WARNING: history from now is going to change (mesa+llvm)

Current WIP, only tested nouveau (3D works very well).

pkgs/development/compilers/llvm/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, perl, groff, cmake, python }:
+{ stdenv, fetchurl, perl, groff, cmake, python, libffi, libcxx }:
 
 let version = "3.2"; in
 
@@ -10,11 +10,32 @@ stdenv.mkDerivation {
     sha256 = "0hv30v5l4fkgyijs56sr1pbrlzgd674pg143x7az2h37sb290l0j";
   };
 
-  buildInputs = [ perl groff cmake python ];
+  preConfigure = ''
+    patchShebangs .
+    export REQUIRES_RTTI=1
+  '';
 
-  cmakeFlags = [ "-DCMAKE_BUILD_TYPE=Release" ];
+  # ToDo: polly, libc++; --enable-cxx11?
+
+  configureFlags = [
+    "--enable-shared" # saves half the size, and even more for e.g. mesa
+    "--disable-assertions" "--enable-optimized"
+    "--disable-timestamps" # embedding timestamps seems a danger to purity
+    "--enable-libffi"
+    #"--enable-experimental-targets=r600"
+    #"--enable-libcpp"
+  ] ;
+
+  patches = [ ./set_soname.patch ]; # http://llvm.org/bugs/show_bug.cgi?id=12334
+  patchFlags = "-p0";
+
+  buildInputs = [ perl groff python ]
+    #++ [ libcxx ]
+    ;
+  propagatedBuildInputs = [ libffi ];
 
   enableParallelBuilding = true;
+  #ToDo: doCheck?
 
   meta = {
     homepage = http://llvm.org/;