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

runtime/vm/stub_code_x64.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_X64)
 
 #include "vm/assembler.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 1700 matching lines @@
 }
 
 
 // Jump to the exception or error handler.
 // TOS + 0: return address
 // Arg1: program counter
 // Arg2: stack pointer
 // Arg3: frame_pointer
 // Arg4: exception object
 // Arg5: stacktrace object
+// Arg6: isolate
 // No Result.
 void StubCode::GenerateJumpToExceptionHandlerStub(Assembler* assembler) {
   ASSERT(kExceptionObjectReg == RAX);
   ASSERT(kStackTraceObjectReg == RDX);
   ASSERT(CallingConventions::kArg4Reg != kStackTraceObjectReg);
   ASSERT(CallingConventions::kArg1Reg != kStackTraceObjectReg);
 
 #if defined(_WIN64)
   Register stacktrace_reg = RBX;
   __ movq(stacktrace_reg, Address(RSP, 5 * kWordSize));
+  Register isolate_reg = CTX;

[regis, 2014/07/14 20:00:34]

You could use RAX.

[Cutch, 2014/07/14 21:32:07]

Can't use RAX because it's used by kExceptionObjectReg. Using RDI which is free.

+  __ movq(isolate_reg, Address(RSP, 6 * kWordSize));
 #else
   Register stacktrace_reg = CallingConventions::kArg5Reg;
+  Register isolate_reg = CallingConventions::kArg6Reg;
 #endif
 
   __ movq(RBP, CallingConventions::kArg3Reg);
   __ movq(RSP, CallingConventions::kArg2Reg);
   __ movq(kStackTraceObjectReg, stacktrace_reg);
   __ movq(kExceptionObjectReg, CallingConventions::kArg4Reg);
+  // Set the tag.
+  __ movq(Address(isolate_reg, Isolate::vm_tag_offset()),
+          Immediate(VMTag::kScriptTagId));
+  // Clear top exit frame.
+  __ movq(Address(isolate_reg, Isolate::top_exit_frame_info_offset()),
+          Immediate(0));
   __ jmp(CallingConventions::kArg1Reg);  // Jump to the exception handler code.
 }
 
 
 // Calls to the runtime to optimize the given function.
 // RDI: function to be reoptimized.
 // R10: argument descriptor (preserved).
 void StubCode::GenerateOptimizeFunctionStub(Assembler* assembler) {
   __ EnterStubFrame();
   __ LoadObject(R12, Object::null_object(), PP);
@@ skipping 119 matching lines @@
 
   __ movq(left, Address(RSP, 2 * kWordSize));
   __ movq(right, Address(RSP, 1 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64