Emit correct kernel arguments debug metadata types when NUMBA_DUMP_LLVM is on.

After shifting out the return value type from the operands of 'types' field of
the 'DISubroutineType' metadata node, compiler needs to clear the cached string
representation of the corresponding MDValue object if NUMBA_DUMP_LLVM is on.

Because at that moment, the cached string has already been filled with the
tuple before kernel_fixup() which has the return value type and continue being
used when printing out the LLVM IR.

This change fixes #135

Author: jiel-nv

numba_cuda/numba/cuda/compiler.py

@@ -427,6 +427,8 @@ def kernel_fixup(kernel, debug):
                         if tm_name == 'types':
                             types = tm_value
                             types.operands = types.operands[1:]
+                            if config.DUMP_LLVM:
+                                types._clear_string_cache()
 
     # Mark as a kernel for NVVM