What are Prologue and Epilogue in Assembly?

Thu, 21 May 2026 00:00:00 +0000

When writing programs in high-level languages, there are many operations handled automatically in the background that we must manage manually in low-level languages (especially Assembly). Among the most critical of these are the prologue and epilogue sequences.

Before diving into this topic, let’s touch upon a few fundamental concepts:

Register: The fastest data storage area within the CPU; data to be processed is held here.
Stack: A memory area operating on a LIFO (Last In, First Out) basis, holding temporary data during function calls.
Stack Frame: A block of memory allocated on the stack each time a function is called, containing arguments and local variables.
ESP/RSP: The stack pointer; it points to the top of the stack. It is called ESP in x86 and RSP in x64 architecture.
EBP/RBP: The base pointer; it holds the base address of the stack frame and serves as a reference point for accessing variables.
Calling Convention: A set of rules determining how arguments are passed to functions and how return values are retrieved.
Push: Pushes a value onto the stack, moving the stack pointer down.
Pop: Pops the value from the top of the stack, moving the stack pointer up.

All these concepts form the foundation for understanding prologue and epilogue operations. Essentially, these two sequences consist entirely of setting up and tearing down the stack frame.

Assembly on 0xGently

What are Prologue and Epilogue in Assembly?