A programming language expressing machine instructions through symbolic operation names, processor registers, labels and data directives. A concrete program must respect its instruction set's operand restrictions and the platform's calling convention.
An assembler convenience that expands into one or more actual machine instructions. Its expansion matters when counting instructions, reasoning about temporary registers, or filling a branch delay slot.
The agreement between a caller and a subroutine on argument and result placement, processor register preservation, and call stack organization. Callee-saved registers retain their incoming values across a call; caller-saved registers must be saved by the caller if their values are still needed afterwards.
The saved instruction address at which execution resumes after a function returns. A recursive call must preserve the current return address before another call overwrites the link register.
The 32-bit calling convention for the ARM architecture family. Its base variant passes initial arguments in
r0–r3, returns a word in r0, preserves r4–r8, r10, r11, and sp, and requires eight-byte stack pointer alignment at public calls.[ref]A processor register that a subroutine may overwrite. A caller retaining a live value in such a processor register must preserve it elsewhere before calling. Argument and result processor registers commonly have this role.
A processor register whose incoming value a called subroutine must restore before returning if it modifies it. This lets a caller retain live values across calls, but the caller must in turn preserve its own caller's values when using these processor registers.
