Re: GCC beaten by ICC in stupid trig test!

[Scott Robert Ladd <coyote at coyotegulch dot com>]

Andrew Pinski wrote:
> Here is a much better benchmark to try, notice that we are doing more
>  work now but the point is that ICC is going to be the transformation
>  and it not going to see that doit is constant so it will not pull it
>  out of the loop and it cannot unroll the loop into just being a 
> constant.

Intel does *not* unroll the original code into a constnt. To wit, the 
code generated on my system:

        .globl main
main:
..B1.1:                         # Preds ..B1.0
        pushl     %ebx                                          #14.1
        movl      %esp, %ebx                                    #14.1
        andl      $-64, %esp                                    #14.1
        pushl     %edi                                          #14.1
        subl      $60, %esp                                     #14.1
        call      __intel_proc_init_N                           #14.1
        pushl     %eax                                          #14.1
        pushl     %eax                                          #14.1
        stmxcsr   (%esp)                                        #14.1
        popl      %eax                                          #14.1
        orl       $32768, %eax                                  #14.1
        pushl     %eax                                          #14.1
        ldmxcsr   (%esp)                                        #14.1
        popl      %eax                                          #14.1
        popl      %eax                                          #14.1
        movapd    _2il0floatpacket.1, %xmm0                     #18.14
        xorl      %edi, %edi                                    #17.5
        pxor      %xmm1, %xmm1                                  #
        movapd    %xmm1, 16(%esp)                               #
        call      vmldSin2                                      #18.14
                                # LOE ebp esi edi xmm0
..B1.7:                         # Preds ..B1.1
        movapd    %xmm0, 32(%esp)                               #18.14
        movapd    _2il0floatpacket.1, %xmm0                     #18.14
        call      vmldCos2                                      #18.14
                                # LOE ebp esi edi xmm0
..B1.8:                         # Preds ..B1.7
        mulpd     %xmm0, %xmm0                                  #18.14
        movapd    32(%esp), %xmm1                               #18.14
        mulpd     %xmm1, %xmm1                                  #18.14
        movapd    16(%esp), %xmm2                               #18.14
        movapd    %xmm1, 32(%esp)                               #18.14
        movapd    32(%esp), %xmm1                               #18.14
        .align    4,0x90
                                # LOE ebp esi edi xmm0 xmm1 xmm2
..B1.2:                         # Preds ..B1.8 ..B1.2
        addpd     %xmm1, %xmm2                                  #18.9
        addpd     %xmm0, %xmm2                                  #18.14
        addl      $2, %edi                                      #17.5
        cmpl      $100000000, %edi                              #17.5
        jb        ..B1.2        # Prob 100%                     #17.5
                                # LOE ebp esi edi xmm0 xmm1 xmm2
..B1.3:                         # Preds ..B1.2
        movapd    %xmm2, 16(%esp)                               #
        movapd    16(%esp), %xmm1                               #17.5
        movapd    %xmm1, %xmm0                                  #17.5
        unpckhpd  %xmm0, %xmm0                                  #17.5
        addsd     %xmm0, %xmm1                                  #
        movl      $__STRING.0, (%esp)                           #20.12
        movsd     %xmm1, 4(%esp)                                #20.23
        call      printf                                        #20.5
                                # LOE ebp esi
..B1.4:                         # Preds ..B1.3
        xorl      %eax, %eax                                    #21.12
        addl      $60, %esp                                     #21.12
        popl      %edi                                          #21.12
        movl      %ebx, %esp                                    #21.12
        popl      %ebx                                          #21.12
        ret                                                     #21.12


I made some minor mention of this in the original post, but it was 
likely too vague for you.

--
Scott Robert Ladd
Coyote Gulch Productions (http://www.coyotegulch.com)
Software Invention for High-Performance Computing