[interpreter] Switch context during stack unwinding.

src/isolate.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/isolate.h"
 
 #include <stdlib.h>
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
@@ skipping 1084 matching lines @@
       code = frame->LookupCode();
       handler_sp = handler->address() + StackHandlerConstants::kSize;
       offset = Smi::cast(code->handler_table()->get(0))->value();
       break;
     }
 
     // For optimized frames we perform a lookup in the handler table.
     if (frame->is_optimized() && catchable_by_js) {
       OptimizedFrame* js_frame = static_cast<OptimizedFrame*>(frame);
       int stack_slots = 0;  // Will contain stack slot count of frame.
-      offset = js_frame->LookupExceptionHandlerInTable(&stack_slots, NULL);
+      offset = js_frame->LookupExceptionHandlerInTable(&stack_slots, nullptr);
       if (offset >= 0) {
         // Compute the stack pointer from the frame pointer. This ensures that
         // argument slots on the stack are dropped as returning would.
         Address return_sp = frame->fp() -
                             StandardFrameConstants::kFixedFrameSizeFromFp -
                             stack_slots * kPointerSize;
 
         // Gather information from the frame.
         code = frame->LookupCode();
         handler_sp = return_sp;
         handler_fp = frame->fp();
         break;
       }
     }
 
     // For interpreted frame we perform a range lookup in the handler table.
     if (frame->is_interpreted() && catchable_by_js) {
       InterpretedFrame* js_frame = static_cast<InterpretedFrame*>(frame);
-      int stack_slots = 0;  // Will contain stack slot count of frame.
-      offset = js_frame->LookupExceptionHandlerInTable(&stack_slots, NULL);
+      int context_reg = 0;  // Will contain register index holding context.
+      offset = js_frame->LookupExceptionHandlerInTable(&context_reg, nullptr);
       if (offset >= 0) {
         // Patch the bytecode offset in the interpreted frame to reflect the
         // position of the exception handler. The special builtin below will
-        // take care of continuing to dispatch at that position.
+        // take care of continuing to dispatch at that position. Also restore
+        // the correct context for the handler from the interpreter register.
+        context = Context::cast(js_frame->GetInterpreterRegister(context_reg));
         js_frame->PatchBytecodeOffset(static_cast<int>(offset));
         offset = 0;
 
         // Gather information from the frame.
         code = *builtins()->InterpreterEnterBytecodeDispatch();
         handler_sp = frame->sp();
         handler_fp = frame->fp();
         break;
       }
     }
 
     // For JavaScript frames we perform a range lookup in the handler table.
     if (frame->is_java_script() && catchable_by_js) {
       JavaScriptFrame* js_frame = static_cast<JavaScriptFrame*>(frame);
-      int stack_slots = 0;  // Will contain operand stack depth of handler.
-      offset = js_frame->LookupExceptionHandlerInTable(&stack_slots, NULL);
+      int stack_depth = 0;  // Will contain operand stack depth of handler.
+      offset = js_frame->LookupExceptionHandlerInTable(&stack_depth, nullptr);
       if (offset >= 0) {
         // Compute the stack pointer from the frame pointer. This ensures that
         // operand stack slots are dropped for nested statements. Also restore
         // correct context for the handler which is pushed within the try-block.
         Address return_sp = frame->fp() -
                             StandardFrameConstants::kFixedFrameSizeFromFp -
-                            stack_slots * kPointerSize;
+                            stack_depth * kPointerSize;
         STATIC_ASSERT(TryBlockConstant::kElementCount == 1);
         context = Context::cast(Memory::Object_at(return_sp - kPointerSize));
 
         // Gather information from the frame.
         code = frame->LookupCode();
         handler_sp = return_sp;
         handler_fp = frame->fp();
         break;
       }
     }
@@ skipping 1696 matching lines @@
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8