First part of new ICData infrastructure: use a wrapper object instead of an array.

runtime/vm/stub_code_x64.cc

Index: runtime/vm/stub_code_x64.cc
===================================================================
--- runtime/vm/stub_code_x64.cc	(revision 4401)
+++ runtime/vm/stub_code_x64.cc	(working copy)
@@ -7,7 +7,6 @@
 
 #include "vm/code_generator.h"
 #include "vm/compiler.h"
-#include "vm/ic_data.h"
 #include "vm/object_store.h"
 #include "vm/pages.h"
 #include "vm/resolver.h"
@@ -371,8 +370,7 @@
   __ cmpq(R13, raw_null);
   __ j(EQUAL, &not_found, Assembler::kNearJump);
 
-  ASSERT(ICData::kNameIndex == 0);
-  __ cmpq(R13, FieldAddress(RBX, Array::data_offset()));
+  __ cmpq(R13, FieldAddress(RBX, ICData::target_name_offset()));
   __ j(NOT_EQUAL, &next_iteration, Assembler::kNearJump);
 
   // Name found, check total argument count and named argument count.
@@ -1537,7 +1535,7 @@
 
 
 // Generate inline cache check for 'num_args'.
-//  RBX: Inline cache data array.
+//  RBX: Inline cache data object.
 //  R10: Arguments array.
 //  TOS(0): return address
 // Control flow:
@@ -1552,7 +1550,7 @@
   ASSERT(num_args > 0);
   // Get receiver.
   __ movq(RAX, FieldAddress(R10, Array::data_offset()));
-  __ movq(RAX, Address(RSP, RAX, TIMES_4, 0));  // RAX is Smi.
+  __ movq(RAX, Address(RSP, RAX, TIMES_4, 0));  // RAX (argument count) is Smi.
 
   Label get_class, ic_miss;
   __ call(&get_class);
@@ -1562,11 +1560,9 @@
 #if defined(DEBUG)
   { Label ok;
     // Check that the IC data array has NumberOfArgumentsChecked() == num_args.
-    __ movq(RCX, FieldAddress(RBX,
-        Array::data_offset() + ICData::kNumArgsCheckedIndex * kWordSize));
-    const Immediate value =
-        Immediate(reinterpret_cast<int64_t>(Smi::New(num_args)));
-    __ cmpq(RCX, value);
+    // 'num_args_tested' is stored as an untagged int.
+    __ movq(RCX, FieldAddress(RBX, ICData::num_args_tested_offset()));
+    __ cmpq(RCX, Immediate(num_args));
     __ j(EQUAL, &ok, Assembler::kNearJump);
     __ Stop("Incorrect stub for IC data");
     __ Bind(&ok);
@@ -1575,10 +1571,11 @@
 
   // Loop that checks if there is an IC data match.
   // RAX: receiver's class.
-  // RBX: IC data array (preserved).
-  __ leaq(R12, FieldAddress(RBX,
-      Array::data_offset() + ICData::kChecksStartIndex * kWordSize));
-  // R12: pointing to a class to check against (into IC data array).
+  // RBX: IC data object (preserved).
+  __ movq(R12, FieldAddress(RBX, ICData::ic_data_offset()));
+  // R12: ic_data_array with check entries: classes and target functions.
+  __ leaq(R12, FieldAddress(R12, Array::data_offset()));
+  // R12: points directly to the first ic data array element.
   const Immediate raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
   Label loop, found;