Set VMTag from stubs when transitioning between Dart and Native

runtime/vm/stub_code_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/compiler.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_compiler.h"
 #include "vm/instructions.h"
 #include "vm/heap.h"
 #include "vm/object_store.h"
 #include "vm/resolver.h"
 #include "vm/scavenger.h"
 #include "vm/stack_frame.h"
 #include "vm/stub_code.h"
+#include "vm/tags.h"
 
 
 #define __ assembler->
 
 namespace dart {
 
 DEFINE_FLAG(bool, inline_alloc, true, "Inline allocation of objects.");
 DEFINE_FLAG(bool, use_slow_path, false,
     "Set to true for debugging & verifying the slow paths.");
 DECLARE_FLAG(bool, trace_optimized_ic_calls);
@@ skipping 22 matching lines @@
   // Save exit frame information to enable stack walking as we are about
   // to transition to Dart VM C++ code.
   __ movl(Address(EAX, Isolate::top_exit_frame_info_offset()), ESP);
 
   // Save current Context pointer into Isolate structure.
   __ movl(Address(EAX, Isolate::top_context_offset()), CTX);
 
   // Cache Isolate pointer into CTX while executing runtime code.
   __ movl(CTX, EAX);
 
+  // Mark that the isolate is executing VM code.

[siva, 2014/03/14 20:45:39]

#if defined(DEBUG)
  check that the vm_tag was kScripttagId here.
#endif

+  __ movl(Address(CTX, Isolate::vm_tag_offset()), Immediate(VMTag::kVMTagId));
+
   // Reserve space for arguments and align frame before entering C++ world.
   __ AddImmediate(ESP, Immediate(-sizeof(NativeArguments)));
   if (OS::ActivationFrameAlignment() > 1) {
     __ andl(ESP, Immediate(~(OS::ActivationFrameAlignment() - 1)));
   }
 
   // Pass NativeArguments structure by value and call runtime.
   __ movl(Address(ESP, isolate_offset), CTX);  // Set isolate in NativeArgs.
   // There are no runtime calls to closures, so we do not need to set the tag
   // bits kClosureFunctionBit and kInstanceFunctionBit in argc_tag_.
   __ movl(Address(ESP, argc_tag_offset), EDX);  // Set argc in NativeArguments.
   __ leal(EAX, Address(EBP, EDX, TIMES_4, 1 * kWordSize));  // Compute argv.
   __ movl(Address(ESP, argv_offset), EAX);  // Set argv in NativeArguments.
   __ addl(EAX, Immediate(1 * kWordSize));  // Retval is next to 1st argument.
   __ movl(Address(ESP, retval_offset), EAX);  // Set retval in NativeArguments.
   __ call(ECX);
 
+  // Mark that the isolate is executing Dart code.
+  __ movl(Address(CTX, Isolate::vm_tag_offset()),
+          Immediate(VMTag::kScriptTagId));
+
   // Reset exit frame information in Isolate structure.
   __ movl(Address(CTX, Isolate::top_exit_frame_info_offset()), Immediate(0));
 
   // Load Context pointer from Isolate structure into ECX.
   __ movl(ECX, Address(CTX, Isolate::top_context_offset()));
 
   // Reset Context pointer in Isolate structure.
   const Immediate& raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
   __ movl(Address(CTX, Isolate::top_context_offset()), raw_null);
@@ skipping 53 matching lines @@
   // Save exit frame information to enable stack walking as we are about
   // to transition to dart VM code.
   __ movl(Address(EDI, Isolate::top_exit_frame_info_offset()), ESP);
 
   // Save current Context pointer into Isolate structure.
   __ movl(Address(EDI, Isolate::top_context_offset()), CTX);
 
   // Cache Isolate pointer into CTX while executing native code.
   __ movl(CTX, EDI);
 
+  // Mark that the isolate is executing Native code.

[siva, 2014/03/14 20:45:39]

Ditto debug assertion here.

+  __ movl(Address(CTX, Isolate::vm_tag_offset()),
+          Immediate(VMTag::kRuntimeNativeTagId));
+
   // Reserve space for the native arguments structure, the outgoing parameters
   // (pointer to the native arguments structure, the C function entry point)
   // and align frame before entering the C++ world.
   __ AddImmediate(ESP, Immediate(-sizeof(NativeArguments) - (2 * kWordSize)));
   if (OS::ActivationFrameAlignment() > 1) {
     __ andl(ESP, Immediate(~(OS::ActivationFrameAlignment() - 1)));
   }
 
   // Pass NativeArguments structure by value and call native function.
   __ movl(Address(ESP, isolate_offset), CTX);  // Set isolate in NativeArgs.
   __ movl(Address(ESP, argc_tag_offset), EDX);  // Set argc in NativeArguments.
   __ movl(Address(ESP, argv_offset), EAX);  // Set argv in NativeArguments.
   __ leal(EAX, Address(EBP, 2 * kWordSize));  // Compute return value addr.
   __ movl(Address(ESP, retval_offset), EAX);  // Set retval in NativeArguments.
   __ leal(EAX, Address(ESP, 2 * kWordSize));  // Pointer to the NativeArguments.
   __ movl(Address(ESP, 0), EAX);  // Pass the pointer to the NativeArguments.
 
   // Call native function (setsup scope if not leaf function).
   Label leaf_call;
   Label done;
   __ testl(EDX, Immediate(NativeArguments::AutoSetupScopeMask()));
   __ j(ZERO, &leaf_call, Assembler::kNearJump);
   __ movl(Address(ESP, kWordSize), ECX);  // Function to call.
   __ call(&NativeEntry::NativeCallWrapperLabel());
   __ jmp(&done);
   __ Bind(&leaf_call);
   __ call(ECX);
   __ Bind(&done);
 
+  // Mark that the isolate is executing Dart code.
+  __ movl(Address(CTX, Isolate::vm_tag_offset()),
+          Immediate(VMTag::kScriptTagId));
+
   // Reset exit frame information in Isolate structure.
   __ movl(Address(CTX, Isolate::top_exit_frame_info_offset()), Immediate(0));
 
   // Load Context pointer from Isolate structure into EDI.
   __ movl(EDI, Address(CTX, Isolate::top_context_offset()));
 
   // Reset Context pointer in Isolate structure.
   const Immediate& raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
   __ movl(Address(CTX, Isolate::top_context_offset()), raw_null);
@@ skipping 32 matching lines @@
   // Save exit frame information to enable stack walking as we are about
   // to transition to dart VM code.
   __ movl(Address(EDI, Isolate::top_exit_frame_info_offset()), ESP);
 
   // Save current Context pointer into Isolate structure.
   __ movl(Address(EDI, Isolate::top_context_offset()), CTX);
 
   // Cache Isolate pointer into CTX while executing native code.
   __ movl(CTX, EDI);
 
+  // Mark that the isolate is executing Native code.

[siva, 2014/03/14 20:45:39]

Ditto debug assertion here.

+  __ movl(Address(CTX, Isolate::vm_tag_offset()),
+          Immediate(VMTag::kRuntimeNativeTagId));
+
   // Reserve space for the native arguments structure, the outgoing parameter
   // (pointer to the native arguments structure) and align frame before
   // entering the C++ world.
   __ AddImmediate(ESP, Immediate(-sizeof(NativeArguments) - kWordSize));
   if (OS::ActivationFrameAlignment() > 1) {
     __ andl(ESP, Immediate(~(OS::ActivationFrameAlignment() - 1)));
   }
 
   // Pass NativeArguments structure by value and call native function.
   __ movl(Address(ESP, isolate_offset), CTX);  // Set isolate in NativeArgs.
   __ movl(Address(ESP, argc_tag_offset), EDX);  // Set argc in NativeArguments.
   __ movl(Address(ESP, argv_offset), EAX);  // Set argv in NativeArguments.
   __ leal(EAX, Address(EBP, 2 * kWordSize));  // Compute return value addr.
   __ movl(Address(ESP, retval_offset), EAX);  // Set retval in NativeArguments.
   __ leal(EAX, Address(ESP, kWordSize));  // Pointer to the NativeArguments.
   __ movl(Address(ESP, 0), EAX);  // Pass the pointer to the NativeArguments.
   __ call(ECX);
 
+  // Mark that the isolate is executing Dart code.
+  __ movl(Address(CTX, Isolate::vm_tag_offset()),
+          Immediate(VMTag::kScriptTagId));
+
   // Reset exit frame information in Isolate structure.
   __ movl(Address(CTX, Isolate::top_exit_frame_info_offset()), Immediate(0));
 
   // Load Context pointer from Isolate structure into EDI.
   __ movl(EDI, Address(CTX, Isolate::top_context_offset()));
 
   // Reset Context pointer in Isolate structure.
   const Immediate& raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
   __ movl(Address(CTX, Isolate::top_context_offset()), raw_null);
@@ skipping 569 matching lines @@
   // Note that VisitObjectPointers will find this saved Context pointer during
   // GC marking, since it traverses any information between SP and
   // FP - kExitLinkSlotFromEntryFp.
   // EntryFrame::SavedContext reads the context saved in this frame.
   // The constant kSavedContextSlotFromEntryFp must be kept in sync with
   // the code below.
   ASSERT(kSavedContextSlotFromEntryFp == -5);
   __ movl(ECX, Address(EDI, Isolate::top_context_offset()));
   __ pushl(ECX);
 
+  // Save the current VMTag on the stack.
+  ASSERT(kSavedVMTagSlotFromEntryFp == -6);
+  __ movl(ECX, Address(EDI, Isolate::vm_tag_offset()));
+  __ pushl(ECX);

[siva, 2014/03/14 20:45:39]

As discussed offline you would have to flip this slot as the
StackIterator::VisitHandles code will visit this slot currently looking for
object pointers.

[Cutch, 2014/03/17 15:46:01]

Done.

We now push in the following order:

vmtag
top_exit_frame_info
context

constants adjusted accordingly.

+
+  // Mark that the isolate is executing Dart code.
+  __ movl(Address(EDI, Isolate::vm_tag_offset()),
+          Immediate(VMTag::kScriptTagId));
+
   // Load arguments descriptor array into EDX.
   __ movl(EDX, Address(EBP, kArgumentsDescOffset));
   __ movl(EDX, Address(EDX, VMHandles::kOffsetOfRawPtrInHandle));
 
   // Load number of arguments into EBX.
   __ movl(EBX, FieldAddress(EDX, ArgumentsDescriptor::count_offset()));
   __ SmiUntag(EBX);
 
   // Set up arguments for the dart call.
   Label push_arguments;
@@ skipping 26 matching lines @@
   // arguments.
   __ movl(EDX, Address(EBP, kArgumentsDescOffset));
   __ movl(EDX, Address(EDX, VMHandles::kOffsetOfRawPtrInHandle));
   __ movl(EDX, FieldAddress(EDX, ArgumentsDescriptor::count_offset()));
   // Get rid of arguments pushed on the stack.
   __ leal(ESP, Address(ESP, EDX, TIMES_2, 0));  // EDX is a Smi.
 
   // Load Isolate pointer from Context structure into CTX. Drop Context.
   __ movl(CTX, FieldAddress(CTX, Context::isolate_offset()));
 
+  // Restore the current VMTag from the stack.
+  __ popl(ECX);
+  __ movl(Address(CTX, Isolate::vm_tag_offset()), ECX);
+
   // Restore the saved Context pointer into the Isolate structure.
   // Uses ECX as a temporary register for this.
   __ popl(ECX);
   __ movl(Address(CTX, Isolate::top_context_offset()), ECX);
 
   // Restore the saved top exit frame info back into the Isolate structure.
   // Uses EDX as a temporary register for this.
   __ popl(EDX);
   __ movl(Address(CTX, Isolate::top_exit_frame_info_offset()), EDX);
 
@@ skipping 1071 matching lines @@
   const Register temp = ECX;
   __ movl(left, Address(ESP, 2 * kWordSize));
   __ movl(right, Address(ESP, 1 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32