Add extra logging in CoreML (pytorch#13890)

Summary: This diff adds extra logging in CoreML to indicate whether the
model in the pte file was pre-compiled.

Differential Revision: D81256207

Author: metascroy

backends/apple/coreml/runtime/delegate/ETCoreMLModelManager.mm

@@ -449,12 +449,14 @@ - (nullable NSURL *)compiledModelURLWithIdentifier:(NSString *)identifier
         case ModelAssetType::CompiledModel: {
             // The model is already compiled; no further action needed.
             // Return the existing model URL.
+            ETCoreMLLogInfo("The model in the pte file is pre-compiled.  Skipping compilation.");
             return modelURL;
         }
 
         case ModelAssetType::Model: {
             // The model is not compiled yet.
             // Compile the model at the specified URL with a maximum wait time of 5 minutes.
+            ETCoreMLLogInfo("The model in the pte file is not pre-compiled.  Compiling with a 5 min timeout.");
             NSURL *compiledModelURL = [ETCoreMLModelCompiler compileModelAtURL:modelURL
                                                           maxWaitTimeInSeconds:(5 * 60)
                                                                          error:error];
@@ -490,6 +492,7 @@ - (nullable ETCoreMLAsset *)compiledModelAssetWithMetadata:(const ModelMetadata&
                                                                  error:error];
         if (compiledModelURL) {
             // Move the compiled model to the asset manager to transfer ownership.
+            ETCoreMLLogInfo("Storing compiled asset with identifier=%@ in the asset manager.", identifier);
             compiledModelAsset = [self.assetManager storeAssetAtURL:compiledModelURL withIdentifier:identifier error:error];
         }
     }];