This change converts the function to an iterative approach using
explicit stacks, which prevents deep recursion and eliminates the risk
of stack overflow.
rg-edit regexp: llama_grammar_advance_stack
rg-edit extra-args: -A30
rg-edit directive: """Rewrite: fix the following segfault:
[..]
⚫ Testing segfault. Grammar:
root ::= ( [x]* )*
root ::= ( [x]* )*
Segmentation fault build/bin/test-grammar-integration
convert from recursive to interactive"""
gptel-context:
(("~/llama.cpp/src/llama-grammar.cpp")
("~/llama.cpp/tests/test-grammar-integration.cpp")
("~/llama.cpp/grammars/./list.gbnf")
("~/llama.cpp/grammars/./json_arr.gbnf")
("~/llama.cpp/grammars/./json.gbnf")
("~/llama.cpp/grammars/./japanese.gbnf")
("~/llama.cpp/grammars/./english.gbnf")
("~/llama.cpp/grammars/./chess.gbnf")
("~/llama.cpp/grammars/./c.gbnf")
("~/llama.cpp/grammars/./arithmetic.gbnf")
("~/llama.cpp/grammars/./README.md"))
v2: Added a `std::set` to perform tree-based lookups with O(N log N)
complexity. Testing with a parallel run of `test-grammar-integration`
shows a double-digit percentage increase in runtime. An
`unordered_set` with O(1) hashing was also evaluated, but the overhead
of constructing hash keys from pointers made it significantly slower
than the rbtree implementation that only requires an ordering
operator. The performance regression in the test suite appears
justified by the overall reduction in algorithmic complexity.
Co-developed-by: Piotr Wilkin (ilintar) <piotr.wilkin@syndatis.com>
fee44e673a