The speaker, Nandini Jomsanas, is a software toolchain engineer who leads the Core V RISC-V GNU toolchain project. In the talk, she gives a tutorial on how to add a GCC built-in to the RISC-V compiler. Built-in functions are functions that are already implemented in the compiler and are more efficient than using inline assembly. Jomsanas explains the process of adding a built-in to the compiler, including defining the instruction patterns, RTL templates, conditions, output templates, and more. She also mentions the availability of different built-in types and function types in the RISC-V architecture. Jomsanas concludes by discussing the testing process for the built-in and provides additional resources for further exploration.