[clr-interp] More minimal tweak for enabling debug stack walking (#119129)

- This just enables the StubPrecode::GetMethodDesc api, as well as ExecutionManager::GetCodeMethodDesc
- It is enough for !clrstack to work correctly

Author: davidwrighton

src/coreclr/vm/codeman.cpp

@@ -5060,7 +5060,26 @@ MethodDesc * ExecutionManager::GetCodeMethodDesc(PCODE currentPC)
     }
     CONTRACTL_END
 
-    EECodeInfo codeInfo(currentPC);
+    ExecutionManager::ScanFlag scanFlag = ExecutionManager::GetScanFlags();
+#ifdef FEATURE_INTERPRETER
+    RangeSection * pRS = ExecutionManager::FindCodeRange(currentPC, scanFlag);
+    if (pRS == NULL)
+        return NULL;
+
+    if (pRS->_flags & RangeSection::RANGE_SECTION_RANGELIST)
+    {
+        if (pRS->_pRangeList->GetCodeBlockKind() == STUB_CODE_BLOCK_STUBPRECODE)
+        {
+            PTR_StubPrecode pStubPrecode = dac_cast<PTR_StubPrecode>(PCODEToPINSTR(currentPC));
+            if (pStubPrecode->GetType() == PRECODE_INTERPRETER)
+            {
+                return dac_cast<PTR_MethodDesc>(pStubPrecode->GetMethodDesc());
+            }
+        }
+    }
+#endif // FEATURE_INTERPRETER
+
+    EECodeInfo codeInfo(currentPC, scanFlag);
     if (!codeInfo.IsValid())
         return NULL;
     return codeInfo.GetMethodDesc();

src/coreclr/vm/codeman.h

@@ -2878,6 +2878,11 @@ class EECodeInfo
         Init(codeAddress);
     }
 
+    EECodeInfo(PCODE codeAddress, ExecutionManager::ScanFlag scanFlag)
+    {
+        Init(codeAddress, scanFlag);
+    }
+
     // Explicit initialization
     void Init(PCODE codeAddress);
     void Init(PCODE codeAddress, ExecutionManager::ScanFlag scanFlag);

src/coreclr/vm/precode.h

@@ -84,6 +84,12 @@ struct ThisPtrRetBufPrecode;
 typedef DPTR(class UMEntryThunk) PTR_UMEntryThunk;
 #define PRECODE_UMENTRY_THUNK_VALUE 0x7 // Define the value here and not in UMEntryThunk to avoid circular dependency with the dllimportcallback.h header
 
+#ifdef FEATURE_INTERPRETER
+struct InterpreterPrecode;
+
+typedef DPTR(InterpreterPrecode) PTR_InterpreterPrecode;
+#endif 
+
 // Regular precode
 struct StubPrecode
 {
@@ -122,6 +128,10 @@ struct StubPrecode
     ThisPtrRetBufPrecode* AsThisPtrRetBufPrecode();
 #endif // HAS_THISPTR_RETBUF_PRECODE
 
+#ifdef FEATURE_INTERPRETER
+    PTR_InterpreterPrecode AsInterpreterPrecode();
+#endif // FEATURE_INTERPRETER
+
 #ifndef DACCESS_COMPILE
     void SetSecretParam(TADDR secretParam)
     {
@@ -340,7 +350,13 @@ struct InterpreterPrecode
     TADDR GetMethodDesc();
 };
 
-typedef DPTR(InterpreterPrecode) PTR_InterpreterPrecode;
+inline PTR_InterpreterPrecode StubPrecode::AsInterpreterPrecode()
+{
+    LIMITED_METHOD_CONTRACT;
+    SUPPORTS_DAC;
+
+    return dac_cast<PTR_InterpreterPrecode>(this);
+}
 
 #endif // FEATURE_INTERPRETER
 
@@ -509,10 +525,11 @@ inline TADDR StubPrecode::GetMethodDesc()
         case PRECODE_PINVOKE_IMPORT:
             return GetSecretParam();
 
-        case PRECODE_UMENTRY_THUNK:
 #ifdef FEATURE_INTERPRETER
         case PRECODE_INTERPRETER:
+            return AsInterpreterPrecode()->GetMethodDesc();
 #endif // FEATURE_INTERPRETER
+        case PRECODE_UMENTRY_THUNK:
 #ifdef FEATURE_STUBPRECODE_DYNAMIC_HELPERS
         case PRECODE_DYNAMIC_HELPERS:
 #endif // FEATURE_STUBPRECODE_DYNAMIC_HELPERS