Move some isolate state setup from C++ code to JumpToExceptionHandler stub

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"
@@ skipping 1911 matching lines @@
 }
 
 
 // Jump to the exception or error handler.
 // RA: return address.
 // A0: program_counter.
 // A1: stack_pointer.
 // A2: frame_pointer.
 // A3: error object.
 // SP + 4*kWordSize: address of stacktrace object.
+// SP + 5*kWordSize: address of isolate.
 // Does not return.
 void StubCode::GenerateJumpToExceptionHandlerStub(Assembler* assembler) {
   ASSERT(kExceptionObjectReg == V0);
   ASSERT(kStackTraceObjectReg == V1);
   __ mov(V0, A3);  // Exception object.
   // MIPS ABI reserves stack space for all arguments. The StackTrace object is
   // the last of five arguments, so it is first pushed on the stack.
   __ lw(V1, Address(SP, 4 * kWordSize));  // StackTrace object.
   __ mov(FP, A2);  // Frame_pointer.
+  __ lw(A3, Address(SP, 5 * kWordSize));  // Isolate.
+  // Set tag.
+  __ LoadImmediate(A2, VMTag::kScriptTagId);
+  __ sw(A2, Address(A3, Isolate::vm_tag_offset()));
+  // Clear top exit frame.
+  __ sw(ZR, Address(A3, Isolate::top_exit_frame_info_offset()));
+
   __ jr(A0);  // Jump to the exception handler code.
   __ delay_slot()->mov(SP, A1);  // Stack pointer.
 }
 
 
 // Calls to the runtime to optimize the given function.
 // T0: function to be reoptimized.
 // S4: argument descriptor (preserved).
 void StubCode::GenerateOptimizeFunctionStub(Assembler* assembler) {
   __ TraceSimMsg("OptimizeFunctionStub");
@@ skipping 153 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