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[builtins] Use uintptr as index in String builtins, pt.1

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The CL refactors the following builtins:
  String.prototype.startsWith
  String.prototype.endsWith

to use ClampToIndexRange(x, len) instead of NumberMin(NumberMax(x, 0), len).

Bug: v8:8996
Change-Id: I20ab42088168e517840385cc2db435361004d9c0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1873702
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64500}
This commit is contained in:
Igor Sheludko 2019-10-23 11:01:59 +02:00 committed by Commit Bot
parent 5958b57ef4
commit b71af5c38a
9 changed files with 100 additions and 71 deletions
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9
src/builtins/base.tq
View File

@ -1409,7 +1409,10 @@ const kMaxTypedArrayInHeap:
const kMaxSafeInteger: constexpr float64 generates 'kMaxSafeInteger';
const kSmiMaxValue: constexpr uintptr generates 'kSmiMaxValue';
const kSmiMax: uintptr = kSmiMaxValue;
// TODO(v8:8996): Use uintptr version instead and drop this one.
const kStringMaxLength: constexpr int31 generates 'String::kMaxLength';
const kStringMaxLengthUintptr:
constexpr uintptr generates 'String::kMaxLength';
const kFixedArrayMaxLength:
constexpr int31 generates 'FixedArray::kMaxLength';
const kObjectAlignmentMask: constexpr intptr
@ -1962,7 +1965,7 @@ extern macro LoadBufferSmi(RawPtr, constexpr int32): Smi;
extern runtime StringEqual(Context, String, String): Oddball;
extern builtin StringLessThan(Context, String, String): Boolean;
extern macro StringCharCodeAt(String, intptr): int32;
extern macro StringCharCodeAt(String, uintptr): int32;
extern runtime StringCompareSequence(Context, String, String, Number): Boolean;
extern macro StringFromSingleCharCode(int32): String;
@ -2169,6 +2172,8 @@ extern macro TryIntPtrAdd(intptr, intptr): intptr labels Overflow;
extern macro TryIntPtrSub(intptr, intptr): intptr labels Overflow;
extern macro TryInt32Mul(int32, int32): int32 labels Overflow;
extern operator '<' macro ConstexprUintPtrLessThan(
constexpr uintptr, constexpr uintptr): constexpr bool;
extern operator '<<' macro ConstexprUintPtrShl(
constexpr uintptr, constexpr int31): constexpr uintptr;
extern operator '>>>' macro ConstexprUintPtrShr(
@ -3685,6 +3690,7 @@ macro ConvertToRelativeIndex(indexNumber: Number, length: uintptr): uintptr {
}
}
case (indexHeapNumber: HeapNumber): {
assert(IsNumberNormalized(indexHeapNumber));
const indexDouble: float64 = Convert<float64>(indexHeapNumber);
// NaNs must already be handled by ConvertToRelativeIndex() version
// above accepting JSAny indices.
@ -3726,6 +3732,7 @@ macro ClampToIndexRange(indexNumber: Number, limit: uintptr): uintptr {
return index;
}
case (indexHeapNumber: HeapNumber): {
assert(IsNumberNormalized(indexHeapNumber));
const indexDouble: float64 = Convert<float64>(indexHeapNumber);
// NaNs must already be handled by ClampToIndexRange() version
// above accepting JSAny indices.

15
src/builtins/builtins-regexp-gen.cc
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@ -1427,6 +1427,9 @@ TNode<Number> RegExpBuiltinsAssembler::AdvanceStringIndex(
TNode<Number> index_plus_one = NumberInc(index);
TVARIABLE(Number, var_result, index_plus_one);
// TODO(v8:9880): Given that we have to convert index from Number to UintPtrT
// anyway, consider using UintPtrT index to simplify the code below.
// Advancing the index has some subtle issues involving the distinction
// between Smis and HeapNumbers. There's three cases:
// * {index} is a Smi, {index_plus_one} is a Smi. The standard case.
@ -1451,16 +1454,18 @@ TNode<Number> RegExpBuiltinsAssembler::AdvanceStringIndex(
BIND(&if_isunicode);
{
TNode<IntPtrT> const string_length = LoadStringLengthAsWord(string);
TNode<IntPtrT> untagged_plus_one = SmiUntag(CAST(index_plus_one));
GotoIfNot(IntPtrLessThan(untagged_plus_one, string_length), &out);
TNode<UintPtrT> string_length = Unsigned(LoadStringLengthAsWord(string));
TNode<UintPtrT> untagged_plus_one =
Unsigned(SmiUntag(CAST(index_plus_one)));
GotoIfNot(UintPtrLessThan(untagged_plus_one, string_length), &out);
TNode<Int32T> const lead = StringCharCodeAt(string, SmiUntag(CAST(index)));
TNode<Int32T> lead =
StringCharCodeAt(string, Unsigned(SmiUntag(CAST(index))));
GotoIfNot(Word32Equal(Word32And(lead, Int32Constant(0xFC00)),
Int32Constant(0xD800)),
&out);
TNode<Int32T> const trail = StringCharCodeAt(string, untagged_plus_one);
TNode<Int32T> trail = StringCharCodeAt(string, untagged_plus_one);
GotoIfNot(Word32Equal(Word32And(trail, Int32Constant(0xFC00)),
Int32Constant(0xDC00)),
&out);

8
src/builtins/builtins-string-gen.cc
View File

@ -1977,13 +1977,14 @@ void StringTrimAssembler::GotoIfNotWhiteSpaceOrLineTerminator(
// Return the |word32| codepoint at {index}. Supports SeqStrings and
// ExternalStrings.
// TODO(v8:9880): Use UintPtrT here.
TNode<Int32T> StringBuiltinsAssembler::LoadSurrogatePairAt(
SloppyTNode<String> string, SloppyTNode<IntPtrT> length,
SloppyTNode<IntPtrT> index, UnicodeEncoding encoding) {
Label handle_surrogate_pair(this), return_result(this);
TVARIABLE(Int32T, var_result);
TVARIABLE(Int32T, var_trail);
var_result = StringCharCodeAt(string, index);
var_result = StringCharCodeAt(string, Unsigned(index));
var_trail = Int32Constant(0);
GotoIf(Word32NotEqual(Word32And(var_result.value(), Int32Constant(0xFC00)),
@ -1992,7 +1993,7 @@ TNode<Int32T> StringBuiltinsAssembler::LoadSurrogatePairAt(
TNode<IntPtrT> next_index = IntPtrAdd(index, IntPtrConstant(1));
GotoIfNot(IntPtrLessThan(next_index, length), &return_result);
var_trail = StringCharCodeAt(string, next_index);
var_trail = StringCharCodeAt(string, Unsigned(next_index));
Branch(Word32Equal(Word32And(var_trail.value(), Int32Constant(0xFC00)),
Int32Constant(0xDC00)),
&handle_surrogate_pair, &return_result);
@ -2154,6 +2155,7 @@ TNode<String> StringBuiltinsAssembler::AllocAndCopyStringCharacters(
return var_result.value();
}
// TODO(v8:9880): Use UintPtrT here.
TNode<String> StringBuiltinsAssembler::SubString(TNode<String> string,
TNode<IntPtrT> from,
TNode<IntPtrT> to) {
@ -2261,7 +2263,7 @@ TNode<String> StringBuiltinsAssembler::SubString(TNode<String> string,
// Substrings of length 1 are generated through CharCodeAt and FromCharCode.
BIND(&single_char);
{
TNode<Int32T> char_code = StringCharCodeAt(string, from);
TNode<Int32T> char_code = StringCharCodeAt(string, Unsigned(from));
var_result = StringFromSingleCharCode(char_code);
Goto(&end);
}

34
src/builtins/string-endswith.tq
View File

@ -4,17 +4,15 @@
namespace string {
macro TryFastStringCompareSequence(
string: String, searchStr: String, start: Number,
searchLength: Smi): Boolean labels Slow {
string: String, searchStr: String, start: uintptr,
searchLength: uintptr): 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);
let searchIndex: uintptr = 0;
let stringIndex: uintptr = start;
while (searchIndex < searchLengthInteger) {
while (searchIndex < searchLength) {
if (StringCharCodeAt(directSearchStr, searchIndex) !=
StringCharCodeAt(directString, stringIndex)) {
return False;
@ -34,10 +32,8 @@ namespace string {
const kBuiltinName: constexpr string = 'String.prototype.endsWith';
// 1. Let O be ? RequireObjectCoercible(this value).
const object: JSAny = RequireObjectCoercible(receiver, kBuiltinName);
// 2. Let S be ? ToString(O).
const string: String = ToString_Inline(context, object);
const string: String = ToThisString(receiver, kBuiltinName);
// 3. Let isRegExp be ? IsRegExp(searchString).
// 4. If isRegExp is true, throw a TypeError exception.
@ -49,25 +45,22 @@ namespace string {
const searchStr: String = ToString_Inline(context, searchString);
// 6. Let len be the length of S.
const len: Number = string.length_smi;
const len: uintptr = string.length_uintptr;
// 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);
const end: uintptr =
(endPosition != Undefined) ? ClampToIndexRange(endPosition, len) : len;
// 9. Let searchLength be the length of searchStr.
const searchLength: Smi = searchStr.length_smi;
const searchLength: uintptr = searchStr.length_uintptr;
// 10. Let start be end - searchLength.
const start = end - searchLength;
const start: uintptr = end - searchLength;
// 11. If start is less than 0, return false.
if (start < 0) return False;
if (Signed(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,
@ -80,7 +73,8 @@ namespace string {
}
label Slow {
// Slow Path: If either of the string is indirect, bail into runtime.
return StringCompareSequence(context, string, searchStr, start);
return StringCompareSequence(
context, string, searchStr, Convert<Number>(start));
}
}
}

24
src/builtins/string-startswith.tq
View File

@ -13,10 +13,8 @@ namespace string {
const kBuiltinName: constexpr string = 'String.prototype.startsWith';
// 1. Let O be ? RequireObjectCoercible(this value).
const object: JSAny = RequireObjectCoercible(receiver, kBuiltinName);
// 2. Let S be ? ToString(O).
const string: String = ToString_Inline(context, object);
const string: String = ToThisString(receiver, kBuiltinName);
// 3. Let isRegExp be ? IsRegExp(searchString).
// 4. If isRegExp is true, throw a TypeError exception.
@ -27,21 +25,22 @@ namespace string {
// 5. Let searchStr be ? ToString(searchString).
const searchStr: String = ToString_Inline(context, searchString);
// 6. Let pos be ? ToInteger(position).
const pos: Number = ToInteger_Inline(context, position);
// 7. Assert: If position is undefined, then pos is 0.
// 8. Let len be the length of S.
const len: Number = string.length_smi;
const len: uintptr = string.length_uintptr;
// 6. Let pos be ? ToInteger(position).
// 7. Assert: If position is undefined, then pos is 0.
// 9. Let start be min(max(pos, 0), len).
const start: Number = NumberMin(NumberMax(pos, 0), len);
const start: uintptr =
(position != Undefined) ? ClampToIndexRange(position, len) : 0;
// 10. Let searchLength be the length of searchStr.
const searchLength: Smi = searchStr.length_smi;
const searchLength: uintptr = searchStr.length_uintptr;
// 11. If searchLength + start is greater than len, return false.
if (searchLength + start > len) return False;
// The comparison is rephrased to be overflow-friendly with unsigned
// indices.
if (searchLength > len - start) 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,
@ -54,7 +53,8 @@ namespace string {
}
label Slow {
// Slow Path: If either of the string is indirect, bail into runtime.
return StringCompareSequence(context, string, searchStr, start);
return StringCompareSequence(
context, string, searchStr, Convert<Number>(start));
}
}
}

45
src/builtins/string.tq
View File

@ -57,19 +57,37 @@ namespace string {
transitioning macro GenerateStringAt(implicit context: Context)(
receiver: JSAny, position: JSAny,
methodName: constexpr string): never labels
IfInBounds(String, intptr, intptr), IfOutOfBounds {
// Check that {receiver} is coercible to Object and convert it to a String.
IfInBounds(String, uintptr, uintptr), IfOutOfBounds {
// 1. Let O be ? RequireObjectCoercible(this value).
// 2. Let S be ? ToString(O).
const string: String = ToThisString(receiver, methodName);
// Convert the {position} to a Smi and check that it's in bounds of
// the {string}.
// 3. Let position be ? ToInteger(pos).
const indexNumber: Number =
ToInteger_Inline(context, position, kTruncateMinusZero);
if (TaggedIsNotSmi(indexNumber)) goto IfOutOfBounds;
const index: intptr = SmiUntag(UnsafeCast<Smi>(indexNumber));
const length: intptr = string.length_intptr;
if (Convert<uintptr>(index) >= Convert<uintptr>(length)) goto IfOutOfBounds;
// Convert the {position} to a uintptr and check that it's in bounds of
// the {string}.
typeswitch (indexNumber) {
case (indexSmi: Smi): {
const length: uintptr = string.length_uintptr;
const index: uintptr = Unsigned(Convert<intptr>(indexSmi));
// Max string length fits Smi range, so we can do an unsigned bounds
// check.
const kMaxStringLengthFitsSmi: constexpr bool =
kStringMaxLengthUintptr < kSmiMaxValue;
StaticAssert(kMaxStringLengthFitsSmi);
if (index >= length) goto IfOutOfBounds;
goto IfInBounds(string, index, length);
}
case (indexHeapNumber: HeapNumber): {
assert(IsNumberNormalized(indexHeapNumber));
// Valid string indices fit into Smi range, so HeapNumber index is
// definitely an out of bounds case.
goto IfOutOfBounds;
}
}
}
// ES6 #sec-string.prototype.charat
transitioning javascript builtin StringPrototypeCharAt(
@ -78,7 +96,7 @@ namespace string {
GenerateStringAt(receiver, position, 'String.prototype.charAt')
otherwise IfInBounds, IfOutOfBounds;
}
label IfInBounds(string: String, index: intptr, _length: intptr) {
label IfInBounds(string: String, index: uintptr, _length: uintptr) {
const code: int32 = StringCharCodeAt(string, index);
return StringFromSingleCharCode(code);
}
@ -94,7 +112,7 @@ namespace string {
GenerateStringAt(receiver, position, 'String.prototype.charCodeAt')
otherwise IfInBounds, IfOutOfBounds;
}
label IfInBounds(string: String, index: intptr, _length: intptr) {
label IfInBounds(string: String, index: uintptr, _length: uintptr) {
const code: int32 = StringCharCodeAt(string, index);
return Convert<Smi>(code);
}
@ -110,10 +128,11 @@ namespace string {
GenerateStringAt(receiver, position, 'String.prototype.codePointAt')
otherwise IfInBounds, IfOutOfBounds;
}
label IfInBounds(string: String, index: intptr, length: intptr) {
label IfInBounds(string: String, index: uintptr, length: uintptr) {
// This is always a call to a builtin from Javascript, so we need to
// produce UTF32.
const code: int32 = LoadSurrogatePairAt(string, length, index, UTF32);
const code: int32 =
LoadSurrogatePairAt(string, Signed(length), Signed(index), UTF32);
return Convert<Smi>(code);
}
label IfOutOfBounds {
@ -190,7 +209,7 @@ namespace string {
}
builtin StringCharAt(implicit context: Context)(
receiver: String, position: intptr): String {
receiver: String, position: uintptr): String {
// Load the character code at the {position} from the {receiver}.
const code: int32 = StringCharCodeAt(receiver, position);
// And return the single character string with only that {code}

19
src/codegen/code-stub-assembler.cc
View File

@ -6765,12 +6765,9 @@ Node* CodeStubAssembler::FixedArraySizeDoesntFitInNewSpace(Node* element_count,
element_count, IntPtrOrSmiConstant(max_newspace_elements, mode), mode);
}
TNode<Int32T> CodeStubAssembler::StringCharCodeAt(SloppyTNode<String> string,
SloppyTNode<IntPtrT> index) {
CSA_ASSERT(this, IsString(string));
CSA_ASSERT(this, IntPtrGreaterThanOrEqual(index, IntPtrConstant(0)));
CSA_ASSERT(this, IntPtrLessThan(index, LoadStringLengthAsWord(string)));
TNode<Int32T> CodeStubAssembler::StringCharCodeAt(TNode<String> string,
TNode<UintPtrT> index) {
CSA_ASSERT(this, UintPtrLessThan(index, LoadStringLengthAsWord(string)));
TVARIABLE(Int32T, var_result);
@ -6779,7 +6776,8 @@ TNode<Int32T> CodeStubAssembler::StringCharCodeAt(SloppyTNode<String> string,
ToDirectStringAssembler to_direct(state(), string);
to_direct.TryToDirect(&if_runtime);
TNode<IntPtrT> const offset = IntPtrAdd(index, to_direct.offset());
TNode<UintPtrT> const offset =
UintPtrAdd(index, Unsigned(to_direct.offset()));
TNode<Int32T> const instance_type = to_direct.instance_type();
TNode<RawPtrT> const string_data = to_direct.PointerToData(&if_runtime);
@ -6804,8 +6802,9 @@ TNode<Int32T> CodeStubAssembler::StringCharCodeAt(SloppyTNode<String> string,
BIND(&if_runtime);
{
TNode<Object> result = CallRuntime(
Runtime::kStringCharCodeAt, NoContextConstant(), string, SmiTag(index));
TNode<Object> result =
CallRuntime(Runtime::kStringCharCodeAt, NoContextConstant(), string,
ChangeUintPtrToTagged(index));
var_result = SmiToInt32(CAST(result));
Goto(&return_result);
}
@ -9395,7 +9394,7 @@ void CodeStubAssembler::BranchIfMaybeSpecialIndex(TNode<String> name_string,
// If the first character of name is not a digit or '-', or we can't match it
// to Infinity or NaN, then this is not a special index.
TNode<Int32T> first_char = StringCharCodeAt(name_string, IntPtrConstant(0));
TNode<Int32T> first_char = StringCharCodeAt(name_string, UintPtrConstant(0));
// If the name starts with '-', it can be a negative index.
GotoIf(Word32Equal(first_char, Int32Constant('-')), if_maybe_special_index);
// If the name starts with 'I', it can be "Infinity".

6
src/codegen/code-stub-assembler.h
View File

@ -2606,8 +2606,7 @@ class V8_EXPORT_PRIVATE CodeStubAssembler
// String helpers.
// Load a character from a String (might flatten a ConsString).
TNode<Int32T> StringCharCodeAt(SloppyTNode<String> string,
SloppyTNode<IntPtrT> index);
TNode<Int32T> StringCharCodeAt(TNode<String> string, TNode<UintPtrT> index);
// Return the single character string with only {code}.
TNode<String> StringFromSingleCharCode(TNode<Int32T> code);
@ -3581,6 +3580,8 @@ class V8_EXPORT_PRIVATE CodeStubAssembler
return val;
}
bool ConstexprUintPtrLessThan(uintptr_t a, uintptr_t b) { return a < b; }
void PerformStackCheck(TNode<Context> context);
void SetPropertyLength(TNode<Context> context, TNode<Object> array,
@ -3961,6 +3962,7 @@ class ToDirectStringAssembler : public CodeStubAssembler {
TVariable<String> var_string_;
TVariable<Int32T> var_instance_type_;
// TODO(v8:9880): Use UintPtrT here.
TVariable<IntPtrT> var_offset_;
TVariable<Word32T> var_is_external_;

9
src/ic/accessor-assembler.cc
View File

@ -397,10 +397,11 @@ void AccessorAssembler::HandleLoadICSmiHandlerCase(
Comment("indexed string");
TNode<String> string_holder = CAST(holder);
TNode<IntPtrT> intptr_index = TryToIntptr(p->name(), miss);
TNode<IntPtrT> length = LoadStringLengthAsWord(string_holder);
GotoIf(UintPtrGreaterThanOrEqual(intptr_index, length), &if_oob);
TNode<Int32T> code = StringCharCodeAt(string_holder, intptr_index);
TNode<UintPtrT> index = Unsigned(TryToIntptr(p->name(), miss));
TNode<UintPtrT> length =
Unsigned(LoadStringLengthAsWord(string_holder));
GotoIf(UintPtrGreaterThanOrEqual(index, length), &if_oob);
TNode<Int32T> code = StringCharCodeAt(string_holder, index);
TNode<String> result = StringFromSingleCharCode(code);
Return(result);