HydrogenCodeStubs consume stack arguments via descriptor.

src/ic/handler-compiler.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/cpu-profiler.h"
 #include "src/ic/call-optimization.h"
 #include "src/ic/handler-compiler.h"
 #include "src/ic/ic.h"
@@ skipping 447 matching lines @@
   int descriptor = transition->LastAdded();
   Handle<DescriptorArray> descriptors(transition->instance_descriptors());
   PropertyDetails details = descriptors->GetDetails(descriptor);
   Representation representation = details.representation();
   DCHECK(!representation.IsNone());
 
   // Stub is never generated for objects that require access checks.
   DCHECK(!transition->is_access_check_needed());
 
   // Call to respective StoreTransitionStub.
+  Register transition_map_reg = StoreTransitionDescriptor::MapRegister();
+  bool push_map_on_stack = transition_map_reg.is(no_reg);
+  Register map_reg = push_map_on_stack ? scratch1() : transition_map_reg;
+
   if (details.type() == DATA_CONSTANT) {
-    GenerateRestoreMap(transition, scratch2(), &miss);
     DCHECK(descriptors->GetValue(descriptor)->IsJSFunction());
-    Register map_reg = StoreTransitionDescriptor::MapRegister();
+    GenerateRestoreMap(transition, map_reg, scratch2(), &miss);
     GenerateConstantCheck(map_reg, descriptor, value(), scratch2(), &miss);
+    if (push_map_on_stack) {
+      GeneratePushMap(map_reg, scratch2());
+    }
     GenerateRestoreName(name);
     StoreTransitionStub stub(isolate());
     GenerateTailCall(masm(), stub.GetCode());
 
   } else {
     if (representation.IsHeapObject()) {
       GenerateFieldTypeChecks(descriptors->GetFieldType(descriptor), value(),
                               &miss);
     }
     StoreTransitionStub::StoreMode store_mode =
         Map::cast(transition->GetBackPointer())->unused_property_fields() == 0
             ? StoreTransitionStub::ExtendStorageAndStoreMapAndValue
             : StoreTransitionStub::StoreMapAndValue;
 
-    GenerateRestoreMap(transition, scratch2(), &miss);
+    GenerateRestoreMap(transition, map_reg, scratch2(), &miss);
+    if (push_map_on_stack) {
+      GeneratePushMap(map_reg, scratch2());
+    }
     GenerateRestoreName(name);
     StoreTransitionStub stub(isolate(),
                              FieldIndex::ForDescriptor(*transition, descriptor),
                              representation, store_mode);
     GenerateTailCall(masm(), stub.GetCode());
   }
 
   GenerateRestoreName(&miss, name);
   TailCallBuiltin(masm(), MissBuiltin(kind()));
 
@@ skipping 81 matching lines @@
                                                  : kNoExtraICState);
         cached_stub = LoadDictionaryElementStub(isolate(), state).GetCode();
       }
     }
 
     handlers->Add(cached_stub);
   }
 }
 }  // namespace internal
 }  // namespace v8