Include multiplication in the megamorphic cache hash to avoid cid ranges overlapping modulo table s…

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 2074 matching lines @@
   __ LoadTaggedClassIdMayBeSmi(RAX, RDI);
   // RAX: class ID of the receiver (smi).
   __ movq(R10,
           FieldAddress(RBX, MegamorphicCache::arguments_descriptor_offset()));
   __ movq(RDI, FieldAddress(RBX, MegamorphicCache::buckets_offset()));
   __ movq(R9, FieldAddress(RBX, MegamorphicCache::mask_offset()));
   // R10: arguments descriptor (result).
   // RDI: cache buckets array.
   // RBX: mask.
   __ movq(RCX, RAX);
+  __ imulq(RCX, Immediate(MegamorphicCache::kSpreadFactor));
 
   Label loop, update, load_target_function;
   __ jmp(&loop);
 
   __ Bind(&update);
   __ AddImmediate(RCX, Immediate(Smi::RawValue(1)));
   __ Bind(&loop);
   __ andq(RCX, R9);
   const intptr_t base = Array::data_offset();
   // RCX is smi tagged, but table entries are two words, so TIMES_8.
@@ skipping 112 matching lines @@
 }
 
 
 void StubCode::GenerateFrameAwaitingMaterializationStub(Assembler* assembler) {
   __ int3();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64