double LSKeyframeAnimationFunctionEaseInOutCubic(double t, double b, double c,
                                                 double d) {
  if ((t /= d / 2) < 1)
    return c / 2 * t * t * t + b;
  return c / 2 * ((t -= 2) * t * t + 2) + b;
}


x86 assembly (clang, -O0):
<LSKeyframeAnimationFunctionEaseInOutCubic>:
push   %rbp
mov    %rsp,%rbp
movsd  %xmm0,-0x10(%rbp)
movsd  %xmm1,-0x18(%rbp)
movsd  %xmm2,-0x20(%rbp)
movsd  %xmm3,-0x28(%rbp)
movsd  -0x28(%rbp),%xmm0
movsd  0xee3(%rip),%xmm1
divsd  %xmm1,%xmm0
movsd  -0x10(%rbp),%xmm1
divsd  %xmm0,%xmm1
movsd  %xmm1,-0x10(%rbp)
movsd  0xec1(%rip),%xmm0
ucomisd %xmm1,%xmm0
jbe    1180 <LSKeyframeAnimationFunctionEaseInOutCubic+0x80>
movsd  -0x20(%rbp),%xmm0
movsd  0xeb2(%rip),%xmm1
divsd  %xmm1,%xmm0
mulsd  -0x10(%rbp),%xmm0
mulsd  -0x10(%rbp),%xmm0
movsd  -0x10(%rbp),%xmm2
movsd  -0x18(%rbp),%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
movsd  %xmm0,-0x8(%rbp)
jmp    11d3 <LSKeyframeAnimationFunctionEaseInOutCubic+0xd3>
movsd  -0x20(%rbp),%xmm0
movsd  0xe7b(%rip),%xmm1
divsd  %xmm1,%xmm0
movsd  -0x10(%rbp),%xmm2
movsd  0xe6a(%rip),%xmm1
subsd  %xmm1,%xmm2
movsd  %xmm2,-0x10(%rbp)
mulsd  -0x10(%rbp),%xmm2
movsd  -0x10(%rbp),%xmm1
mulsd  %xmm1,%xmm2
movsd  0xe4b(%rip),%xmm1
addsd  %xmm1,%xmm2
movsd  -0x18(%rbp),%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
movsd  %xmm0,-0x8(%rbp)
movsd  -0x8(%rbp),%xmm0
pop    %rbp
ret

x86 assembly (clang, -O2):
<LSKeyframeAnimationFunctionEaseInOutCubic>:
movsd  0xef8(%rip),%xmm4
mulsd  %xmm4,%xmm3
divsd  %xmm3,%xmm0
movsd  0xef0(%rip),%xmm3
ucomisd %xmm0,%xmm3
mulsd  %xmm4,%xmm2
jbe    1130 <LSKeyframeAnimationFunctionEaseInOutCubic+0x30>
mulsd  %xmm0,%xmm2
mulsd  %xmm0,%xmm2
mulsd  %xmm0,%xmm2
jmp    1150 <LSKeyframeAnimationFunctionEaseInOutCubic+0x50>
addsd  0xed8(%rip),%xmm0
movapd %xmm0,%xmm3
mulsd  %xmm0,%xmm3
mulsd  %xmm0,%xmm3
addsd  0xecc(%rip),%xmm3
mulsd  %xmm3,%xmm2
addsd  %xmm1,%xmm2
movapd %xmm2,%xmm0
ret

LLVM IR (-O0):
define double @LSKeyframeAnimationFunctionEaseInOutCubic(double %0, double %1, double %2, double %3) {
%5 = alloca double
%6 = alloca double
%7 = alloca double
%8 = alloca double
%9 = alloca double
store double %0, double* %6
store double %1, double* %7
store double %2, double* %8
store double %3, double* %9
%10 = load double, double* %9
%11 = fdiv double %10, 2.000000e+00
%12 = load double, double* %6
%13 = fdiv double %12, %11
store double %13, double* %6
%14 = fcmp olt double %13, 1.000000e+00
br i1 %14, label %15, label %25
15: ; preds = %4
%16 = load double, double* %8
%17 = fdiv double %16, 2.000000e+00
%18 = load double, double* %6
%19 = fmul double %17, %18
%20 = load double, double* %6
%21 = fmul double %19, %20
%22 = load double, double* %6
%23 = load double, double* %7
%24 = call double @llvm.fmuladd.f64(double %21, double %22, double %23)
store double %24, double* %5
br label %36
25: ; preds = %4
%26 = load double, double* %8
%27 = fdiv double %26, 2.000000e+00
%28 = load double, double* %6
%29 = fsub double %28, 2.000000e+00
store double %29, double* %6
%30 = load double, double* %6
%31 = fmul double %29, %30
%32 = load double, double* %6
%33 = call double @llvm.fmuladd.f64(double %31, double %32, double 2.000000e+00)
%34 = load double, double* %7
%35 = call double @llvm.fmuladd.f64(double %27, double %33, double %34)
store double %35, double* %5
br label %36
36: ; preds = %25, %15
%37 = load double, double* %5
ret double %37
}

LLVM IR (-O2):
define double @LSKeyframeAnimationFunctionEaseInOutCubic(double %0, double %1, double %2, double %3) {
%5 = fmul double %3, 5.000000e-01
%6 = fdiv double %0, %5
%7 = fcmp olt double %6, 1.000000e+00
%8 = fmul double %2, 5.000000e-01
br i1 %7, label %9, label %13
9: ; preds = %4
%10 = fmul double %8, %6
%11 = fmul double %6, %10
%12 = tail call double @llvm.fmuladd.f64(double %11, double %6, double %1)
br label %18
13: ; preds = %4
%14 = fadd double %6, -2.000000e+00
%15 = fmul double %14, %14
%16 = tail call double @llvm.fmuladd.f64(double %15, double %14, double 2.000000e+00)
%17 = tail call double @llvm.fmuladd.f64(double %8, double %16, double %1)
br label %18
18: ; preds = %13, %9
%19 = phi double [ %12, %9 ], [ %17, %13 ]
ret double %19
}