Set VMTag from stubs when transitioning between Dart and Native

runtime/vm/stub_code_arm.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_ARM)
 
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_compiler.h"
 #include "vm/heap.h"
 #include "vm/instructions.h"
 #include "vm/object_store.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.
   __ StoreToOffset(kWord, SP, R0, Isolate::top_exit_frame_info_offset());
 
   // Save current Context pointer into Isolate structure.
   __ StoreToOffset(kWord, CTX, R0, Isolate::top_context_offset());
 
   // Cache Isolate pointer into CTX while executing runtime code.
   __ mov(CTX, ShifterOperand(R0));
 
+#if defined(DEBUG)
+  { Label ok;
+    // Check that we are always entering from Dart code.
+    __ LoadFromOffset(kWord, R6, CTX, Isolate::vm_tag_offset());
+    __ CompareImmediate(R6, VMTag::kScriptTagId);
+    __ b(&ok, EQ);
+    __ Stop("Not coming from Dart code.");
+    __ Bind(&ok);
+  }
+#endif
+
+  // Mark that the isolate is executing VM code.
+  __ LoadImmediate(R6, VMTag::kVMTagId);
+  __ StoreToOffset(kWord, R6, CTX, Isolate::vm_tag_offset());
+
   // Reserve space for arguments and align frame before entering C++ world.
   // NativeArguments are passed in registers.
   ASSERT(sizeof(NativeArguments) == 4 * kWordSize);
   __ ReserveAlignedFrameSpace(0);
 
   // Pass NativeArguments structure by value and call runtime.
   // Registers R0, R1, R2, and R3 are used.
 
   ASSERT(isolate_offset == 0 * kWordSize);
   // Set isolate in NativeArgs: R0 already contains CTX.
 
   // There are no runtime calls to closures, so we do not need to set the tag
   // bits kClosureFunctionBit and kInstanceFunctionBit in argc_tag_.
   ASSERT(argc_tag_offset == 1 * kWordSize);
   __ mov(R1, ShifterOperand(R4));  // Set argc in NativeArguments.
 
   ASSERT(argv_offset == 2 * kWordSize);
   __ add(R2, FP, ShifterOperand(R4, LSL, 2));  // Compute argv.
   // Set argv in NativeArguments.
   __ AddImmediate(R2, exitframe_last_param_slot_from_fp * kWordSize);
 
   ASSERT(retval_offset == 3 * kWordSize);
   __ add(R3, R2, ShifterOperand(kWordSize));  // Retval is next to 1st argument.
 
   // Call runtime or redirection via simulator.
   __ blx(R5);
 
+  // Mark that the isolate is executing Dart code.
+  __ LoadImmediate(R2, VMTag::kScriptTagId);
+  __ StoreToOffset(kWord, R2, CTX, Isolate::vm_tag_offset());
+
   // Reset exit frame information in Isolate structure.
   __ LoadImmediate(R2, 0);
   __ StoreToOffset(kWord, R2, CTX, Isolate::top_exit_frame_info_offset());
 
   // Load Context pointer from Isolate structure into R2.
   __ LoadFromOffset(kWord, R2, CTX, Isolate::top_context_offset());
 
   // Reset Context pointer in Isolate structure.
   __ LoadImmediate(R3, reinterpret_cast<intptr_t>(Object::null()));
   __ StoreToOffset(kWord, R3, CTX, Isolate::top_context_offset());
@@ skipping 49 matching lines @@
   // Save exit frame information to enable stack walking as we are about
   // to transition to native code.
   __ StoreToOffset(kWord, SP, R0, Isolate::top_exit_frame_info_offset());
 
   // Save current Context pointer into Isolate structure.
   __ StoreToOffset(kWord, CTX, R0, Isolate::top_context_offset());
 
   // Cache Isolate pointer into CTX while executing native code.
   __ mov(CTX, ShifterOperand(R0));
 
+#if defined(DEBUG)
+  { Label ok;
+    // Check that we are always entering from Dart code.
+    __ LoadFromOffset(kWord, R6, CTX, Isolate::vm_tag_offset());
+    __ CompareImmediate(R6, VMTag::kScriptTagId);
+    __ b(&ok, EQ);
+    __ Stop("Not coming from Dart code.");
+    __ Bind(&ok);
+  }
+#endif
+
+  // Mark that the isolate is executing Native code.
+  __ LoadImmediate(R6, VMTag::kRuntimeNativeTagId);
+  __ StoreToOffset(kWord, R6, CTX, Isolate::vm_tag_offset());
+
   // Reserve space for the native arguments structure passed on the stack (the
   // outgoing pointer parameter to the native arguments structure is passed in
   // R0) and align frame before entering the C++ world.
   __ ReserveAlignedFrameSpace(sizeof(NativeArguments));
 
   // Initialize NativeArguments structure and call native function.
   // Registers R0, R1, R2, and R3 are used.
 
   ASSERT(isolate_offset == 0 * kWordSize);
   // Set isolate in NativeArgs: R0 already contains CTX.
@@ skipping 33 matching lines @@
   __ BranchLink(&NativeEntry::NativeCallWrapperLabel());
 #endif
   __ b(&done);
 
   __ Bind(&leaf_call);
   // Call native function or redirection via simulator.
   __ blx(R5);
 
   __ Bind(&done);
 
+  // Mark that the isolate is executing Dart code.
+  __ LoadImmediate(R2, VMTag::kScriptTagId);
+  __ StoreToOffset(kWord, R2, CTX, Isolate::vm_tag_offset());
+
   // Reset exit frame information in Isolate structure.
   __ LoadImmediate(R2, 0);
   __ StoreToOffset(kWord, R2, CTX, Isolate::top_exit_frame_info_offset());
 
   // Load Context pointer from Isolate structure into R2.
   __ LoadFromOffset(kWord, R2, CTX, Isolate::top_context_offset());
 
   // Reset Context pointer in Isolate structure.
   __ LoadImmediate(R3, reinterpret_cast<intptr_t>(Object::null()));
   __ StoreToOffset(kWord, R3, CTX, Isolate::top_context_offset());
@@ skipping 30 matching lines @@
   // Save exit frame information to enable stack walking as we are about
   // to transition to native code.
   __ StoreToOffset(kWord, SP, R0, Isolate::top_exit_frame_info_offset());
 
   // Save current Context pointer into Isolate structure.
   __ StoreToOffset(kWord, CTX, R0, Isolate::top_context_offset());
 
   // Cache Isolate pointer into CTX while executing native code.
   __ mov(CTX, ShifterOperand(R0));
 
+#if defined(DEBUG)
+  { Label ok;
+    // Check that we are always entering from Dart code.
+    __ LoadFromOffset(kWord, R6, CTX, Isolate::vm_tag_offset());
+    __ CompareImmediate(R6, VMTag::kScriptTagId);
+    __ b(&ok, EQ);
+    __ Stop("Not coming from Dart code.");
+    __ Bind(&ok);
+  }
+#endif
+
+  // Mark that the isolate is executing Native code.
+  __ LoadImmediate(R6, VMTag::kRuntimeNativeTagId);
+  __ StoreToOffset(kWord, R6, CTX, Isolate::vm_tag_offset());
+
   // Reserve space for the native arguments structure passed on the stack (the
   // outgoing pointer parameter to the native arguments structure is passed in
   // R0) and align frame before entering the C++ world.
   __ ReserveAlignedFrameSpace(sizeof(NativeArguments));
 
   // Initialize NativeArguments structure and call native function.
   // Registers R0, R1, R2, and R3 are used.
 
   ASSERT(isolate_offset == 0 * kWordSize);
   // Set isolate in NativeArgs: R0 already contains CTX.
@@ skipping 11 matching lines @@
 
   // TODO(regis): Should we pass the structure by value as in runtime calls?
   // It would require changing Dart API for native functions.
   // For now, space is reserved on the stack and we pass a pointer to it.
   __ stm(IA, SP,  (1 << R0) | (1 << R1) | (1 << R2) | (1 << R3));
   __ mov(R0, ShifterOperand(SP));  // Pass the pointer to the NativeArguments.
 
   // Call native function or redirection via simulator.
   __ blx(R5);
 
+  // Mark that the isolate is executing Dart code.
+  __ LoadImmediate(R2, VMTag::kScriptTagId);
+  __ StoreToOffset(kWord, R2, CTX, Isolate::vm_tag_offset());
+
   // Reset exit frame information in Isolate structure.
   __ LoadImmediate(R2, 0);
   __ StoreToOffset(kWord, R2, CTX, Isolate::top_exit_frame_info_offset());
 
   // Load Context pointer from Isolate structure into R2.
   __ LoadFromOffset(kWord, R2, CTX, Isolate::top_context_offset());
 
   // Reset Context pointer in Isolate structure.
   __ LoadImmediate(R3, reinterpret_cast<intptr_t>(Object::null()));
   __ StoreToOffset(kWord, R3, CTX, Isolate::top_context_offset());
@@ skipping 529 matching lines @@
   // available in generated code and calls to Isolate::Current() need not be
   // done. The assumption is that this register will never be clobbered by
   // compiled or runtime stub code.
 
   // Cache the new Context pointer into CTX while executing Dart code.
   __ ldr(CTX, Address(R3, VMHandles::kOffsetOfRawPtrInHandle));
 
   // Load Isolate pointer from Context structure into temporary register R8.
   __ ldr(R8, FieldAddress(CTX, Context::isolate_offset()));
 
+  // Save the current VMTag on the stack.
+  ASSERT(kSavedVMTagSlotFromEntryFp == -25);
+  __ LoadFromOffset(kWord, R5, R8, Isolate::vm_tag_offset());
+  __ Push(R5);
+
+  // Mark that the isolate is executing Dart code.
+  __ LoadImmediate(R5, VMTag::kScriptTagId);
+  __ StoreToOffset(kWord, R5, R8, Isolate::vm_tag_offset());
+
   // Save the top exit frame info. Use R5 as a temporary register.
   // StackFrameIterator reads the top exit frame info saved in this frame.
   __ LoadFromOffset(kWord, R5, R8, Isolate::top_exit_frame_info_offset());
   __ LoadImmediate(R6, 0);
   __ StoreToOffset(kWord, R6, R8, Isolate::top_exit_frame_info_offset());
 
   // Save the old Context pointer. Use R4 as a temporary register.
   // 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.
   __ LoadFromOffset(kWord, R4, R8, Isolate::top_context_offset());
 
   // The constants kSavedContextSlotFromEntryFp and
   // kExitLinkSlotFromEntryFp must be kept in sync with the code below.
-  ASSERT(kExitLinkSlotFromEntryFp == -25);
-  ASSERT(kSavedContextSlotFromEntryFp == -26);
+  ASSERT(kExitLinkSlotFromEntryFp == -26);
+  ASSERT(kSavedContextSlotFromEntryFp == -27);
   __ PushList((1 << R4) | (1 << R5));
 
   // Load arguments descriptor array into R4, which is passed to Dart code.
   __ ldr(R4, Address(R1, VMHandles::kOffsetOfRawPtrInHandle));
 
   // Load number of arguments into R5.
   __ ldr(R5, FieldAddress(R4, ArgumentsDescriptor::count_offset()));
   __ SmiUntag(R5);
 
   // Compute address of 'arguments array' data area into R2.
@@ skipping 29 matching lines @@
   __ ldr(CTX, FieldAddress(CTX, Context::isolate_offset()));
 
   // Restore the saved Context pointer into the Isolate structure.
   // Uses R4 as a temporary register for this.
   // Restore the saved top exit frame info back into the Isolate structure.
   // Uses R5 as a temporary register for this.
   __ PopList((1 << R4) | (1 << R5));
   __ StoreToOffset(kWord, R4, CTX, Isolate::top_context_offset());
   __ StoreToOffset(kWord, R5, CTX, Isolate::top_exit_frame_info_offset());
 
+  // Restore the current VMTag from the stack.
+  __ Pop(R4);
+  __ StoreToOffset(kWord, R4, CTX, Isolate::vm_tag_offset());
+
   // Restore C++ ABI callee-saved registers.
   // Restore FPU registers. 2 D registers per Q register.
   __ vldmd(IA_W, SP, firstd, 2 * kAbiPreservedFpuRegCount);
   // Restore CPU registers.
   __ PopList((1 << R3) | kAbiPreservedCpuRegs);  // Ignore restored R3.
 
   // Restore the frame pointer and return.
   __ LeaveFrame((1 << FP) | (1 << LR));
   __ Ret();
 }
@@ skipping 1027 matching lines @@
   const Register right = R0;
   __ ldr(left, Address(SP, 1 * kWordSize));
   __ ldr(right, Address(SP, 0 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp);
   __ Ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM