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


x86 assembly (clang, -O0):
<multbymG>:
push   %rbp
mov    %rsp,%rbp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    -0x10(%rbp),%rax
movsd  0x18(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  0xecc(%rip),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,(%rax)
mov    -0x10(%rbp),%rax
movsd  0x20(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  0xe98(%rip),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x8(%rax)
mov    -0x10(%rbp),%rax
movsd  0x28(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  0xe63(%rip),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x10(%rax)
mov    -0x10(%rbp),%rax
movsd  0x30(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  0xe2e(%rip),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x18(%rax)
mov    -0x10(%rbp),%rax
movsd  0x38(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  0xdf9(%rip),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x20(%rax)
mov    -0x10(%rbp),%rax
movsd  0x40(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  0xdc4(%rip),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x28(%rax)
mov    -0x10(%rbp),%rax
movsd  0x48(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  0xd8f(%rip),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x30(%rax)
mov    -0x10(%rbp),%rax
movsd  0x50(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  0xd5a(%rip),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x38(%rax)
pop    %rbp
ret

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

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

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