HydrogenCodeStubs consume stack arguments via descriptor.

src/ia32/interface-descriptors-ia32.cc

 // Copyright 2012 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"
 
 #if V8_TARGET_ARCH_IA32
 
 #include "src/interface-descriptors.h"
 
@@ skipping 14 matching lines @@
 const Register StoreDescriptor::NameRegister() { return ecx; }
 const Register StoreDescriptor::ValueRegister() { return eax; }
 
 
 const Register VectorStoreICTrampolineDescriptor::SlotRegister() { return edi; }
 
 
 const Register VectorStoreICDescriptor::VectorRegister() { return ebx; }
 
 
-const Register StoreTransitionDescriptor::MapRegister() { return ebx; }
+const Register StoreTransitionDescriptor::MapRegister() {
+  return FLAG_vector_stores ? no_reg : ebx;
+}
 
 
 const Register LoadGlobalViaContextDescriptor::DepthRegister() { return edx; }
 const Register LoadGlobalViaContextDescriptor::SlotRegister() { return ebx; }
 const Register LoadGlobalViaContextDescriptor::NameRegister() { return ecx; }
 
 
 const Register StoreGlobalViaContextDescriptor::DepthRegister() { return edx; }
 const Register StoreGlobalViaContextDescriptor::SlotRegister() { return ebx; }
 const Register StoreGlobalViaContextDescriptor::NameRegister() { return ecx; }
@@ skipping 16 matching lines @@
 
 const Register MathPowIntegerDescriptor::exponent() {
   return MathPowTaggedDescriptor::exponent();
 }
 
 
 const Register GrowArrayElementsDescriptor::ObjectRegister() { return eax; }
 const Register GrowArrayElementsDescriptor::KeyRegister() { return ebx; }
 
 
+void StoreTransitionDescriptor::InitializePlatformSpecific(
+    CallInterfaceDescriptorData* data) {
+  Register registers[] = {ReceiverRegister(), NameRegister(), ValueRegister(),
+                          MapRegister()};
+
+  // When FLAG_vector_stores is true, we want to pass the map register on the
+  // stack instead of in a register.
+  DCHECK(FLAG_vector_stores || !MapRegister().is(no_reg));
+
+  int register_count = FLAG_vector_stores ? 3 : 4;
+  data->InitializePlatformSpecific(register_count, registers);
+}
+
+
 void FastNewClosureDescriptor::InitializePlatformSpecific(
     CallInterfaceDescriptorData* data) {
   Register registers[] = {ebx};
   data->InitializePlatformSpecific(arraysize(registers), registers, NULL);
 }
 
 
 void FastNewContextDescriptor::InitializePlatformSpecific(
     CallInterfaceDescriptorData* data) {
   Register registers[] = {edi};
@@ skipping 272 matching lines @@
       edi,  // math rounding function
       edx,  // vector slot id
       ebx   // type vector
   };
   data->InitializePlatformSpecific(arraysize(registers), registers);
 }
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_IA32