[demangler][NFC] Utility header cleanups
a) Using a do...while loop in the number formatter means we do not
have to special case zero.
b) Let's use 'if (auto size = ...) {}' for appending to the output
buffer.
c) We should also be using memcpy there, not memmove -- the string
being appended is never part of the current buffer.
d) Let's put all the operator<< functions together.
e) I find 'if (cond) frob(..., true) ; elseOD frob(..., false)'
somewhat confusing. Let's just use std::abs in the signed integer
printer and let CSE decide about the duplicate < 0 testing.
f) Let's have as many as possible return *this. That's both more
consistent, and allows tailcalls in some cases (the actual number
formatter has a local array though).
These changes removed around 100 bytes from the demangler's
instructions on x86_64.
Reviewed By: ChuanqiXu
Differential Revision: https://reviews.llvm.org/D119176
GitOrigin-RevId: f0ef708dc12eb7d3ec5d8af9abbae40bd27c07cd
1 file changed
