double getorisig(double *F, double *ec, double *u) {
  double s1, s2;
  s1 = F[0] * u[3] + F[3] * u[4] + F[6] * u[5];
  s2 = ec[1] * u[2] - ec[2] * u[1];
  return (s1 * s2);
}


x86 assembly (clang, -O0):
<getorisig>:
push   %rbp
mov    %rsp,%rbp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    %rdx,-0x18(%rbp)
mov    -0x8(%rbp),%rax
movsd  (%rax),%xmm1
mov    -0x18(%rbp),%rax
movsd  0x18(%rax),%xmm2
mov    -0x8(%rbp),%rax
movsd  0x18(%rax),%xmm0
mov    -0x18(%rbp),%rax
mulsd  0x20(%rax),%xmm0
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
mov    -0x8(%rbp),%rax
movsd  0x30(%rax),%xmm0
mov    -0x18(%rbp),%rax
movsd  0x28(%rax),%xmm2
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
movsd  %xmm0,-0x20(%rbp)
mov    -0x10(%rbp),%rax
movsd  0x8(%rax),%xmm0
mov    -0x18(%rbp),%rax
movsd  0x10(%rax),%xmm2
mov    -0x10(%rbp),%rax
movsd  0x10(%rax),%xmm1
mov    -0x18(%rbp),%rax
mulsd  0x8(%rax),%xmm1
movq   %xmm1,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
movsd  %xmm0,-0x28(%rbp)
movsd  -0x20(%rbp),%xmm0
mulsd  -0x28(%rbp),%xmm0
pop    %rbp
ret

x86 assembly (clang, -O2):
<getorisig>:
movsd  0x18(%rdi),%xmm0
mulsd  0x20(%rdx),%xmm0
movsd  (%rdi),%xmm1
mulsd  0x18(%rdx),%xmm1
addsd  %xmm0,%xmm1
movsd  0x30(%rdi),%xmm2
mulsd  0x28(%rdx),%xmm2
addsd  %xmm1,%xmm2
movsd  0x8(%rsi),%xmm0
movsd  0x8(%rdx),%xmm1
mulsd  0x10(%rsi),%xmm1
mulsd  0x10(%rdx),%xmm0
subsd  %xmm1,%xmm0
mulsd  %xmm2,%xmm0
ret

LLVM IR (-O0):
define double @getorisig(double* %0, double* %1, double* %2) {
%4 = alloca double*
%5 = alloca double*
%6 = alloca double*
%7 = alloca double
%8 = alloca double
store double* %0, double** %4
store double* %1, double** %5
store double* %2, double** %6
%9 = load double*, double** %4
%10 = getelementptr inbounds double, double* %9, i64 0
%11 = load double, double* %10
%12 = load double*, double** %6
%13 = getelementptr inbounds double, double* %12, i64 3
%14 = load double, double* %13
%15 = load double*, double** %4
%16 = getelementptr inbounds double, double* %15, i64 3
%17 = load double, double* %16
%18 = load double*, double** %6
%19 = getelementptr inbounds double, double* %18, i64 4
%20 = load double, double* %19
%21 = fmul double %17, %20
%22 = call double @llvm.fmuladd.f64(double %11, double %14, double %21)
%23 = load double*, double** %4
%24 = getelementptr inbounds double, double* %23, i64 6
%25 = load double, double* %24
%26 = load double*, double** %6
%27 = getelementptr inbounds double, double* %26, i64 5
%28 = load double, double* %27
%29 = call double @llvm.fmuladd.f64(double %25, double %28, double %22)
store double %29, double* %7
%30 = load double*, double** %5
%31 = getelementptr inbounds double, double* %30, i64 1
%32 = load double, double* %31
%33 = load double*, double** %6
%34 = getelementptr inbounds double, double* %33, i64 2
%35 = load double, double* %34
%36 = load double*, double** %5
%37 = getelementptr inbounds double, double* %36, i64 2
%38 = load double, double* %37
%39 = load double*, double** %6
%40 = getelementptr inbounds double, double* %39, i64 1
%41 = load double, double* %40
%42 = fmul double %38, %41
%43 = fneg double %42
%44 = call double @llvm.fmuladd.f64(double %32, double %35, double %43)
store double %44, double* %8
%45 = load double, double* %7
%46 = load double, double* %8
%47 = fmul double %45, %46
ret double %47
}

LLVM IR (-O2):
define double @getorisig(double* nocapture %0, double* nocapture %1, double* nocapture %2) {
%4 = load double, double* %0
%5 = getelementptr inbounds double, double* %2, i64 3
%6 = load double, double* %5
%7 = getelementptr inbounds double, double* %0, i64 3
%8 = load double, double* %7
%9 = getelementptr inbounds double, double* %2, i64 4
%10 = load double, double* %9
%11 = fmul double %8, %10
%12 = tail call double @llvm.fmuladd.f64(double %4, double %6, double %11)
%13 = getelementptr inbounds double, double* %0, i64 6
%14 = load double, double* %13
%15 = getelementptr inbounds double, double* %2, i64 5
%16 = load double, double* %15
%17 = tail call double @llvm.fmuladd.f64(double %14, double %16, double %12)
%18 = getelementptr inbounds double, double* %1, i64 1
%19 = load double, double* %18
%20 = getelementptr inbounds double, double* %2, i64 2
%21 = load double, double* %20
%22 = getelementptr inbounds double, double* %1, i64 2
%23 = load double, double* %22
%24 = getelementptr inbounds double, double* %2, i64 1
%25 = load double, double* %24
%26 = fneg double %23
%27 = fmul double %25, %26
%28 = tail call double @llvm.fmuladd.f64(double %19, double %21, double %27)
%29 = fmul double %17, %28
ret double %29
}