1 files changed, 331 insertions, 0 deletions
diff --git a/js/src/frontend/PrivateOpEmitter.cpp b/js/src/frontend/PrivateOpEmitter.cpp
new file mode 100644
index 0000000000..9e617b209e
--- /dev/null
+++ b/js/src/frontend/PrivateOpEmitter.cpp
@@ -0,0 +1,331 @@
+/* -*- 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/PrivateOpEmitter.h"
+
+#include "frontend/BytecodeEmitter.h"
+#include "frontend/NameOpEmitter.h"
+#include "vm/Opcodes.h"
+#include "vm/ThrowMsgKind.h"  // ThrowMsgKind
+
+using namespace js;
+using namespace js::frontend;
+
+PrivateOpEmitter::PrivateOpEmitter(BytecodeEmitter* bce, Kind kind,
+                                   TaggedParserAtomIndex name)
+    : bce_(bce), kind_(kind), name_(name) {
+  MOZ_ASSERT(kind_ != Kind::Delete);
+}
+
+bool PrivateOpEmitter::init() {
+  // Static analysis needs us to initialise this to something, so use Dynamic()
+  NameLocation loc = NameLocation::Dynamic();
+  bce_->lookupPrivate(name_, loc, brandLoc_);
+  loc_ = mozilla::Some(loc);
+  return true;
+}
+
+bool PrivateOpEmitter::emitLoad(TaggedParserAtomIndex name,
+                                const NameLocation& loc) {
+  NameOpEmitter noe(bce_, name, loc, NameOpEmitter::Kind::Get);
+  return noe.emitGet();
+}
+
+bool PrivateOpEmitter::emitLoadPrivateBrand() {
+  return emitLoad(TaggedParserAtomIndex::WellKnown::dotPrivateBrand(),
+                  *brandLoc_);
+}
+
+bool PrivateOpEmitter::emitBrandCheck() {
+  MOZ_ASSERT(state_ == State::Reference);
+
+  if (isBrandCheck()) {
+    // Emit a CheckPrivateField CheckRhs; note: The message is irrelvant here,
+    // it will never be thrown, so DoubleInit was chosen arbitrarily.
+    if (!bce_->emitCheckPrivateField(ThrowCondition::OnlyCheckRhs,
+                                     ThrowMsgKind::PrivateDoubleInit)) {
+      //            [stack] OBJ KEY BBOOL
+      return false;
+    }
+
+    return true;
+  }
+
+  //                [stack] OBJ KEY
+  if (isFieldInit()) {
+    if (!bce_->emitCheckPrivateField(ThrowCondition::ThrowHas,
+                                     ThrowMsgKind::PrivateDoubleInit)) {
+      //            [stack] OBJ KEY false
+      return false;
+    }
+  } else {
+    bool assigning =
+        isSimpleAssignment() || isCompoundAssignment() || isIncDec();
+    if (!bce_->emitCheckPrivateField(ThrowCondition::ThrowHasNot,
+                                     assigning
+                                         ? ThrowMsgKind::MissingPrivateOnSet
+                                         : ThrowMsgKind::MissingPrivateOnGet)) {
+      //            [stack] OBJ KEY true
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool PrivateOpEmitter::emitReference() {
+  MOZ_ASSERT(state_ == State::Start);
+
+  if (!init()) {
+    return false;
+  }
+
+  if (brandLoc_) {
+    if (!emitLoadPrivateBrand()) {
+      //            [stack] OBJ BRAND
+      return false;
+    }
+  } else {
+    if (!emitLoad(name_, loc_.ref())) {
+      //            [stack] OBJ NAME
+      return false;
+    }
+  }
+#ifdef DEBUG
+  state_ = State::Reference;
+#endif
+  return true;
+}
+
+bool PrivateOpEmitter::skipReference() {
+  MOZ_ASSERT(state_ == State::Start);
+
+  if (!init()) {
+    return false;
+  }
+
+#ifdef DEBUG
+  state_ = State::Reference;
+#endif
+  return true;
+}
+
+bool PrivateOpEmitter::emitGet() {
+  MOZ_ASSERT(state_ == State::Reference);
+
+  //                [stack] OBJ NAME
+
+  if (brandLoc_) {
+    // Note that the decision of what we leave on the stack depends on kind_,
+    // not loc_->bindingKind().  We can't emit code for a call just because this
+    // private member is a method. `obj.#method` is allowed without a call,
+    // just fetching the function object (it's useful in code like
+    // `obj.#method.bind(...)`). Even if the user says `obj.#method += 7`, we
+    // emit honest bytecode for the brand check, method load, and addition, and
+    // throw the error later. This preserves stack nuses/ndefs balance.
+    if (!emitBrandCheck()) {
+      //            [stack] OBJ BRAND true
+      return false;
+    }
+
+    if (isCompoundAssignment()) {
+      if (!bce_->emit1(JSOp::Pop)) {
+        //          [stack] OBJ BRAND
+        return false;
+      }
+    } else if (isCall()) {
+      if (!bce_->emitPopN(2)) {
+        //          [stack] OBJ
+        return false;
+      }
+    } else {
+      if (!bce_->emitPopN(3)) {
+        //          [stack]
+        return false;
+      }
+    }
+
+    if (!emitLoad(name_, loc_.ref())) {
+      //            [stack] OBJ BRAND METHOD  # if isCompoundAssignment
+      //            [stack] OBJ METHOD        # if call
+      //            [stack] METHOD            # otherwise
+      return false;
+    }
+  } else {
+    if (isCall()) {
+      if (!bce_->emitDupAt(1)) {
+        //          [stack] OBJ NAME OBJ
+        return false;
+      }
+      if (!bce_->emit1(JSOp::Swap)) {
+        //          [stack] OBJ OBJ NAME
+        return false;
+      }
+    }
+    //              [stack] OBJ? OBJ NAME
+    if (!emitBrandCheck()) {
+      //            [stack] OBJ? OBJ NAME true
+      return false;
+    }
+    if (!bce_->emit1(JSOp::Pop)) {
+      //            [stack] OBJ? OBJ NAME
+      return false;
+    }
+
+    if (isCompoundAssignment()) {
+      if (!bce_->emit1(JSOp::Dup2)) {
+        //          [stack] OBJ NAME OBJ NAME
+        return false;
+      }
+    }
+
+    if (!bce_->emitElemOpBase(JSOp::GetElem)) {
+      //            [stack] OBJ NAME VALUE  # if isCompoundAssignment
+      //            [stack] OBJ METHOD      # if Call
+      //            [stack] VALUE           # otherwise
+      return false;
+    }
+  }
+
+  if (isCall()) {
+    if (!bce_->emit1(JSOp::Swap)) {
+      //            [stack] METHOD OBJ
+      return false;
+    }
+  }
+
+  //                [stack] OBJ NAME VALUE  # if isCompoundAssignment
+  //                [stack] METHOD OBJ      # if call
+  //                [stack] VALUE           # otherwise
+
+#ifdef DEBUG
+  state_ = State::Get;
+#endif
+  return true;
+}
+
+bool PrivateOpEmitter::emitGetForCallOrNew() { return emitGet(); }
+
+bool PrivateOpEmitter::emitAssignment() {
+  MOZ_ASSERT(isSimpleAssignment() || isFieldInit() || isCompoundAssignment());
+  MOZ_ASSERT_IF(!isCompoundAssignment(), state_ == State::Reference);
+  MOZ_ASSERT_IF(isCompoundAssignment(), state_ == State::Get);
+
+  //                [stack] OBJ KEY RHS
+
+  if (brandLoc_) {
+    if (!bce_->emit2(JSOp::ThrowMsg,
+                     uint8_t(ThrowMsgKind::AssignToPrivateMethod))) {
+      return false;
+    }
+
+    // Balance the expression stack.
+    if (!bce_->emitPopN(2)) {
+      //            [stack] OBJ
+      return false;
+    }
+  } else {
+    // Emit a brand check. If this is compound assignment, emitGet() already
+    // emitted a check for this object and key. There's no point checking
+    // again--a private field can't be removed from an object.
+    if (!isCompoundAssignment()) {
+      if (!bce_->emitUnpickN(2)) {
+        //          [stack] RHS OBJ KEY
+        return false;
+      }
+      if (!emitBrandCheck()) {
+        //          [stack] RHS OBJ KEY BOOL
+        return false;
+      }
+      if (!bce_->emit1(JSOp::Pop)) {
+        //          [stack] RHS OBJ KEY
+        return false;
+      }
+      if (!bce_->emitPickN(2)) {
+        //          [stack] OBJ KEY RHS
+        return false;
+      }
+    }
+
+    JSOp setOp = isFieldInit() ? JSOp::InitElem : JSOp::StrictSetElem;
+    if (!bce_->emitElemOpBase(setOp)) {
+      //            [stack] RHS
+      return false;
+    }
+  }
+
+#ifdef DEBUG
+  state_ = State::Assignment;
+#endif
+  return true;
+}
+
+bool PrivateOpEmitter::emitIncDec(ValueUsage valueUsage) {
+  MOZ_ASSERT(state_ == State::Reference);
+  MOZ_ASSERT(isIncDec());
+  //                [stack] OBJ NAME
+
+  if (!bce_->emitDupAt(1, 2)) {
+    //              [stack] OBJ NAME OBJ NAME
+    return false;
+  }
+
+  if (!emitGet()) {
+    //              [stack] OBJ NAME VALUE
+    return false;
+  }
+
+  MOZ_ASSERT(state_ == State::Get);
+
+  JSOp incOp = isInc() ? JSOp::Inc : JSOp::Dec;
+
+  if (!bce_->emit1(JSOp::ToNumeric)) {
+    //              [stack] OBJ NAME N
+    return false;
+  }
+  if (isPostIncDec() && valueUsage == ValueUsage::WantValue) {
+    //              [stack] OBJ NAME N
+    if (!bce_->emit1(JSOp::Dup)) {
+      //            [stack] OBJ NAME N N
+      return false;
+    }
+    if (!bce_->emit2(JSOp::Unpick, 3)) {
+      //            [stack] N OBJ NAME N
+      return false;
+    }
+  }
+  if (!bce_->emit1(incOp)) {
+    //              [stack] N? OBJ NAME N+1
+    return false;
+  }
+
+  if (brandLoc_) {
+    if (!bce_->emit2(JSOp::ThrowMsg,
+                     uint8_t(ThrowMsgKind::AssignToPrivateMethod))) {
+      return false;
+    }
+
+    // Balance the expression stack.
+    if (!bce_->emitPopN(2)) {
+      //            [stack] N? N+1
+      return false;
+    }
+  } else {
+    if (!bce_->emitElemOpBase(JSOp::StrictSetElem)) {
+      //            [stack] N? N+1
+      return false;
+    }
+  }
+
+  if (isPostIncDec() && valueUsage == ValueUsage::WantValue) {
+    if (!bce_->emit1(JSOp::Pop)) {
+      //            [stack] N
+      return false;
+    }
+  }
+
+  return true;
+}