[Bug tree-optimization/71361] [7/8 Regression] Changes in ivopts caused perf regression on x86

["amker at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71361

--- Comment #5 from amker at gcc dot gnu.org ---
(In reply to Jakub Jelinek from comment #4)
> So shall we defer this PR to GCC 8 then (i.e. [8 Regression] and Target
> Milestone: 8.0?  Richard, are you ok with that?

With ivopt rewriting, we now generate below code:
.L5:
        movl    (%esi,%ecx,4), %eax
        movl    40(%esp), %edx
        movl    44(%esp), %ebx
        imull   (%edi,%ecx,4), %ebx
        imull   %eax, %edx
        imull   44(%esp), %eax
        addl    %ebx, %edx
        movl    40(%esp), %ebx
        imull   (%edi,%ecx,4), %ebx
        addl    %ebx, %eax
        movl    36(%esp), %ebx
        movl    %edx, (%ebx,%ecx,4)
        movl    32(%esp), %ebx
        movl    %edx, (%edi,%ecx,4)
        movl    %eax, (%ebx,%ecx,4)
        movl    %eax, (%esi,%ecx,4)
        addl    28(%esp), %ecx
        cmpl    $511, %ecx
        jle     .L5

Which I think is optimal.  Shall we consider this fixed?