Rahmenzeiger

Rahmenzeiger is a German term used in computing to denote the frame pointer, a register or reference used to address the current function’s stack frame. The concept is part of many calling conventions where a stable base pointer is provided for accessing function parameters and local variables during the execution of a procedure.

In typical stack frame layouts, the frame pointer points to a fixed position within the current function’s stack frame. From this reference point, parameters passed to the function and saved registers are accessed via fixed offsets, while local variables are addressed with negative offsets. The frame pointer remains constant throughout the function’s execution even as the stack pointer fluctuates with pushes and pops. This stabilizes frame layouts, simplifies debugging, and makes stack unwinding easier for exceptions and backtraces.

Usage and variations: The frame pointer is commonly implemented by a dedicated register on many architectures. On x86 and x86-64, the registers EBP (32-bit) and RBP (64-bit) have historically served as frame pointers. Some architectures use a designated frame-pointer register such as FP, while others may allow frame pointer elimination, where the compiler omits a separate frame pointer to free a register for other uses. Frame-pointer elimination can improve optimization and performance but may complicate debugging and certain runtime features.

Historical and current role: Frame pointers were central in earlier compiler generations and many debugging tools. Today, many compilers default to omit-frame-pointer in optimized builds but preserve the frame pointer in debuggable builds or for certain debugging, exception handling, and ABI requirements.

See also: stack frame, calling convention, frame pointer elimination, debugging.