[ignition] Reactivate check for jumps to unbound targets.

- Move the check from the BytecodeArrayBuilder destructor, which doesn't get
  called, to the ToBytecodeArray function.
- Remove the now empty destructor.
- For generators, bind unused resume point labels somewhere.

R=rmcilroy@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/1924093005
Cr-Commit-Position: refs/heads/master@{#35862}

src/interpreter/bytecode-array-builder.cc

@@ -121,8 +121,6 @@ BytecodeArrayBuilder::BytecodeArrayBuilder(Isolate* isolate, Zone* zone,
                                source_position_table_builder()));
 }
 
-BytecodeArrayBuilder::~BytecodeArrayBuilder() { DCHECK_EQ(0, unbound_jumps_); }
-
 Register BytecodeArrayBuilder::first_context_register() const {
   DCHECK_GT(context_register_count_, 0);
   return Register(local_register_count_);
@@ -147,6 +145,7 @@ bool BytecodeArrayBuilder::RegisterIsParameterOrLocal(Register reg) const {
 
 
 Handle<BytecodeArray> BytecodeArrayBuilder::ToBytecodeArray() {
+  DCHECK_EQ(0, unbound_jumps_);
   DCHECK_EQ(bytecode_generated_, false);
   DCHECK(exit_seen_in_block_);
 

src/interpreter/bytecode-array-builder.h

@@ -28,7 +28,6 @@ class BytecodeArrayBuilder final : public ZoneObject {
   BytecodeArrayBuilder(Isolate* isolate, Zone* zone, int parameter_count,
                        int context_count, int locals_count,
                        FunctionLiteral* literal = nullptr);
-  ~BytecodeArrayBuilder();
 
   Handle<BytecodeArray> ToBytecodeArray();
 

src/interpreter/bytecode-generator.cc

@@ -601,6 +601,14 @@ Handle<BytecodeArray> BytecodeGenerator::MakeBytecode() {
     MakeBytecodeBody();
   }
 
+  // In generator functions, we may not have visited every yield in the AST
+  // since we skip some obviously dead code. Hence the generated bytecode may
+  // contain jumps to unbound labels (resume points that will never be used).
+  // We bind these now.
+  for (auto& label : generator_resume_points_) {
+    if (!label.is_bound()) builder()->Bind(&label);
+  }
+
   builder()->EnsureReturn();
   return builder()->ToBytecodeArray();
 }