[Interpreter] Ensure that block breaks are within the correct context scope.

Fixes a bug where the context would be popped before labeled block break target
location.

BUG=v8:4280
LOG=N

Review URL: https://codereview.chromium.org/1601153002

Cr-Commit-Position: refs/heads/master@{#33388}

src/interpreter/bytecode-generator.cc

@@ -422,24 +422,24 @@ void BytecodeGenerator::MakeBytecodeBody() {
 
 
 void BytecodeGenerator::VisitBlock(Block* stmt) {
-  BlockBuilder block_builder(this->builder());
-  ControlScopeForBreakable execution_control(this, stmt, &block_builder);
-
-  if (stmt->scope() == NULL) {
-    // Visit statements in the same scope, no declarations.
-    VisitStatements(stmt->statements());
-  } else {
-    // Visit declarations and statements in a block scope.
-    if (stmt->scope()->NeedsContext()) {
+  // Visit declarations and statements.
+  if (stmt->scope() != nullptr && stmt->scope()->NeedsContext()) {
     VisitNewLocalBlockContext(stmt->scope());
     ContextScope scope(this, stmt->scope());
-      VisitDeclarations(stmt->scope()->declarations());
-      VisitStatements(stmt->statements());
+    VisitBlockDeclarationsAndStatements(stmt);
   } else {
-      VisitDeclarations(stmt->scope()->declarations());
-      VisitStatements(stmt->statements());
+    VisitBlockDeclarationsAndStatements(stmt);
   }
+}
+
+
+void BytecodeGenerator::VisitBlockDeclarationsAndStatements(Block* stmt) {
+  BlockBuilder block_builder(builder());
+  ControlScopeForBreakable execution_control(this, stmt, &block_builder);
+  if (stmt->scope() != nullptr) {
+    VisitDeclarations(stmt->scope()->declarations());
   }
+  VisitStatements(stmt->statements());
   if (stmt->labels() != nullptr) block_builder.EndBlock();
 }
 

src/interpreter/bytecode-generator.h

@@ -79,6 +79,7 @@ class BytecodeGenerator final : public AstVisitor {
   void VisitNewTargetVariable(Variable* variable);
   void VisitNewLocalFunctionContext();
   void VisitBuildLocalActivationContext();
+  void VisitBlockDeclarationsAndStatements(Block* stmt);
   void VisitNewLocalBlockContext(Scope* scope);
   void VisitFunctionClosureForContext();
   void VisitSetHomeObject(Register value, Register home_object,

test/cctest/interpreter/test-bytecode-generator.cc

@@ -2188,7 +2188,10 @@ TEST(BreakableBlocks) {
   InitializedHandleScope handle_scope;
   BytecodeGeneratorHelper helper;
 
-  ExpectedSnippet<int> snippets[] = {
+  int closure = Register::function_closure().index();
+  int context = Register::function_context().index();
+
+  ExpectedSnippet<InstanceType> snippets[] = {
       {"var x = 0;\n"
        "label: {\n"
        "  x = x + 1;\n"
@@ -2266,6 +2269,37 @@ TEST(BreakableBlocks) {
            B(Ldar), R(0),           //
            B(Return),               //
        }},
+      {"outer: {\n"
+       "  let y = 10;"
+       "  function f() { return y; }\n"
+       "  break outer;\n"
+       "}\n",
+       5 * kPointerSize,
+       1,
+       39,
+       {
+           B(LdaConstant), U8(0),                                         //
+           B(Star), R(3),                                                 //
+           B(Ldar), R(closure),                                           //
+           B(Star), R(4),                                                 //
+           B(CallRuntime), U16(Runtime::kPushBlockContext), R(3), U8(2),  //
+           B(PushContext), R(2),                                          //
+           B(LdaTheHole),                                                 //
+           B(StaContextSlot), R(2), U8(4),                                //
+           B(CreateClosure), U8(1), U8(0),                                //
+           B(Star), R(0),                                                 //
+           B(LdaSmi8), U8(10),                                            //
+           B(StaContextSlot), R(2), U8(4),                                //
+           B(Ldar), R(0),                                                 //
+           B(Star), R(1),                                                 //
+           B(Jump), U8(2),                                                //
+           B(PopContext), R(context),                                     //
+           B(LdaUndefined),                                               //
+           B(Return),                                                     //
+       },
+       2,
+       {InstanceType::FIXED_ARRAY_TYPE,
+        InstanceType::SHARED_FUNCTION_INFO_TYPE}},
   };
 
   for (size_t i = 0; i < arraysize(snippets); i++) {