void multbymGT(double *lhs, double *rhs) {
  lhs[0] = 0;
  lhs[1] = 0;
  lhs[2] = 0;
  lhs[3] = -rhs[0] * (-1);
  lhs[4] = -rhs[1] * (-1);
  lhs[5] = -rhs[2] * (-1);
  lhs[6] = -rhs[3] * (-1);
  lhs[7] = -rhs[4] * (-1);
  lhs[8] = -rhs[5] * (-1);
  lhs[9] = -rhs[6] * (-1);
  lhs[10] = -rhs[7] * (-1);
}


x86 assembly (clang, -O0):
<multbymGT>:
push   %rbp
mov    %rsp,%rbp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movsd  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movsd  %xmm0,0x8(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movsd  %xmm0,0x10(%rax)
mov    -0x10(%rbp),%rax
movsd  (%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  0xeaa(%rip),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x18(%rax)
mov    -0x10(%rbp),%rax
movsd  0x8(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  0xe75(%rip),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x20(%rax)
mov    -0x10(%rbp),%rax
movsd  0x10(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  0xe40(%rip),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x28(%rax)
mov    -0x10(%rbp),%rax
movsd  0x18(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  0xe0b(%rip),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x30(%rax)
mov    -0x10(%rbp),%rax
movsd  0x20(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  0xdd6(%rip),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x38(%rax)
mov    -0x10(%rbp),%rax
movsd  0x28(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  0xda1(%rip),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x40(%rax)
mov    -0x10(%rbp),%rax
movsd  0x30(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  0xd6c(%rip),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x48(%rax)
mov    -0x10(%rbp),%rax
movsd  0x38(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  0xd37(%rip),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x50(%rax)
pop    %rbp
ret

x86 assembly (clang, -O2):
<multbymGT>:
xorps  %xmm0,%xmm0
movups %xmm0,(%rdi)
movq   $0x0,0x10(%rdi)
movsd  (%rsi),%xmm0
movsd  %xmm0,0x18(%rdi)
movsd  0x8(%rsi),%xmm0
movsd  %xmm0,0x20(%rdi)
movsd  0x10(%rsi),%xmm0
movsd  %xmm0,0x28(%rdi)
movsd  0x18(%rsi),%xmm0
movsd  %xmm0,0x30(%rdi)
movsd  0x20(%rsi),%xmm0
movsd  %xmm0,0x38(%rdi)
movsd  0x28(%rsi),%xmm0
movsd  %xmm0,0x40(%rdi)
movsd  0x30(%rsi),%xmm0
movsd  %xmm0,0x48(%rdi)
movsd  0x38(%rsi),%xmm0
movsd  %xmm0,0x50(%rdi)
ret

LLVM IR (-O0):
define void @multbymGT(double* %0, double* %1) {
%3 = alloca double*
%4 = alloca double*
store double* %0, double** %3
store double* %1, double** %4
%5 = load double*, double** %3
%6 = getelementptr inbounds double, double* %5, i64 0
store double 0.000000e+00, double* %6
%7 = load double*, double** %3
%8 = getelementptr inbounds double, double* %7, i64 1
store double 0.000000e+00, double* %8
%9 = load double*, double** %3
%10 = getelementptr inbounds double, double* %9, i64 2
store double 0.000000e+00, double* %10
%11 = load double*, double** %4
%12 = getelementptr inbounds double, double* %11, i64 0
%13 = load double, double* %12
%14 = fneg double %13
%15 = fmul double %14, -1.000000e+00
%16 = load double*, double** %3
%17 = getelementptr inbounds double, double* %16, i64 3
store double %15, double* %17
%18 = load double*, double** %4
%19 = getelementptr inbounds double, double* %18, i64 1
%20 = load double, double* %19
%21 = fneg double %20
%22 = fmul double %21, -1.000000e+00
%23 = load double*, double** %3
%24 = getelementptr inbounds double, double* %23, i64 4
store double %22, double* %24
%25 = load double*, double** %4
%26 = getelementptr inbounds double, double* %25, i64 2
%27 = load double, double* %26
%28 = fneg double %27
%29 = fmul double %28, -1.000000e+00
%30 = load double*, double** %3
%31 = getelementptr inbounds double, double* %30, i64 5
store double %29, double* %31
%32 = load double*, double** %4
%33 = getelementptr inbounds double, double* %32, i64 3
%34 = load double, double* %33
%35 = fneg double %34
%36 = fmul double %35, -1.000000e+00
%37 = load double*, double** %3
%38 = getelementptr inbounds double, double* %37, i64 6
store double %36, double* %38
%39 = load double*, double** %4
%40 = getelementptr inbounds double, double* %39, i64 4
%41 = load double, double* %40
%42 = fneg double %41
%43 = fmul double %42, -1.000000e+00
%44 = load double*, double** %3
%45 = getelementptr inbounds double, double* %44, i64 7
store double %43, double* %45
%46 = load double*, double** %4
%47 = getelementptr inbounds double, double* %46, i64 5
%48 = load double, double* %47
%49 = fneg double %48
%50 = fmul double %49, -1.000000e+00
%51 = load double*, double** %3
%52 = getelementptr inbounds double, double* %51, i64 8
store double %50, double* %52
%53 = load double*, double** %4
%54 = getelementptr inbounds double, double* %53, i64 6
%55 = load double, double* %54
%56 = fneg double %55
%57 = fmul double %56, -1.000000e+00
%58 = load double*, double** %3
%59 = getelementptr inbounds double, double* %58, i64 9
store double %57, double* %59
%60 = load double*, double** %4
%61 = getelementptr inbounds double, double* %60, i64 7
%62 = load double, double* %61
%63 = fneg double %62
%64 = fmul double %63, -1.000000e+00
%65 = load double*, double** %3
%66 = getelementptr inbounds double, double* %65, i64 10
store double %64, double* %66
ret void
}

LLVM IR (-O2):
define void @multbymGT(double* nocapture writeonly %0, double* nocapture %1) {
%3 = bitcast double* %0 to i8*
%4 = load double, double* %1
%5 = getelementptr inbounds double, double* %0, i64 3
store double %4, double* %5
%6 = getelementptr inbounds double, double* %1, i64 1
%7 = load double, double* %6
%8 = getelementptr inbounds double, double* %0, i64 4
store double %7, double* %8
%9 = getelementptr inbounds double, double* %1, i64 2
%10 = load double, double* %9
%11 = getelementptr inbounds double, double* %0, i64 5
store double %10, double* %11
%12 = getelementptr inbounds double, double* %1, i64 3
%13 = load double, double* %12
%14 = getelementptr inbounds double, double* %0, i64 6
store double %13, double* %14
%15 = getelementptr inbounds double, double* %1, i64 4
%16 = load double, double* %15
%17 = getelementptr inbounds double, double* %0, i64 7
store double %16, double* %17
%18 = getelementptr inbounds double, double* %1, i64 5
%19 = load double, double* %18
%20 = getelementptr inbounds double, double* %0, i64 8
store double %19, double* %20
%21 = getelementptr inbounds double, double* %1, i64 6
%22 = load double, double* %21
%23 = getelementptr inbounds double, double* %0, i64 9
store double %22, double* %23
%24 = getelementptr inbounds double, double* %1, i64 7
%25 = load double, double* %24
%26 = getelementptr inbounds double, double* %0, i64 10
store double %25, double* %26
ret void
}