Introduce a new PrettyStackTraceDecl.
Use it to add the top level LLVM IR generation stuff in
Backend.cpp to stack traces. We now get crashes like:
Stack dump:
0. Program arguments: clang t.c -emit-llvm
1. <eof> parser at end of file
2. t.c:1:5: LLVM IR generation of declaration 'a'
Abort
for IR generation crashes.
llvm-svn: 66153