swift234

Work around an elusive crash in DwarfDebug::endFunction().
<rdar://problem/18592152> Unchecked Swift builder is sometimes crashing in AsmPrinter::EmitFunctionBody

DIBuilder adds all DIVariables to a temporary named MDNode in
order to add them to the variables field in their parent
DISubprogram in DIBuilder::finalize(). In the absence of an
llvm::Function DIBuilder uses the human-readable name as a name
for this temporary MDnode, which in the case of specialized
generic functions (which are then SILinlining and thus
zombiefied, making them loose their llvm::Function) is not
unique, because the specialization is not encoded in the
human-readable name. Until either of these problems are fixed,
use the mangled name as human-readable name IR-less functions
here.
Work is underway to upstream an assertion in LLVM that will
ensure this won't regress.

Swift SVN r22687