Hi, I am sure that the standard "Function Calling Sequence" described in Sys V ABI specs (both i386 and AMD64) applies to the calling of those extern functions in a C library, but does it applies to the calling of those static C functions too if we do not take the compiler's "inline" optimization into account (say such "inline" optimization has been switched off)? I think it should have two possibilities -- A and B: A. The calling of those un-inlined static C functions should also comply with the function calling sequence details (including registers usage, stack frame, parameters passing, variable arguments...) which is defined in the Sys V ABI spec just like the extern C functions do. I think A should be correct. But I didn't manage to find any detailed reference in the Sys V ABI specs (i386 & AMD64) or in the C standard. B. The calling of those un-inlined static C functions does not have to comply with the function calling sequence defined in the ABI spec. And because the calling of the function pointers which are pointing to the static C functions has to work correctly as the C standard described, so it is the compiler's free will to decide any "calling sequence" that as long as could satisfy both the Sys V ABI and the C standard. If B is right, then what is the special "calling sequence" GCC chooses for calling static C functions? Is GCC just use the same "Function Calling Sequence" rule which has been described in Sys V ABI specs (same as the calling of those extern C functions)? Thank you very much. PS: This question has been discussed on the SO yesterday, but I didn't manage to get an exact answer. -- https://stackoverflow.com/questions/53958062/does-the-standard-function-calling-sequence-described-in-sys-v-abi-specs-both Thanks a lot.
