Awesome

JIT Inspector

A tool for inspecting Mono JIT code in Unity.

Usage

Open the tool from the Window -> JIT Inspector View menu option.

JIT Configuration

You can configure the JIT using the following class:

#if ENABLE_MONO
using System.Text;
using System.Runtime.InteropServices;

internal static unsafe class MonoJitConfig
{
    private const string Optimizations = "-float32";

    [DllImport("__Internal")]
    private static extern void mono_jit_parse_options(int argc, byte** argv);

#if UNITY_EDITOR
    [UnityEditor.InitializeOnLoadMethod]
#else
    [UnityEngine.RuntimeInitializeOnLoadMethod(UnityEngine.RuntimeInitializeLoadType.SubsystemRegistration)]
#endif
    private static void ParseOptions()
    {
        fixed (byte* arg = Encoding.UTF8.GetBytes("-O=" + Optimizations + "\0"))
        {
            mono_jit_parse_options(1, &arg);
        }
    }
}
#endif

The Optimizations string is a comma-separated (without spaces) list of optimization passes for the JIT to perform. Prefixing an optimization with a minus (-) will disable it.

You may use all to enable all optimizations and -all to disable all optimizations.

Entries later in the list will override entries before them, meaning -branch,branch will result in branch being enabled. -all,branch will result in only branch being enabled.

Available optimization passes are:

Name	Description	Enabled By Default
`peephole`	Peephole postpass	Yes
`branch`	Branch optimizations	Yes
`inline`	Inline method calls	Yes
`cfold`	Constant folding	Yes
`consprop`	Constant propagation	Yes
`copyprop`	Copy propagation	Yes
`deadce`	Dead code elimination	Yes
`linears`	Linear scan global reg allocation	Yes
`cmov`	Conditional moves	Yes
`shared`	Emit per-domain code	No<sup>1</sup>
`sched`	Instruction scheduling	No
`intrins`	Intrinsic method implementations	Yes
`tailc`	Tail recursion and tailcalls	No
`loop`	Loop related optimizations	Yes
`fcmov`	Fast x86 FP compares	No
`leaf`	Leaf procedures and optimizations	No
`aot`	Usage of Ahead Of Time compiled code	Yes
`precomp`	Precompile all methods before executing	No<sup>1</sup>
`abcrem`	Array bound checks removal	No
`ssapre`	SSA based Partial Redundancy	No
`exception`	Optimize exception catch blocks	Yes
`ssa`	Use plain SSA form	No
`float32`	Use 32 bit float arithmetic if possible	No<sup>2</sup>
`sse2`	SSE2 instructions on x86	No
`gsharedvt`	Generic sharing for valuetypes	No<sup>1</sup>
`gshared`	Generic Sharing	Yes
`simd`	Simd intrinsics	Yes
`unsafe`	Remove bound checks and perform other dangerous changes	No<sup>1</sup>
`alias-analysis`	Alias analysis of locals	Yes
`aggressive-inlining`	Aggressive Inlining	No

<sup>1</sup> These optimizations are not enabled by all and must be specified manually.

<sup>2</sup> Enabled by default in Mono, disabled by default in Unity.