1 files changed, 492 insertions, 0 deletions
diff --git a/js/src/frontend/SharedContext.cpp b/js/src/frontend/SharedContext.cpp
new file mode 100644
index 0000000000..4ebbd03361
--- /dev/null
+++ b/js/src/frontend/SharedContext.cpp
@@ -0,0 +1,492 @@
+/* -*- 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/SharedContext.h"
+
+#include "mozilla/RefPtr.h"
+
+#include "frontend/AbstractScopePtr.h"
+#include "frontend/FunctionSyntaxKind.h"  // FunctionSyntaxKind
+#include "frontend/ModuleSharedContext.h"
+#include "vm/FunctionFlags.h"          // js::FunctionFlags
+#include "vm/GeneratorAndAsyncKind.h"  // js::GeneratorKind, js::FunctionAsyncKind
+#include "vm/JSScript.h"  // js::FillImmutableFlagsFromCompileOptionsForTopLevel, js::FillImmutableFlagsFromCompileOptionsForFunction
+#include "vm/StencilEnums.h"  // ImmutableScriptFlagsEnum
+#include "wasm/AsmJS.h"
+#include "wasm/WasmModule.h"
+
+#include "frontend/ParseContext-inl.h"
+#include "vm/EnvironmentObject-inl.h"
+
+namespace js {
+namespace frontend {
+
+SharedContext::SharedContext(JSContext* cx, Kind kind,
+                             CompilationStencil& stencil, Directives directives,
+                             SourceExtent extent)
+    : cx_(cx),
+      stencil_(stencil),
+      extent_(extent),
+      allowNewTarget_(false),
+      allowSuperProperty_(false),
+      allowSuperCall_(false),
+      allowArguments_(true),
+      inWith_(false),
+      inClass_(false),
+      localStrict(false),
+      hasExplicitUseStrict_(false),
+      isScriptFieldCopiedToStencil(false) {
+  // Compute the script kind "input" flags.
+  if (kind == Kind::FunctionBox) {
+    setFlag(ImmutableFlags::IsFunction);
+  } else if (kind == Kind::Module) {
+    MOZ_ASSERT(!stencil.input.options.nonSyntacticScope);
+    setFlag(ImmutableFlags::IsModule);
+  } else if (kind == Kind::Eval) {
+    setFlag(ImmutableFlags::IsForEval);
+  } else {
+    MOZ_ASSERT(kind == Kind::Global);
+  }
+
+  // Note: This is a mix of transitive and non-transitive options.
+  const JS::ReadOnlyCompileOptions& options = stencil.input.options;
+
+  // Initialize the transitive "input" flags. These are applied to all
+  // SharedContext in this compilation and generally cannot be determined from
+  // the source text alone.
+  if (isTopLevelContext()) {
+    js::FillImmutableFlagsFromCompileOptionsForTopLevel(options,
+                                                        immutableFlags_);
+  } else {
+    js::FillImmutableFlagsFromCompileOptionsForFunction(options,
+                                                        immutableFlags_);
+  }
+
+  // Initialize the strict flag. This may be updated by the parser as we observe
+  // further directives in the body.
+  setFlag(ImmutableFlags::Strict, directives.strict());
+}
+
+void ScopeContext::computeThisEnvironment(Scope* scope) {
+  uint32_t envCount = 0;
+  for (ScopeIter si(scope); si; si++) {
+    if (si.kind() == ScopeKind::Function) {
+      JSFunction* fun = si.scope()->as<FunctionScope>().canonicalFunction();
+
+      // Arrow function inherit the "this" environment of the enclosing script,
+      // so continue ignore them.
+      if (!fun->isArrow()) {
+        allowNewTarget = true;
+
+        if (fun->allowSuperProperty()) {
+          allowSuperProperty = true;
+          enclosingThisEnvironmentHops = envCount;
+        }
+
+        if (fun->isClassConstructor()) {
+          memberInitializers =
+              mozilla::Some(fun->baseScript()->getMemberInitializers());
+          MOZ_ASSERT(memberInitializers->valid);
+        }
+
+        if (fun->isDerivedClassConstructor()) {
+          allowSuperCall = true;
+        }
+
+        if (fun->isFieldInitializer()) {
+          allowArguments = false;
+        }
+
+        // Found the effective "this" environment, so stop.
+        return;
+      }
+    }
+
+    if (si.scope()->hasEnvironment()) {
+      envCount++;
+    }
+  }
+}
+
+void ScopeContext::computeThisBinding(Scope* scope) {
+  // Inspect the scope-chain.
+  for (ScopeIter si(scope); si; si++) {
+    if (si.kind() == ScopeKind::Module) {
+      thisBinding = ThisBinding::Module;
+      return;
+    }
+
+    if (si.kind() == ScopeKind::Function) {
+      JSFunction* fun = si.scope()->as<FunctionScope>().canonicalFunction();
+
+      // Arrow functions don't have their own `this` binding.
+      if (fun->isArrow()) {
+        continue;
+      }
+
+      // Derived class constructors (and their nested arrow functions and evals)
+      // use ThisBinding::DerivedConstructor, which ensures TDZ checks happen
+      // when accessing |this|.
+      if (fun->isDerivedClassConstructor()) {
+        thisBinding = ThisBinding::DerivedConstructor;
+      } else {
+        thisBinding = ThisBinding::Function;
+      }
+
+      return;
+    }
+  }
+
+  thisBinding = ThisBinding::Global;
+}
+
+void ScopeContext::computeInScope(Scope* scope) {
+  for (ScopeIter si(scope); si; si++) {
+    if (si.kind() == ScopeKind::ClassBody) {
+      inClass = true;
+    }
+
+    if (si.kind() == ScopeKind::With) {
+      inWith = true;
+    }
+  }
+}
+
+/* static */
+Scope* ScopeContext::determineEffectiveScope(Scope* scope,
+                                             JSObject* environment) {
+  // If the scope-chain is non-syntactic, we may still determine a more precise
+  // effective-scope to use instead.
+  if (environment && scope->hasOnChain(ScopeKind::NonSyntactic)) {
+    JSObject* env = environment;
+    while (env) {
+      // Look at target of any DebugEnvironmentProxy, but be sure to use
+      // enclosingEnvironment() of the proxy itself.
+      JSObject* unwrapped = env;
+      if (env->is<DebugEnvironmentProxy>()) {
+        unwrapped = &env->as<DebugEnvironmentProxy>().environment();
+      }
+
+      if (unwrapped->is<CallObject>()) {
+        JSFunction* callee = &unwrapped->as<CallObject>().callee();
+        return callee->nonLazyScript()->bodyScope();
+      }
+
+      env = env->enclosingEnvironment();
+    }
+  }
+
+  return scope;
+}
+
+GlobalSharedContext::GlobalSharedContext(JSContext* cx, ScopeKind scopeKind,
+                                         CompilationStencil& stencil,
+                                         Directives directives,
+                                         SourceExtent extent)
+    : SharedContext(cx, Kind::Global, stencil, directives, extent),
+      scopeKind_(scopeKind),
+      bindings(nullptr) {
+  MOZ_ASSERT(scopeKind == ScopeKind::Global ||
+             scopeKind == ScopeKind::NonSyntactic);
+  MOZ_ASSERT(thisBinding_ == ThisBinding::Global);
+}
+
+EvalSharedContext::EvalSharedContext(JSContext* cx, CompilationStencil& stencil,
+                                     CompilationState& compilationState,
+                                     SourceExtent extent)
+    : SharedContext(cx, Kind::Eval, stencil, compilationState.directives,
+                    extent),
+      bindings(nullptr) {
+  // Eval inherits syntax and binding rules from enclosing environment.
+  allowNewTarget_ = compilationState.scopeContext.allowNewTarget;
+  allowSuperProperty_ = compilationState.scopeContext.allowSuperProperty;
+  allowSuperCall_ = compilationState.scopeContext.allowSuperCall;
+  allowArguments_ = compilationState.scopeContext.allowArguments;
+  thisBinding_ = compilationState.scopeContext.thisBinding;
+  inWith_ = compilationState.scopeContext.inWith;
+}
+
+SuspendableContext::SuspendableContext(JSContext* cx, Kind kind,
+                                       CompilationStencil& stencil,
+                                       Directives directives,
+                                       SourceExtent extent, bool isGenerator,
+                                       bool isAsync)
+    : SharedContext(cx, kind, stencil, directives, extent) {
+  setFlag(ImmutableFlags::IsGenerator, isGenerator);
+  setFlag(ImmutableFlags::IsAsync, isAsync);
+}
+
+FunctionBox::FunctionBox(JSContext* cx, SourceExtent extent,
+                         CompilationStencil& stencil,
+                         CompilationState& compilationState,
+                         Directives directives, GeneratorKind generatorKind,
+                         FunctionAsyncKind asyncKind, const ParserAtom* atom,
+                         FunctionFlags flags, ScriptIndex index)
+    : SuspendableContext(cx, Kind::FunctionBox, stencil, directives, extent,
+                         generatorKind == GeneratorKind::Generator,
+                         asyncKind == FunctionAsyncKind::AsyncFunction),
+      compilationState_(compilationState),
+      atom_(atom),
+      funcDataIndex_(index),
+      flags_(FunctionFlags::clearMutableflags(flags)),
+      emitBytecode(false),
+      wasEmitted_(false),
+      isAnnexB(false),
+      useAsm(false),
+      hasParameterExprs(false),
+      hasDestructuringArgs(false),
+      hasDuplicateParameters(false),
+      hasExprBody_(false),
+      isFunctionFieldCopiedToStencil(false) {}
+
+void FunctionBox::initFromLazyFunction(JSFunction* fun) {
+  BaseScript* lazy = fun->baseScript();
+  immutableFlags_ = lazy->immutableFlags();
+  extent_ = lazy->extent();
+}
+
+void FunctionBox::initWithEnclosingParseContext(ParseContext* enclosing,
+                                                FunctionFlags flags,
+                                                FunctionSyntaxKind kind) {
+  SharedContext* sc = enclosing->sc();
+
+  // HasModuleGoal and useAsm are inherited from enclosing context.
+  useAsm = sc->isFunctionBox() && sc->asFunctionBox()->useAsmOrInsideUseAsm();
+  setHasModuleGoal(sc->hasModuleGoal());
+
+  // Arrow functions don't have their own `this` binding.
+  if (flags.isArrow()) {
+    allowNewTarget_ = sc->allowNewTarget();
+    allowSuperProperty_ = sc->allowSuperProperty();
+    allowSuperCall_ = sc->allowSuperCall();
+    allowArguments_ = sc->allowArguments();
+    thisBinding_ = sc->thisBinding();
+  } else {
+    if (IsConstructorKind(kind)) {
+      auto stmt =
+          enclosing->findInnermostStatement<ParseContext::ClassStatement>();
+      MOZ_ASSERT(stmt);
+      stmt->constructorBox = this;
+    }
+
+    allowNewTarget_ = true;
+    allowSuperProperty_ = flags.allowSuperProperty();
+
+    if (kind == FunctionSyntaxKind::DerivedClassConstructor) {
+      setDerivedClassConstructor();
+      allowSuperCall_ = true;
+      thisBinding_ = ThisBinding::DerivedConstructor;
+    } else {
+      thisBinding_ = ThisBinding::Function;
+    }
+
+    if (kind == FunctionSyntaxKind::FieldInitializer) {
+      setFieldInitializer();
+      allowArguments_ = false;
+    }
+  }
+
+  if (sc->inWith()) {
+    inWith_ = true;
+  } else {
+    auto isWith = [](ParseContext::Statement* stmt) {
+      return stmt->kind() == StatementKind::With;
+    };
+
+    inWith_ = enclosing->findInnermostStatement(isWith);
+  }
+
+  if (sc->inClass()) {
+    inClass_ = true;
+  } else {
+    auto isClass = [](ParseContext::Statement* stmt) {
+      return stmt->kind() == StatementKind::Class;
+    };
+
+    inClass_ = enclosing->findInnermostStatement(isClass);
+  }
+}
+
+void FunctionBox::initStandalone(ScopeContext& scopeContext,
+                                 FunctionFlags flags, FunctionSyntaxKind kind) {
+  if (flags.isArrow()) {
+    allowNewTarget_ = scopeContext.allowNewTarget;
+    allowSuperProperty_ = scopeContext.allowSuperProperty;
+    allowSuperCall_ = scopeContext.allowSuperCall;
+    allowArguments_ = scopeContext.allowArguments;
+    thisBinding_ = scopeContext.thisBinding;
+  } else {
+    allowNewTarget_ = true;
+    allowSuperProperty_ = flags.allowSuperProperty();
+
+    if (kind == FunctionSyntaxKind::DerivedClassConstructor) {
+      setDerivedClassConstructor();
+      allowSuperCall_ = true;
+      thisBinding_ = ThisBinding::DerivedConstructor;
+    } else {
+      thisBinding_ = ThisBinding::Function;
+    }
+
+    if (kind == FunctionSyntaxKind::FieldInitializer) {
+      setFieldInitializer();
+      allowArguments_ = false;
+    }
+  }
+
+  inWith_ = scopeContext.inWith;
+  inClass_ = scopeContext.inClass;
+}
+
+void FunctionBox::setEnclosingScopeForInnerLazyFunction(ScopeIndex scopeIndex) {
+  // For lazy functions inside a function which is being compiled, we cache
+  // the incomplete scope object while compiling, and store it to the
+  // BaseScript once the enclosing script successfully finishes compilation
+  // in FunctionBox::finish.
+  MOZ_ASSERT(enclosingScopeIndex_.isNothing());
+  enclosingScopeIndex_ = mozilla::Some(scopeIndex);
+  if (isFunctionFieldCopiedToStencil) {
+    copyUpdatedEnclosingScopeIndex();
+  }
+}
+
+bool FunctionBox::setAsmJSModule(const JS::WasmModule* module) {
+  MOZ_ASSERT(!isFunctionFieldCopiedToStencil);
+
+  MOZ_ASSERT(flags_.kind() == FunctionFlags::NormalFunction);
+
+  // Update flags we will use to allocate the JSFunction.
+  flags_.clearBaseScript();
+  flags_.setIsExtended();
+  flags_.setKind(FunctionFlags::AsmJS);
+
+  if (!stencil_.asmJS.putNew(index(), module)) {
+    js::ReportOutOfMemory(cx_);
+    return false;
+  }
+  return true;
+}
+
+ModuleSharedContext::ModuleSharedContext(JSContext* cx,
+                                         CompilationStencil& stencil,
+                                         ModuleBuilder& builder,
+                                         SourceExtent extent)
+    : SuspendableContext(cx, Kind::Module, stencil, Directives(true), extent,
+                         /* isGenerator = */ false,
+                         /* isAsync = */ false),
+      bindings(nullptr),
+      builder(builder) {
+  thisBinding_ = ThisBinding::Module;
+  setFlag(ImmutableFlags::HasModuleGoal);
+}
+
+ScriptStencil& FunctionBox::functionStencil() const {
+  return compilationState_.scriptData[funcDataIndex_];
+}
+
+ScriptStencilExtra& FunctionBox::functionExtraStencil() const {
+  return compilationState_.scriptExtra[funcDataIndex_];
+}
+
+bool FunctionBox::hasFunctionExtraStencil() const {
+  return funcDataIndex_ < compilationState_.scriptExtra.length();
+}
+
+void SharedContext::copyScriptFields(ScriptStencil& script) {
+  MOZ_ASSERT(!isScriptFieldCopiedToStencil);
+  isScriptFieldCopiedToStencil = true;
+}
+
+void SharedContext::copyScriptExtraFields(ScriptStencilExtra& scriptExtra) {
+  scriptExtra.immutableFlags = immutableFlags_;
+  scriptExtra.extent = extent_;
+}
+
+void FunctionBox::finishScriptFlags() {
+  MOZ_ASSERT(!isScriptFieldCopiedToStencil);
+
+  using ImmutableFlags = ImmutableScriptFlagsEnum;
+  immutableFlags_.setFlag(ImmutableFlags::HasMappedArgsObj, hasMappedArgsObj());
+}
+
+void FunctionBox::copyScriptFields(ScriptStencil& script) {
+  MOZ_ASSERT(&script == &functionStencil());
+
+  SharedContext::copyScriptFields(script);
+
+  if (memberInitializers_) {
+    script.setMemberInitializers(*memberInitializers_);
+  }
+
+  isScriptFieldCopiedToStencil = true;
+}
+
+void FunctionBox::copyFunctionFields(ScriptStencil& script) {
+  MOZ_ASSERT(&script == &functionStencil());
+  MOZ_ASSERT(!isFunctionFieldCopiedToStencil);
+
+  if (atom_) {
+    atom_->markUsedByStencil();
+    script.functionAtom = atom_->toIndex();
+  }
+  script.functionFlags = flags_;
+  if (enclosingScopeIndex_) {
+    script.setLazyFunctionEnclosingScopeIndex(*enclosingScopeIndex_);
+  }
+  if (wasEmitted_) {
+    script.setWasFunctionEmitted();
+  }
+
+  isFunctionFieldCopiedToStencil = true;
+}
+
+void FunctionBox::copyFunctionExtraFields(ScriptStencilExtra& scriptExtra) {
+  scriptExtra.nargs = nargs_;
+}
+
+void FunctionBox::copyUpdatedImmutableFlags() {
+  if (hasFunctionExtraStencil()) {
+    ScriptStencilExtra& scriptExtra = functionExtraStencil();
+    scriptExtra.immutableFlags = immutableFlags_;
+  }
+}
+
+void FunctionBox::copyUpdatedExtent() {
+  ScriptStencilExtra& scriptExtra = functionExtraStencil();
+  scriptExtra.extent = extent_;
+}
+
+void FunctionBox::copyUpdatedMemberInitializers() {
+  ScriptStencil& script = functionStencil();
+  if (memberInitializers_) {
+    script.setMemberInitializers(*memberInitializers_);
+  }
+}
+
+void FunctionBox::copyUpdatedEnclosingScopeIndex() {
+  ScriptStencil& script = functionStencil();
+  if (enclosingScopeIndex_) {
+    script.setLazyFunctionEnclosingScopeIndex(*enclosingScopeIndex_);
+  }
+}
+
+void FunctionBox::copyUpdatedAtomAndFlags() {
+  ScriptStencil& script = functionStencil();
+  if (atom_) {
+    atom_->markUsedByStencil();
+    script.functionAtom = atom_->toIndex();
+  }
+  script.functionFlags = flags_;
+}
+
+void FunctionBox::copyUpdatedWasEmitted() {
+  ScriptStencil& script = functionStencil();
+  if (wasEmitted_) {
+    script.setWasFunctionEmitted();
+  }
+}
+
+}  // namespace frontend
+}  // namespace js