double cephes_hyperg(a, b, x)
double a, b, x;
{
  double asum, psum, acanc, pcanc, temp;
  temp = b - a;
  if (fabs(temp) < 0.001 * fabs(a))
    return (cephes_exp(x) * cephes_hyperg(temp, b, -x));
  psum = hy1f1p(a, b, x, &pcanc);
  if (pcanc < 1.0e-15)
    goto done;
  asum = hy1f1a(a, b, x, &acanc);
  if (acanc < pcanc) {
    pcanc = acanc;
    psum = asum;
  }
done:
  if (pcanc > 1.0e-12)
    mtherr("hyperg", 6);
  return (psum);
}


x86 assembly (clang, -O0):
<cephes_hyperg>:
push   %rbp
mov    %rsp,%rbp
sub    $0x50,%rsp
movsd  %xmm0,-0x10(%rbp)
movsd  %xmm1,-0x18(%rbp)
movsd  %xmm2,-0x20(%rbp)
movsd  -0x18(%rbp),%xmm0
subsd  -0x10(%rbp),%xmm0
movsd  %xmm0,-0x48(%rbp)
movsd  -0x48(%rbp),%xmm1
movaps 0xe9e(%rip),%xmm0
pand   %xmm0,%xmm1
movsd  -0x10(%rbp),%xmm2
movaps 0xe8e(%rip),%xmm0
pand   %xmm0,%xmm2
movsd  0xe62(%rip),%xmm0
mulsd  %xmm2,%xmm0
ucomisd %xmm1,%xmm0
jbe    1202 <cephes_hyperg+0xb2>
movsd  -0x20(%rbp),%xmm0
mov    $0x1,%al
call   1050 <cephes_exp@plt>
cvtsi2sd %eax,%xmm0
movsd  %xmm0,-0x50(%rbp)
movsd  -0x48(%rbp),%xmm0
movsd  -0x18(%rbp),%xmm1
movsd  -0x20(%rbp),%xmm2
movq   %xmm2,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm2
call   1030 <cephes_hyperg@plt>
movaps %xmm0,%xmm1
movsd  -0x50(%rbp),%xmm0
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x8(%rbp)
jmp    12c1 <cephes_hyperg+0x171>
movsd  -0x10(%rbp),%xmm0
movsd  -0x18(%rbp),%xmm1
movsd  -0x20(%rbp),%xmm2
lea    -0x40(%rbp),%rdi
mov    $0x3,%al
call   1040 <hy1f1p@plt>
cvtsi2sd %eax,%xmm0
movsd  %xmm0,-0x30(%rbp)
movsd  0xddb(%rip),%xmm0
ucomisd -0x40(%rbp),%xmm0
jbe    123d <cephes_hyperg+0xed>
jmp    128d <cephes_hyperg+0x13d>
movsd  -0x10(%rbp),%xmm0
movsd  -0x18(%rbp),%xmm1
movsd  -0x20(%rbp),%xmm2
lea    -0x38(%rbp),%rdi
mov    $0x3,%al
call   1060 <hy1f1a@plt>
cvtsi2sd %eax,%xmm0
movsd  %xmm0,-0x28(%rbp)
movsd  -0x38(%rbp),%xmm1
movsd  -0x40(%rbp),%xmm0
ucomisd %xmm1,%xmm0
jbe    1288 <cephes_hyperg+0x138>
movsd  -0x38(%rbp),%xmm0
movsd  %xmm0,-0x40(%rbp)
movsd  -0x28(%rbp),%xmm0
movsd  %xmm0,-0x30(%rbp)
jmp    128d <cephes_hyperg+0x13d>
movsd  -0x40(%rbp),%xmm0
movsd  0xd76(%rip),%xmm1
ucomisd %xmm1,%xmm0
jbe    12b7 <cephes_hyperg+0x167>
lea    0xd85(%rip),%rdi
mov    $0x6,%esi
mov    $0x0,%al
call   1070 <mtherr@plt>
movsd  -0x30(%rbp),%xmm0
movsd  %xmm0,-0x8(%rbp)
movsd  -0x8(%rbp),%xmm0
add    $0x50,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<cephes_hyperg>:
push   %rbx
sub    $0x50,%rsp
movapd %xmm1,%xmm5
subsd  %xmm0,%xmm5
movapd 0xe9b(%rip),%xmm4
movapd %xmm5,%xmm3
andpd  %xmm4,%xmm3
andpd  %xmm0,%xmm4
mulsd  0xea7(%rip),%xmm4
ucomisd %xmm3,%xmm4
movaps %xmm2,0x10(%rsp)
movsd  %xmm1,0x8(%rsp)
jbe    11d1 <cephes_hyperg+0x81>
movaps %xmm2,%xmm0
mov    $0x1,%al
movapd %xmm5,0x40(%rsp)
call   1050 <cephes_exp@plt>
xorps  %xmm0,%xmm0
cvtsi2sd %eax,%xmm0
movsd  %xmm0,0x20(%rsp)
movapd 0x10(%rsp),%xmm2
xorpd  0xe5b(%rip),%xmm2
movapd 0x40(%rsp),%xmm0
movsd  0x8(%rsp),%xmm1
call   1030 <cephes_hyperg@plt>
mulsd  0x20(%rsp),%xmm0
jmp    125f <cephes_hyperg+0x10f>
mov    %rsp,%rdi
movapd %xmm0,0x20(%rsp)
mov    $0x3,%al
call   1040 <hy1f1p@plt>
mov    %eax,%ebx
movsd  (%rsp),%xmm2
movsd  0xe38(%rip),%xmm1
ucomisd %xmm2,%xmm1
ja     122f <cephes_hyperg+0xdf>
lea    0x38(%rsp),%rdi
movapd 0x20(%rsp),%xmm0
movsd  0x8(%rsp),%xmm1
movaps 0x10(%rsp),%xmm2
mov    $0x3,%al
call   1060 <hy1f1a@plt>
movsd  0x38(%rsp),%xmm1
movsd  (%rsp),%xmm2
ucomisd %xmm1,%xmm2
jbe    122f <cephes_hyperg+0xdf>
movsd  %xmm1,(%rsp)
movapd %xmm1,%xmm2
mov    %eax,%ebx
xorps  %xmm0,%xmm0
cvtsi2sd %ebx,%xmm0
ucomisd 0xdf2(%rip),%xmm2
jbe    125f <cephes_hyperg+0x10f>
lea    0xdf1(%rip),%rdi
mov    $0x6,%esi
xor    %eax,%eax
movsd  %xmm0,0x10(%rsp)
call   1070 <mtherr@plt>
movsd  0x10(%rsp),%xmm0
add    $0x50,%rsp
pop    %rbx
ret

LLVM IR (-O0):
@.str = [7 x i8] c"hyperg\00"
define double @cephes_hyperg(double %0, double %1, double %2) {
%4 = alloca double
%5 = alloca double
%6 = alloca double
%7 = alloca double
%8 = alloca double
%9 = alloca double
%10 = alloca double
%11 = alloca double
%12 = alloca double
store double %0, double* %5
store double %1, double* %6
store double %2, double* %7
%13 = load double, double* %6
%14 = load double, double* %5
%15 = fsub double %13, %14
store double %15, double* %12
%16 = load double, double* %12
%17 = call double @llvm.fabs.f64(double %16)
%18 = load double, double* %5
%19 = call double @llvm.fabs.f64(double %18)
%20 = fmul double 1.000000e-03, %19
%21 = fcmp olt double %17, %20
br i1 %21, label %22, label %32
22: ; preds = %3
%23 = load double, double* %7
%24 = call i32 (double, ...) bitcast (i32 (...)* @cephes_exp to i32 (double, ...)*)(double %23)
%25 = sitofp i32 %24 to double
%26 = load double, double* %12
%27 = load double, double* %6
%28 = load double, double* %7
%29 = fneg double %28
%30 = call double @cephes_hyperg(double %26, double %27, double %29)
%31 = fmul double %25, %30
store double %31, double* %4
br label %61
32: ; preds = %3
%33 = load double, double* %5
%34 = load double, double* %6
%35 = load double, double* %7
%36 = call i32 (double, double, double, double*, ...) bitcast (i32 (...)* @hy1f1p to i32 (double, double, double, double*, ...)*)(double %33, double %34, double %35, double* %11)
%37 = sitofp i32 %36 to double
store double %37, double* %9
%38 = load double, double* %11
%39 = fcmp olt double %38, 1.000000e-15
br i1 %39, label %40, label %41
40: ; preds = %32
br label %54
41: ; preds = %32
%42 = load double, double* %5
%43 = load double, double* %6
%44 = load double, double* %7
%45 = call i32 (double, double, double, double*, ...) bitcast (i32 (...)* @hy1f1a to i32 (double, double, double, double*, ...)*)(double %42, double %43, double %44, double* %10)
%46 = sitofp i32 %45 to double
store double %46, double* %8
%47 = load double, double* %10
%48 = load double, double* %11
%49 = fcmp olt double %47, %48
br i1 %49, label %50, label %53
50: ; preds = %41
%51 = load double, double* %10
store double %51, double* %11
%52 = load double, double* %8
store double %52, double* %9
br label %53
53: ; preds = %50, %41
br label %54
54: ; preds = %53, %40
%55 = load double, double* %11
%56 = fcmp ogt double %55, 0x3D719799812DEA11
br i1 %56, label %57, label %59
57: ; preds = %54
%58 = call i32 (i8*, i32, ...) bitcast (i32 (...)* @mtherr to i32 (i8*, i32, ...)*)(i8* getelementptr inbounds ([7 x i8], [7 x i8]* @.str, i64 0, i64 0), i32 6)
br label %59
59: ; preds = %57, %54
%60 = load double, double* %9
store double %60, double* %4
br label %61
61: ; preds = %59, %22
%62 = load double, double* %4
ret double %62
}

LLVM IR (-O2):
@.str = [7 x i8] c"hyperg\00"
define double @cephes_hyperg(double %0, double %1, double %2) {
%4 = alloca double
%5 = alloca double
%6 = bitcast double* %4 to i8*
%7 = bitcast double* %5 to i8*
%8 = fsub double %1, %0
%9 = tail call double @llvm.fabs.f64(double %8)
%10 = tail call double @llvm.fabs.f64(double %0)
%11 = fmul double %10, 1.000000e-03
%12 = fcmp olt double %9, %11
br i1 %12, label %13, label %19
13: ; preds = %3
%14 = tail call i32 (double, ...) bitcast (i32 (...)* @cephes_exp to i32 (double, ...)*)(double %2)
%15 = sitofp i32 %14 to double
%16 = fneg double %2
%17 = tail call double @cephes_hyperg(double %8, double %1, double %16)
%18 = fmul double %17, %15
br label %36
19: ; preds = %3
%20 = call i32 (double, double, double, double*, ...) bitcast (i32 (...)* @hy1f1p to i32 (double, double, double, double*, ...)*)(double %0, double %1, double %2, double* %5)
%21 = load double, double* %5
%22 = fcmp olt double %21, 1.000000e-15
br i1 %22, label %29, label %23
23: ; preds = %19
%24 = call i32 (double, double, double, double*, ...) bitcast (i32 (...)* @hy1f1a to i32 (double, double, double, double*, ...)*)(double %0, double %1, double %2, double* %4)
%25 = load double, double* %4
%26 = load double, double* %5
%27 = fcmp olt double %25, %26
br i1 %27, label %28, label %29
28: ; preds = %23
store double %25, double* %5
br label %29
29: ; preds = %23, %28, %19
%30 = phi double [ %26, %23 ], [ %25, %28 ], [ %21, %19 ]
%31 = phi i32 [ %20, %23 ], [ %24, %28 ], [ %20, %19 ]
%32 = sitofp i32 %31 to double
%33 = fcmp ogt double %30, 0x3D719799812DEA11
br i1 %33, label %34, label %36
34: ; preds = %29
%35 = call i32 (i8*, i32, ...) bitcast (i32 (...)* @mtherr to i32 (i8*, i32, ...)*)(i8* getelementptr inbounds ([7 x i8], [7 x i8]* @.str, i64 0, i64 0), i32 6)
br label %36
36: ; preds = %29, %34, %13
%37 = phi double [ %18, %13 ], [ %32, %34 ], [ %32, %29 ]
ret double %37
}