Remember all deopt reasons in ic_data, not just the last one.

runtime/vm/stub_code_x64.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 1195 matching lines @@
   __ incq(FieldAddress(func_reg, Function::usage_counter_offset()));
 }
 
 
 // Loads function into 'temp_reg', preserves 'ic_reg'.
 void StubCode::GenerateUsageCounterIncrement(Assembler* assembler,
                                              Register temp_reg) {
   Register ic_reg = RBX;
   Register func_reg = temp_reg;
   ASSERT(ic_reg != func_reg);
-  __ movq(func_reg, FieldAddress(ic_reg, ICData::function_offset()));
+  __ movq(func_reg, FieldAddress(ic_reg, ICData::owner_offset()));
   __ incq(FieldAddress(func_reg, Function::usage_counter_offset()));
 }
 
 
 // Generate inline cache check for 'num_args'.
 //  RBX: Inline cache data object.
 //  TOS(0): return address
 // Control flow:
 // - If receiver is null -> jump to IC miss.
 // - If receiver is Smi -> load Smi class.
 // - If receiver is not-Smi -> load receiver's class.
 // - Check if 'num_args' (including receiver) match any IC data group.
 // - Match found -> jump to target.
 // - Match not found -> jump to IC miss.
 void StubCode::GenerateNArgsCheckInlineCacheStub(
     Assembler* assembler,
     intptr_t num_args,
     const RuntimeEntry& handle_ic_miss) {
   ASSERT(num_args > 0);
 #if defined(DEBUG)
   { Label ok;
-    // Check that the IC data array has NumberOfArgumentsChecked() == num_args.
-    // 'num_args_tested' is stored as an untagged int.
-    __ movq(RCX, FieldAddress(RBX, ICData::num_args_tested_offset()));
+    // Check that the IC data array has NumArgsTested() == num_args.
+    // 'NumArgsTested' is stored in the least significant bits of 'state_bits'.
+    __ movl(RCX, FieldAddress(RBX, ICData::state_bits_offset()));
+    ASSERT(ICData::NumArgsTestedShift() == 0);  // No shift needed.
+    __ andq(RCX, Immediate(ICData::NumArgsTestedMask()));
     __ cmpq(RCX, Immediate(num_args));
     __ j(EQUAL, &ok, Assembler::kNearJump);
     __ Stop("Incorrect stub for IC data");
     __ Bind(&ok);
   }
 #endif  // DEBUG
 
   // Check single stepping.
   Label not_stepping;
   __ movq(RAX, FieldAddress(CTX, Context::isolate_offset()));
@@ skipping 202 matching lines @@
 }
 
 
 // Intermediary stub between a static call and its target. ICData contains
 // the target function and the call count.
 // RBX: ICData
 void StubCode::GenerateZeroArgsUnoptimizedStaticCallStub(Assembler* assembler) {
   GenerateUsageCounterIncrement(assembler, RCX);
 #if defined(DEBUG)
   { Label ok;
-    // Check that the IC data array has NumberOfArgumentsChecked() == 0.
-    // 'num_args_tested' is stored as an untagged int.
-    __ movq(RCX, FieldAddress(RBX, ICData::num_args_tested_offset()));
+    // Check that the IC data array has NumArgsTested() == 0.
+    // 'NumArgsTested' is stored in the least significant bits of 'state_bits'.
+    __ movl(RCX, FieldAddress(RBX, ICData::state_bits_offset()));
+    ASSERT(ICData::NumArgsTestedShift() == 0);  // No shift needed.
+    __ andq(RCX, Immediate(ICData::NumArgsTestedMask()));
     __ cmpq(RCX, Immediate(0));
     __ j(EQUAL, &ok, Assembler::kNearJump);
     __ Stop("Incorrect IC data for unoptimized static call");
     __ Bind(&ok);
   }
 #endif  // DEBUG
 
   // Check single stepping.
   Label not_stepping;
   __ movq(RAX, FieldAddress(CTX, Context::isolate_offset()));
@@ skipping 365 matching lines @@
 
   __ movq(left, Address(RSP, 2 * kWordSize));
   __ movq(right, Address(RSP, 1 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64