Reduce indirect function calls (#24980)

* Reduce indirect dispatch in hot paths in metadata

* Remove allocation indirections in utilcode for coreclr
- we no longer have a multi-dll distribution of code that needs to share heaps

* Remove unused code in GetCLRFunction

* Remove virtual dispatch around impl/decl methodtable access in MethodData

2 files changed, 43 insertions, 6 deletions

diff --git a/src/inc/clrhost.h b/src/inc/clrhost.h
index c210652a8d..88a917d59f 100644
--- a/src/inc/clrhost.h
+++ b/src/inc/clrhost.h
@@ -182,8 +182,11 @@ inline void ClrFlsSetValue(DWORD slot, void *pData)
     }
 }
 
-typedef LPVOID (*FastAllocInProcessHeapFunc)(DWORD dwFlags, SIZE_T dwBytes);
-extern FastAllocInProcessHeapFunc __ClrAllocInProcessHeap;
+#ifndef SELF_NO_HOST
+LPVOID EEHeapAllocInProcessHeap(DWORD dwFlags, SIZE_T dwBytes);
+BOOL EEHeapFreeInProcessHeap(DWORD dwFlags, LPVOID lpMem);
+#endif
+
 inline LPVOID ClrAllocInProcessHeap(DWORD dwFlags, S_SIZE_T dwBytes)
 {
     STATIC_CONTRACT_SUPPORTS_DAC_HOST_ONLY;
@@ -193,7 +196,7 @@ inline LPVOID ClrAllocInProcessHeap(DWORD dwFlags, S_SIZE_T dwBytes)
     }
 
 #ifndef SELF_NO_HOST
-    return __ClrAllocInProcessHeap(dwFlags, dwBytes.Value());
+    return EEHeapAllocInProcessHeap(dwFlags, dwBytes.Value());
 #else
 #undef HeapAlloc
 #undef GetProcessHeap
@@ -206,13 +209,11 @@ inline LPVOID ClrAllocInProcessHeap(DWORD dwFlags, S_SIZE_T dwBytes)
 #endif
 }
 
-typedef BOOL (*FastFreeInProcessHeapFunc)(DWORD dwFlags, LPVOID lpMem);
-extern FastFreeInProcessHeapFunc __ClrFreeInProcessHeap;
 inline BOOL ClrFreeInProcessHeap(DWORD dwFlags, LPVOID lpMem)
 {
     STATIC_CONTRACT_SUPPORTS_DAC_HOST_ONLY;
 #ifndef SELF_NO_HOST
-    return __ClrFreeInProcessHeap(dwFlags, lpMem);
+    return EEHeapFreeInProcessHeap(dwFlags, lpMem);
 #else
 #undef HeapFree
 #undef GetProcessHeap
diff --git a/src/inc/stgpool.h b/src/inc/stgpool.h
index 4486695507..67d78b24db 100644
--- a/src/inc/stgpool.h
+++ b/src/inc/stgpool.h
@@ -234,6 +234,42 @@ public:
         
         return hr;
     }
+
+//*****************************************************************************
+// Return a pointer to a null terminated string given an offset previously
+// handed out by AddString or FindString. Only valid for use if the Storage pool is actuall ReadOnly, and not derived
+//*****************************************************************************
+    __checkReturn 
+    inline HRESULT GetStringReadOnly(
+                    UINT32  nIndex, 
+        __deref_out LPCSTR *pszString)
+    {
+        HRESULT hr;
+        
+        // Size of the data in the heap will be ignored, because we have verified during creation of the string 
+        // heap (code:Initialize) and when adding new strings (e.g. code:AddString, 
+        // code:AddTemporaryStringBuffer), that the heap is null-terminated, therefore we don't have to check it 
+        // for each string in the heap
+        MetaData::DataBlob stringData;
+        
+        // Get data from the heap (clears stringData on error)
+        IfFailGo(GetDataReadOnly(
+            nIndex, 
+            &stringData));
+        _ASSERTE(hr == S_OK);
+        // Raw data are always at least 1 byte long, otherwise it would be invalid offset and hr != S_OK
+        PREFAST_ASSUME(stringData.GetDataPointer() != NULL);
+        // Fills output string
+        *pszString = reinterpret_cast<LPSTR>(stringData.GetDataPointer());
+        //_ASSERTE(stringData.GetSize() > strlen(*pszString));
+        
+        return hr;
+    ErrExit:
+        // Clears output string on error
+        *pszString = NULL;
+        
+        return hr;
+    }
 #ifdef _PREFAST_
 #pragma warning(pop)
 #endif