cache EECodeInfo based on given code pointer, not start of the method

The EECodeInfo includes the relative offset (given ip - start of method) so it's not ok to share for different code pointers into the same method

docs/design/datacontracts/ExecutionManager.md

@@ -7,10 +7,10 @@ managed method corresponding to that address.
 ## APIs of contract
 
 ```csharp
-internal struct EECodeInfoHandle
+struct EECodeInfoHandle
 {
-    // no public constructor
     public readonly TargetPointer Address;
+    // no public constructor
     internal EECodeInfoHandle(TargetPointer address) => Address = address;
 }
 ```
@@ -75,13 +75,18 @@ The bulk of the work is donee by the `GetEECodeInfoHandle` API that maps a code
     }
     EECodeInfoHandle? IExecutionManager.GetEECodeInfoHandle(TargetCodePointer ip)
     {
+        TargetPointer key = ip.AsTargetPointer;
+        if (/*cache*/.ContainsKey(key))
+        {
+            return new EECodeInfoHandle(key);
+        }
         EECodeInfo? info = GetEECodeInfo(ip);
         if (info == null || !info.Valid)
         {
             return null;
         }
-        TargetPointer key = info.CodeHeaderAddress;
-        AddToCache(key, info);/* add a mapping from key to info to a chache */
+        /*cache*/.TryAdd(key, info);
+        return new EECodeInfoHandle(key);
         return new EECodeInfoHandle(key);
     }
 ```

src/native/managed/cdacreader/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/ExecutionManager_1.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
-using Microsoft.Diagnostics.DataContractReader.ExecutionManagerHelpers;
 
 namespace Microsoft.Diagnostics.DataContractReader.Contracts;
 
@@ -29,6 +28,8 @@ public ExecutionManager_1(Target target, Data.RangeSectionMap topRangeSectionMap
         _r2rJitManager = new ReadyToRunJitManager(_target);
     }
 
+    // Note, because of RelativeOffset, this code info is per code pointer, not per method
+    // TODO: rethink whether this makes sense. We don't need to copy the runtime's notion of EECodeInfo verbatim
     private class EECodeInfo
     {
         private readonly int _codeHeaderOffset;
@@ -165,14 +166,16 @@ private JitManager GetJitManager(Data.RangeSection rangeSectionData)
     }
     EECodeInfoHandle? IExecutionManager.GetEECodeInfoHandle(TargetCodePointer ip)
     {
-        // TODO: some kind of cache based on ip, too?
-        // we don't know if the ip is the start of the code.
+        TargetPointer key = ip.AsTargetPointer; // FIXME: thumb bit. It's harmless (we potentialy have 2 cache entries per IP), but we should fix it
+        if (_codeInfos.ContainsKey(key))
+        {
+            return new EECodeInfoHandle(key);
+        }
         EECodeInfo? info = GetEECodeInfo(ip);
         if (info == null || !info.Valid)
         {
             return null;
         }
-        TargetPointer key = info.CodeHeaderAddress;
         _codeInfos.TryAdd(key, info);
         return new EECodeInfoHandle(key);
     }