Support MPS Backend also on iOS < 16 (pytorch#9089)

Differential Revision: D70795041

Pull Request resolved: pytorch#9095

Author: f-meloni

backends/apple/mps/runtime/MPSDevice.mm

@@ -22,11 +22,11 @@ static inline MTLLanguageVersion getMetalLanguageVersion(const id<MTLDevice>& de
   // MPS Advanced Indexing needs at least Metal 2.0 (support for Argument Buffers and function constants)
   // host_name attribute needs at least Metal 2.2 and ulong needs Metal 2.3 (supported on MacOS 11+)
   MTLLanguageVersion languageVersion = MTLLanguageVersion2_3;
-#if defined(__MAC_13_0)
-  if (macOS13Plus) {
-    languageVersion = MTLLanguageVersion3_0;
+  if (@available(iOS 16, macOS 13, *)) {
+    if (macOS13Plus) {
+      languageVersion = MTLLanguageVersion3_0;
+    }
   }
-#endif
 
   ET_CHECK_MSG([device supportsFamily:MTLGPUFamilyMac2], "Missing Metal support for MTLGPUFamilyMac2");
   return languageVersion;

backends/apple/mps/runtime/operations/IndexingOps.mm

@@ -206,25 +206,32 @@
 
 Error
 MPSGraphBuilder::mpsScatterOp(NodePtr nodePtr) {
-  auto graphNode = nodePtr->mpsnode_union_as_MPSScatter();
-  ET_LOG(
-    Debug, "%s %d: %d",
-    __FUNCTION__, graphNode->input1_id(), graphNode->output_id()
-  );
+  if (@available(iOS 15.4, macOS 12.3, *)) {
+    auto graphNode = nodePtr->mpsnode_union_as_MPSScatter();
+    ET_LOG(
+      Debug, "%s %d: %d",
+      __FUNCTION__, graphNode->input1_id(), graphNode->output_id()
+    );
 
-  int64_t dim = graphNode->dim();
-  MPSGraphTensor* inputTensor = getMPSGraphTensor(graphNode->input1_id());
-  MPSGraphTensor* indicesTensor = getMPSGraphTensor(graphNode->idx_id());
-  MPSGraphTensor* updatesTensor = getMPSGraphTensor(graphNode->src_id());
+    int64_t dim = graphNode->dim();
+    MPSGraphTensor* inputTensor = getMPSGraphTensor(graphNode->input1_id());
+    MPSGraphTensor* indicesTensor = getMPSGraphTensor(graphNode->idx_id());
+    MPSGraphTensor* updatesTensor = getMPSGraphTensor(graphNode->src_id());
 
-  _idToMPSGraphTensor[graphNode->output_id()] =
-    [_mpsGraph scatterAlongAxis:dim
-                 withDataTensor:inputTensor
-                  updatesTensor:updatesTensor
-                  indicesTensor:indicesTensor
-                           mode:MPSGraphScatterModeSet
-                           name:nil];
-  return Error::Ok;
+    _idToMPSGraphTensor[graphNode->output_id()] =
+      [_mpsGraph scatterAlongAxis:dim
+                   withDataTensor:inputTensor
+                    updatesTensor:updatesTensor
+                    indicesTensor:indicesTensor
+                             mode:MPSGraphScatterModeSet
+                             name:nil];
+
+    return Error::Ok;
+  } else {
+    ET_LOG(Error, "MPS: scatter op is not supported on iOS < 15.4 and macOS < 12.3");
+
+    return Error::NotSupported;
+  }
 }