Set VMTag from stubs when transitioning between Dart and Native

runtime/vm/stub_code_mips.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_MIPS)
 
 #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 26 matching lines @@
   // Save exit frame information to enable stack walking as we are about
   // to transition to Dart VM C++ code.
   __ sw(SP, Address(A0, Isolate::top_exit_frame_info_offset()));
 
   // Save current Context pointer into Isolate structure.
   __ sw(CTX, Address(A0, Isolate::top_context_offset()));
 
   // Cache Isolate pointer into CTX while executing runtime code.
   __ mov(CTX, A0);
 
+#if defined(DEBUG)
+  { Label ok;
+    // Check that we are always entering from Dart code.
+    __ lw(T0, Address(A0, Isolate::vm_tag_offset()));
+    __ BranchEqual(T0, VMTag::kScriptTagId, &ok);
+    __ Stop("Not coming from Dart code.");
+    __ Bind(&ok);
+  }
+#endif
+
+  // Mark that the isolate is executing VM code.
+  __ LoadImmediate(T0, VMTag::kVMTagId);
+  __ sw(T0, Address(A0, 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(4 * kWordSize);  // Reserve space for arguments.
 
   // Pass NativeArguments structure by value and call runtime.
   // Registers A0, A1, A2, and A3 are used.
 
   ASSERT(isolate_offset == 0 * kWordSize);
   // Set isolate in NativeArgs: A0 already contains CTX.
@@ skipping 14 matching lines @@
   // We defensively always jalr through T9 because it is sometimes required by
   // the MIPS ABI.
   __ mov(T9, S5);
   __ jalr(T9);
 
     ASSERT(retval_offset == 3 * kWordSize);
   // Retval is next to 1st argument.
   __ delay_slot()->addiu(A3, A2, Immediate(kWordSize));
   __ TraceSimMsg("CallToRuntimeStub return");
 
+  // Mark that the isolate is executing Dart code.
+  __ LoadImmediate(A2, VMTag::kScriptTagId);
+  __ sw(A2, Address(CTX, Isolate::vm_tag_offset()));
+
   // Reset exit frame information in Isolate structure.
   __ sw(ZR, Address(CTX, Isolate::top_exit_frame_info_offset()));
 
   // Load Context pointer from Isolate structure into A2.
   __ lw(A2, Address(CTX, Isolate::top_context_offset()));
 
   // Load null.
   __ LoadImmediate(TMP, reinterpret_cast<intptr_t>(Object::null()));
 
   // Reset Context pointer in Isolate structure.
@@ skipping 55 matching lines @@
   // Save exit frame information to enable stack walking as we are about
   // to transition to native code.
   __ sw(SP, Address(A0, Isolate::top_exit_frame_info_offset()));
 
   // Save current Context pointer into Isolate structure.
   __ sw(CTX, Address(A0, Isolate::top_context_offset()));
 
   // Cache Isolate pointer into CTX while executing native code.
   __ mov(CTX, A0);
 
+#if defined(DEBUG)
+  { Label ok;
+    // Check that we are always entering from Dart code.
+    __ lw(T0, Address(A0, Isolate::vm_tag_offset()));
+    __ BranchEqual(T0, VMTag::kScriptTagId, &ok);
+    __ Stop("Not coming from Dart code.");
+    __ Bind(&ok);
+  }
+#endif
+
+  // Mark that the isolate is executing Native code.
+  __ LoadImmediate(T0, VMTag::kRuntimeNativeTagId);
+  __ sw(T0, Address(A0, Isolate::vm_tag_offset()));
+
   // Initialize NativeArguments structure and call native function.
   // Registers A0, A1, A2, and A3 are used.
 
   ASSERT(isolate_offset == 0 * kWordSize);
   // Set isolate in NativeArgs: A0 already contains CTX.
 
   // There are no native 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);
   // Set argc in NativeArguments: A1 already contains argc.
@@ skipping 40 matching lines @@
   __ ReserveAlignedFrameSpace(kWordSize);  // Just passing A0.
 
 
   // We defensively always jalr through T9 because it is sometimes required by
   // the MIPS ABI.
   __ mov(T9, T5);
   __ jalr(T9);
 
   __ Bind(&done);
 
+  // Mark that the isolate is executing Dart code.
+  __ LoadImmediate(A2, VMTag::kScriptTagId);
+  __ sw(A2, Address(CTX, Isolate::vm_tag_offset()));
+
   // Reset exit frame information in Isolate structure.
   __ sw(ZR, Address(CTX, Isolate::top_exit_frame_info_offset()));
 
   // Load Context pointer from Isolate structure into A2.
   __ lw(A2, Address(CTX, Isolate::top_context_offset()));
 
   // Load null.
   __ LoadImmediate(TMP, reinterpret_cast<intptr_t>(Object::null()));
 
   // Reset Context pointer in Isolate structure.
@@ skipping 36 matching lines @@
   // Save exit frame information to enable stack walking as we are about
   // to transition to native code.
   __ sw(SP, Address(A0, Isolate::top_exit_frame_info_offset()));
 
   // Save current Context pointer into Isolate structure.
   __ sw(CTX, Address(A0, Isolate::top_context_offset()));
 
   // Cache Isolate pointer into CTX while executing native code.
   __ mov(CTX, A0);
 
+#if defined(DEBUG)
+  { Label ok;
+    // Check that we are always entering from Dart code.
+    __ lw(T0, Address(A0, Isolate::vm_tag_offset()));
+    __ BranchEqual(T0, VMTag::kScriptTagId, &ok);
+    __ Stop("Not coming from Dart code.");
+    __ Bind(&ok);
+  }
+#endif
+
+  // Mark that the isolate is executing Native code.
+  __ LoadImmediate(T0, VMTag::kRuntimeNativeTagId);
+  __ sw(T0, Address(A0, Isolate::vm_tag_offset()));
+
   // Initialize NativeArguments structure and call native function.
   // Registers A0, A1, A2, and A3 are used.
 
   ASSERT(isolate_offset == 0 * kWordSize);
   // Set isolate in NativeArgs: A0 already contains CTX.
 
   // There are no native 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);
   // Set argc in NativeArguments: A1 already contains argc.
@@ skipping 17 matching lines @@
   __ ReserveAlignedFrameSpace(kWordSize);  // Just passing A0.
 
   // Call native function or redirection via simulator.
 
   // We defensively always jalr through T9 because it is sometimes required by
   // the MIPS ABI.
   __ mov(T9, T5);
   __ jalr(T9);
   __ TraceSimMsg("CallNativeCFunctionStub return");
 
+  // Mark that the isolate is executing Dart code.
+  __ LoadImmediate(A2, VMTag::kScriptTagId);
+  __ sw(A2, Address(CTX, Isolate::vm_tag_offset()));
+
   // Reset exit frame information in Isolate structure.
   __ sw(ZR, Address(CTX, Isolate::top_exit_frame_info_offset()));
 
   // Load Context pointer from Isolate structure into A2.
   __ lw(A2, Address(CTX, Isolate::top_context_offset()));
 
   // Load null.
   __ LoadImmediate(TMP, reinterpret_cast<intptr_t>(Object::null()));
 
   // Reset Context pointer in Isolate structure.
@@ skipping 601 matching lines @@
 //   A1 : arguments descriptor array.
 //   A2 : arguments array.
 //   A3 : new context containing the current isolate pointer.
 void StubCode::GenerateInvokeDartCodeStub(Assembler* assembler) {
   // Save frame pointer coming in.
   __ TraceSimMsg("InvokeDartCodeStub");
   __ EnterFrame();
 
   // Save new context and C++ ABI callee-saved registers.
 
-  // The new context, the top exit frame, and the old context.
-  const intptr_t kPreservedContextSlots = 3;
+  // The new context, saved vm tag, the top exit frame, and the old context.
+  const intptr_t kPreservedContextSlots = 4;
   const intptr_t kNewContextOffsetFromFp =
       -(1 + kAbiPreservedCpuRegCount + kAbiPreservedFpuRegCount) * kWordSize;
   const intptr_t kPreservedRegSpace =
       kWordSize * (kAbiPreservedCpuRegCount + kAbiPreservedFpuRegCount +
                    kPreservedContextSlots);
 
   __ addiu(SP, SP, Immediate(-kPreservedRegSpace));
   for (int i = S0; i <= S7; i++) {
     Register r = static_cast<Register>(i);
     const intptr_t slot = i - S0 + kPreservedContextSlots;
     __ sw(r, Address(SP, slot * kWordSize));
   }
 
   for (intptr_t i = kAbiFirstPreservedFpuReg;
        i <= kAbiLastPreservedFpuReg; i++) {
     FRegister r = static_cast<FRegister>(i);
     const intptr_t slot =
         kAbiPreservedCpuRegCount + kPreservedContextSlots + i -
         kAbiFirstPreservedFpuReg;
     __ swc1(r, Address(SP, slot * kWordSize));
   }
 
-  __ sw(A3, Address(SP, 2 * kWordSize));
+  __ sw(A3, Address(SP, 3 * kWordSize));
 
   // We now load the pool pointer(PP) as we are about to invoke dart code and we
   // could potentially invoke some intrinsic functions which need the PP to be
   // set up.
   __ LoadPoolPointer();
 
   // The new Context structure contains a pointer to the current Isolate
   // structure. Cache the Context pointer in the CTX register so that it is
   // 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.
   __ lw(CTX, Address(A3, VMHandles::kOffsetOfRawPtrInHandle));
 
   // Load Isolate pointer from Context structure into temporary register R8.
   __ lw(T2, FieldAddress(CTX, Context::isolate_offset()));
 
+  // Save the current VMTag on the stack.
+  ASSERT(kSavedVMTagSlotFromEntryFp == -22);
+  __ lw(T1, Address(T2, Isolate::vm_tag_offset()));
+  __ sw(T1, Address(SP, 2 * kWordSize));
+
+  // Mark that the isolate is executing Dart code.
+  __ LoadImmediate(T0, VMTag::kScriptTagId);
+  __ sw(T0, Address(T2, Isolate::vm_tag_offset()));
+
   // Save the top exit frame info. Use T0 as a temporary register.
   // StackFrameIterator reads the top exit frame info saved in this frame.
   __ lw(T0, Address(T2, Isolate::top_exit_frame_info_offset()));
   __ sw(ZR, Address(T2, Isolate::top_exit_frame_info_offset()));
 
   // Save the old Context pointer. Use T1 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.
   __ lw(T1, Address(T2, Isolate::top_context_offset()));
 
   // The constants kSavedContextSlotFromEntryFp and
   // kExitLinkSlotFromEntryFp must be kept in sync with the code below.
-  ASSERT(kExitLinkSlotFromEntryFp == -22);
-  ASSERT(kSavedContextSlotFromEntryFp == -23);
+  ASSERT(kExitLinkSlotFromEntryFp == -23);
+  ASSERT(kSavedContextSlotFromEntryFp == -24);
   __ sw(T0, Address(SP, 1 * kWordSize));
   __ sw(T1, Address(SP, 0 * kWordSize));
 
   // After the call, The stack pointer is restored to this location.
   // Pushed A3, S0-7, F20-31, T0, T1 = 23.
 
   // Load arguments descriptor array into S4, which is passed to Dart code.
   __ lw(S4, Address(A1, VMHandles::kOffsetOfRawPtrInHandle));
 
   // Load number of arguments into S5.
@@ skipping 28 matching lines @@
   // Read the saved new Context pointer.
   __ lw(CTX, Address(FP, kNewContextOffsetFromFp));
   __ lw(CTX, Address(CTX, VMHandles::kOffsetOfRawPtrInHandle));
 
   // Get rid of arguments pushed on the stack.
   __ AddImmediate(SP, FP, kSavedContextSlotFromEntryFp * kWordSize);
 
   // Load Isolate pointer from Context structure into CTX. Drop Context.
   __ lw(CTX, FieldAddress(CTX, Context::isolate_offset()));
 
+  // Restore the current VMTag from the stack.
+  __ lw(T1, Address(SP, 2 * kWordSize));
+  __ sw(T1, Address(CTX, Isolate::vm_tag_offset()));
+
   // Restore the saved Context pointer into the Isolate structure.
   // Uses T1 as a temporary register for this.
   // Restore the saved top exit frame info back into the Isolate structure.
   // Uses T0 as a temporary register for this.
   __ lw(T1, Address(SP, 0 * kWordSize));
   __ lw(T0, Address(SP, 1 * kWordSize));
   __ sw(T1, Address(CTX, Isolate::top_context_offset()));
   __ sw(T0, Address(CTX, Isolate::top_exit_frame_info_offset()));
 
   // Restore C++ ABI callee-saved registers.
   for (int i = S0; i <= S7; i++) {
     Register r = static_cast<Register>(i);
     const intptr_t slot = i - S0 + kPreservedContextSlots;
     __ lw(r, Address(SP, slot * kWordSize));
   }
 
   for (intptr_t i = kAbiFirstPreservedFpuReg;
        i <= kAbiLastPreservedFpuReg; i++) {
     FRegister r = static_cast<FRegister>(i);
     const intptr_t slot =
         kAbiPreservedCpuRegCount + kPreservedContextSlots + i -
         kAbiFirstPreservedFpuReg;
     __ lwc1(r, Address(SP, slot * kWordSize));
   }
 
-  __ lw(A3, Address(SP, 2 * kWordSize));
+  __ lw(A3, Address(SP, 3 * kWordSize));
   __ addiu(SP, SP, Immediate(kPreservedRegSpace));
 
   // Restore the frame pointer and return.
   __ LeaveFrameAndReturn();
 }
 
 
 // Called for inline allocation of contexts.
 // Input:
 //   T1: number of context variables.
@@ skipping 1137 matching lines @@
   const Register right = T0;
   __ lw(left, Address(SP, 1 * kWordSize));
   __ lw(right, Address(SP, 0 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp1, temp2);
   __ Ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_MIPS