The following pattern in MD5 intrinsic is inefficient. The updated value is written to the memory and immediately read back from the memory.

loop0:
  movl(rax, Address(rdi, 0)); // 4) read the value at the address stored in rdi (The value was just written to the memory.)
  // loop body
  addl(Address(rdi, 0), rax); // 1) read the value at the address stored in rdi, 2) add the value of rax, 3) write back to the address stored in rdi
  // jump to loop0