Generalized deterministic parsing is an extension to deterministic parsing that temporarily handles ambiguous grammars under the idea that further input will resolve apparent conflicts. The first such one was called Generalized LR or GLR, under the idea that this technique (forking and parsing parallel parse trees each time an ambiguity was found) would only work with LR. Then, once a GLL parser was demonstrated, it was hard to call the method GLR. I’m going by the naming that Grune and Jacobs gave it in their 2007 masterpiece Parsing techniques.
Bison supports GLR, and I don’t know why it’s not the default. GLR only costs more than LR when you have ambiguities in the grammar, and even C++ has only temporary ambiguities that resolve quickly. Also, you don’t need to try to rewrite the grammar to create a LALR parser.
A Practical GLR Parser Generator for Software Reverse Engineering is a paper behind a gate in ResearchGate, e.g. here
DParser, although doesn’t seem to have had much activity since initial creation in 2006.
Island Grammar-Based Parsing Using GLL and Tom. I think Adrian Johnstone is the one who demonstrated the possibility of GLL parsers.