1 files changed, 57 insertions, 0 deletions
diff --git a/js/src/frontend/ExpressionStatementEmitter.cpp b/js/src/frontend/ExpressionStatementEmitter.cpp
new file mode 100644
index 0000000000..1c3ba12a02
--- /dev/null
+++ b/js/src/frontend/ExpressionStatementEmitter.cpp
@@ -0,0 +1,57 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "frontend/ExpressionStatementEmitter.h"
+
+#include "frontend/BytecodeEmitter.h"
+#include "vm/Opcodes.h"
+
+using namespace js;
+using namespace js::frontend;
+
+using mozilla::Maybe;
+
+ExpressionStatementEmitter::ExpressionStatementEmitter(BytecodeEmitter* bce,
+                                                       ValueUsage valueUsage)
+    : bce_(bce), valueUsage_(valueUsage) {}
+
+bool ExpressionStatementEmitter::prepareForExpr(
+    const Maybe<uint32_t>& beginPos) {
+  MOZ_ASSERT(state_ == State::Start);
+
+  if (beginPos) {
+    if (!bce_->updateSourceCoordNotes(*beginPos)) {
+      return false;
+    }
+  }
+
+#ifdef DEBUG
+  depth_ = bce_->bytecodeSection().stackDepth();
+  state_ = State::Expr;
+#endif
+  return true;
+}
+
+bool ExpressionStatementEmitter::emitEnd() {
+  MOZ_ASSERT(state_ == State::Expr);
+  MOZ_ASSERT(bce_->bytecodeSection().stackDepth() == depth_ + 1);
+
+  //                [stack] VAL
+
+  JSOp op = valueUsage_ == ValueUsage::WantValue ? JSOp::SetRval : JSOp::Pop;
+  if (!bce_->emit1(op)) {
+    //              [stack] # if WantValue
+    //              [stack] VAL
+    //              [stack] # otherwise
+    //              [stack]
+    return false;
+  }
+
+#ifdef DEBUG
+  state_ = State::End;
+#endif
+  return true;
+}