Revert "[builtins] Fix Array.p.join length overflow and invalid string length handling"

This reverts commit ec969ea3.

Reason for revert: test fails consistently on arm bots.
I can't repro the failure locally, but it does consume ~512MB of memory (for a single string, I think?), so my guess is that the bots don't have enough contiguous address space.

Original change's description:
> [builtins] Fix Array.p.join length overflow and invalid string length handling
> 
> - Fixes and simplify allocating the temporary fixed array for ToString-ed elements.
>   - When the array size is greater than representable by an intptr, it overflowed into a negative value causing a non-negative assert to fail.
>   - Simplify fallback behavior by always allocating a conservatively sized temporary fixed array. Previously, if the array had dictionary elements, the temporary fixed array was sized based on %GetNumberDictionaryNumberOfElements() and then resized when entering the fallback.
> 
> - Fixes related invalid string length handling. When the running total of the resulting string length overflowed or exceeded String::kMaxLength, a RangeError is thrown. Previously, this thrown RangeError bypassed JoinStackPop and left the receiver on the stack.
> 
> Bug: chromium:897404
> Change-Id: I157b71ef04ab06125a5b1c3454e5ed3713bdb591
> Reviewed-on: https://chromium-review.googlesource.com/c/1293070
> Commit-Queue: Peter Wong <peter.wm.wong@gmail.com>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#56907}

TBR=danno@chromium.org,peter.wm.wong@gmail.com,jgruber@chromium.org,tebbi@chromium.org

Change-Id: I8ca80bd75833aacc94ccb25ceb82bbc8880991db
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:897404
Reviewed-on: https://chromium-review.googlesource.com/c/1297471Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56915}

src/builtins/array-join.tq

@@ -10,9 +10,15 @@ module array {
   extern macro CallJSArrayArrayJoinConcatToSequentialString(
       FixedArray, intptr, String, String): String;
 
-  extern macro CallArrayJoin(
-      Context, constexpr bool, JSReceiver, String, Number, Object, Object):
-      String
+  extern macro CallLoadJoinElement(implicit context: Context)(
+      LoadJoinElementFn, JSReceiver, Number): Object
+      labels IfException(Object);
+
+  extern macro CallConvertToLocaleString(implicit context: Context)(
+      Object, Object, Object): String
+      labels IfException(Object);
+
+  extern macro CallToString(implicit context: Context)(Object): String
       labels IfException(Object);
 
   builtin LoadJoinElement<T: type>(
@@ -142,11 +148,11 @@ module array {
     isOneByte: bool;
   }
 
-  macro BufferInit(len: uintptr, sep: String): Buffer {
-    const cappedBufferSize: intptr = len > kFixedArrayMaxLength ?
+  macro BufferInit(estimatedNonHoleyElements: uintptr, sep: String): Buffer {
+    const bufferSize: intptr = Signed(estimatedNonHoleyElements + 1);
+    const cappedBufferSize: intptr = bufferSize > kFixedArrayMaxLength ?
         FromConstexpr<intptr>(kFixedArrayMaxLength) :
-        Signed(len);
-    assert(cappedBufferSize > 0);
+        bufferSize;
     const fixedArray: FixedArray = AllocateZeroedFixedArray(cappedBufferSize);
     const isOneByte: bool = HasOnlyOneByteChars(sep.instanceType);
     return Buffer{fixedArray, 0, 0, isOneByte};
@@ -214,62 +220,76 @@ module array {
   macro ArrayJoinImpl(
       context: Context, receiver: JSReceiver, sep: String, lengthNumber: Number,
       useToLocaleString: constexpr bool, locales: Object, options: Object,
-      initialLoadJoinElement: LoadJoinElementFn): String {
+      estimatedNonHoleyElements: uintptr,
+      initialLoadJoinElement: LoadJoinElementFn): String
+      labels IfException(Object) {
     const initialMap: Map = receiver.map;
     const len: uintptr = Convert<uintptr>(lengthNumber);
     const separatorLength: intptr = sep.length;
     let nofSeparators: intptr = 0;
     let loadJoinElements: LoadJoinElementFn = initialLoadJoinElement;
-    let buffer: Buffer = BufferInit(len, sep);
-
-    // 6. Let k be 0.
-    let k: uintptr = 0;
-
-    // 7. Repeat, while k < len
-    while (k < len) {
-      if (k > 0) {
-        // a. If k > 0, let R be the string-concatenation of R and sep.
-        nofSeparators = nofSeparators + 1;
-
-        // Verify the current LoadJoinElement specialization can safely be
-        // used. Otherwise, fall back to generic element access (see
-        // LoadJoinElement<GenericElementsAccessor>).
-        if (loadJoinElements != LoadJoinElement<GenericElementsAccessor>&&
-            CannotUseSameArrayAccessor(initialMap, lengthNumber, receiver))
-          deferred {
-            loadJoinElements = LoadJoinElement<GenericElementsAccessor>;
-          }
-      }
-
-      // b. Let element be ? Get(O, ! ToString(k)).
-      const element: Object =
-          loadJoinElements(context, receiver, Convert<Number>(k++));
+    let buffer: Buffer = BufferInit(estimatedNonHoleyElements, sep);
+
+    if (estimatedNonHoleyElements != 0) {
+      // 6. Let k be 0.
+      let k: uintptr = 0;
+
+      // 7. Repeat, while k < len
+      while (k < len) {
+        if (k > 0) {
+          // a. If k > 0, let R be the string-concatenation of R and sep.
+          nofSeparators = nofSeparators + 1;
+
+          // Verify the current LoadJoinElement specialization can safely be
+          // used. Otherwise, fall back to generic element access (see
+          // LoadJoinElement<GenericElementsAccessor>).
+          if (loadJoinElements != LoadJoinElement<GenericElementsAccessor>&&
+              CannotUseSameArrayAccessor(initialMap, lengthNumber, receiver))
+            deferred {
+              loadJoinElements = LoadJoinElement<GenericElementsAccessor>;
+
+              // Join the current buffer into a single string and add it to a
+              // new buffer that the fall back will continue with.
+              const temp: String = BufferJoin(buffer, sep);
+              buffer = BufferInit((len - k + 1), sep);
+              buffer = BufferAdd(buffer, temp, 0, separatorLength);
+            }
+        }
 
-      // c. If element is undefined or null, let next be the empty String;
-      //    otherwise, let next be ? ToString(element).
-      let next: String;
-      if constexpr (useToLocaleString) {
-        next = ConvertToLocaleString(context, element, locales, options);
-        if (next == kEmptyString) continue;
-      } else {
-        typeswitch (element) {
-          case (str: String): {
-            if (str == kEmptyString) continue;
-            next = str;
-          }
-          case (num: Number): {
-            next = NumberToString(num);
-          }
-          case (obj: HeapObject): {
-            if (IsNullOrUndefined(obj)) continue;
-            next = ToString(context, obj);
+        // b. Let element be ? Get(O, ! ToString(k)).
+        const element: Object = CallLoadJoinElement(
+            loadJoinElements, receiver, Convert<Number>(k++))
+            otherwise IfException;
+
+        // c. If element is undefined or null, let next be the empty String;
+        //    otherwise, let next be ? ToString(element).
+        let next: String;
+        if constexpr (useToLocaleString) {
+          next = CallConvertToLocaleString(element, locales, options)
+              otherwise IfException;
+          if (next == kEmptyString) continue;
+        } else {
+          typeswitch (element) {
+            case (str: String): {
+              if (str == kEmptyString) continue;
+              next = str;
+            }
+            case (num: Number): {
+              next = NumberToString(num);
+            }
+            case (obj: HeapObject): {
+              if (IsNullOrUndefined(obj)) continue;
+              next = CallToString(obj) otherwise IfException;
+            }
           }
         }
-      }
 
-      // d. Set R to the string-concatenation of R and next.
-      buffer = BufferAdd(buffer, next, nofSeparators, separatorLength);
-      nofSeparators = 0;
+        // d. Set R to the string-concatenation of R and next.
+        buffer = BufferAdd(buffer, next, nofSeparators, separatorLength);
+        nofSeparators = 0;
+      }
+    } else {
+      nofSeparators = Signed(len - 1);
     }
 
     // Add any separators at the end.
@@ -281,7 +301,8 @@ module array {
 
   macro ArrayJoin(implicit context: Context)(
       useToLocaleString: constexpr bool, receiver: JSReceiver, sep: String,
-      lenNumber: Number, locales: Object, options: Object): Object {
+      lenNumber: Number, locales: Object, options: Object): Object
+      labels IfException(Object) {
     const map: Map = receiver.map;
     const kind: ElementsKind = map.elements_kind;
     const len: uintptr = Convert<uintptr>(lenNumber);
@@ -289,6 +310,7 @@ module array {
     // Estimated number of elements that are not holes. This is conservatively
     // defaulted to `len`. When the receiver has dictionary elements, a better
     // estimate can be determined through GetNumberDictionaryNumberOfElements.
+    let estimatedNonHoleyElements: uintptr = len;
     let loadJoinElements: LoadJoinElementFn;
 
     try {
@@ -301,26 +323,14 @@ module array {
         loadJoinElements = LoadJoinElement<FastSmiOrObjectElements>;
       } else if (IsElementsKindLessThanOrEqual(kind, HOLEY_DOUBLE_ELEMENTS)) {
         loadJoinElements = LoadJoinElement<FastDoubleElements>;
-      } else if (kind == DICTIONARY_ELEMENTS)
-        deferred {
-          const dict: NumberDictionary =
-              UnsafeCast<NumberDictionary>(array.elements);
-          const nofElements: Smi = GetNumberDictionaryNumberOfElements(dict);
-          if (nofElements == 0) {
-            if (sep == kEmptyString) return kEmptyString;
-            try {
-              const nofSeparators: Smi =
-                  Cast<Smi>(lenNumber - 1) otherwise IfNotSmi;
-              return StringRepeat(context, sep, nofSeparators);
-            }
-            label IfNotSmi {
-              ThrowRangeError(context, kInvalidStringLength);
-            }
-          } else {
-            loadJoinElements = LoadJoinElement<DictionaryElements>;
-          }
-        }
-      else {
+      } else if (kind == DICTIONARY_ELEMENTS) {
+        const dict: NumberDictionary =
+            UnsafeCast<NumberDictionary>(array.elements);
+        estimatedNonHoleyElements =
+            Unsigned(Convert<intptr>(GetNumberDictionaryNumberOfElements(dict)))
+            << 1;
+        loadJoinElements = LoadJoinElement<DictionaryElements>;
+      } else {
         goto IfSlowPath;
       }
     }
@@ -329,19 +339,8 @@ module array {
     }
     return ArrayJoinImpl(
         context, receiver, sep, lenNumber, useToLocaleString, locales, options,
-        loadJoinElements);
-  }
-
-  builtin ArrayJoinWithToLocaleString(
-      context: Context, receiver: JSReceiver, sep: String, len: Number,
-      locales: Object, options: Object): Object {
-    return ArrayJoin(true, receiver, sep, len, locales, options);
-  }
-
-  builtin ArrayJoinWithoutToLocaleString(
-      context: Context, receiver: JSReceiver, sep: String, len: Number,
-      locales: Object, options: Object): Object {
-    return ArrayJoin(false, receiver, sep, len, locales, options);
+        estimatedNonHoleyElements, loadJoinElements)
+        otherwise IfException;
   }
 
   // The Join Stack detects cyclical calls to Array Join builtins
@@ -473,8 +472,8 @@ module array {
 
       JoinStackPushInline(o) otherwise IfReturnEmpty;
 
-      const result: Object = CallArrayJoin(
-          context, useToLocaleString, o, sep, len, locales, options)
+      const result: Object =
+          ArrayJoin(useToLocaleString, o, sep, len, locales, options)
           otherwise IfException;
 
       JoinStackPopInline(o);

src/builtins/base.tq

@@ -1168,4 +1168,3 @@ extern macro TryIntPtrAdd(intptr, intptr): intptr
     labels IfOverflow;
 
 extern builtin ObjectToString(Context, Object): Object;
-extern builtin StringRepeat(Context, String, Number): String;

src/builtins/builtins-array-gen.h

@@ -91,16 +91,43 @@ class ArrayBuiltinsAssembler : public BaseBuiltinsFromDSLAssembler {
 
   // Temporary Torque support for Array.prototype.join().
   // TODO(pwong): Remove this when Torque supports exception handlers.
-  TNode<String> CallArrayJoin(TNode<Context> context, bool use_to_locale_string,
-                              TNode<JSReceiver> receiver, TNode<String> sep,
-                              TNode<Number> len, TNode<Object> locales,
-                              TNode<Object> options, Label* if_exception,
-                              TVariable<Object>* var_exception) {
-    Builtins::Name builtin = use_to_locale_string
-                                 ? Builtins::kArrayJoinWithToLocaleString
-                                 : Builtins::kArrayJoinWithoutToLocaleString;
-    TNode<Object> result =
-        CallBuiltin(builtin, context, receiver, sep, len, locales, options);
+  TNode<Object> CallLoadJoinElement(TNode<Context> context,
+                                    TNode<Code> loadJoinElement,
+                                    TNode<JSReceiver> receiver, TNode<Number> k,
+                                    Label* if_exception,
+                                    TVariable<Object>* var_exception) {
+    // Calling a specialization of LoadJoinElement (see array-join.tq), requires
+    // a descriptor.  We arbitrarily use one of specialization's descriptor, as
+    // all specializations share the same interface.
+    TNode<Object> result = CallStub(
+        Builtins::CallableFor(isolate(),
+                              Builtins::kLoadJoinElement20ATDictionaryElements)
+            .descriptor(),
+        loadJoinElement, context, receiver, k);
+    GotoIfException(result, if_exception, var_exception);
+    return result;
+  }
+
+  // Temporary Torque support for Array.prototype.join().
+  // TODO(pwong): Remove this when Torque supports exception handlers.
+  TNode<String> CallConvertToLocaleString(TNode<Context> context,
+                                          TNode<Object> element,
+                                          TNode<Object> locales,
+                                          TNode<Object> options,
+                                          Label* if_exception,
+                                          TVariable<Object>* var_exception) {
+    TNode<Object> result = CallBuiltin(Builtins::kConvertToLocaleString,
+                                       context, element, locales, options);
+    GotoIfException(result, if_exception, var_exception);
+    return CAST(result);
+  }
+
+  // Temporary Torque support for Array.prototype.join().
+  // TODO(pwong): Remove this when Torque supports exception handlers.
+  TNode<String> CallToString(TNode<Context> context, TNode<Object> obj,
+                             Label* if_exception,
+                             TVariable<Object>* var_exception) {
+    TNode<Object> result = CallBuiltin(Builtins::kToString, context, obj);
     GotoIfException(result, if_exception, var_exception);
     return CAST(result);
   }

src/builtins/builtins-string-gen.cc

@@ -1257,6 +1257,7 @@ TF_BUILTIN(StringRepeat, StringBuiltinsAssembler) {
   CSA_ASSERT(this, IsString(string));
   CSA_ASSERT(this, Word32BinaryNot(IsEmptyString(string)));
   CSA_ASSERT(this, TaggedIsPositiveSmi(count));
+  CSA_ASSERT(this, SmiLessThanOrEqual(count, SmiConstant(String::kMaxLength)));
 
   // The string is repeated with the following algorithm:
   //   let n = count;

src/torque/csa-generator.cc

@@ -254,11 +254,7 @@ void CSAGenerator::EmitInstruction(
       out_ << ", &" << var_names[i][j];
     }
   }
-  if (return_type->IsStructType()) {
-    out_ << ").Flatten();\n";
-  } else {
-    out_ << ");\n";
-  }
+  out_ << ");\n";
   if (instruction.return_continuation) {
     out_ << "    Goto(&" << BlockName(*instruction.return_continuation);
     for (const std::string& value : *stack) {

test/mjsunit/array-join-invalid-string-length.js

-// Copyright 2018 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.
-
-// Flags: --allow-natives-syntax
-
-(function DictionaryStringRepeatFastPath() {
-  const a = new Array(%StringMaxLength());
-  assertTrue(%HasDictionaryElements(a));
-  const sep = '12';
-  assertThrows(() => a.join(sep), RangeError);
-
-  // Verifies cycle detection still works properly after thrown error.
-  assertThrows(() => a.join(sep), RangeError);
-
-  a.length = 3;
-  a[0] = 'a';
-  a[1] = 'b';
-  a[2] = 'c';
-  assertSame('a,b,c', a.join());
-})();
-
-(function SeparatorOverflow() {
-  const a = ['a',,,,,'b'];
-
-  const sep = ','.repeat(%StringMaxLength());
-  assertThrows(() => a.join(sep), RangeError);
-
-  // Verifies cycle detection still works properly after thrown error.
-  assertThrows(() => a.join(sep), RangeError);
-  assertSame('a,,,,,b', a.join());
-})();
-
-(function ElementOverflow() {
-  const el = ','.repeat(%StringMaxLength());
-  const a = [el, el, el, el, el];
-
-  assertThrows(() => a.join(), RangeError);
-
-  // Verifies cycle detection still works properly after thrown error.
-  assertThrows(() => a.join(), RangeError);
-  a[0] = 'a';
-  a[1] = 'b';
-  a[2] = 'c';
-  a[3] = 'd';
-  a[4] = 'e';
-  assertSame('a,b,c,d,e', a.join());
-})();
-
-(function ElementSeparatorOverflow() {
-  const el = ','.repeat(%StringMaxLength());
-  const a = [el, el, el, el];
-
-  assertThrows(() => a.join(el), RangeError);
-
-  // Verifies cycle detection still works properly after thrown error.
-  assertThrows(() => a.join(el), RangeError);
-  a[0] = 'a';
-  a[1] = 'b';
-  a[2] = 'c';
-  a[3] = 'd';
-  assertSame('a,b,c,d', a.join());
-})();

test/mjsunit/messages.js

@@ -570,10 +570,6 @@ test(function() {
   "a".repeat(1 << 30);
 }, "Invalid string length", RangeError);
 
-test(function() {
-  new Array(1 << 30).join();
-}, "Invalid string length", RangeError);
-
 // kNormalizationForm
 test(function() {
   "".normalize("ABC");

test/mjsunit/regress/regress-crbug-897404.js

-// Copyright 2018 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.
-
-function TestError() {}
-
-// Force slow, generic assess path that will always allocate a temporary fixed
-// array.
-String.prototype.__defineGetter__(0, function() { });
-
-const a = new Array(2**32 - 1);
-
-// Force early exit to avoid an unreasonably long test.
-a[0] = {
-  toString() { throw new TestError(); }
-};
-
-// Verify join throws test error and does not fail due to asserts (Negative
-// length fixed array allocation).
-assertThrows(() => a.join(), TestError);