LLVM IR function names which disable mangling start with '\01'
(https://www.llvm.org/docs/LangRef.html#identifiers).
When an identifier like "\01@abc@" gets dumped to MIR, it is quoted, but
only with single quotes.
http://www.yaml.org/spec/1.2/spec.html#id2770814:
"The allowed character range explicitly excludes the C0 control block
allowed), the surrogate block #xD800-#xDFFF, #xFFFE, and #xFFFF."
http://www.yaml.org/spec/1.2/spec.html#id2776092:
"All non-printable characters must be escaped.
[...]
Note that escape sequences are only interpreted in double-quoted scalars."
This patch adds support for printing escaped non-printable characters
between double quotes if needed.
Should also fix PR31743.
Differential Revision: https://reviews.llvm.org/D41290
llvm-svn: 320996
Francis Visoiu Mistrih