - Deleting build files is really easy, you just delete the build
> directory (  /Users/josephmorgan/build )
> 
> I would stick with doing out of source builds, so this is fine.

This makes sense to me now. :)


>> 5. #configure (I am still not clear on what is purpose of prefix here)
>> /Users/josephmorgan/llvm/configure --prefix=/Users/josephmorgan/build
>> --enable-targets=x86,x86_64
> 
> If you read [1] you'll see that ``--prefix=`` is optional and that it
> sets the install location. I think you are confused between "building"
> and "installing". Building (i.e. running ``make``) builds the binaries
> in the build directory (e.g. You'll probably find the built binaries
> in /Users/josephmorgan/build/Release+Asserts/bin/). This does not
> install the binaries. By running ``make install`` this will install
> 
> LLVM Binaries to <prefix>/bin
> LLVM Libraries to <prefix>/lib
> LLVM header files to <prefix>/include
> 
> where <prefix> is what was specified using ``--prefix=`` (or the
> default /usr/local if it was not specified). Telling configure to
> build and install LLVM in the same directory like you did does not
> make any sense so if you're still confused just don't specify the
> ``--prefix=`` flag.

I am now leaving out the ``--prefix=`` flag when I make install it was able to find the includes as expected. 

> For the kaleidoscope tutorial it is actually not necessary to install
> LLVM, you can use it directly from your build directory
> (``/Users/josephmorgan/build``).
> 
> Once you've successfully built LLVM you can then build the
> Kaleidoscope example by doing something like
> 
> ```
> clang++ -g -O3 toy.cpp
> `/Users/josephmorgan/build/Release+Assert/bin/llvm-config --cppflags
> --ldflags --libs core` -o toy

I also tried this before doing a make install and it was able to find the includes as expected. Not having it originally installed in usr/local was really what caused my confusion. Installing in the build folder as you suggested in an earlier email was the culprit for me. Had I not specified "—prefix=“ flag all the includes would have been located automatically. I didn’t know that I needed to specify where the binary was for llvm-config. So I understand now.


So now that the includes are being found building the tutorial results in 74 warnings and 20 errors. Heres a couple examples:

In file included from /usr/local/include/llvm/IR/DerivedTypes.h:21:
In file included from /usr/local/include/llvm/IR/Type.h:19:
In file included from /usr/local/include/llvm/ADT/APFloat.h:20:
In file included from /usr/local/include/llvm/ADT/APInt.h:19:
In file included from /usr/local/include/llvm/ADT/ArrayRef.h:14:
/usr/local/include/llvm/ADT/SmallVector.h:232:20: warning: rvalue references are a C++11 extension [-Wc++11-extensions]
  void push_back(T &&Elt) {
                   ^
/usr/local/include/llvm/ADT/SmallVector.h:476:33: warning: rvalue references are a C++11 extension [-Wc++11-extensions]
  iterator insert(iterator I, T &&Elt) {



In file included from toy.cpp:3:
In file included from /usr/local/include/llvm/IR/IRBuilder.h:24:
In file included from /usr/local/include/llvm/IR/Instructions.h:22:
In file included from /usr/local/include/llvm/IR/Attributes.h:20:
In file included from /usr/local/include/llvm/ADT/FoldingSet.h:21:
/usr/local/include/llvm/Support/Allocator.h:134:70: error: expected expression
          BumpPtrAllocatorImpl<AllocatorT, SlabSize, SizeThreshold>> {
                                                                     ^
/usr/local/include/llvm/Support/Allocator.h:346:2: error: expected a type
};


Do you know what would cause these errors?


Thank you!
Joseph