[Target] Don't return a std::string in getRegAsmName
getRegAsmName ends up making a copy of the register's name in order to
make a lower-case version of it. This is bad because
getRegForInlineAsmConstraint, it's sole caller, does a lowercase
comparison anyway.
This resulted in a significant regression in compile time for the Linux
kernel because getRegAsmName is called in a loop by
getRegForInlineAsmConstraint.
Instead, forgo the call to lower in getRegAsmName and have it return a
StringRef.
No functionality change is intended.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@270099 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed