[api] Avoid handles for const API functions

Handles are notorious for preventing compiler optimizations. We should
avoid them for simple const functions.

- Mark more API functions const
- Mark more String functions const

Bug: v8:11195, chromium:808503, v8:11263
Change-Id: I9940e85600bc7d19027039d807b3313e2dcccdc7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2575065Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73159}

include/v8.h

@@ -1491,7 +1491,7 @@ class V8_EXPORT UnboundScript {
    */
   Local<Script> BindToCurrentContext();
 
-  int GetId();
+  int GetId() const;
   Local<Value> GetScriptName();
 
   /**
@@ -1701,7 +1701,7 @@ class V8_EXPORT Module : public Data {
    *
    * The module must be a SourceTextModule and must not have a kErrored status.
    */
-  int ScriptId();
+  int ScriptId() const;
 
   /**
    * Returns whether this module or any of its requested modules is async,
@@ -3525,12 +3525,12 @@ class V8_EXPORT String : public Name {
   /**
    * Returns true if this string can be made external.
    */
-  bool CanMakeExternal();
+  bool CanMakeExternal() const;
 
   /**
    * Returns true if the strings values are equal. Same as JS ==/===.
    */
-  bool StringEquals(Local<String> str);
+  bool StringEquals(Local<String> str) const;
 
   /**
    * Converts an object to a UTF-8-encoded character array.  Useful if
@@ -4137,7 +4137,7 @@ class V8_EXPORT Object : public Value {
   Maybe<bool> SetIntegrityLevel(Local<Context> context, IntegrityLevel level);
 
   /** Gets the number of internal fields for this Object. */
-  int InternalFieldCount();
+  int InternalFieldCount() const;
 
   /** Same as above, but works for PersistentBase. */
   V8_INLINE static int InternalFieldCount(
@@ -4247,10 +4247,10 @@ class V8_EXPORT Object : public Value {
       Local<Context> context, Local<Name> key);
 
   /** Tests for a named lookup interceptor.*/
-  bool HasNamedLookupInterceptor();
+  bool HasNamedLookupInterceptor() const;
 
   /** Tests for an index lookup interceptor.*/
-  bool HasIndexedLookupInterceptor();
+  bool HasIndexedLookupInterceptor() const;
 
   /**
    * Returns the identity hash for this object. The current implementation
@@ -4290,12 +4290,12 @@ class V8_EXPORT Object : public Value {
    * ObjectTemplate::SetCallAsFunctionHandler method.
    * When an Object is callable this method returns true.
    */
-  bool IsCallable();
+  bool IsCallable() const;
 
   /**
    * True if this object is a constructor.
    */
-  bool IsConstructor();
+  bool IsConstructor() const;
 
   /**
    * True if this object can carry information relevant to the embedder in its
@@ -4304,14 +4304,14 @@ class V8_EXPORT Object : public Value {
    * V8 automatically adds internal fields at compile time, such as e.g.
    * v8::ArrayBuffer.
    */
-  bool IsApiWrapper();
+  bool IsApiWrapper() const;
 
   /**
    * True if this object was created from an object template which was marked
    * as undetectable. See v8::ObjectTemplate::MarkAsUndetectable for more
    * information.
    */
-  bool IsUndetectable();
+  bool IsUndetectable() const;
 
   /**
    * Call an Object as a function if a callback is set by the
@@ -4370,7 +4370,7 @@ class V8_EXPORT Object : public Value {
    *
    * See also: v8::ObjectTemplate::SetCodeLike
    */
-  bool IsCodeLike(Isolate* isolate);
+  bool IsCodeLike(Isolate* isolate) const;
 
  private:
   Object();
@@ -4868,7 +4868,7 @@ class V8_EXPORT Promise : public Object {
    * Returns true if the promise has at least one derived promise, and
    * therefore resolve/reject handlers (including default handler).
    */
-  bool HasHandler();
+  bool HasHandler() const;
 
   /**
    * Returns the content of the [[PromiseResult]] field. The Promise must not
@@ -4976,7 +4976,7 @@ class V8_EXPORT Proxy : public Object {
  public:
   Local<Value> GetTarget();
   Local<Value> GetHandler();
-  bool IsRevoked();
+  bool IsRevoked() const;
   void Revoke();
 
   /**
@@ -7168,7 +7168,7 @@ class V8_EXPORT ObjectTemplate : public Template {
    * Gets the number of internal fields for objects generated from
    * this template.
    */
-  int InternalFieldCount();
+  int InternalFieldCount() const;
 
   /**
    * Sets the number of internal fields for objects generated from
@@ -7179,7 +7179,7 @@ class V8_EXPORT ObjectTemplate : public Template {
   /**
    * Returns true if the object will be an immutable prototype exotic object.
    */
-  bool IsImmutableProto();
+  bool IsImmutableProto() const;
 
   /**
    * Makes the ObjectTemplate for an immutable prototype exotic object, with an
@@ -7197,7 +7197,7 @@ class V8_EXPORT ObjectTemplate : public Template {
    * Reference: https://github.com/tc39/proposal-dynamic-code-brand-checks
    */
   void SetCodeLike();
-  bool IsCodeLike();
+  bool IsCodeLike() const;
 
   V8_INLINE static ObjectTemplate* Cast(Data* data);
 
@@ -10735,7 +10735,7 @@ class V8_EXPORT Context : public Data {
    * Returns true if code generation from strings is allowed for the context.
    * For more details see AllowCodeGenerationFromStrings(bool) documentation.
    */
-  bool IsCodeGenerationFromStringsAllowed();
+  bool IsCodeGenerationFromStringsAllowed() const;
 
   /**
    * Sets the error description for the exception that is thrown when

src/objects/string-inl.h

@@ -133,49 +133,51 @@ StringShape::StringShape(InstanceType t) : type_(static_cast<uint32_t>(t)) {
   DCHECK_EQ(type_ & kIsNotStringMask, kStringTag);
 }
 
-bool StringShape::IsInternalized() {
+bool StringShape::IsInternalized() const {
   DCHECK(valid());
   STATIC_ASSERT(kNotInternalizedTag != 0);
   return (type_ & (kIsNotStringMask | kIsNotInternalizedMask)) ==
          (kStringTag | kInternalizedTag);
 }
 
-bool StringShape::IsCons() {
+bool StringShape::IsCons() const {
   return (type_ & kStringRepresentationMask) == kConsStringTag;
 }
 
-bool StringShape::IsThin() {
+bool StringShape::IsThin() const {
   return (type_ & kStringRepresentationMask) == kThinStringTag;
 }
 
-bool StringShape::IsSliced() {
+bool StringShape::IsSliced() const {
   return (type_ & kStringRepresentationMask) == kSlicedStringTag;
 }
 
-bool StringShape::IsIndirect() {
+bool StringShape::IsIndirect() const {
   return (type_ & kIsIndirectStringMask) == kIsIndirectStringTag;
 }
 
-bool StringShape::IsExternal() {
+bool StringShape::IsExternal() const {
   return (type_ & kStringRepresentationMask) == kExternalStringTag;
 }
 
-bool StringShape::IsSequential() {
+bool StringShape::IsSequential() const {
   return (type_ & kStringRepresentationMask) == kSeqStringTag;
 }
 
-bool StringShape::IsUncachedExternal() {
+bool StringShape::IsUncachedExternal() const {
   return (type_ & kUncachedExternalStringMask) == kUncachedExternalStringTag;
 }
 
-StringRepresentationTag StringShape::representation_tag() {
+StringRepresentationTag StringShape::representation_tag() const {
   uint32_t tag = (type_ & kStringRepresentationMask);
   return static_cast<StringRepresentationTag>(tag);
 }
 
-uint32_t StringShape::encoding_tag() { return type_ & kStringEncodingMask; }
+uint32_t StringShape::encoding_tag() const {
+  return type_ & kStringEncodingMask;
+}
 
-uint32_t StringShape::full_representation_tag() {
+uint32_t StringShape::full_representation_tag() const {
   return (type_ & (kStringRepresentationMask | kStringEncodingMask));
 }
 
@@ -185,15 +187,15 @@ STATIC_ASSERT((kStringRepresentationMask | kStringEncodingMask) ==
 STATIC_ASSERT(static_cast<uint32_t>(kStringEncodingMask) ==
               Internals::kStringEncodingMask);
 
-bool StringShape::IsSequentialOneByte() {
+bool StringShape::IsSequentialOneByte() const {
   return full_representation_tag() == (kSeqStringTag | kOneByteStringTag);
 }
 
-bool StringShape::IsSequentialTwoByte() {
+bool StringShape::IsSequentialTwoByte() const {
   return full_representation_tag() == (kSeqStringTag | kTwoByteStringTag);
 }
 
-bool StringShape::IsExternalOneByte() {
+bool StringShape::IsExternalOneByte() const {
   return full_representation_tag() == (kExternalStringTag | kOneByteStringTag);
 }
 
@@ -202,7 +204,7 @@ STATIC_ASSERT((kExternalStringTag | kOneByteStringTag) ==
 
 STATIC_ASSERT(v8::String::ONE_BYTE_ENCODING == kOneByteStringTag);
 
-bool StringShape::IsExternalTwoByte() {
+bool StringShape::IsExternalTwoByte() const {
   return full_representation_tag() == (kExternalStringTag | kTwoByteStringTag);
 }
 
@@ -298,7 +300,7 @@ bool String::IsOneByteRepresentationUnderneath(String string) {
   }
 }
 
-uc32 FlatStringReader::Get(int index) {
+uc32 FlatStringReader::Get(int index) const {
   if (is_one_byte_) {
     return Get<uint8_t>(index);
   } else {
@@ -307,7 +309,7 @@ uc32 FlatStringReader::Get(int index) {
 }
 
 template <typename Char>
-Char FlatStringReader::Get(int index) {
+Char FlatStringReader::Get(int index) const {
   DCHECK_EQ(is_one_byte_, sizeof(Char) == 1);
   DCHECK(0 <= index && index < length_);
   if (sizeof(Char) == 1) {
@@ -432,7 +434,7 @@ class SeqSubStringKey final : public StringTableKey {
 using SeqOneByteSubStringKey = SeqSubStringKey<SeqOneByteString>;
 using SeqTwoByteSubStringKey = SeqSubStringKey<SeqTwoByteString>;
 
-bool String::Equals(String other) {
+bool String::Equals(String other) const {
   if (other == *this) return true;
   if (this->IsInternalizedString() && other.IsInternalizedString()) {
     return false;
@@ -440,6 +442,7 @@ bool String::Equals(String other) {
   return SlowEquals(other);
 }
 
+// static
 bool String::Equals(Isolate* isolate, Handle<String> one, Handle<String> two) {
   if (one.is_identical_to(two)) return true;
   if (one->IsInternalizedString() && two->IsInternalizedString()) {
@@ -539,7 +542,7 @@ bool String::IsEqualToImpl(
 bool String::IsOneByteEqualTo(Vector<const char> str) { return IsEqualTo(str); }
 
 template <typename Char>
-const Char* String::GetChars(const DisallowGarbageCollection& no_gc) {
+const Char* String::GetChars(const DisallowGarbageCollection& no_gc) const {
   DCHECK(!SharedStringAccessGuardIfNeeded::IsNeeded(*this));
   return StringShape(*this).IsExternal()
              ? CharTraits<Char>::ExternalString::cast(*this).GetChars()
@@ -549,7 +552,7 @@ const Char* String::GetChars(const DisallowGarbageCollection& no_gc) {
 template <typename Char>
 const Char* String::GetChars(
     const DisallowGarbageCollection& no_gc,
-    const SharedStringAccessGuardIfNeeded& access_guard) {
+    const SharedStringAccessGuardIfNeeded& access_guard) const {
   return StringShape(*this).IsExternal()
              ? CharTraits<Char>::ExternalString::cast(*this).GetChars()
              : CharTraits<Char>::String::cast(*this).GetChars(no_gc,
@@ -580,17 +583,17 @@ Handle<String> String::Flatten(LocalIsolate* isolate, Handle<String> string,
   return string;
 }
 
-uint16_t String::Get(int index, Isolate* isolate) {
+uint16_t String::Get(int index, Isolate* isolate) const {
   DCHECK(!SharedStringAccessGuardIfNeeded::IsNeeded(*this));
   return GetImpl(index);
 }
 
-uint16_t String::Get(int index, LocalIsolate* local_isolate) {
+uint16_t String::Get(int index, LocalIsolate* local_isolate) const {
   SharedStringAccessGuardIfNeeded scope(local_isolate);
   return GetImpl(index);
 }
 
-uint16_t String::GetImpl(int index) {
+uint16_t String::GetImpl(int index) const {
   DCHECK(index >= 0 && index < length());
 
   class StringGetDispatcher : public AllStatic {
@@ -619,12 +622,12 @@ void String::Set(int index, uint16_t value) {
              : SeqTwoByteString::cast(*this).SeqTwoByteStringSet(index, value);
 }
 
-bool String::IsFlat() {
+bool String::IsFlat() const {
   if (!StringShape(*this).IsCons()) return true;
   return ConsString::cast(*this).second().length() == 0;
 }
 
-String String::GetUnderlying() {
+String String::GetUnderlying() const {
   // Giving direct access to underlying string only makes sense if the
   // wrapping string is already flattened.
   DCHECK(this->IsFlat());
@@ -728,7 +731,7 @@ uint32_t String::ToValidIndex(Object number) {
   return index;
 }
 
-uint8_t SeqOneByteString::Get(int index) {
+uint8_t SeqOneByteString::Get(int index) const {
   DCHECK(index >= 0 && index < length());
   return ReadField<byte>(kHeaderSize + index * kCharSize);
 }
@@ -738,11 +741,12 @@ void SeqOneByteString::SeqOneByteStringSet(int index, uint16_t value) {
   WriteField<byte>(kHeaderSize + index * kCharSize, static_cast<byte>(value));
 }
 
-Address SeqOneByteString::GetCharsAddress() {
+Address SeqOneByteString::GetCharsAddress() const {
   return field_address(kHeaderSize);
 }
 
-uint8_t* SeqOneByteString::GetChars(const DisallowGarbageCollection& no_gc) {
+uint8_t* SeqOneByteString::GetChars(
+    const DisallowGarbageCollection& no_gc) const {
   USE(no_gc);
   DCHECK(!SharedStringAccessGuardIfNeeded::IsNeeded(*this));
   return reinterpret_cast<uint8_t*>(GetCharsAddress());
@@ -750,17 +754,17 @@ uint8_t* SeqOneByteString::GetChars(const DisallowGarbageCollection& no_gc) {
 
 uint8_t* SeqOneByteString::GetChars(
     const DisallowGarbageCollection& no_gc,
-    const SharedStringAccessGuardIfNeeded& access_guard) {
+    const SharedStringAccessGuardIfNeeded& access_guard) const {
   USE(no_gc);
   USE(access_guard);
   return reinterpret_cast<uint8_t*>(GetCharsAddress());
 }
 
-Address SeqTwoByteString::GetCharsAddress() {
+Address SeqTwoByteString::GetCharsAddress() const {
   return field_address(kHeaderSize);
 }
 
-uc16* SeqTwoByteString::GetChars(const DisallowGarbageCollection& no_gc) {
+uc16* SeqTwoByteString::GetChars(const DisallowGarbageCollection& no_gc) const {
   USE(no_gc);
   DCHECK(!SharedStringAccessGuardIfNeeded::IsNeeded(*this));
   return reinterpret_cast<uc16*>(GetCharsAddress());
@@ -768,13 +772,13 @@ uc16* SeqTwoByteString::GetChars(const DisallowGarbageCollection& no_gc) {
 
 uc16* SeqTwoByteString::GetChars(
     const DisallowGarbageCollection& no_gc,
-    const SharedStringAccessGuardIfNeeded& access_guard) {
+    const SharedStringAccessGuardIfNeeded& access_guard) const {
   USE(no_gc);
   USE(access_guard);
   return reinterpret_cast<uc16*>(GetCharsAddress());
 }
 
-uint16_t SeqTwoByteString::Get(int index) {
+uint16_t SeqTwoByteString::Get(int index) const {
   DCHECK(index >= 0 && index < length());
   return ReadField<uint16_t>(kHeaderSize + index * kShortSize);
 }
@@ -901,7 +905,7 @@ void ExternalOneByteString::set_resource(
   if (resource != nullptr) update_data_cache(isolate);
 }
 
-const uint8_t* ExternalOneByteString::GetChars() {
+const uint8_t* ExternalOneByteString::GetChars() const {
   DisallowGarbageCollection no_gc;
   if (is_uncached()) {
     if (resource()->IsCacheable()) {
@@ -923,7 +927,7 @@ const uint8_t* ExternalOneByteString::GetChars() {
   return reinterpret_cast<const uint8_t*>(resource()->data());
 }
 
-uint8_t ExternalOneByteString::Get(int index) {
+uint8_t ExternalOneByteString::Get(int index) const {
   DCHECK(index >= 0 && index < length());
   return GetChars()[index];
 }
@@ -966,7 +970,7 @@ void ExternalTwoByteString::set_resource(
   if (resource != nullptr) update_data_cache(isolate);
 }
 
-const uint16_t* ExternalTwoByteString::GetChars() {
+const uint16_t* ExternalTwoByteString::GetChars() const {
   DisallowGarbageCollection no_gc;
   if (is_uncached()) {
     if (resource()->IsCacheable()) {
@@ -988,7 +992,7 @@ const uint16_t* ExternalTwoByteString::GetChars() {
   return resource()->data();
 }
 
-uint16_t ExternalTwoByteString::Get(int index) {
+uint16_t ExternalTwoByteString::Get(int index) const {
   DCHECK(index >= 0 && index < length());
   return GetChars()[index];
 }

src/objects/string.cc

@@ -773,7 +773,7 @@ template Handle<FixedArray> String::CalculateLineEnds(LocalIsolate* isolate,
                                                       Handle<String> src,
                                                       bool include_ending_line);
 
-bool String::SlowEquals(String other) {
+bool String::SlowEquals(String other) const {
   DisallowGarbageCollection no_gc;
   // Fast check: negative check with lengths.
   int len = length();
@@ -825,6 +825,7 @@ bool String::SlowEquals(String other) {
   return comparator.Equals(*this, other);
 }
 
+// static
 bool String::SlowEquals(Isolate* isolate, Handle<String> one,
                         Handle<String> two) {
   // Fast check: negative check with lengths.
@@ -1437,7 +1438,7 @@ void SeqTwoByteString::clear_padding() {
          SizeFor(length()) - data_size);
 }
 
-uint16_t ConsString::Get(int index) {
+uint16_t ConsString::Get(int index) const {
   DCHECK(index >= 0 && index < this->length());
 
   // Check for a flattened cons string
@@ -1466,9 +1467,11 @@ uint16_t ConsString::Get(int index) {
   UNREACHABLE();
 }
 
-uint16_t ThinString::Get(int index) { return actual().Get(index); }
+uint16_t ThinString::Get(int index) const { return actual().Get(index); }
 
-uint16_t SlicedString::Get(int index) { return parent().Get(offset() + index); }
+uint16_t SlicedString::Get(int index) const {
+  return parent().Get(offset() + index);
+}
 
 int ExternalString::ExternalPayloadSize() const {
   int length_multiplier = IsTwoByteRepresentation() ? i::kShortSize : kCharSize;

src/objects/string.h

@@ -44,25 +44,25 @@ class StringShape {
   inline explicit StringShape(const String s);
   inline explicit StringShape(Map s);
   inline explicit StringShape(InstanceType t);
-  inline bool IsSequential();
-  inline bool IsExternal();
-  inline bool IsCons();
-  inline bool IsSliced();
-  inline bool IsThin();
-  inline bool IsIndirect();
-  inline bool IsUncachedExternal();
-  inline bool IsExternalOneByte();
-  inline bool IsExternalTwoByte();
-  inline bool IsSequentialOneByte();
-  inline bool IsSequentialTwoByte();
-  inline bool IsInternalized();
-  inline StringRepresentationTag representation_tag();
-  inline uint32_t encoding_tag();
-  inline uint32_t full_representation_tag();
+  inline bool IsSequential() const;
+  inline bool IsExternal() const;
+  inline bool IsCons() const;
+  inline bool IsSliced() const;
+  inline bool IsThin() const;
+  inline bool IsIndirect() const;
+  inline bool IsUncachedExternal() const;
+  inline bool IsExternalOneByte() const;
+  inline bool IsExternalTwoByte() const;
+  inline bool IsSequentialOneByte() const;
+  inline bool IsSequentialTwoByte() const;
+  inline bool IsInternalized() const;
+  inline StringRepresentationTag representation_tag() const;
+  inline uint32_t encoding_tag() const;
+  inline uint32_t full_representation_tag() const;
 #ifdef DEBUG
-  inline uint32_t type() { return type_; }
+  inline uint32_t type() const { return type_; }
   inline void invalidate() { valid_ = false; }
-  inline bool valid() { return valid_; }
+  inline bool valid() const { return valid_; }
 #else
   inline void invalidate() {}
 #endif
@@ -181,13 +181,13 @@ class String : public TorqueGeneratedString<String, Name> {
   // SharedStringAccessGuard is not needed (i.e. on the main thread or on
   // read-only strings).
   template <typename Char>
-  inline const Char* GetChars(const DisallowGarbageCollection& no_gc);
+  inline const Char* GetChars(const DisallowGarbageCollection& no_gc) const;
 
   // Get chars from sequential or external strings.
   template <typename Char>
   inline const Char* GetChars(
       const DisallowGarbageCollection& no_gc,
-      const SharedStringAccessGuardIfNeeded& access_guard);
+      const SharedStringAccessGuardIfNeeded& access_guard) const;
 
   // Returns the address of the character at an offset into this string.
   // Requires: this->IsFlat()
@@ -217,8 +217,8 @@ class String : public TorqueGeneratedString<String, Name> {
   // to this method are not efficient unless the string is flat.
   // If it is called from a background thread, the LocalIsolate version should
   // be used.
-  V8_INLINE uint16_t Get(int index, Isolate* isolate = nullptr);
-  V8_INLINE uint16_t Get(int index, LocalIsolate* local_isolate);
+  V8_INLINE uint16_t Get(int index, Isolate* isolate = nullptr) const;
+  V8_INLINE uint16_t Get(int index, LocalIsolate* local_isolate) const;
 
   // ES6 section 7.1.3.1 ToNumber Applied to the String Type
   static Handle<Object> ToNumber(Isolate* isolate, Handle<String> subject);
@@ -253,7 +253,7 @@ class String : public TorqueGeneratedString<String, Name> {
 
   // Returns the parent of a sliced string or first part of a flat cons string.
   // Requires: StringShape(this).IsIndirect() && this->IsFlat()
-  inline String GetUnderlying();
+  inline String GetUnderlying() const;
 
   // String relational comparison, implemented according to ES6 section 7.2.11
   // Abstract Relational Comparison (step 5): The comparison of Strings uses a
@@ -314,7 +314,7 @@ class String : public TorqueGeneratedString<String, Name> {
       int start_index = 0);
 
   // String equality operations.
-  inline bool Equals(String other);
+  inline bool Equals(String other) const;
   inline static bool Equals(Isolate* isolate, Handle<String> one,
                             Handle<String> two);
 
@@ -412,7 +412,7 @@ class String : public TorqueGeneratedString<String, Name> {
   DECL_PRINTER(String)
   DECL_VERIFIER(String)
 
-  inline bool IsFlat();
+  inline bool IsFlat() const;
 
   // Max char codes.
   static const int32_t kMaxOneByteCharCode = unibrow::Latin1::kMaxChar;
@@ -534,7 +534,7 @@ class String : public TorqueGeneratedString<String, Name> {
   friend class InternalizedStringKey;
 
   // Implementation of the Get() public methods. Do not use directly.
-  V8_INLINE uint16_t GetImpl(int index);
+  V8_INLINE uint16_t GetImpl(int index) const;
 
   // Implementation of the IsEqualTo() public methods. Do not use directly.
   template <EqualityType kEqType, typename Char>
@@ -547,7 +547,7 @@ class String : public TorqueGeneratedString<String, Name> {
 
   // Slow case of String::Equals.  This implementation works on any strings
   // but it is most efficient on strings that are almost flat.
-  V8_EXPORT_PRIVATE bool SlowEquals(String other);
+  V8_EXPORT_PRIVATE bool SlowEquals(String other) const;
 
   V8_EXPORT_PRIVATE static bool SlowEquals(Isolate* isolate, Handle<String> one,
                                            Handle<String> two);
@@ -619,20 +619,21 @@ class SeqOneByteString
   using Char = uint8_t;
 
   // Dispatched behavior.
-  inline uint8_t Get(int index);
+  inline uint8_t Get(int index) const;
   inline void SeqOneByteStringSet(int index, uint16_t value);
 
   // Get the address of the characters in this string.
-  inline Address GetCharsAddress();
+  inline Address GetCharsAddress() const;
 
   // Get a pointer to the characters of the string. May only be called when a
   // SharedStringAccessGuard is not needed (i.e. on the main thread or on
   // read-only strings).
-  inline uint8_t* GetChars(const DisallowGarbageCollection& no_gc);
+  inline uint8_t* GetChars(const DisallowGarbageCollection& no_gc) const;
 
   // Get a pointer to the characters of the string.
-  inline uint8_t* GetChars(const DisallowGarbageCollection& no_gc,
-                           const SharedStringAccessGuardIfNeeded& access_guard);
+  inline uint8_t* GetChars(
+      const DisallowGarbageCollection& no_gc,
+      const SharedStringAccessGuardIfNeeded& access_guard) const;
 
   // Clear uninitialized padding space. This ensures that the snapshot content
   // is deterministic.
@@ -664,20 +665,21 @@ class SeqTwoByteString
   using Char = uint16_t;
 
   // Dispatched behavior.
-  inline uint16_t Get(int index);
+  inline uint16_t Get(int index) const;
   inline void SeqTwoByteStringSet(int index, uint16_t value);
 
   // Get the address of the characters in this string.
-  inline Address GetCharsAddress();
+  inline Address GetCharsAddress() const;
 
   // Get a pointer to the characters of the string. May only be called when a
   // SharedStringAccessGuard is not needed (i.e. on the main thread or on
   // read-only strings).
-  inline uc16* GetChars(const DisallowGarbageCollection& no_gc);
+  inline uc16* GetChars(const DisallowGarbageCollection& no_gc) const;
 
   // Get a pointer to the characters of the string.
-  inline uc16* GetChars(const DisallowGarbageCollection& no_gc,
-                        const SharedStringAccessGuardIfNeeded& access_guard);
+  inline uc16* GetChars(
+      const DisallowGarbageCollection& no_gc,
+      const SharedStringAccessGuardIfNeeded& access_guard) const;
 
   // Clear uninitialized padding space. This ensures that the snapshot content
   // is deterministic.
@@ -720,7 +722,7 @@ class ConsString : public TorqueGeneratedConsString<ConsString, String> {
   inline Object unchecked_second();
 
   // Dispatched behavior.
-  V8_EXPORT_PRIVATE uint16_t Get(int index);
+  V8_EXPORT_PRIVATE uint16_t Get(int index) const;
 
   // Minimum length for a cons string.
   static const int kMinLength = 13;
@@ -743,7 +745,7 @@ class ThinString : public TorqueGeneratedThinString<ThinString, String> {
  public:
   DECL_GETTER(unchecked_actual, HeapObject)
 
-  V8_EXPORT_PRIVATE uint16_t Get(int index);
+  V8_EXPORT_PRIVATE uint16_t Get(int index) const;
 
   DECL_VERIFIER(ThinString)
 
@@ -769,7 +771,7 @@ class SlicedString : public TorqueGeneratedSlicedString<SlicedString, String> {
   inline void set_parent(String parent,
                          WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
   // Dispatched behavior.
-  V8_EXPORT_PRIVATE uint16_t Get(int index);
+  V8_EXPORT_PRIVATE uint16_t Get(int index) const;
 
   // Minimum length for a sliced string.
   static const int kMinLength = 13;
@@ -848,10 +850,10 @@ class ExternalOneByteString : public ExternalString {
   // which the pointer cache has to be refreshed.
   inline void update_data_cache(Isolate* isolate);
 
-  inline const uint8_t* GetChars();
+  inline const uint8_t* GetChars() const;
 
   // Dispatched behavior.
-  inline uint8_t Get(int index);
+  inline uint8_t Get(int index) const;
 
   DECL_CAST(ExternalOneByteString)
 
@@ -894,10 +896,10 @@ class ExternalTwoByteString : public ExternalString {
   // which the pointer cache has to be refreshed.
   inline void update_data_cache(Isolate* isolate);
 
-  inline const uint16_t* GetChars();
+  inline const uint16_t* GetChars() const;
 
   // Dispatched behavior.
-  inline uint16_t Get(int index);
+  inline uint16_t Get(int index) const;
 
   // For regexp code.
   inline const uint16_t* ExternalTwoByteStringGetData(unsigned start);
@@ -927,9 +929,9 @@ class V8_EXPORT_PRIVATE FlatStringReader : public Relocatable {
  public:
   FlatStringReader(Isolate* isolate, Handle<String> str);
   void PostGarbageCollection() override;
-  inline uc32 Get(int index);
+  inline uc32 Get(int index) const;
   template <typename Char>
-  inline Char Get(int index);
+  inline Char Get(int index) const;
   int length() { return length_; }
 
  private: