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+/* -*- 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/. */
+
+#ifndef vm_StencilEnums_h
+#define vm_StencilEnums_h
+
+#include <stdint.h> // uint8_t
+
+//
+// Enum definitions shared between frontend, stencil, and the VM.
+//
+
+namespace js {
+
+// [SMDOC] Try Notes
+//
+// Trynotes are attached to regions that are involved with
+// exception unwinding. They can be broken up into four categories:
+//
+// 1. Catch and Finally: Basic exception handling. A Catch trynote
+// covers the range of the associated try. A Finally trynote covers
+// the try and the catch.
+//
+// 2. ForIn and Destructuring: These operations create an iterator
+// which must be cleaned up (by calling IteratorClose) during
+// exception unwinding.
+//
+// 3. ForOf and ForOfIterclose: For-of loops handle unwinding using
+// catch blocks. These trynotes are used for for-of breaks/returns,
+// which create regions that are lexically within a for-of block,
+// but logically outside of it. See TryNoteIter::settle for more
+// details.
+//
+// 4. Loop: This represents normal for/while/do-while loops. It is
+// unnecessary for exception unwinding, but storing the boundaries
+// of loops here is helpful for heuristics that need to know
+// whether a given op is inside a loop.
+enum class TryNoteKind : uint8_t {
+ Catch,
+ Finally,
+ ForIn,
+ Destructuring,
+ ForOf,
+ ForOfIterClose,
+ Loop
+};
+
+// [SMDOC] Script Flags
+//
+// Interpreted scripts represented by the BaseScript type use two flag words to
+// encode an assortment of conditions and attributes about the script.
+//
+// The "immutable" flags are a combination of input flags describing aspects of
+// the execution context that affect parsing (such as if we are an ES module or
+// normal script), and flags derived from source text. These flags are preserved
+// during cloning and serializing. As well, they should never change after the
+// BaseScript is created (although there are currently a few exceptions for
+// de-/re-lazification that remain).
+//
+// The "mutable" flags are temporary flags that are used by subsystems in the
+// engine such as the debugger or JITs. These flags are not preserved through
+// serialization or cloning since the attributes are generally associated with
+// one specific instance of a BaseScript.
+
+enum class ImmutableScriptFlagsEnum : uint32_t {
+ // Input Flags
+ //
+ // These flags are from CompileOptions or the Parser entry point. They
+ // generally cannot be derived from the source text alone.
+ // ----
+
+ // A script may have one of the following kinds: Global, Eval, Module,
+ // Function. At most one flag can be set, with a default of Global.
+ IsForEval = 1 << 0,
+ IsModule = 1 << 1,
+ IsFunction = 1 << 2,
+
+ // The script is compiled as engine-internal self-hosted JavaScript. This mode
+ // is used to implement certain library functions and has special parse,
+ // bytecode, and runtime behaviour that differs from normal script.
+ SelfHosted = 1 << 3,
+
+ // The script was compiled with the default mode set to strict mode. Note that
+ // this tracks the default value, while the actual mode used (after processing
+ // source and its directives) is the `Strict` flag below.
+ ForceStrict = 1 << 4,
+
+ // The script has a non-syntactic scope on its environment chain. That is,
+ // there may be objects about which we know nothing between the outermost
+ // syntactic scope and the global.
+ HasNonSyntacticScope = 1 << 5,
+
+ // The script return value will not be used and simplified code will be
+ // generated. This can only be applied to top-level scripts. The value this
+ // script returns will be UndefinedValue instead of what the spec normally
+ // prescribes.
+ NoScriptRval = 1 << 6,
+
+ // TreatAsRunOnce roughly indicates that a script is expected to be run no
+ // more than once. This affects optimizations and heuristics.
+ //
+ // On top-level global/eval/module scripts, this is set when the embedding
+ // ensures this script will not be re-used. In this case, parser literals may
+ // be exposed directly instead of being cloned.
+ TreatAsRunOnce = 1 << 7,
+ // ----
+
+ // Parser Flags
+ //
+ // Flags computed by the Parser from the source text and input flags.
+ // ----
+
+ // Generated code will execute in strict mode. This is due to either the
+ // ForceStrict flag being specified above, or due to source text itself (such
+ // as "use strict" directives).
+ Strict = 1 << 8,
+
+ // Script is parsed with a top-level goal of Module. This may be a top-level
+ // or an inner-function script.
+ HasModuleGoal = 1 << 9,
+
+ // Script contains inner functions.
+ //
+ // Note: This prevents relazification since inner function close-over the
+ // current scripts scopes.
+ HasInnerFunctions = 1 << 10,
+
+ // There is a direct eval statement in this script OR in any of its inner
+ // functions.
+ //
+ // Note: This prevents relazification since it can introduce inner functions.
+ HasDirectEval = 1 << 11,
+
+ // The (static) bindings of this script must support dynamic name access for
+ // read/write. The environment chain is used to do these dynamic lookups and
+ // optimizations to avoid allocating environments are suppressed.
+ //
+ // This includes direct-eval, `with`, and `delete` in this script OR in any of
+ // its inner functions.
+ //
+ // Note: Access through the arguments object is not considered dynamic binding
+ // access since it does not go through the normal name lookup mechanism.
+ BindingsAccessedDynamically = 1 << 12,
+
+ // A tagged template exists in the body (which will use JSOp::CallSiteObj in
+ // bytecode).
+ //
+ // Note: This prevents relazification since the template's object is
+ // observable to the user and cannot be recreated.
+ HasCallSiteObj = 1 << 13,
+
+ // Parser Flags for Functions
+ // ----
+
+ // This function's initial prototype is one of Function, GeneratorFunction,
+ // AsyncFunction, or AsyncGeneratorFunction as indicated by these flags.
+ //
+ // If either of these flags is set, the script may suspend and resume as it
+ // executes. Stack frames for this script also have a generator object.
+ IsAsync = 1 << 14,
+ IsGenerator = 1 << 15,
+
+ // This function's body serves as the `var` environment for a non-strict
+ // direct eval. This matters because it's the only way bindings can be
+ // dynamically added to a local environment, possibly shadowing other
+ // variables.
+ FunHasExtensibleScope = 1 << 16,
+
+ // This function has an internal .this binding and we need to emit
+ // JSOp::FunctionThis in the prologue to initialize it. This binding may be
+ // used directly for "this", or indirectly (such as class constructors).
+ FunctionHasThisBinding = 1 << 17,
+
+ // This function is a class method that must uses an internal [[HomeObject]]
+ // slot. This slot is initialized when the class definition is executed in the
+ // enclosing function.
+ NeedsHomeObject = 1 << 18,
+
+ // This function is a constructor for a derived class. This is a class that
+ // uses the `extends` syntax.
+ IsDerivedClassConstructor = 1 << 19,
+
+ // This function is synthesized by the Parser. This is used for field
+ // initializer lambdas and missing constructors for classes. These functions
+ // have unusual source coordinates and may be hidden from things like
+ // Reflect.parse.
+ IsSyntheticFunction = 1 << 20,
+
+ // This function is a class constructor that has MemberInitializer data
+ // associated with it.
+ UseMemberInitializers = 1 << 21,
+
+ // This function has a rest (`...`) parameter.
+ HasRest = 1 << 22,
+
+ // This function needs a call object or named lambda environment to be created
+ // in order to execute the function. This is done in the Stack or JIT frame
+ // setup code _before_ the bytecode prologue starts.
+ NeedsFunctionEnvironmentObjects = 1 << 23,
+
+ // An extra VarScope is used as the body scope instead of the normal
+ // FunctionScope. This is needed when parameter expressions are used AND the
+ // function has var bindings or a sloppy-direct-eval. For example,
+ // `function(x = eval("")) { var y; }`
+ FunctionHasExtraBodyVarScope = 1 << 24,
+
+ // This function must define the implicit `arguments` binding on the function
+ // scope. If there are no free uses or an appropriate explicit binding exists,
+ // then this flag is unset.
+ //
+ // Note: Parameter expressions will not see an explicit `var arguments;`
+ // binding in the body and an implicit binding on the function-scope must
+ // still be used in that case.
+ ShouldDeclareArguments = 1 << 25,
+
+ // This function has a local (implicit or explicit) `arguments` binding. This
+ // binding is initialized by the JSOp::Arguments bytecode.
+ //
+ // Technically, every function has a binding named `arguments`. Internally,
+ // this binding is only added when `arguments` is mentioned by the function
+ // body.
+ //
+ // Examples:
+ // ```
+ // // Explicit definition
+ // function f() { var arguments; return arguments; }
+ //
+ // // Implicit use
+ // function f() { return arguments; }
+ //
+ // // Implicit use in arrow function
+ // function f() { return () => arguments; }
+ //
+ // // Implicit use in parameter expression
+ // function f(a = arguments) { return a; }
+ // ```
+ NeedsArgsObj = 1 << 26,
+
+ // This function must use the "mapped" form of an arguments object. This flag
+ // is set independently of whether we actually use an `arguments` binding. The
+ // conditions are specified in the ECMAScript spec.
+ HasMappedArgsObj = 1 << 27,
+
+ // Large self-hosted methods that should be inlined anyway by the JIT for
+ // performance reasons can be marked with this flag.
+ IsInlinableLargeFunction = 1 << 28,
+
+ // This function has an internal .newTarget binding and we need to emit
+ // JSOp::NewTarget in the prologue to initialize it. This binding may be
+ // used directly for "new.target", or indirectly (e.g. in super() calls).
+ FunctionHasNewTargetBinding = 1 << 29,
+
+ // Whether this is a self-hosted function that uses the ArgumentsLength or
+ // GetArgument intrinsic.
+ UsesArgumentsIntrinsics = 1 << 30,
+};
+
+enum class MutableScriptFlagsEnum : uint32_t {
+ // Number of times the |warmUpCount| was forcibly discarded. The counter is
+ // reset when a script is successfully jit-compiled.
+ WarmupResets_MASK = 0xFF,
+
+ // If treatAsRunOnce, whether script has executed.
+ HasRunOnce = 1 << 8,
+
+ // Script has been reused for a clone.
+ HasBeenCloned = 1 << 9,
+
+ // Script has an entry in Realm::scriptCountsMap.
+ HasScriptCounts = 1 << 10,
+
+ // Script has an entry in Realm::debugScriptMap.
+ HasDebugScript = 1 << 11,
+
+ // (1 << 12) is unused.
+ // (1 << 13) is unused.
+
+ // Script supports relazification where it releases bytecode and gcthings to
+ // save memory. This process is opt-in since various complexities may disallow
+ // this for some scripts.
+ // NOTE: Must check for isRelazifiable() before setting this flag.
+ AllowRelazify = 1 << 14,
+
+ // Set if the script has opted into spew.
+ SpewEnabled = 1 << 15,
+
+ // Set if we care about a script's final warmup count.
+ NeedsFinalWarmUpCount = 1 << 16,
+
+ //
+ // IonMonkey compilation hints.
+ //
+
+ // Whether Baseline or Ion compilation has been disabled for this script.
+ // IonDisabled is equivalent to |jitScript->canIonCompile() == false| but
+ // JitScript can be discarded on GC and we don't want this to affect
+ // observable behavior (see ArgumentsGetterImpl comment).
+ BaselineDisabled = 1 << 17,
+ IonDisabled = 1 << 18,
+
+ // This script should not be inlined into others. This happens after inlining
+ // has failed.
+ Uninlineable = 1 << 19,
+
+ // Indicates that this script has no eager baseline hint available
+ // in the cache, used to prevent further lookups.
+ NoEagerBaselineHint = 1 << 20,
+
+ // *****************************************************************
+ // The flags below are set when we bail out and invalidate a script.
+ // When we recompile, we will be more conservative.
+ // *****************************************************************
+
+ // A hoisted bounds check bailed out.
+ FailedBoundsCheck = 1 << 21,
+
+ // An instruction hoisted by LICM bailed out.
+ HadLICMInvalidation = 1 << 22,
+
+ // An instruction hoisted by InstructionReordering bailed out.
+ HadReorderingBailout = 1 << 23,
+
+ // An instruction inserted or truncated by Range Analysis bailed out.
+ HadEagerTruncationBailout = 1 << 24,
+
+ // A lexical check bailed out.
+ FailedLexicalCheck = 1 << 25,
+
+ // A guard inserted by phi specialization bailed out.
+ HadSpeculativePhiBailout = 1 << 26,
+
+ // An unbox folded with a load bailed out.
+ HadUnboxFoldingBailout = 1 << 27,
+};
+
+// Retrievable source can be retrieved using the source hook (and therefore
+// need not be XDR'd, can be discarded if desired because it can always be
+// reconstituted later, etc.).
+enum class SourceRetrievable { No = 0, Yes };
+
+} // namespace js
+
+#endif /* vm_StencilEnums_h */