Fix x86 steady state tiered compilation performance (#17476)

* Fix x86 steady state tiered compilation performance

Also included - a few tiered compilation only test hooks + small logging fix for JitBench

Tiered compilation wasn't correctly implementing the MayHavePrecode and RequiresStableEntryPoint policy functions. On x64 this was a non-issue, but due to compact entrypoints on x86 it lead to methods allocating both FuncPtrStubs and Precodes. The FuncPtrStubs would never get backpatched which caused never ending invocations of the Prestub for some methods. Although such code still runs correctly, it is much slower than it needs to be. On MusicStore x86 I am seeing a 20% improvement in steady state RPS after this fix, bringing us inline with what I've seen on x64.

1 files changed, 4 insertions, 6 deletions

diff --git a/tests/src/performance/Scenario/JitBench/Runner/Benchmark.cs b/tests/src/performance/Scenario/JitBench/Runner/Benchmark.cs
index 85185b449a..13554c896e 100644
--- a/tests/src/performance/Scenario/JitBench/Runner/Benchmark.cs
+++ b/tests/src/performance/Scenario/JitBench/Runner/Benchmark.cs
@@ -71,15 +71,13 @@ namespace JitBench
                     startInfo.WorkingDirectory = WorkingDirPath;
                     startInfo.RedirectStandardError = true;
                     startInfo.RedirectStandardOutput = true;
-                    foreach (KeyValuePair<string, string> kv in config.EnvironmentVariables)
+                    IEnumerable<KeyValuePair<string, string>> extraEnvVars = config.EnvironmentVariables.Concat(EnvironmentVariables).Append(new KeyValuePair<string, string>("DOTNET_MULTILEVEL_LOOKUP", "0"));
+                    foreach (KeyValuePair<string, string> kv in extraEnvVars)
                     {
                         startInfo.Environment[kv.Key] = kv.Value;
                     }
-                    foreach (KeyValuePair<string, string> kv in EnvironmentVariables)
-                    {
-                        startInfo.Environment[kv.Key] = kv.Value;
-                    }
-                    startInfo.Environment["DOTNET_MULTILEVEL_LOOKUP"] = "0";
+                    output.WriteLine("XUnitPerfHarness doesn't log env vars it uses to run processes. To workaround, logging them here:");
+                    output.WriteLine(string.Join(", ", extraEnvVars.Select(kv => kv.Key + "=" + kv.Value)));
 
                     BenchmarkRunResult result = new BenchmarkRunResult(this, config);
                     StringBuilder stderr = new StringBuilder();