Using SubtypeTestCache object instead of an array, that way we do not need to patch and can communi…

runtime/vm/stub_code_ia32.cc

Index: runtime/vm/stub_code_ia32.cc
===================================================================
--- runtime/vm/stub_code_ia32.cc	(revision 7302)
+++ runtime/vm/stub_code_ia32.cc	(working copy)
@@ -1822,13 +1822,13 @@
 // TOS + 0: return address.
 // TOS + 1: instantiator type arguments (can be NULL).
 // TOS + 2: instance.
-// TOS + 3: cache array.
+// TOS + 3: SubtypeTestCache.
 // Result in ECX: null -> not found, otherwise result (true or false).
 static void GenerateSubtypeNTestCacheStub(Assembler* assembler, int n) {
   ASSERT((1 <= n) && (n <= 3));
   const intptr_t kInstantiatorTypeArgumentsInBytes = 1 * kWordSize;
   const intptr_t kInstanceOffsetInBytes = 2 * kWordSize;
-  const intptr_t kCacheArrayOffsetInBytes = 3 * kWordSize;
+  const intptr_t kCacheOffsetInBytes = 3 * kWordSize;
   const Immediate raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
   Label not_found;
@@ -1848,8 +1848,9 @@
     __ Bind(&has_no_type_arguments);
   }
   // EBX: instance type arguments (null if none).
-  __ movl(EDX, Address(ESP, kCacheArrayOffsetInBytes));
-  // EDX: cache.
+  __ movl(EDX, Address(ESP, kCacheOffsetInBytes));
+  // EDX: SubtypeTestCache.
+  __ movl(EDX, FieldAddress(EDX, SubtypeTestCache::cache_offset()));
   __ addl(EDX, Immediate(Array::data_offset() - kHeapObjectTag));
 
   Label loop, found, next_iteration;
@@ -1857,7 +1858,7 @@
   // ECX: instance class.
   // EBX: instance type arguments
   __ Bind(&loop);
-  __ movl(EDI, Address(EDX, kWordSize * SubTypeTestCache::kInstanceClass));
+  __ movl(EDI, Address(EDX, kWordSize * SubtypeTestCache::kInstanceClass));
   __ cmpl(EDI, raw_null);
   __ j(EQUAL, &not_found, Assembler::kNearJump);
   __ cmpl(EDI, ECX);
@@ -1866,7 +1867,7 @@
   } else {
     __ j(NOT_EQUAL, &next_iteration, Assembler::kNearJump);
     __ movl(EDI,
-          Address(EDX, kWordSize * SubTypeTestCache::kInstanceTypeArguments));
+          Address(EDX, kWordSize * SubtypeTestCache::kInstanceTypeArguments));
     __ cmpl(EDI, EBX);
     if (n == 2) {
       __ j(EQUAL, &found, Assembler::kNearJump);
@@ -1874,13 +1875,13 @@
       __ j(NOT_EQUAL, &next_iteration, Assembler::kNearJump);
       __ movl(EDI,
               Address(EDX, kWordSize *
-                           SubTypeTestCache::kInstantiatorTypeArguments));
+                           SubtypeTestCache::kInstantiatorTypeArguments));
       __ cmpl(EDI, Address(ESP, kInstantiatorTypeArgumentsInBytes));
       __ j(EQUAL, &found, Assembler::kNearJump);
     }
   }
   __ Bind(&next_iteration);
-  __ addl(EDX, Immediate(kWordSize * SubTypeTestCache::kNumEntries));
+  __ addl(EDX, Immediate(kWordSize * SubtypeTestCache::kTestEntryLength));
   __ jmp(&loop, Assembler::kNearJump);
   // Fall through to not found.
   __ Bind(&not_found);
@@ -1888,7 +1889,7 @@
   __ ret();
 
   __ Bind(&found);
-  __ movl(ECX, Address(EDX, kWordSize * SubTypeTestCache::kTestResult));
+  __ movl(ECX, Address(EDX, kWordSize * SubtypeTestCache::kTestResult));
   __ ret();
 }