Reland Vector ICs: platform support for vector-based stores.

src/ic/x64/access-compiler-x64.cc

Index: src/ic/x64/access-compiler-x64.cc
diff --git a/src/ic/x64/access-compiler-x64.cc b/src/ic/x64/access-compiler-x64.cc
index 63e60f0b912471464362a4ddffcc7e5bf0474021..85b44ef47570dee57f59626ef619ad29618b5202 100644
--- a/src/ic/x64/access-compiler-x64.cc
+++ b/src/ic/x64/access-compiler-x64.cc
@@ -31,7 +31,8 @@ Register* PropertyAccessCompiler::store_calling_convention() {
   // receiver, name, scratch1, scratch2, scratch3.
   Register receiver = StoreDescriptor::ReceiverRegister();
   Register name = StoreDescriptor::NameRegister();
-  DCHECK(rbx.is(StoreTransitionDescriptor::MapRegister()));
+  DCHECK(FLAG_vector_stores ||
+         rbx.is(StoreTransitionDescriptor::MapRegister()));
   static Register registers[] = {receiver, name, rbx, rdi, r8};
   return registers;
 }