BypassReadyToRun when initializing ProbabilisticMap

src/coreclr/System.Private.CoreLib/System.Private.CoreLib.csproj

@@ -201,7 +201,6 @@
     <Compile Include="$(BclSourcesRoot)\System\Reflection\RuntimePropertyInfo.cs" />
     <Compile Include="$(BclSourcesRoot)\System\Reflection\TypeNameResolver.CoreCLR.cs" />
     <Compile Include="$(BclSourcesRoot)\System\Reflection\Metadata\RuntimeTypeMetadataUpdateHandler.cs" />
-    <Compile Include="$(BclSourcesRoot)\System\Runtime\BypassReadyToRunAttribute.cs" />
     <Compile Include="$(BclSourcesRoot)\System\Runtime\CompilerServices\CastHelpers.cs" />
     <Compile Include="$(BclSourcesRoot)\System\Runtime\CompilerServices\GenericsHelpers.cs" />
     <Compile Include="$(BclSourcesRoot)\System\Runtime\CompilerServices\InitHelpers.cs" />

src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems

@@ -807,6 +807,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Resources\SatelliteContractVersionAttribute.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Resources\UltimateResourceFallbackLocation.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\AmbiguousImplementationException.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\BypassReadyToRunAttribute.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\AccessedThroughPropertyAttribute.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\AsyncHelpers.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\AsyncIteratorMethodBuilder.cs" />

src/libraries/System.Private.CoreLib/src/System/SearchValues/ProbabilisticMap.cs

@@ -3,6 +3,7 @@
 
 using System.Diagnostics;
 using System.Numerics;
+using System.Runtime;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Runtime.Intrinsics;
@@ -72,7 +73,11 @@ public ProbabilisticMap(ReadOnlySpan<char> values)
             }
         }
 
+        // SetCharBit and IsCharBitSet must bypass R2R because the set of supported intrinsics impacts how the type is constructed in memory,
+        // so which branch is taken must never change during program execution as we're tiering up. Other methods in this type only check for
+        // intrinsics as a fast path where the fallback path behaves identically, so they are fine to compile R2R.
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        [BypassReadyToRun]
         private static void SetCharBit(ref uint charMap, byte value)
         {
             if (Sse41.IsSupported || AdvSimd.Arm64.IsSupported)
@@ -86,6 +91,7 @@ private static void SetCharBit(ref uint charMap, byte value)
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        [BypassReadyToRun]
         private static bool IsCharBitSet(ref uint charMap, byte value) => Sse41.IsSupported || AdvSimd.Arm64.IsSupported
             ? (Unsafe.Add(ref Unsafe.As<uint, byte>(ref charMap), value & VectorizedIndexMask) & (1u << (value >> VectorizedIndexShift))) != 0
             : (Unsafe.Add(ref charMap, value & PortableIndexMask) & (1u << (value >> PortableIndexShift))) != 0;