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[ic] KeyedLoadIC error on strings with negative indexes

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We need to check if the index is less than zero and miss to the runtime
if this is so.

Bug: chromium:1257519
Change-Id: I7d22f2765232815120b8baf7b8b83d5b00024375
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3218975
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77380}
This commit is contained in:
Mike Stanton 2021-10-12 23:42:25 +02:00 committed by V8 LUCI CQ
parent 2a00a4eceb
commit 84cfc9ca71
2 changed files with 26 additions and 2 deletions
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5
src/ic/accessor-assembler.cc
View File

@ -590,15 +590,16 @@ void AccessorAssembler::HandleLoadICSmiHandlerCase(
Comment("indexed string");
TNode<String> string_holder = CAST(holder);
TNode<UintPtrT> index = Unsigned(TryToIntptr(p->name(), miss));
TNode<IntPtrT> index = TryToIntptr(p->name(), miss);
TNode<UintPtrT> length =
Unsigned(LoadStringLengthAsWord(string_holder));
GotoIf(UintPtrGreaterThanOrEqual(index, length), &if_oob_string);
TNode<Int32T> code = StringCharCodeAt(string_holder, index);
TNode<Int32T> code = StringCharCodeAt(string_holder, Unsigned(index));
TNode<String> result = StringFromSingleCharCode(code);
Return(result);
BIND(&if_oob_string);
GotoIf(IntPtrLessThan(index, IntPtrConstant(0)), miss);
TNode<BoolT> allow_out_of_bounds =
IsSetWord<LoadHandler::AllowOutOfBoundsBits>(handler_word);
GotoIfNot(allow_out_of_bounds, miss);

23
test/mjsunit/regress/regress-crbug-1257519.js Normal file
View File

@ -0,0 +1,23 @@
// Copyright 2021 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: --no-lazy-feedback-allocation
var a = "hello";
function foo(i) {
var x = a[i];
return x;
}
// Set up the KeyedLoadIC for monomorphic string load.
foo(4);
foo(4);
foo(4);
// That also handles out of bounds indexes.
assertEquals(foo(8), undefined);
// Add a negative indexed property (not an element, so the
// NoElement protector will not fire).
Object.prototype[-1] = 2;
assertEquals(2, foo(-1));