[Interpreter] Handles legacy constants in strict mode.

src/interpreter/bytecode-generator.cc

Index: src/interpreter/bytecode-generator.cc
diff --git a/src/interpreter/bytecode-generator.cc b/src/interpreter/bytecode-generator.cc
index 619ed89a942807cd3d55f7c5bb450452ea5e2392..91f57f75b0d15bb94e3ad34cb7db901c43c43509 100644
--- a/src/interpreter/bytecode-generator.cc
+++ b/src/interpreter/bytecode-generator.cc
@@ -1967,11 +1967,15 @@ void BytecodeGenerator::VisitVariableAssignment(Variable* variable,
           // Break here because the value should not be stored unconditionally.
           break;
         } else if (mode == CONST_LEGACY && op != Token::INIT) {
-          DCHECK(!is_strict(language_mode()));
-          // Ensure accumulator is in the correct state.
-          builder()->LoadAccumulatorWithRegister(value_temp);
-          // Break here, non-initializing assignments to legacy constants are
-          // ignored.
+          if (is_strict(language_mode())) {
+            builder()->CallRuntime(Runtime::kThrowConstAssignError, Register(),
+                                   0);
+          } else {
+            // Ensure accumulator is in the correct state.
+            builder()->LoadAccumulatorWithRegister(value_temp);
+          }
+          // Non-initializing assignments to legacy constants are ignored
+          // in sloppy mode. Break here to avoid storing into variable.
           break;
         } else {
           BuildHoleCheckForVariableAssignment(variable, op);
@@ -2034,11 +2038,15 @@ void BytecodeGenerator::VisitVariableAssignment(Variable* variable,
           // The above code performs the store conditionally.
           break;
         } else if (mode == CONST_LEGACY && op != Token::INIT) {
-          DCHECK(!is_strict(language_mode()));
-          // Ensure accumulator is in the correct state.
-          builder()->LoadAccumulatorWithRegister(value_temp);
-          // Break here, non-initializing assignments to legacy constants are
-          // ignored.
+          if (is_strict(language_mode())) {
+            builder()->CallRuntime(Runtime::kThrowConstAssignError, Register(),
+                                   0);
+          } else {
+            // Ensure accumulator is in the correct state.
+            builder()->LoadAccumulatorWithRegister(value_temp);
+          }
+          // Non-initializing assignments to legacy constants are ignored
+          // in sloppy mode. Break hear to avoid storing into variable.

[rmcilroy, 2016/04/05 08:44:21]

/s/hear/here

[mythria, 2016/04/11 10:10:05]

Done.

           break;
         } else {
           BuildHoleCheckForVariableAssignment(variable, op);
@@ -2066,8 +2074,12 @@ void BytecodeGenerator::VisitVariableAssignment(Variable* variable,
             .StoreAccumulatorInRegister(name)
             .CallRuntime(Runtime::kInitializeLegacyConstLookupSlot, value, 3);
       } else if (mode == CONST_LEGACY && op != Token::INIT) {
-        // Non-intializing assignments to legacy constants are ignored.
-        DCHECK(!is_strict(language_mode()));
+        // Non-intializing assignments to legacy constants are ignored in sloppy
+        // mode and throws TypeError in strict mode.
+        if (is_strict(language_mode())) {

[Michael Starzinger, 2016/04/04 12:02:24]

nit: The Runtime_StoreLookupSlot_[Strict|Sloppy] method family should handle
this case correctly. I think we can just remove the entire {mode == CONST_LEGACY
&& op != Token::INIT} case and rely on the runtime function to do the right
thing IIUC.

[mythria, 2016/04/11 10:10:05]

Done.

+          builder()->CallRuntime(Runtime::kThrowConstAssignError, Register(),
+                                 0);
+        }
       } else {
         builder()->StoreLookupSlot(variable->name(), language_mode());
       }