Fixing up a few small issues

The instruction matcher was missing a few details, which made it faster
than it should have been. Right now I'm trying to keep the design of
these in sync. Once I fixed that it exposed a legitimate bug that was
blocking the github benchmark.

benchmarks/Microsoft.AspNetCore.Routing.Performance/Matchers/AzureMatcherBenchmark.cs

@@ -61,10 +61,6 @@ namespace Microsoft.AspNetCore.Routing.Matchers
             for (var i = 0; i < SampleCount; i++)
             {
                 var sample = _samples[i];
-                if (sample == 805)
-                {
-                    GC.KeepAlive(5);
-                }
                 var httpContext = _requests[sample];
                 await _dfa.MatchAsync(httpContext, feature);
                 Validate(httpContext, _endpoints[sample], feature.Endpoint);

benchmarks/Microsoft.AspNetCore.Routing.Performance/Matchers/GithubMatcherBenchmark.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
 using System.Threading.Tasks;
 using BenchmarkDotNet.Attributes;
 

test/Microsoft.AspNetCore.Routing.Tests/Matchers/InstructionMatcher.cs

@@ -63,7 +63,7 @@ namespace Microsoft.AspNetCore.Routing.Matchers
             }
 
             var i = 0;
-            Candidate match = default(Candidate);
+            var candidates = new List<Candidate>();
             while (i < state.Instructions.Length)
             {
                 var instruction = state.Instructions[i];
@@ -73,7 +73,7 @@ namespace Microsoft.AspNetCore.Routing.Matchers
                         {
                             if (count == instruction.Depth)
                             {
-                                match = state.Candidates[instruction.Payload];
+                                candidates.Add(state.Candidates[instruction.Payload]);
                             }
                             i++;
                             break;
@@ -92,10 +92,11 @@ namespace Microsoft.AspNetCore.Routing.Matchers
                 }
             }
 
-            if (match.Endpoint != null)
+            var matches = new List<(Endpoint, RouteValueDictionary)>();
+            for (i = 0; i < candidates.Count; i++)
             { 
                 var values = new RouteValueDictionary();
-                var parameters = match.Parameters;
+                var parameters = candidates[i].Parameters;
                 if (parameters != null)
                 {
                     for (var j = 0; j < parameters.Length; j++)
@@ -113,13 +114,13 @@ namespace Microsoft.AspNetCore.Routing.Matchers
                     }
                 }
 
-                feature.Endpoint = match.Endpoint;
+                matches.Add((candidates[i].Endpoint, values));
-                feature.Values = values;
 
                 notmatch:;
             }
 
-
+            feature.Endpoint = matches.Count == 0 ? null : matches[0].Item1;
+            feature.Values = matches.Count == 0 ? null : matches[0].Item2;
 
             return Task.CompletedTask;
         }

test/Microsoft.AspNetCore.Routing.Tests/Matchers/InstructionMatcherBuilder.cs

@@ -35,7 +35,7 @@ namespace Microsoft.AspNetCore.Routing.Matchers
                     return comparison;
                 }
 
-                comparison = y.Precedence.CompareTo(x.Precedence);
+                comparison = x.Precedence.CompareTo(y.Precedence);
                 if (comparison != 0)
                 {
                     return comparison;