double rate_Hep(t)
double t;
{
  if (t == 0.0) {
    return 0.0;
  }
  return 1.55e-26 * pow(t, .3647) +
         4.95e-22 * sqrt(t) * exp(-631515.0 / t) / (1.0 + sqrt(t / 1e5)) +
         5.54e-17 * pow(t, -.397) * exp(-473638.0 / t) / (1.0 + sqrt(t / 1e5)) +
         1.24e-13 * pow(t, -1.5) * exp(-4.7e5 / t) *
             (exp(-9.4e4 / t) * .3 + 1.0);
}


x86 assembly (clang, -O0):
<rate_Hep>:
push   %rbp
mov    %rsp,%rbp
sub    $0x60,%rsp
movsd  %xmm0,-0x10(%rbp)
movsd  -0x10(%rbp),%xmm0
xorps  %xmm1,%xmm1
ucomisd %xmm1,%xmm0
jne    1162 <rate_Hep+0x32>
jp     1162 <rate_Hep+0x32>
xorps  %xmm0,%xmm0
movsd  %xmm0,-0x8(%rbp)
jmp    1314 <rate_Hep+0x1e4>
movsd  -0x10(%rbp),%xmm0
movsd  0xef9(%rip),%xmm1
call   1040 <pow@plt>
movsd  %xmm0,-0x48(%rbp)
movsd  -0x10(%rbp),%xmm0
call   1050 <sqrt@plt>
movaps %xmm0,%xmm1
movsd  0xed2(%rip),%xmm0
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x58(%rbp)
movsd  0xeb9(%rip),%xmm0
divsd  -0x10(%rbp),%xmm0
call   1030 <exp@plt>
movaps %xmm0,%xmm1
movsd  -0x58(%rbp),%xmm0
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x50(%rbp)
movsd  -0x10(%rbp),%xmm0
movsd  0xe69(%rip),%xmm1
divsd  %xmm1,%xmm0
call   1050 <sqrt@plt>
movsd  -0x50(%rbp),%xmm1
movaps %xmm0,%xmm3
movsd  -0x48(%rbp),%xmm0
movsd  0xe23(%rip),%xmm2
addsd  %xmm3,%xmm2
divsd  %xmm2,%xmm1
movsd  0xe5b(%rip),%xmm2
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
movsd  %xmm0,-0x30(%rbp)
movsd  -0x10(%rbp),%xmm0
movsd  0xe39(%rip),%xmm1
call   1040 <pow@plt>
movaps %xmm0,%xmm1
movsd  0xe21(%rip),%xmm0
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x40(%rbp)
movsd  0xe08(%rip),%xmm0
divsd  -0x10(%rbp),%xmm0
call   1030 <exp@plt>
movaps %xmm0,%xmm1
movsd  -0x40(%rbp),%xmm0
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x38(%rbp)
movsd  -0x10(%rbp),%xmm0
movsd  0xdd8(%rip),%xmm1
divsd  %xmm1,%xmm0
call   1050 <sqrt@plt>
movsd  -0x38(%rbp),%xmm1
movaps %xmm0,%xmm3
movsd  -0x30(%rbp),%xmm0
movsd  0xd92(%rip),%xmm2
addsd  %xmm3,%xmm2
divsd  %xmm2,%xmm1
addsd  %xmm1,%xmm0
movsd  %xmm0,-0x20(%rbp)
movsd  -0x10(%rbp),%xmm0
movsd  0xd94(%rip),%xmm1
call   1040 <pow@plt>
movaps %xmm0,%xmm1
movsd  0xd7c(%rip),%xmm0
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x28(%rbp)
movsd  0xd63(%rip),%xmm0
divsd  -0x10(%rbp),%xmm0
call   1030 <exp@plt>
movaps %xmm0,%xmm1
movsd  -0x28(%rbp),%xmm0
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x18(%rbp)
movsd  0xd38(%rip),%xmm0
divsd  -0x10(%rbp),%xmm0
call   1030 <exp@plt>
movsd  -0x20(%rbp),%xmm1
movaps %xmm0,%xmm2
movsd  -0x18(%rbp),%xmm0
movsd  0xd09(%rip),%xmm3
mulsd  %xmm3,%xmm2
movsd  0xd05(%rip),%xmm3
addsd  %xmm3,%xmm2
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
movsd  %xmm0,-0x8(%rbp)
movsd  -0x8(%rbp),%xmm0
add    $0x60,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<rate_Hep>:
xorpd  %xmm1,%xmm1
ucomisd %xmm1,%xmm0
jne    1141 <rate_Hep+0x11>
jp     1141 <rate_Hep+0x11>
xorpd  %xmm0,%xmm0
ret
sub    $0x28,%rsp
movsd  0xeb3(%rip),%xmm1
movsd  %xmm0,0x8(%rsp)
movsd  0x8(%rsp),%xmm0
call   1040 <pow@plt>
movsd  %xmm0,0x10(%rsp)
movsd  0x8(%rsp),%xmm1
ucomisd 0xefe(%rip),%xmm1
jb     117d <rate_Hep+0x4d>
xorps  %xmm0,%xmm0
sqrtsd %xmm1,%xmm0
jmp    1186 <rate_Hep+0x56>
movapd %xmm1,%xmm0
call   1050 <sqrt@plt>
mulsd  0xe7a(%rip),%xmm0
movsd  %xmm0,(%rsp)
movsd  0xe75(%rip),%xmm0
divsd  0x8(%rsp),%xmm0
call   1030 <exp@plt>
movapd %xmm0,%xmm3
mulsd  (%rsp),%xmm3
movsd  0x8(%rsp),%xmm1
divsd  0xe5b(%rip),%xmm1
xorps  %xmm0,%xmm0
sqrtsd %xmm1,%xmm0
xorpd  %xmm2,%xmm2
movsd  %xmm1,(%rsp)
ucomisd %xmm2,%xmm1
movsd  %xmm0,0x20(%rsp)
jae    11ef <rate_Hep+0xbf>
movsd  (%rsp),%xmm0
movsd  %xmm3,0x18(%rsp)
call   1050 <sqrt@plt>
movsd  0x18(%rsp),%xmm3
addsd  0xe29(%rip),%xmm0
divsd  %xmm0,%xmm3
movsd  0x10(%rsp),%xmm0
mulsd  0xe1f(%rip),%xmm0
addsd  %xmm3,%xmm0
movsd  %xmm0,0x10(%rsp)
movsd  0xe15(%rip),%xmm1
movsd  0x8(%rsp),%xmm0
call   1040 <pow@plt>
mulsd  0xe0a(%rip),%xmm0
movsd  %xmm0,0x18(%rsp)
movsd  0xe04(%rip),%xmm0
divsd  0x8(%rsp),%xmm0
call   1030 <exp@plt>
movapd %xmm0,%xmm1
mulsd  0x18(%rsp),%xmm1
movsd  (%rsp),%xmm0
ucomisd 0xe12(%rip),%xmm0
movsd  0x20(%rsp),%xmm0
jae    127a <rate_Hep+0x14a>
movsd  (%rsp),%xmm0
movsd  %xmm1,(%rsp)
call   1050 <sqrt@plt>
movsd  (%rsp),%xmm1
addsd  0xd9e(%rip),%xmm0
divsd  %xmm0,%xmm1
movsd  0x10(%rsp),%xmm0
addsd  %xmm1,%xmm0
movsd  %xmm0,0x10(%rsp)
movsd  0xdaa(%rip),%xmm1
movsd  0x8(%rsp),%xmm0
call   1040 <pow@plt>
mulsd  0xd9f(%rip),%xmm0
movsd  %xmm0,(%rsp)
movsd  0xd9a(%rip),%xmm0
divsd  0x8(%rsp),%xmm0
call   1030 <exp@plt>
mulsd  (%rsp),%xmm0
movsd  %xmm0,(%rsp)
movsd  0xd85(%rip),%xmm0
divsd  0x8(%rsp),%xmm0
call   1030 <exp@plt>
mulsd  0xd7a(%rip),%xmm0
addsd  0xd2a(%rip),%xmm0
mulsd  (%rsp),%xmm0
addsd  0x10(%rsp),%xmm0
add    $0x28,%rsp
ret

LLVM IR (-O0):
define double @rate_Hep(double %0) {
%2 = alloca double
%3 = alloca double
store double %0, double* %3
%4 = load double, double* %3
%5 = fcmp oeq double %4, 0.000000e+00
br i1 %5, label %6, label %7
6: ; preds = %1
store double 0.000000e+00, double* %2
br label %48
7: ; preds = %1
%8 = load double, double* %3
%9 = call double @pow(double %8, double 3.647000e-01)
%10 = load double, double* %3
%11 = call double @sqrt(double %10)
%12 = fmul double 4.950000e-22, %11
%13 = load double, double* %3
%14 = fdiv double -6.315150e+05, %13
%15 = call double @exp(double %14)
%16 = fmul double %12, %15
%17 = load double, double* %3
%18 = fdiv double %17, 1.000000e+05
%19 = call double @sqrt(double %18)
%20 = fadd double 1.000000e+00, %19
%21 = fdiv double %16, %20
%22 = call double @llvm.fmuladd.f64(double 1.550000e-26, double %9, double %21)
%23 = load double, double* %3
%24 = call double @pow(double %23, double -3.970000e-01)
%25 = fmul double 5.540000e-17, %24
%26 = load double, double* %3
%27 = fdiv double -4.736380e+05, %26
%28 = call double @exp(double %27)
%29 = fmul double %25, %28
%30 = load double, double* %3
%31 = fdiv double %30, 1.000000e+05
%32 = call double @sqrt(double %31)
%33 = fadd double 1.000000e+00, %32
%34 = fdiv double %29, %33
%35 = fadd double %22, %34
%36 = load double, double* %3
%37 = call double @pow(double %36, double -1.500000e+00)
%38 = fmul double 1.240000e-13, %37
%39 = load double, double* %3
%40 = fdiv double -4.700000e+05, %39
%41 = call double @exp(double %40)
%42 = fmul double %38, %41
%43 = load double, double* %3
%44 = fdiv double -9.400000e+04, %43
%45 = call double @exp(double %44)
%46 = call double @llvm.fmuladd.f64(double %45, double 3.000000e-01, double 1.000000e+00)
%47 = call double @llvm.fmuladd.f64(double %42, double %46, double %35)
store double %47, double* %2
br label %48
48: ; preds = %7, %6
%49 = load double, double* %2
ret double %49
}

LLVM IR (-O2):
define double @rate_Hep(double %0) {
%2 = fcmp oeq double %0, 0.000000e+00
br i1 %2, label %33, label %3
3: ; preds = %1
%4 = tail call double @pow(double %0, double 3.647000e-01)
%5 = tail call double @sqrt(double %0)
%6 = fmul double %5, 4.950000e-22
%7 = fdiv double -6.315150e+05, %0
%8 = tail call double @exp(double %7)
%9 = fmul double %6, %8
%10 = fdiv double %0, 1.000000e+05
%11 = tail call double @sqrt(double %10)
%12 = fadd double %11, 1.000000e+00
%13 = fdiv double %9, %12
%14 = tail call double @llvm.fmuladd.f64(double %4, double 1.550000e-26, double %13)
%15 = tail call double @pow(double %0, double -3.970000e-01)
%16 = fmul double %15, 5.540000e-17
%17 = fdiv double -4.736380e+05, %0
%18 = tail call double @exp(double %17)
%19 = fmul double %16, %18
%20 = tail call double @sqrt(double %10)
%21 = fadd double %20, 1.000000e+00
%22 = fdiv double %19, %21
%23 = fadd double %14, %22
%24 = tail call double @pow(double %0, double -1.500000e+00)
%25 = fmul double %24, 1.240000e-13
%26 = fdiv double -4.700000e+05, %0
%27 = tail call double @exp(double %26)
%28 = fmul double %25, %27
%29 = fdiv double -9.400000e+04, %0
%30 = tail call double @exp(double %29)
%31 = tail call double @llvm.fmuladd.f64(double %30, double 3.000000e-01, double 1.000000e+00)
%32 = tail call double @llvm.fmuladd.f64(double %28, double %31, double %23)
br label %33
33: ; preds = %1, %3
%34 = phi double [ %32, %3 ], [ 0.000000e+00, %1 ]
ret double %34
}