[Interpreter] Marks that 'throw' has returned a value.

src/interpreter/bytecode-generator.cc

 // Copyright 2015 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/interpreter/bytecode-generator.h"
 
 #include "src/ast/scopes.h"
 #include "src/compiler.h"
 #include "src/interpreter/control-flow-builders.h"
 #include "src/objects.h"
@@ skipping 1521 matching lines @@
   execution_result()->SetResultInAccumulator();
 }
 
 
 void BytecodeGenerator::VisitYield(Yield* expr) { UNIMPLEMENTED(); }
 
 
 void BytecodeGenerator::VisitThrow(Throw* expr) {
   VisitForAccumulatorValue(expr->exception());
   builder()->Throw();
+  // For script and eval scopes expression statements are converted to
+  // assignment statements in Rewriter::ReWrite pass. An assignment statement
+  // expects a value in the accumulator. This is a hack to avoid DCHECK fails
+  // assert accumulator has been set.
+  if (info()->literal()->scope()->is_script_scope() ||

[Michael Starzinger, 2016/01/18 21:23:03]

I wouldn't even narrow this to script or eval scopes, but in general just mark
all throw expressions as delivering the completion value in the accumulator
unconditionally.

As discussed offline today: This is a short-coming of our AST, where "throw"is
modeled as an expression instead of a statement (as the spec defines it),
exactly because of the internal replacement we perform. With proper
do-expressions such a rewriting could be done without this hack AFAICT. But that
is cleanup for another day.

[mythria, 2016/01/19 10:48:04]

Done.

+      info()->literal()->scope()->is_eval_scope()) {
+    execution_result()->SetResultInAccumulator();
+  }
 }
 
 
 void BytecodeGenerator::VisitPropertyLoad(Register obj, Property* expr) {
   LhsKind property_kind = Property::GetAssignType(expr);
   FeedbackVectorSlot slot = expr->PropertyFeedbackSlot();
   switch (property_kind) {
     case VARIABLE:
       UNREACHABLE();
     case NAMED_PROPERTY: {
@@ skipping 685 matching lines @@
 }
 
 
 int BytecodeGenerator::feedback_index(FeedbackVectorSlot slot) const {
   return info()->feedback_vector()->GetIndex(slot);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8