[string] port String.p.endsWith to torque

Port String.prototype.endsWith from a CPP builtin to a Torque builtin.

Spec: https://tc39.github.io/ecma262/#sec-string.prototype.endswith
Bug: v8:8400
Change-Id: I4ac8cb92acb68389db844deaecc9ae1c6e7d6bd5
Reviewed-on: https://chromium-review.googlesource.com/c/1454677
Commit-Queue: Simon Zünd <szuend@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59441}

BUILD.gn

@@ -882,6 +882,7 @@ torque_files = [
   "src/builtins/extras-utils.tq",
   "src/builtins/object-fromentries.tq",
   "src/builtins/iterator.tq",
+  "src/builtins/string-endswith.tq",
   "src/builtins/string-startswith.tq",
   "src/builtins/typed-array.tq",
   "src/builtins/typed-array-createtypedarray.tq",

src/builtins/base.tq

@@ -506,7 +506,7 @@ extern macro LoadAndUntagToWord32Root(constexpr RootIndex): int32;
 extern runtime StringEqual(Context, String, String): Oddball;
 extern builtin StringLessThan(Context, String, String): Boolean;
 extern macro StringCharCodeAt(String, intptr): int32;
-extern runtime StringStartsWith(Context, String, String, Number): Boolean;
+extern runtime StringCompareSequence(Context, String, String, Number): Boolean;
 
 extern macro StrictEqual(Object, Object): Boolean;
 extern macro SmiLexicographicCompare(Smi, Smi): Smi;

src/builtins/builtins-definitions.h

@@ -1061,8 +1061,6 @@ namespace internal {
   TFJ(StringPrototypeCodePointAt, 1, kReceiver, kPosition)                     \
   /* ES6 #sec-string.prototype.concat */                                       \
   TFJ(StringPrototypeConcat, SharedFunctionInfo::kDontAdaptArgumentsSentinel)  \
-  /* ES6 #sec-string.prototype.endswith */                                     \
-  CPP(StringPrototypeEndsWith)                                                 \
   /* ES6 #sec-string.prototype.fontcolor */                                    \
   TFJ(StringPrototypeFontcolor, 1, kReceiver, kValue)                          \
   /* ES6 #sec-string.prototype.fontsize */                                     \

src/builtins/builtins-string.cc

@@ -118,70 +118,6 @@ BUILTIN(StringFromCodePoint) {
   return *result;
 }
 
-// ES6 section 21.1.3.6
-// String.prototype.endsWith ( searchString [ , endPosition ] )
-BUILTIN(StringPrototypeEndsWith) {
-  HandleScope handle_scope(isolate);
-  TO_THIS_STRING(str, "String.prototype.endsWith");
-
-  // Check if the search string is a regExp and fail if it is.
-  Handle<Object> search = args.atOrUndefined(isolate, 1);
-  Maybe<bool> is_reg_exp = RegExpUtils::IsRegExp(isolate, search);
-  if (is_reg_exp.IsNothing()) {
-    DCHECK(isolate->has_pending_exception());
-    return ReadOnlyRoots(isolate).exception();
-  }
-  if (is_reg_exp.FromJust()) {
-    THROW_NEW_ERROR_RETURN_FAILURE(
-        isolate, NewTypeError(MessageTemplate::kFirstArgumentNotRegExp,
-                              isolate->factory()->NewStringFromStaticChars(
-                                  "String.prototype.endsWith")));
-  }
-  Handle<String> search_string;
-  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, search_string,
-                                     Object::ToString(isolate, search));
-
-  Handle<Object> position = args.atOrUndefined(isolate, 2);
-  int end;
-
-  if (position->IsUndefined(isolate)) {
-    end = str->length();
-  } else {
-    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, position,
-                                       Object::ToInteger(isolate, position));
-    end = str->ToValidIndex(*position);
-  }
-
-  int start = end - search_string->length();
-  if (start < 0) return ReadOnlyRoots(isolate).false_value();
-
-  str = String::Flatten(isolate, str);
-  search_string = String::Flatten(isolate, search_string);
-
-  DisallowHeapAllocation no_gc;  // ensure vectors stay valid
-  String::FlatContent str_content = str->GetFlatContent(no_gc);
-  String::FlatContent search_content = search_string->GetFlatContent(no_gc);
-
-  if (str_content.IsOneByte() && search_content.IsOneByte()) {
-    Vector<const uint8_t> str_vector = str_content.ToOneByteVector();
-    Vector<const uint8_t> search_vector = search_content.ToOneByteVector();
-
-    return isolate->heap()->ToBoolean(memcmp(str_vector.start() + start,
-                                             search_vector.start(),
-                                             search_string->length()) == 0);
-  }
-
-  FlatStringReader str_reader(isolate, str);
-  FlatStringReader search_reader(isolate, search_string);
-
-  for (int i = 0; i < search_string->length(); i++) {
-    if (str_reader.Get(start + i) != search_reader.Get(i)) {
-      return ReadOnlyRoots(isolate).false_value();
-    }
-  }
-  return ReadOnlyRoots(isolate).true_value();
-}
-
 // ES6 section 21.1.3.9
 // String.prototype.lastIndexOf ( searchString [ , position ] )
 BUILTIN(StringPrototypeLastIndexOf) {

src/builtins/string-endswith.tq

@@ -0,0 +1,86 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+namespace string {
+  macro TryFastStringCompareSequence(
+      string: String, searchStr: String, start: Number,
+      searchLength: Smi): Boolean labels Slow {
+    const directString = Cast<DirectString>(string) otherwise Slow;
+    const directSearchStr = Cast<DirectString>(searchStr) otherwise Slow;
+    const stringIndexSmi: Smi = Cast<Smi>(start) otherwise Slow;
+
+    let searchIndex: intptr = 0;
+    let stringIndex = Convert<intptr>(stringIndexSmi);
+    const searchLengthInteger = Convert<intptr>(searchLength);
+
+    while (searchIndex < searchLengthInteger) {
+      if (StringCharCodeAt(directSearchStr, searchIndex) !=
+          StringCharCodeAt(directString, stringIndex)) {
+        return False;
+      }
+
+      searchIndex++;
+      stringIndex++;
+    }
+    return True;
+  }
+
+  // https://tc39.github.io/ecma262/#sec-string.prototype.endswith
+  transitioning javascript builtin StringPrototypeEndsWith(
+      context: Context, receiver: Object, ...arguments): Boolean {
+    const searchString: Object = arguments[0];
+    const endPosition: Object = arguments[1];
+
+    // 1. Let O be ? RequireObjectCoercible(this value).
+    const object: Object = RequireObjectCoercible(receiver);
+
+    // 2. Let S be ? ToString(O).
+    const string: String = ToString_Inline(context, object);
+
+    // 3. Let isRegExp be ? IsRegExp(searchString).
+    // 4. If isRegExp is true, throw a TypeError exception.
+    if (IsRegExp(searchString)) {
+      ThrowTypeError(
+          context, kFirstArgumentNotRegExp, 'String.prototype.endsWith');
+    }
+
+    // 5. Let searchStr be ? ToString(searchString).
+    const searchStr: String = ToString_Inline(context, searchString);
+
+    // 6. Let len be the length of S.
+    const len: Number = string.length_smi;
+
+    // 7. If endPosition is undefined, let pos be len,
+    // else let pos be ? ToInteger(endPosition).
+    const pos: Number = (endPosition == Undefined) ?
+        len :
+        ToInteger_Inline(context, endPosition);
+
+    // 8. Let end be min(max(pos, 0), len).
+    const end: Number = NumberMin(NumberMax(pos, 0), len);
+
+    // 9. Let searchLength be the length of searchStr.
+    const searchLength: Smi = searchStr.length_smi;
+
+    // 10. Let start be end - searchLength.
+    let start = end - searchLength;
+
+    // 11. If start is less than 0, return false.
+    if (start < 0) return False;
+
+    // 12. If the sequence of code units of S starting at start of length
+    // searchLength is the same as the full code unit sequence of searchStr,
+    // return true.
+    // 13. Otherwise, return false.
+    try {
+      // Fast Path: If both strings are direct and relevant indices are Smis.
+      return TryFastStringCompareSequence(
+          string, searchStr, start, searchLength) otherwise Slow;
+    }
+    label Slow {
+      // Slow Path: If either of the string is indirect, bail into runtime.
+      return StringCompareSequence(context, string, searchStr, start);
+    }
+  }
+}

src/builtins/string-startswith.tq

@@ -59,32 +59,15 @@ namespace string {
     // 12. If the sequence of code units of S starting at start of length
     // searchLength is the same as the full code unit sequence of searchStr,
     // return true.
-
+    // 13. Otherwise, return false.
     try {
       // Fast Path: If both strings are direct and relevant indices are Smis.
-      const directString = Cast<DirectString>(string) otherwise Slow;
-      const directSearchStr = Cast<DirectString>(searchStr) otherwise Slow;
-      const stringIndexSmi: Smi = Cast<Smi>(start) otherwise Slow;
-
-      let searchIndex: intptr = 0;
-      let stringIndex: intptr = Convert<intptr>(stringIndexSmi);
-      const searchLengthInteger: intptr = Convert<intptr>(searchLength);
-
-      while (searchIndex < searchLengthInteger) {
-        if (StringCharCodeAt(directSearchStr, searchIndex) !=
-            StringCharCodeAt(directString, stringIndex)) {
-          // 13. Otherwise, return false.
-          return False;
-        }
-
-        searchIndex++;
-        stringIndex++;
-      }
-      return True;
+      return TryFastStringCompareSequence(
+          string, searchStr, start, searchLength) otherwise Slow;
     }
     label Slow {
       // Slow Path: If either of the string is indirect, bail into runtime.
-      return StringStartsWith(context, string, searchStr, start);
+      return StringCompareSequence(context, string, searchStr, start);
     }
   }
 }

src/runtime/runtime-strings.cc

@@ -713,7 +713,7 @@ RUNTIME_FUNCTION(Runtime_StringMaxLength) {
   return Smi::FromInt(String::kMaxLength);
 }
 
-RUNTIME_FUNCTION(Runtime_StringStartsWith) {
+RUNTIME_FUNCTION(Runtime_StringCompareSequence) {
   HandleScope handle_scope(isolate);
   DCHECK_EQ(3, args.length());
   CONVERT_ARG_HANDLE_CHECKED(String, string, 0);

src/runtime/runtime.h

@@ -421,7 +421,7 @@ namespace internal {
   F(StringLessThanOrEqual, 2, 1)          \
   F(StringMaxLength, 0, 1)                \
   F(StringReplaceOneCharWithString, 3, 1) \
-  F(StringStartsWith, 3, 1)               \
+  F(StringCompareSequence, 3, 1)          \
   F(StringSubstring, 3, 1)                \
   F(StringToArray, 2, 1)                  \
   F(StringTrim, 2, 1)

test/mjsunit/es6/string-endswith.js

@@ -417,3 +417,13 @@ assertThrows(function() {
 }, TypeError);
 re[Symbol.match] = false;
 assertEquals(false, "".startsWith(re));
+
+let didThrow = false;
+try {
+  "".endsWith(/./);
+} catch (err) {
+  didThrow = true;
+  assertEquals(err.name, "TypeError");
+  assertEquals(err.message, "First argument to String.prototype.endsWith must not be a regular expression");
+}
+assertTrue(didThrow);