double _orbita_models_plummer_rho(const void *par, const double *pos) {
  double M = *((double *)par), b = *((double *)par + 1);
  double R_sq =
      ((pos)[0] * (pos)[0] + (pos)[1] * (pos)[1] + (pos)[2] * (pos)[2]);
  return (3 * M) * pow(1. + R_sq / ((b) * (b)), -2.5) /
         (4 * (3.14159265358979323846264338327950288419716939937510) *
          ((b) * (b) * (b)));
}


x86 assembly (clang, -O0):
<_orbita_models_plummer_rho>:
push   %rbp
mov    %rsp,%rbp
sub    $0x30,%rsp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    -0x8(%rbp),%rax
movsd  (%rax),%xmm0
movsd  %xmm0,-0x18(%rbp)
mov    -0x8(%rbp),%rax
movsd  0x8(%rax),%xmm0
movsd  %xmm0,-0x20(%rbp)
mov    -0x10(%rbp),%rax
movsd  (%rax),%xmm1
mov    -0x10(%rbp),%rax
movsd  (%rax),%xmm2
mov    -0x10(%rbp),%rax
movsd  0x8(%rax),%xmm0
mov    -0x10(%rbp),%rax
mulsd  0x8(%rax),%xmm0
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
mov    -0x10(%rbp),%rax
movsd  0x10(%rax),%xmm0
mov    -0x10(%rbp),%rax
movsd  0x10(%rax),%xmm2
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
movsd  %xmm0,-0x28(%rbp)
movsd  0xe8c(%rip),%xmm0
mulsd  -0x18(%rbp),%xmm0
movsd  %xmm0,-0x30(%rbp)
movsd  -0x28(%rbp),%xmm1
movsd  -0x20(%rbp),%xmm0
mulsd  -0x20(%rbp),%xmm0
divsd  %xmm0,%xmm1
movsd  0xe5f(%rip),%xmm0
addsd  %xmm1,%xmm0
movsd  0xe4b(%rip),%xmm1
call   1030 <pow@plt>
movaps %xmm0,%xmm1
movsd  -0x30(%rbp),%xmm0
mulsd  %xmm1,%xmm0
movsd  -0x20(%rbp),%xmm2
mulsd  -0x20(%rbp),%xmm2
mulsd  -0x20(%rbp),%xmm2
movsd  0xe1b(%rip),%xmm1
mulsd  %xmm2,%xmm1
divsd  %xmm1,%xmm0
add    $0x30,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<_orbita_models_plummer_rho>:
sub    $0x28,%rsp
movupd (%rdi),%xmm2
movapd %xmm2,0x10(%rsp)
movsd  (%rsi),%xmm1
movsd  0x8(%rsi),%xmm0
mulsd  %xmm0,%xmm0
mulsd  %xmm1,%xmm1
addsd  %xmm0,%xmm1
movsd  0x10(%rsi),%xmm0
mulsd  %xmm0,%xmm0
addsd  %xmm1,%xmm0
movapd %xmm2,%xmm1
mulpd  %xmm2,%xmm1
movapd %xmm1,(%rsp)
unpckhpd %xmm1,%xmm1
divsd  %xmm1,%xmm0
addsd  0xea3(%rip),%xmm0
movsd  0xea3(%rip),%xmm1
call   1030 <pow@plt>
movapd (%rsp),%xmm1
movlpd 0xe99(%rip),%xmm1
shufpd $0x2,0xea0(%rip),%xmm0
mulpd  0x10(%rsp),%xmm1
mulpd  %xmm1,%xmm0
movapd %xmm0,%xmm1
unpckhpd %xmm0,%xmm1
divsd  %xmm1,%xmm0
add    $0x28,%rsp
ret

LLVM IR (-O0):
define double @_orbita_models_plummer_rho(i8* %0, double* %1) {
%3 = alloca i8*
%4 = alloca double*
%5 = alloca double
%6 = alloca double
%7 = alloca double
store i8* %0, i8** %3
store double* %1, double** %4
%8 = load i8*, i8** %3
%9 = bitcast i8* %8 to double*
%10 = load double, double* %9
store double %10, double* %5
%11 = load i8*, i8** %3
%12 = bitcast i8* %11 to double*
%13 = getelementptr inbounds double, double* %12, i64 1
%14 = load double, double* %13
store double %14, double* %6
%15 = load double*, double** %4
%16 = getelementptr inbounds double, double* %15, i64 0
%17 = load double, double* %16
%18 = load double*, double** %4
%19 = getelementptr inbounds double, double* %18, i64 0
%20 = load double, double* %19
%21 = load double*, double** %4
%22 = getelementptr inbounds double, double* %21, i64 1
%23 = load double, double* %22
%24 = load double*, double** %4
%25 = getelementptr inbounds double, double* %24, i64 1
%26 = load double, double* %25
%27 = fmul double %23, %26
%28 = call double @llvm.fmuladd.f64(double %17, double %20, double %27)
%29 = load double*, double** %4
%30 = getelementptr inbounds double, double* %29, i64 2
%31 = load double, double* %30
%32 = load double*, double** %4
%33 = getelementptr inbounds double, double* %32, i64 2
%34 = load double, double* %33
%35 = call double @llvm.fmuladd.f64(double %31, double %34, double %28)
store double %35, double* %7
%36 = load double, double* %5
%37 = fmul double 3.000000e+00, %36
%38 = load double, double* %7
%39 = load double, double* %6
%40 = load double, double* %6
%41 = fmul double %39, %40
%42 = fdiv double %38, %41
%43 = fadd double 1.000000e+00, %42
%44 = call double @pow(double %43, double -2.500000e+00)
%45 = fmul double %37, %44
%46 = load double, double* %6
%47 = load double, double* %6
%48 = fmul double %46, %47
%49 = load double, double* %6
%50 = fmul double %48, %49
%51 = fmul double 0x402921FB54442D18, %50
%52 = fdiv double %45, %51
ret double %52
}

LLVM IR (-O2):
define double @_orbita_models_plummer_rho(i8* nocapture %0, double* nocapture %1) {
%3 = bitcast i8* %0 to <2 x double>*
%4 = load <2 x double>, <2 x double>* %3
%5 = load double, double* %1
%6 = getelementptr inbounds double, double* %1, i64 1
%7 = load double, double* %6
%8 = fmul double %7, %7
%9 = tail call double @llvm.fmuladd.f64(double %5, double %5, double %8)
%10 = getelementptr inbounds double, double* %1, i64 2
%11 = load double, double* %10
%12 = tail call double @llvm.fmuladd.f64(double %11, double %11, double %9)
%13 = fmul <2 x double> %4, %4
%14 = extractelement <2 x double> %13, i64 1
%15 = fdiv double %12, %14
%16 = fadd double %15, 1.000000e+00
%17 = tail call double @pow(double %16, double -2.500000e+00)
%18 = insertelement <2 x double> %13, double 3.000000e+00, i64 0
%19 = fmul <2 x double> %4, %18
%20 = insertelement <2 x double> <double poison, double 0x402921FB54442D18>, double %17, i64 0
%21 = fmul <2 x double> %19, %20
%22 = extractelement <2 x double> %21, i64 0
%23 = extractelement <2 x double> %21, i64 1
%24 = fdiv double %22, %23
ret double %24
}