double pnorm(z)
double z;
{
  double t, pd;
  t = 1 / (1 + 0.2316419 * z);
  pd = 1 - 0.3989423 * exp(-z * z / 2) *
               ((((1.330274429 * t - 1.821255978) * t + 1.781477937) * t -
                 0.356563782) *
                    t +
                0.319381530) *
               t;
  return (pd);
}


x86 assembly (clang, -O0):
<pnorm>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
movsd  %xmm0,-0x8(%rbp)
movsd  -0x8(%rbp),%xmm1
movsd  0xf16(%rip),%xmm0
mulsd  %xmm0,%xmm1
movsd  0xeca(%rip),%xmm0
addsd  %xmm0,%xmm1
movsd  0xebe(%rip),%xmm0
divsd  %xmm1,%xmm0
movsd  %xmm0,-0x10(%rbp)
movsd  -0x8(%rbp),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
mulsd  -0x8(%rbp),%xmm0
movsd  0xec4(%rip),%xmm1
divsd  %xmm1,%xmm0
call   1030 <exp@plt>
movaps %xmm0,%xmm1
movsd  0xea8(%rip),%xmm0
mulsd  %xmm1,%xmm0
movsd  -0x10(%rbp),%xmm1
movsd  0xe87(%rip),%xmm2
mulsd  %xmm2,%xmm1
movsd  0xe83(%rip),%xmm2
addsd  %xmm2,%xmm1
movsd  -0x10(%rbp),%xmm2
mulsd  %xmm2,%xmm1
movsd  0xe5e(%rip),%xmm2
addsd  %xmm2,%xmm1
movsd  -0x10(%rbp),%xmm2
mulsd  %xmm2,%xmm1
movsd  0xe41(%rip),%xmm2
addsd  %xmm2,%xmm1
movsd  -0x10(%rbp),%xmm2
mulsd  %xmm2,%xmm1
movsd  0xe24(%rip),%xmm2
addsd  %xmm2,%xmm1
mulsd  %xmm1,%xmm0
movsd  -0x10(%rbp),%xmm1
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
mulsd  %xmm1,%xmm0
movsd  0xdec(%rip),%xmm1
addsd  %xmm1,%xmm0
movsd  %xmm0,-0x18(%rbp)
movsd  -0x18(%rbp),%xmm0
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<pnorm>:
push   %rax
movsd  0xee7(%rip),%xmm1
mulsd  %xmm0,%xmm1
movsd  0xee3(%rip),%xmm2
addsd  %xmm2,%xmm1
divsd  %xmm1,%xmm2
movsd  %xmm2,(%rsp)
mulsd  %xmm0,%xmm0
mulsd  0xed2(%rip),%xmm0
call   1030 <exp@plt>
movsd  0xecd(%rip),%xmm1
movsd  (%rsp),%xmm2
mulsd  %xmm2,%xmm1
addsd  0xec4(%rip),%xmm1
mulsd  %xmm2,%xmm1
addsd  0xec0(%rip),%xmm1
mulsd  %xmm2,%xmm1
addsd  0xebc(%rip),%xmm1
mulsd  %xmm2,%xmm1
addsd  0xeb8(%rip),%xmm1
mulsd  0xeb8(%rip),%xmm0
mulsd  %xmm1,%xmm0
mulsd  %xmm2,%xmm0
addsd  0xe70(%rip),%xmm0
pop    %rax
ret

LLVM IR (-O0):
define double @pnorm(double %0) {
%2 = alloca double
%3 = alloca double
%4 = alloca double
store double %0, double* %2
%5 = load double, double* %2
%6 = call double @llvm.fmuladd.f64(double 0x3FCDA6711871100E, double %5, double 1.000000e+00)
%7 = fdiv double 1.000000e+00, %6
store double %7, double* %3
%8 = load double, double* %2
%9 = fneg double %8
%10 = load double, double* %2
%11 = fmul double %9, %10
%12 = fdiv double %11, 2.000000e+00
%13 = call double @exp(double %12)
%14 = fmul double 0x3FD9884548DF6CE3, %13
%15 = load double, double* %3
%16 = call double @llvm.fmuladd.f64(double 0x3FF548CDD6F42943, double %15, double 0xBFFD23DD4EF278D0)
%17 = load double, double* %3
%18 = call double @llvm.fmuladd.f64(double %16, double %17, double 0x3FFC80EF025F5E68)
%19 = load double, double* %3
%20 = call double @llvm.fmuladd.f64(double %18, double %19, double 0xBFD6D1F0E5A8325B)
%21 = load double, double* %3
%22 = call double @llvm.fmuladd.f64(double %20, double %21, double 0x3FD470BF3A92F8EC)
%23 = fmul double %14, %22
%24 = load double, double* %3
%25 = fneg double %23
%26 = call double @llvm.fmuladd.f64(double %25, double %24, double 1.000000e+00)
store double %26, double* %4
%27 = load double, double* %4
ret double %27
}

LLVM IR (-O2):
define double @pnorm(double %0) {
%2 = tail call double @llvm.fmuladd.f64(double %0, double 0x3FCDA6711871100E, double 1.000000e+00)
%3 = fdiv double 1.000000e+00, %2
%4 = fneg double %0
%5 = fmul double %4, %0
%6 = fmul double %5, 5.000000e-01
%7 = tail call double @exp(double %6)
%8 = tail call double @llvm.fmuladd.f64(double %3, double 0x3FF548CDD6F42943, double 0xBFFD23DD4EF278D0)
%9 = tail call double @llvm.fmuladd.f64(double %8, double %3, double 0x3FFC80EF025F5E68)
%10 = tail call double @llvm.fmuladd.f64(double %9, double %3, double 0xBFD6D1F0E5A8325B)
%11 = tail call double @llvm.fmuladd.f64(double %10, double %3, double 0x3FD470BF3A92F8EC)
%12 = fmul double %7, 0xBFD9884548DF6CE3
%13 = fmul double %11, %12
%14 = tail call double @llvm.fmuladd.f64(double %13, double %3, double 1.000000e+00)
ret double %14
}