Disassembled inner loop from ATLAS sdot

gistfile1.txt

=> 0x00007fffefc226b0 <+0>:     movslq %edi,%rax
   0x00007fffefc226b3 <+3>:     vxorps %xmm0,%xmm0,%xmm0
   0x00007fffefc226b7 <+7>:     and    $0xfffffffc,%edi
   0x00007fffefc226ba <+10>:    lea    (%rsi,%rax,4),%r8
   0x00007fffefc226be <+14>:    movslq %edi,%rdi
   0x00007fffefc226c1 <+17>:    lea    (%rsi,%rdi,4),%rdi
   0x00007fffefc226c5 <+21>:    cmp    %rdi,%rsi
   0x00007fffefc226c8 <+24>:    je     0x7fffefc22754 <ATL_sdot_xp1yp1aXbX+164>
   0x00007fffefc226ce <+30>:    vxorps %xmm1,%xmm1,%xmm1
   0x00007fffefc226d2 <+34>:    mov    %rcx,%rdx
   0x00007fffefc226d5 <+37>:    mov    %rsi,%rax
   0x00007fffefc226d8 <+40>:    vmovaps %xmm1,%xmm2
   0x00007fffefc226dc <+44>:    vmovaps %xmm1,%xmm3
   0x00007fffefc226e0 <+48>:    vmovaps %xmm1,%xmm0
   0x00007fffefc226e4 <+52>:    nopl   0x0(%rax)
   0x00007fffefc226e8 <+56>:    prefetchnta 0x140(%rax)
   0x00007fffefc226ef <+63>:    vmovss (%rax),%xmm4
   0x00007fffefc226f3 <+67>:    vmulss (%rdx),%xmm4,%xmm4
   0x00007fffefc226f7 <+71>:    vaddss %xmm4,%xmm1,%xmm1
   0x00007fffefc226fb <+75>:    vmovss 0x4(%rax),%xmm4
   0x00007fffefc22700 <+80>:    vmulss 0x4(%rdx),%xmm4,%xmm4
   0x00007fffefc22705 <+85>:    vaddss %xmm4,%xmm0,%xmm0
   0x00007fffefc22709 <+89>:    vmovss 0x8(%rax),%xmm4
   0x00007fffefc2270e <+94>:    vmulss 0x8(%rdx),%xmm4,%xmm4
   0x00007fffefc22713 <+99>:    vaddss %xmm4,%xmm3,%xmm3
   0x00007fffefc22717 <+103>:   vmovss 0xc(%rax),%xmm4
   0x00007fffefc2271c <+108>:   add    $0x10,%rax
   0x00007fffefc22720 <+112>:   vmulss 0xc(%rdx),%xmm4,%xmm4
   0x00007fffefc22725 <+117>:   add    $0x10,%rdx
   0x00007fffefc22729 <+121>:   vaddss %xmm4,%xmm2,%xmm2
   0x00007fffefc2272d <+125>:   cmp    %rdi,%rax
   0x00007fffefc22730 <+128>:   jne    0x7fffefc226e8 <ATL_sdot_xp1yp1aXbX+56>
   0x00007fffefc22732 <+130>:   add    $0x10,%rsi
   0x00007fffefc22736 <+134>:   mov    %rdi,%rax
   0x00007fffefc22739 <+137>:   vaddss %xmm0,%xmm1,%xmm0
   0x00007fffefc2273d <+141>:   sub    %rsi,%rax
   0x00007fffefc22740 <+144>:   vaddss %xmm2,%xmm3,%xmm2
   0x00007fffefc22744 <+148>:   mov    %rax,%rsi
   0x00007fffefc22747 <+151>:   vaddss %xmm2,%xmm0,%xmm0
   0x00007fffefc2274b <+155>:   and    $0xfffffffffffffff0,%rsi
   0x00007fffefc2274f <+159>:   lea    0x10(%rcx,%rsi,1),%rcx
   0x00007fffefc22754 <+164>:   cmp    %rdi,%r8
   0x00007fffefc22757 <+167>:   je     0x7fffefc22779 <ATL_sdot_xp1yp1aXbX+201>
   0x00007fffefc22759 <+169>:   mov    %rdi,%rax
   0x00007fffefc2275c <+172>:   nopl   0x0(%rax)
   0x00007fffefc22760 <+176>:   vmovss (%rax),%xmm1
   0x00007fffefc22764 <+180>:   add    $0x4,%rax
---Type <return> to continue, or q <return> to quit---
   0x00007fffefc22768 <+184>:   vmulss (%rcx),%xmm1,%xmm1
   0x00007fffefc2276c <+188>:   add    $0x4,%rcx
   0x00007fffefc22770 <+192>:   vaddss %xmm1,%xmm0,%xmm0
   0x00007fffefc22774 <+196>:   cmp    %rax,%r8
   0x00007fffefc22777 <+199>:   jne    0x7fffefc22760 <ATL_sdot_xp1yp1aXbX+176>
   0x00007fffefc22779 <+201>:   repz retq 

This is basically the scalar loop unrolled four times.