Enable tiered jitting for R2R methods (#15967)

Enable tiered jitting for R2R methods

- Included R2R methods and generics over value types in CoreLib for tiered jitting. Tier 0 for R2R methods is the precompiled code if available, and tier 1 is selectively scheduled based on call counting.
- Added a delay before starting to count calls for tier 1 promotion. The delay is a short duration after frequent tier 0 jitting stops (current heuristic for identifying startup).
- Startup time and steady-state performance have improved on JitBench. There is a regression shortly following startup due to call counting and tier 1 jitting, for a short duration before steady-state performance stabilizes.
- Added two new config values, one for configuring the call count threshold for promoting to tier 1, and another for specifying the delay from the last tier 0 JIT invocation before starting to count calls

1 files changed, 10 insertions, 0 deletions

diff --git a/src/vm/eeconfig.cpp b/src/vm/eeconfig.cpp
index 95a7133bb9..ab83463256 100644
--- a/src/vm/eeconfig.cpp
+++ b/src/vm/eeconfig.cpp
@@ -376,6 +376,8 @@ HRESULT EEConfig::Init()
 
 #if defined(FEATURE_TIERED_COMPILATION)
     fTieredCompilation = false;
+    tieredCompilation_tier1CallCountThreshold = 1;
+    tieredCompilation_tier1CallCountingDelayMs = 0;
 #endif
     
 #if defined(FEATURE_GDBJIT) && defined(_DEBUG)
@@ -1239,6 +1241,14 @@ HRESULT EEConfig::sync()
 
 #if defined(FEATURE_TIERED_COMPILATION)
     fTieredCompilation = CLRConfig::GetConfigValue(CLRConfig::UNSUPPORTED_TieredCompilation) != 0;
+    tieredCompilation_tier1CallCountThreshold =
+        CLRConfig::GetConfigValue(CLRConfig::UNSUPPORTED_TieredCompilation_Tier1CallCountThreshold);
+    if (tieredCompilation_tier1CallCountThreshold < 1)
+    {
+        tieredCompilation_tier1CallCountThreshold = 1;
+    }
+    tieredCompilation_tier1CallCountingDelayMs =
+        CLRConfig::GetConfigValue(CLRConfig::UNSUPPORTED_TieredCompilation_Tier1CallCountingDelayMs);
 #endif
 
 #if defined(FEATURE_GDBJIT) && defined(_DEBUG)