double atan_137s(double x) {
  static const double c1 = 48.70107004404898384;
  static const double c2 = 49.5326263772254345;
  static const double c3 = 9.40604244231624;
  static const double c4 = 48.70107004404996166;
  static const double c5 = 65.7663163908956299;
  static const double c6 = 21.587934067020262;
  double x2;
  x2 = x * x;
  return (x * (c1 + x2 * (c2 + x2 * c3)) / (c4 + x2 * (c5 + x2 * (c6 + x2))));
}


x86 assembly (clang, -O0):
<atan_137s>:
push   %rbp
mov    %rsp,%rbp
movsd  %xmm0,-0x8(%rbp)
movsd  -0x8(%rbp),%xmm0
mulsd  -0x8(%rbp),%xmm0
movsd  %xmm0,-0x10(%rbp)
movsd  -0x8(%rbp),%xmm0
movsd  -0x10(%rbp),%xmm1
movsd  -0x10(%rbp),%xmm2
movsd  0xef1(%rip),%xmm3
mulsd  %xmm3,%xmm2
movsd  0xeed(%rip),%xmm3
addsd  %xmm3,%xmm2
mulsd  %xmm2,%xmm1
movsd  0xecd(%rip),%xmm2
addsd  %xmm2,%xmm1
mulsd  %xmm1,%xmm0
movsd  -0x10(%rbp),%xmm1
movsd  -0x10(%rbp),%xmm2
movsd  0xeab(%rip),%xmm3
addsd  -0x10(%rbp),%xmm3
mulsd  %xmm3,%xmm2
movsd  0xe92(%rip),%xmm3
addsd  %xmm3,%xmm2
mulsd  %xmm2,%xmm1
movsd  0xe7a(%rip),%xmm2
addsd  %xmm2,%xmm1
divsd  %xmm1,%xmm0
pop    %rbp
ret

x86 assembly (clang, -O2):
<atan_137s>:
movapd %xmm0,%xmm1
mulsd  %xmm0,%xmm1
movsd  0xef0(%rip),%xmm2
mulsd  %xmm1,%xmm2
addsd  0xeec(%rip),%xmm2
mulsd  %xmm1,%xmm2
addsd  0xee8(%rip),%xmm2
mulsd  %xmm2,%xmm0
movsd  0xee4(%rip),%xmm2
addsd  %xmm1,%xmm2
mulsd  %xmm1,%xmm2
addsd  0xedc(%rip),%xmm2
mulsd  %xmm1,%xmm2
addsd  0xed8(%rip),%xmm2
divsd  %xmm2,%xmm0
ret

LLVM IR (-O0):
@atan_137s.c1 = internal constant double 0x404859BCA9C7B2A5
@atan_137s.c2 = internal constant double 0x4048C42D19E395C9
@atan_137s.c3 = internal constant double 0x4022CFE4CB85128B
@atan_137s.c4 = internal constant double 0x404859BCA9C7B32F
@atan_137s.c5 = internal constant double 0x4050710B53E75245
@atan_137s.c6 = internal constant double 0x40359682D8D60E6A
define double @atan_137s(double %0) {
%2 = alloca double
%3 = alloca double
store double %0, double* %2
%4 = load double, double* %2
%5 = load double, double* %2
%6 = fmul double %4, %5
store double %6, double* %3
%7 = load double, double* %2
%8 = load double, double* %3
%9 = load double, double* %3
%10 = call double @llvm.fmuladd.f64(double %9, double 0x4022CFE4CB85128B, double 0x4048C42D19E395C9)
%11 = call double @llvm.fmuladd.f64(double %8, double %10, double 0x404859BCA9C7B2A5)
%12 = fmul double %7, %11
%13 = load double, double* %3
%14 = load double, double* %3
%15 = load double, double* %3
%16 = fadd double 0x40359682D8D60E6A, %15
%17 = call double @llvm.fmuladd.f64(double %14, double %16, double 0x4050710B53E75245)
%18 = call double @llvm.fmuladd.f64(double %13, double %17, double 0x404859BCA9C7B32F)
%19 = fdiv double %12, %18
ret double %19
}

LLVM IR (-O2):
define double @atan_137s(double %0) {
%2 = fmul double %0, %0
%3 = tail call double @llvm.fmuladd.f64(double %2, double 0x4022CFE4CB85128B, double 0x4048C42D19E395C9)
%4 = tail call double @llvm.fmuladd.f64(double %2, double %3, double 0x404859BCA9C7B2A5)
%5 = fmul double %4, %0
%6 = fadd double %2, 0x40359682D8D60E6A
%7 = tail call double @llvm.fmuladd.f64(double %2, double %6, double 0x4050710B53E75245)
%8 = tail call double @llvm.fmuladd.f64(double %2, double %7, double 0x404859BCA9C7B32F)
%9 = fdiv double %5, %8
ret double %9
}