x86_64 abi

x86_64-abi.txt

http://en.wikipedia.org/wiki/X86_calling_conventions#AMD64_ABI_convention

rax function(rdi, rsi, rdx, rcx, r8, r9, ...);

                                                                Preserved across
Register     Usage                                              function calls
%rax         temporary register; with variable arguments        No
             passes information about the number of SSE
             registers used; 1st return register 
%rbx         callee-saved register; optionally used as base     Yes
             pointer
%rcx         used to pass 4th argument to functions             No
%rdx         used to pass 3rd argument to functions;            No
             2nd return register
%rsp         stack pointer                                      Yes
%rbp         callee-saved register; optionally used as frame    Yes
             pointer
%rsi         used to pass 2nd argument to functions             No
%rdi         used to pass 1st argument to functions             No
%r8          used to pass 5th argument to functions             No
%r9          used to pass 6th argument to functions             No
%r10         temporary register, used for passing a function's  No
             static chain pointer
%r11         temporary register                                 No
%r12-r15     callee-saved registers                             Yes

%xmm0-%xmm1  used to pass and return floating point arguments   No
%xmm2-%xmm7  used to pass floating point arguments              No
%xmm8-%xmm15 temporary registers                                No
%mmx0-%mmx7  temporary registers                                No
%st0,%st1    temporary registers; used to return long           No
             double arguments
%st2-%st7    temporary registers                                No
%fs          Reserved for system (as thread specific data       No
             register)      
mxcsr        SSE2 control and status word                       partial
x87 SW       x87 status word                                    No
x87 CW       x87 control word                                   Yes