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Registers which are using when passing function arguments on x86_64

Brief notes for me which registers are used when passing function arguments on x86_64:

%rdi - 1st argument (%rdi:64, %edi:32, %di:16, %dl:8)

%rsi - 2nd argument (%rsi:64, %esi:32, %si:16, %sl:8)

%rdx - 3rd argument (%rdx:64, %edx:32, %dx:16, %dl:8)

%rcx - 4th argument (%rcx:64, %ecx:32, %cx:16, %cl:8)

%r8 - 5th argument (%r8:64, %r8d:32, %r8w:16, %r8b:8)

%r9 - 6th argument (%r9:64, %r9d:32, %r9w:16, %r9b:8)

%rsp - Stack pointer

%rax - Return value

More detailed information about x86_64 registers and other useful instructions can be found here:

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About Me

A software engineer who loves any technologies that makes life easier. That’s why I love Linux and Mac at the same time.


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