According to the ARM Architecture Procedure Call Standard (AAPCS), which registers are typically used to pass the first four integer or pointer arguments to a subroutine?
Think about the registers reserved for argument passing before the stack is used.
The AAPCS specifies that the first four integer or pointer arguments are passed in registers r0, r1, r2, and r3. Additional arguments are passed on the stack.
What is the required stack alignment in bytes at a subroutine call boundary according to the AAPCS?
Consider the minimum alignment to maintain data consistency and performance.
The AAPCS requires the stack to be 16-byte aligned at a subroutine call boundary to ensure proper data alignment and efficient access.
In the AAPCS, where is the return value of a function typically placed if it is a 32-bit integer?
Think about where the first argument register overlaps with return values.
The AAPCS specifies that the return value for 32-bit integers is placed in the r0 register.
Which of the following registers are callee-saved according to the AAPCS?
Consider which registers the called function must preserve.
Registers r4 to r11 are callee-saved, meaning the called function must save and restore them if it uses them.
What is the most likely consequence if a subroutine call violates the 8-byte stack alignment rule specified by the AAPCS?
Think about hardware requirements for memory access alignment.
Violating the 8-byte stack alignment can cause misaligned memory accesses, which may lead to data corruption or unpredictable program behavior on ARM processors.