"To call a function, the program should place the first six integer or pointer parameters in the registers %rdi, %rsi, %rdx, %rcx, %r8, and %r9." This sounds li

"To call a function, the program should place the first six integer or pointer parameters in the registers %rdi, %rsi, %rdx, %rcx, %r8, and %r9." This sounds like System V, hence GCC.