n = (n * i)

0x100000a41:  movq   %rax, %rbx
0x100000a44:  movq   %rcx, %rax
0x100000a47:  mulq   %rbx
0x100000a4a:  imulq  %rcx, %rdi
0x100000a4e:  addq   %rdx, %rdi
0x100000a51:  imulq  %rsi, %rbx
0x100000a55:  addq   $0x1, %rcx
0x100000a59:  adcq   $0x0, %rsi
0x100000a5d:  cmpq   $0x3b9aca00, %rcx
0x100000a64:  setb   %dl
0x100000a67:  testq  %rsi, %rsi
0x100000a6a:  sets   %r8b
0x100000a6e:  je     0x100000a73
0x100000a70:  movb   %r8b, %dl
0x100000a73:  addq   %rbx, %rdi
0x100000a76:  testb  %dl, %dl
0x100000a78:  jne    0x100000a41


n = (n * i) >> 2

0x100000a31:  movq   %rax, %rbx
0x100000a34:  movq   %rcx, %rax
0x100000a37:  mulq   %rbx
0x100000a3a:  imulq  %rcx, %rdi
0x100000a3e:  addq   %rdx, %rdi
0x100000a41:  imulq  %rsi, %rbx
0x100000a45:  addq   %rdi, %rbx
0x100000a48:  addq   $0x1, %rcx
0x100000a4c:  adcq   $0x0, %rsi
0x100000a50:  cmpq   $0x3b9aca00, %rcx
0x100000a57:  setb   %dl
0x100000a5a:  testq  %rsi, %rsi
0x100000a5d:  sets   %dil
0x100000a61:  je     0x100000a66
0x100000a63:  movb   %dil, %dl
0x100000a66:  shrdq  $0x2, %rbx, %rax
0x100000a6b:  sarq   $0x2, %rbx
0x100000a6f:  testb  %dl, %dl
0x100000a71:  movq   %rbx, %rdi
0x100000a74:  jne    0x100000a31