- Add a per-isolate pseudo random number generator to the

runtime/vm/assembler_ia32.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_IA32)
 
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/heap.h"
@@ skipping 65 matching lines @@
  public:
   void Process(const MemoryRegion& region, intptr_t position) {
     // Direct calls are relative to the following instruction on x86.
     int32_t pointer = region.Load<int32_t>(position);
     int32_t delta = region.start() + position + sizeof(int32_t);
     region.Store<int32_t>(position, pointer - delta);
   }
 };
 
 
+int32_t Assembler::jit_cookie() {
+  if (jit_cookie_ == 0) {
+    jit_cookie_ = static_cast<int32_t>(
+        Isolate::Current()->random()->NextUInt32());
+  }
+  return jit_cookie_;
+}
+
+
 void Assembler::InitializeMemoryWithBreakpoints(uword data, intptr_t length) {
   memset(reinterpret_cast<void*>(data), Instr::kBreakPointInstruction, length);
 }
 
 
 void Assembler::call(Register reg) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   EmitUint8(0xFF);
   EmitRegisterOperand(2, reg);
 }
@@ skipping 1846 matching lines @@
     EmitUint8(0xB8 + dst);
     buffer_.EmitObject(object);
   }
 }
 
 
 void Assembler::LoadObjectSafely(Register dst, const Object& object) {
   if (Assembler::IsSafe(object)) {
     LoadObject(dst, object);
   } else {
-    movl(dst,
-         Immediate(reinterpret_cast<int32_t>(object.raw()) ^ jit_cookie_));
-    xorl(dst, Immediate(jit_cookie_));
+    int32_t cookie = jit_cookie();
+    movl(dst, Immediate(reinterpret_cast<int32_t>(object.raw()) ^ cookie));
+    xorl(dst, Immediate(cookie));
   }
 }
 
 
 void Assembler::PushObject(const Object& object) {
   if (object.IsSmi() || object.InVMHeap()) {
     pushl(Immediate(reinterpret_cast<int32_t>(object.raw())));
   } else {
     ASSERT(object.IsNotTemporaryScopedHandle());
     ASSERT(object.IsOld());
@@ skipping 542 matching lines @@
 
 const char* Assembler::FpuRegisterName(FpuRegister reg) {
   ASSERT((0 <= reg) && (reg < kNumberOfXmmRegisters));
   return xmm_reg_names[reg];
 }
 
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32