Will CPU registers be pushed onto the stack when BX and BLX instructions are executed?

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  Nick Posted on 2020/12/22 11:18:25

  It seems that the hardware pushes the stack only when the interrupt is entered, other times it is software PUSH, remember that according to the ATPCS, R0-R3 are used to pass parameters, and neither push nor pop the stack when calling sub-functions and exiting functions. Sometimes there are too many temporary variables in the sub-function, then the compiler will use the PUSH instruction to save the working register when the sub-function is called, then there will be POP when the sub-function is exited, but this and interrupt hardware will automatically push the stack and output The stack is different.

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