double var_urassr(int ura) {
  double std;
  if (ura <= 0)
    return ((0.15) * (0.15));
  if (ura >= 63)
    return ((5.4665) * (5.4665));
  std = (pow(3.0, (ura >> 3) & 7) * (1.0 + (ura & 7) / 4.0) - 1.0) * 1E-3;
  return ((std) * (std));
}


x86 assembly (clang, -O0):
<var_urassr>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %edi,-0xc(%rbp)
cmpl   $0x0,-0xc(%rbp)
jg     1137 <var_urassr+0x27>
movsd  0xf03(%rip),%xmm0
movsd  %xmm0,-0x8(%rbp)
jmp    11bf <var_urassr+0xaf>
cmpl   $0x3f,-0xc(%rbp)
jl     1153 <var_urassr+0x43>
movsd  0xedf(%rip),%xmm0
movsd  %xmm0,-0x8(%rbp)
jmp    11bf <var_urassr+0xaf>
mov    -0xc(%rbp),%eax
sar    $0x3,%eax
and    $0x7,%eax
cvtsi2sd %eax,%xmm1
movsd  0xeb8(%rip),%xmm0
call   1030 <pow@plt>
mov    -0xc(%rbp),%eax
and    $0x7,%eax
cvtsi2sd %eax,%xmm2
movsd  0xe99(%rip),%xmm1
divsd  %xmm1,%xmm2
movsd  0xe85(%rip),%xmm1
addsd  %xmm2,%xmm1
mulsd  %xmm1,%xmm0
movsd  0xe6d(%rip),%xmm1
addsd  %xmm1,%xmm0
movsd  0xe59(%rip),%xmm1
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x18(%rbp)
movsd  -0x18(%rbp),%xmm0
mulsd  -0x18(%rbp),%xmm0
movsd  %xmm0,-0x8(%rbp)
movsd  -0x8(%rbp),%xmm0
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<var_urassr>:
push   %rbx
test   %edi,%edi
jle    1126 <var_urassr+0x16>
mov    %edi,%ebx
cmp    $0x3e,%edi
jbe    1130 <var_urassr+0x20>
movsd  0xee4(%rip),%xmm1
jmp    1178 <var_urassr+0x68>
movsd  0xed2(%rip),%xmm1
jmp    1178 <var_urassr+0x68>
mov    %ebx,%eax
shr    $0x3,%eax
cvtsi2sd %eax,%xmm1
movsd  0xecf(%rip),%xmm0
call   1030 <pow@plt>
and    $0x7,%ebx
xorps  %xmm1,%xmm1
cvtsi2sd %ebx,%xmm1
mulsd  0xec0(%rip),%xmm1
addsd  0xec0(%rip),%xmm1
mulsd  %xmm0,%xmm1
addsd  0xebc(%rip),%xmm1
mulsd  0xebc(%rip),%xmm1
mulsd  %xmm1,%xmm1
movapd %xmm1,%xmm0
pop    %rbx
ret

LLVM IR (-O0):
define double @var_urassr(i32 %0) {
%2 = alloca double
%3 = alloca i32
%4 = alloca double
store i32 %0, i32* %3
%5 = load i32, i32* %3
%6 = icmp sle i32 %5, 0
br i1 %6, label %7, label %8
7: ; preds = %1
store double 2.250000e-02, double* %2
br label %28
8: ; preds = %1
%9 = load i32, i32* %3
%10 = icmp sge i32 %9, 63
br i1 %10, label %11, label %12
11: ; preds = %8
store double 0x403DE1F3882278D1, double* %2
br label %28
12: ; preds = %8
%13 = load i32, i32* %3
%14 = ashr i32 %13, 3
%15 = and i32 %14, 7
%16 = sitofp i32 %15 to double
%17 = call double @pow(double 3.000000e+00, double %16)
%18 = load i32, i32* %3
%19 = and i32 %18, 7
%20 = sitofp i32 %19 to double
%21 = fdiv double %20, 4.000000e+00
%22 = fadd double 1.000000e+00, %21
%23 = call double @llvm.fmuladd.f64(double %17, double %22, double -1.000000e+00)
%24 = fmul double %23, 1.000000e-03
store double %24, double* %4
%25 = load double, double* %4
%26 = load double, double* %4
%27 = fmul double %25, %26
store double %27, double* %2
br label %28
28: ; preds = %12, %11, %7
%29 = load double, double* %2
ret double %29
}

LLVM IR (-O2):
define double @var_urassr(i32 %0) {
%2 = icmp slt i32 %0, 1
br i1 %2, label %16, label %3
3: ; preds = %1
%4 = icmp ugt i32 %0, 62
br i1 %4, label %16, label %5
5: ; preds = %3
%6 = lshr i32 %0, 3
%7 = sitofp i32 %6 to double
%8 = tail call double @pow(double 3.000000e+00, double %7)
%9 = and i32 %0, 7
%10 = sitofp i32 %9 to double
%11 = fmul double %10, 2.500000e-01
%12 = fadd double %11, 1.000000e+00
%13 = tail call double @llvm.fmuladd.f64(double %8, double %12, double -1.000000e+00)
%14 = fmul double %13, 1.000000e-03
%15 = fmul double %14, %14
br label %16
16: ; preds = %3, %1, %5
%17 = phi double [ %15, %5 ], [ 2.250000e-02, %1 ], [ 0x403DE1F3882278D1, %3 ]
ret double %17
}