Revert "Revert "JumpToFrame refactor"" + Fix

runtime/vm/stub_code_x64.cc

Index: runtime/vm/stub_code_x64.cc
diff --git a/runtime/vm/stub_code_x64.cc b/runtime/vm/stub_code_x64.cc
index 9ca6a6e2b27e0ed5a5fe162117d3c8e209cd8f9f..167154b0879d8c515d929e4a1b98c2cff9935c90 100644
--- a/runtime/vm/stub_code_x64.cc
+++ b/runtime/vm/stub_code_x64.cc
@@ -1845,33 +1845,17 @@ void StubCode::GenerateGetStackPointerStub(Assembler* assembler) {
 }
 
 
-// Jump to the exception or error handler.
+// Jump to a frame on the call stack.
 // TOS + 0: return address
 // Arg1: program counter
 // Arg2: stack pointer
 // Arg3: frame_pointer
-// Arg4: exception object
-// Arg5: stacktrace object
-// Arg6: thread
+// Arg4: thread
 // 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));
-  __ movq(THR, Address(RSP, 6 * kWordSize));
-#else
-  Register stacktrace_reg = CallingConventions::kArg5Reg;
-  __ movq(THR, CallingConventions::kArg6Reg);
-#endif
+void StubCode::GenerateJumpToFrameStub(Assembler* assembler) {
+  __ movq(THR, CallingConventions::kArg4Reg);
   __ movq(RBP, CallingConventions::kArg3Reg);
   __ movq(RSP, CallingConventions::kArg2Reg);
-  __ movq(kStackTraceObjectReg, stacktrace_reg);
-  __ movq(kExceptionObjectReg, CallingConventions::kArg4Reg);
   // Set the tag.
   __ movq(Assembler::VMTagAddress(), Immediate(VMTag::kDartTagId));
   // Clear top exit frame.
@@ -1879,7 +1863,31 @@ void StubCode::GenerateJumpToExceptionHandlerStub(Assembler* assembler) {
   // Restore the pool pointer.
   __ RestoreCodePointer();
   __ LoadPoolPointer(PP);
-  __ jmp(CallingConventions::kArg1Reg);  // Jump to the exception handler code.
+  __ jmp(CallingConventions::kArg1Reg);  // Jump to program counter.
+}
+
+
+// Run an exception handler.  Execution comes from JumpToFrame stub.
+//
+// The arguments are stored in the Thread object.
+// No result.
+void StubCode::GenerateRunExceptionHandlerStub(Assembler* assembler) {
+  ASSERT(kExceptionObjectReg == RAX);
+  ASSERT(kStackTraceObjectReg == RDX);
+  __ movq(CallingConventions::kArg1Reg,
+          Address(THR, Thread::resume_pc_offset()));
+
+  // Load the exception from the current thread.
+  Address exception_addr(THR, Thread::active_exception_offset());
+  __ movq(kExceptionObjectReg, exception_addr);
+  __ movq(exception_addr, Immediate(0));
+
+  // Load the stacktrace from the current thread.
+  Address stacktrace_addr(THR, Thread::active_stacktrace_offset());
+  __ movq(kStackTraceObjectReg, stacktrace_addr);
+  __ movq(stacktrace_addr, Immediate(0));
+
+  __ jmp(CallingConventions::kArg1Reg);  // Jump to continuation point.
 }