[LLVMdev] Segfault calling LLVM libs from a clang-compiled executable

[Talin]

A couple of months ago, I started the process of updating my CMake scripts
to allow my compiler to be compiled with clang. I quickly ran into a problem
calling the LLVM libraries, which is that I would get segfaults when calling
LLVM API functions. I posted about this on both the clang and llvm-dev
lists, but there was no response, so I decided to put the clang-related work
on hold.

Last week I decided to pick this up again. My motivation for doing so is
that it's much easier to work with clang's error diagnostics, and coding is
generally more productive. However, I once again observed the same problem,
which I will now attempt to describe in some detail:

I start with a fresh checkout of both llvm and clang. Both get compiled with
gcc (this is on the most recent version of Ubuntu, 64-bit although I've seen
the same problem on other OS configurations.) Then I compile my compiler
with clang, and link it against the llvm libs. Everything works fine up to a
point - that is, I'm able to use all of the ADT classes, derived types, and
so on - until I get into the code generation phase, at which point things
blow up. Specifically, I get a segfault in DIBuilder::createPointerType()
(well, actually the segfault is several stack levels down from that.)

Looking in gdb, it appears that there is some sort of calling convention
mismatch - my code is calling createPointerType() with an empty StringRef(),
but when I attempt to look at the StringRef argument from within the
createPointerType() function, the field values are garbage. This is exactly
at the point where execution is transitioning from clang-compiled code to
gcc-compiled code.

If I instead compile my frontend with gcc, everything works fine.

If you want to see what command-line flags I'm passing to clang, here's what
my CMakeLists.txt looks like:

http://code.google.com/p/tart/source/browse/trunk/CMakeLists.txt#156

-- 
-- Talin
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