How does CRuby guarantee object identity and correctness using VALUE tagging and heap pointers?

CRuby uses tagged VALUE types where small integers and symbols are encoded directly while heap objects are referenced via pointers.

CRuby represents every Ruby object as a VALUE. Some values are immediate (Fixnum, Symbol, true/false/nil) encoded directly in bits, while others are heap pointers pointing to RVALUE structures. This design avoids allocation overhead for common primitives. The VM distinguishes types using bit patterns. This hybrid representation improves performance but requires careful masking logic for type checks and operations.