Startup optimization w.r.t. manifest access in composite mode

src/coreclr/src/vm/ceeload.cpp

@@ -99,10 +99,10 @@ BOOL Module::HasNativeOrReadyToRunInlineTrackingMap()
 {
     LIMITED_METHOD_DAC_CONTRACT;
 #ifdef FEATURE_READYTORUN
-	if (IsReadyToRun() && GetReadyToRunInfo()->GetInlineTrackingMap() != NULL)
-	{
-		return TRUE;
-	}
+    if (IsReadyToRun() && GetReadyToRunInfo()->GetInlineTrackingMap() != NULL)
+    {
+        return TRUE;
+    }
 #endif
     return (m_pPersistentInlineTrackingMapNGen != NULL);
 }
@@ -500,10 +500,9 @@ BOOL Module::IsPersistedObject(void *address)
 
 uint32_t Module::GetNativeMetadataAssemblyCount()
 {
-    NativeImage *compositeImage = GetCompositeNativeImage();
-    if (compositeImage != NULL)
+    if (m_pNativeImage != NULL)
     {
-        return compositeImage->GetManifestAssemblyCount();
+        return m_pNativeImage->GetManifestAssemblyCount();
     }
     else
     {
@@ -593,15 +592,25 @@ void Module::Initialize(AllocMemTracker *pamTracker, LPCWSTR szName)
 #endif // FEATURE_COLLECTIBLE_TYPES
 
 #ifdef FEATURE_READYTORUN
+    m_pNativeImage = NULL;
     if (!HasNativeImage() && !IsResource())
     {
         if ((m_pReadyToRunInfo = ReadyToRunInfo::Initialize(this, pamTracker)) != NULL)
         {
-            COUNT_T cMeta = 0;
-            if (GetFile()->GetOpenedILimage()->GetNativeManifestMetadata(&cMeta) != NULL)
+            m_pNativeImage = m_pReadyToRunInfo->GetNativeImage();
+            if (m_pNativeImage != NULL)
+            {
+                m_NativeMetadataAssemblyRefMap = m_pNativeImage->GetManifestMetadataAssemblyRefMap();
+            }
+            else
             {
-                // Load the native assembly import
-                GetNativeAssemblyImport(TRUE /* loadAllowed */);
+                // For composite images, manifest metadata gets loaded as part of the native image
+                COUNT_T cMeta = 0;
+                if (GetFile()->GetOpenedILimage()->GetNativeManifestMetadata(&cMeta) != NULL)
+                {
+                    // Load the native assembly import
+                    GetNativeAssemblyImport(TRUE /* loadAllowed */);
+                }
             }
         }
     }
@@ -9619,7 +9628,14 @@ void Module::Fixup(DataImage *image)
     image->ZeroField(this, offsetof(Module, m_AssemblyRefByNameCount), sizeof(m_AssemblyRefByNameCount));
     image->ZeroPointerField(this, offsetof(Module, m_AssemblyRefByNameTable));
 
-    image->ZeroPointerField(this,offsetof(Module, m_NativeMetadataAssemblyRefMap));
+#ifdef FEATURE_READYTORUN
+    // For composite ready-to-run images, the manifest assembly ref map is stored in the native image
+    // and shared by all its component images.
+    if (m_pNativeImage == NULL)
+#endif
+    {
+        image->ZeroPointerField(this,offsetof(Module, m_NativeMetadataAssemblyRefMap));
+    }
 
     //
     // Fixup statics

src/coreclr/src/vm/ceeload.h

@@ -1615,6 +1615,7 @@ class Module
 #ifdef FEATURE_READYTORUN
 private:
     PTR_ReadyToRunInfo      m_pReadyToRunInfo;
+    PTR_NativeImage         m_pNativeImage;
 #endif
 
 private:
@@ -2924,17 +2925,17 @@ class Module
 #endif
     }
 
-    NativeImage *GetCompositeNativeImage() const
+#ifdef FEATURE_READYTORUN
+    PTR_ReadyToRunInfo GetReadyToRunInfo() const
     {
         LIMITED_METHOD_DAC_CONTRACT;
-        return (m_pReadyToRunInfo != NULL ? m_pReadyToRunInfo->GetNativeImage() : NULL);
+        return m_pReadyToRunInfo;
     }
 
-#ifdef FEATURE_READYTORUN
-    PTR_ReadyToRunInfo GetReadyToRunInfo() const
+    PTR_NativeImage GetCompositeNativeImage() const
     {
         LIMITED_METHOD_DAC_CONTRACT;
-        return m_pReadyToRunInfo;
+        return m_pNativeImage;
     }
 #endif
 

src/coreclr/src/vm/nativeimage.cpp

@@ -74,6 +74,11 @@ void NativeImage::Initialize(READYTORUN_HEADER *pHeader, LoaderAllocator *pLoade
     // count may exceed its component assembly count as it may contain references to
     // assemblies outside of the composite image that are part of its version bubble.
     _ASSERTE(m_manifestAssemblyCount >= m_componentAssemblyCount);
+
+    S_SIZE_T dwAllocSize = S_SIZE_T(sizeof(PTR_Assembly)) * S_SIZE_T(m_manifestAssemblyCount);
+
+    // Note: Memory allocated on loader heap is zero filled
+    m_pNativeMetadataAssemblyRefMap = (PTR_Assembly*)pamTracker->Track(pLoaderAllocator->GetLowFrequencyHeap()->AllocMem(dwAllocSize));
 }
 
 NativeImage::~NativeImage()

src/coreclr/src/vm/nativeimage.h

@@ -62,6 +62,7 @@ class NativeImage
     ReadyToRunInfo *m_pReadyToRunInfo;
     IMDInternalImport *m_pManifestMetadata;
     PEImageLayout *m_pImageLayout;
+    PTR_Assembly *m_pNativeMetadataAssemblyRefMap;
 
     IMAGE_DATA_DIRECTORY *m_pComponentAssemblies;
     uint32_t m_componentAssemblyCount;
@@ -95,6 +96,7 @@ class NativeImage
     ReadyToRunInfo *GetReadyToRunInfo() const { return m_pReadyToRunInfo; }
     IMDInternalImport *GetManifestMetadata() const { return m_pManifestMetadata; }
     uint32_t GetManifestAssemblyCount() const { return m_manifestAssemblyCount; }
+    PTR_Assembly *GetManifestMetadataAssemblyRefMap() { return m_pNativeMetadataAssemblyRefMap; }
 
     Assembly *LoadManifestAssembly(uint32_t rowid);