问题
My question is about some popular but not well documented code I have found in ARM CORTEX M startup files like this STM32.
The 'pattern' is:
.size X,.-X
,where X is a symbol or label.
I have found this answer and understand how .size directive and dot special symbol work, but still complete line seems to do nothing to me. The result of the operation .-X isn't stored anywhere.
Could anybody explain what the line does?
回答1:
That is placed at the end of function X, and the size of the function is the difference between the end of the function and the beginning. . is the current location so it's saying .size x is the difference between here and the label x.
来源：https://stackoverflow.com/questions/52818114/what-does-code-pattern-like-size-x-x-do