Enable opti on Microsoft.ML.OnnxRuntime with RelWithDebInfo config (#…

…23463)

Microsoft.ML.OnnxRuntime is not built with the Release configuration but
RelWithDebInfo which is not recognized by the MSBuild SDK. Consequently,
the optimizations are not enabled. A fix would be to simply force the
configuration to be Release when building the .NET code even if it was
set to RelWithDebInfo in the command line arguments but I could not find
an easy way to do that. Instead, I try to mimic the behavior of the
Release configuration by setting the optimize property.

I can see a 15% performance improvement using this simple model summing
up the 3 inputs:
```csharp
using System.Buffers;
using System.Collections.Frozen;
using System.Net;
using System.Net.Sockets;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Text;
using System.Text.RegularExpressions;
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Configs;
using BenchmarkDotNet.Running;
using Microsoft.ML.OnnxRuntime;

var config = DefaultConfig.Instance; //.WithOptions(ConfigOptions.DisableOptimizationsValidator);
BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args, config);

public class OnnxBench
{
    private const int Iterations = 100_000;
    private const int BatchSize = 50;
    
    private InferenceSession _session = default!;
    private string[] _inputNames = default!;
    private OrtValue[] _inputValues = default!;
    private RunOptions _runOptions = default!;

    [GlobalSetup]
    public void GlobalSetup()
    {
        using SessionOptions sessionOptions = new();
        sessionOptions.InterOpNumThreads = 1;
        sessionOptions.IntraOpNumThreads = 1;
        sessionOptions.GraphOptimizationLevel = GraphOptimizationLevel.ORT_ENABLE_ALL;
        sessionOptions.ExecutionMode = ExecutionMode.ORT_SEQUENTIAL;

        _session = new InferenceSession(
            Convert.FromBase64String("CAo6cAoOCgFBCgFCEgFEIgNBZGQKDgoBQwoBRBIBWCIDQWRkEgJscloRCgFBEgwKCggBEgYKAAoCCAFaEQoBQhIMCgoIARIGCgAKAggBWhEKAUMSDAoKCAESBgoACgIIAWIRCgFYEgwKCggBEgYKAAoCCAFCBAoAEBU="),
            sessionOptions);
        _inputNames = ["A", "B", "C"];
        _inputValues =
        [
            OrtValue.CreateTensorValueFromMemory(new float[BatchSize], [BatchSize, 1]),
            OrtValue.CreateTensorValueFromMemory(new float[BatchSize], [BatchSize, 1]),
            OrtValue.CreateTensorValueFromMemory(new float[BatchSize], [BatchSize, 1]),
        ];
        _runOptions = new RunOptions();
    }

    [Benchmark(OperationsPerInvoke = Iterations)]
    public float Run()
    {
        var inputValues0Span = _inputValues[0].GetTensorMutableDataAsSpan<float>();
        var inputValues1Span = _inputValues[1].GetTensorMutableDataAsSpan<float>();
        var inputValues2Span = _inputValues[2].GetTensorMutableDataAsSpan<float>();
        for (int i = 0; i < BatchSize; i += 1)
        {
            inputValues0Span[i] = Random.Shared.NextSingle();
            inputValues1Span[i] = Random.Shared.NextSingle();
            inputValues2Span[i] = Random.Shared.NextSingle();
        }
        
        float sum = 0f;
        for (int i = 0; i < Iterations; i += 1)
        {
            using var output = _session.Run(_runOptions, _inputNames, _inputValues, _session.OutputNames);
            ReadOnlySpan<float> outputData = output[0].GetTensorDataAsSpan<float>();
            for (int j = 0; j < outputData.Length; j += 1)
            {
                sum += outputData[j];
            }
        }
        
        return sum;
    }
}
```

| Method | Mean     | Error     | StdDev    |
|------- |---------:|----------:|----------:|
| Before | 5.003 us | 0.0318 us | 0.0297 us |
| After   | 4.325 us | 0.0568 us | 0.0503 us |

csharp/src/Microsoft.ML.OnnxRuntime/Microsoft.ML.OnnxRuntime.csproj

@@ -127,6 +127,11 @@
     <OrtConstants>$(OrtConstants);__ENABLE_TRAINING_APIS__</OrtConstants>
   </PropertyGroup>
 
+  <!-- Enable same optimizations as configuration Release for the custom RelWithDebInfo -->
+  <PropertyGroup Condition="'$(Configuration)' == 'RelWithDebInfo'">
+    <Optimize>true</Optimize>
+  </PropertyGroup>
+
   <!--
     Properties that are used when creating the managed package using the Pack target.
   -->