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StringType.cpp
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StringType.cpp
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "vm/StringType-inl.h"
#include "mozilla/ArrayUtils.h"
#include "mozilla/Casting.h"
#include "mozilla/EndianUtils.h"
#include "mozilla/HashFunctions.h"
#include "mozilla/Latin1.h"
#include "mozilla/MathAlgorithms.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/PodOperations.h"
#include "mozilla/RangedPtr.h"
#include "mozilla/TextUtils.h"
#include "mozilla/Unused.h"
#include "mozilla/Utf8.h"
#include "mozilla/Vector.h"
#include <algorithm> // std::{all_of,copy_n,enable_if,is_const,move}
#include <type_traits> // std::is_same, std::is_unsigned
#include "jsfriendapi.h"
#include "frontend/BytecodeCompiler.h"
#include "gc/Marking.h"
#include "gc/MaybeRooted.h"
#include "gc/Nursery.h"
#include "js/CharacterEncoding.h"
#include "js/StableStringChars.h"
#include "js/Symbol.h"
#include "js/UbiNode.h"
#include "util/StringBuffer.h"
#include "util/Unicode.h"
#include "vm/GeckoProfiler.h"
#include "vm/ToSource.h" // js::ValueToSource
#include "vm/GeckoProfiler-inl.h"
#include "vm/JSContext-inl.h"
#include "vm/JSObject-inl.h"
#include "vm/Realm-inl.h"
using namespace js;
using mozilla::ArrayEqual;
using mozilla::AssertedCast;
using mozilla::AsWritableChars;
using mozilla::ConvertLatin1toUtf16;
using mozilla::IsAsciiDigit;
using mozilla::IsUtf16Latin1;
using mozilla::LossyConvertUtf16toLatin1;
using mozilla::MakeSpan;
using mozilla::PodCopy;
using mozilla::RangedPtr;
using mozilla::RoundUpPow2;
using mozilla::Unused;
using JS::AutoCheckCannotGC;
using JS::AutoStableStringChars;
using UniqueLatin1Chars = UniquePtr<Latin1Char[], JS::FreePolicy>;
size_t JSString::sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) {
// JSRope: do nothing, we'll count all children chars when we hit the leaf
// strings.
if (isRope()) {
return 0;
}
MOZ_ASSERT(isLinear());
// JSDependentString: do nothing, we'll count the chars when we hit the base
// string.
if (isDependent()) {
return 0;
}
// JSExternalString: Ask the embedding to tell us what's going on.
if (isExternal()) {
// Our callback isn't supposed to cause GC.
JS::AutoSuppressGCAnalysis nogc;
return asExternal().callbacks()->sizeOfBuffer(asExternal().twoByteChars(),
mallocSizeOf);
}
// JSExtensibleString: count the full capacity, not just the used space.
if (isExtensible()) {
JSExtensibleString& extensible = asExtensible();
return extensible.hasLatin1Chars()
? mallocSizeOf(extensible.rawLatin1Chars())
: mallocSizeOf(extensible.rawTwoByteChars());
}
// JSInlineString, JSFatInlineString [JSInlineAtom, JSFatInlineAtom]: the
// chars are inline.
if (isInline()) {
return 0;
}
// Everything else: measure the space for the chars.
JSLinearString& linear = asLinear();
MOZ_ASSERT(linear.ownsMallocedChars());
return linear.hasLatin1Chars() ? mallocSizeOf(linear.rawLatin1Chars())
: mallocSizeOf(linear.rawTwoByteChars());
}
JS::ubi::Node::Size JS::ubi::Concrete<JSString>::size(
mozilla::MallocSizeOf mallocSizeOf) const {
JSString& str = get();
size_t size;
if (str.isAtom()) {
size =
str.isFatInline() ? sizeof(js::FatInlineAtom) : sizeof(js::NormalAtom);
} else {
size = str.isFatInline() ? sizeof(JSFatInlineString) : sizeof(JSString);
}
if (IsInsideNursery(&str)) {
size += Nursery::stringHeaderSize();
}
size += str.sizeOfExcludingThis(mallocSizeOf);
return size;
}
const char16_t JS::ubi::Concrete<JSString>::concreteTypeName[] = u"JSString";
mozilla::Maybe<mozilla::Tuple<size_t, size_t> > JSString::encodeUTF8Partial(
const JS::AutoRequireNoGC& nogc, mozilla::Span<char> buffer) const {
mozilla::Vector<const JSString*, 16, SystemAllocPolicy> stack;
const JSString* current = this;
char16_t pendingLeadSurrogate = 0; // U+0000 means no pending lead surrogate
size_t totalRead = 0;
size_t totalWritten = 0;
for (;;) {
if (current->isRope()) {
JSRope& rope = current->asRope();
if (!stack.append(rope.rightChild())) {
// OOM
return mozilla::Nothing();
}
current = rope.leftChild();
continue;
}
JSLinearString& linear = current->asLinear();
if (MOZ_LIKELY(linear.hasLatin1Chars())) {
if (MOZ_UNLIKELY(pendingLeadSurrogate)) {
if (buffer.Length() < 3) {
return mozilla::Some(mozilla::MakeTuple(totalRead, totalWritten));
}
buffer[0] = '\xEF';
buffer[1] = '\xBF';
buffer[2] = '\xBD';
buffer = buffer.From(3);
totalRead += 1; // pendingLeadSurrogate
totalWritten += 3;
pendingLeadSurrogate = 0;
}
auto src = mozilla::AsChars(
mozilla::MakeSpan(linear.latin1Chars(nogc), linear.length()));
size_t read;
size_t written;
mozilla::Tie(read, written) =
mozilla::ConvertLatin1toUtf8Partial(src, buffer);
buffer = buffer.From(written);
totalRead += read;
totalWritten += written;
if (read < src.Length()) {
return mozilla::Some(mozilla::MakeTuple(totalRead, totalWritten));
}
} else {
auto src = mozilla::MakeSpan(linear.twoByteChars(nogc), linear.length());
if (MOZ_UNLIKELY(pendingLeadSurrogate)) {
char16_t first = 0;
if (!src.IsEmpty()) {
first = src[0];
}
if (unicode::IsTrailSurrogate(first)) {
// Got a surrogate pair
if (buffer.Length() < 4) {
return mozilla::Some(mozilla::MakeTuple(totalRead, totalWritten));
}
uint32_t astral = unicode::UTF16Decode(pendingLeadSurrogate, first);
buffer[0] = char(0b1111'0000 | (astral >> 18));
buffer[1] = char(0b1000'0000 | ((astral >> 12) & 0b11'1111));
buffer[2] = char(0b1000'0000 | ((astral >> 6) & 0b11'1111));
buffer[3] = char(0b1000'0000 | (astral & 0b11'1111));
src = src.From(1);
buffer = buffer.From(4);
totalRead += 2; // both pendingLeadSurrogate and first!
totalWritten += 4;
} else {
// unpaired surrogate
if (buffer.Length() < 3) {
return mozilla::Some(mozilla::MakeTuple(totalRead, totalWritten));
}
buffer[0] = '\xEF';
buffer[1] = '\xBF';
buffer[2] = '\xBD';
buffer = buffer.From(3);
totalRead += 1; // pendingLeadSurrogate
totalWritten += 3;
}
pendingLeadSurrogate = 0;
}
if (src.IsEmpty()) {
return mozilla::Some(mozilla::MakeTuple(totalRead, totalWritten));
}
char16_t last = src[src.Length() - 1];
if (unicode::IsLeadSurrogate(last)) {
src = src.To(src.Length() - 1);
pendingLeadSurrogate = last;
} else {
MOZ_ASSERT(!pendingLeadSurrogate);
}
size_t read;
size_t written;
mozilla::Tie(read, written) =
mozilla::ConvertUtf16toUtf8Partial(src, buffer);
buffer = buffer.From(written);
totalRead += read;
totalWritten += written;
if (read < src.Length()) {
return mozilla::Some(mozilla::MakeTuple(totalRead, totalWritten));
}
}
if (stack.empty()) {
break;
}
current = stack.popCopy();
}
if (MOZ_UNLIKELY(pendingLeadSurrogate)) {
if (buffer.Length() < 3) {
return mozilla::Some(mozilla::MakeTuple(totalRead, totalWritten));
}
buffer[0] = '\xEF';
buffer[1] = '\xBF';
buffer[2] = '\xBD';
// No need to update buffer and pendingLeadSurrogate anymore
totalRead += 1;
totalWritten += 3;
}
return mozilla::Some(mozilla::MakeTuple(totalRead, totalWritten));
}
#if defined(DEBUG) || defined(JS_JITSPEW)
template <typename CharT>
/*static */
void JSString::dumpChars(const CharT* s, size_t n, js::GenericPrinter& out) {
if (n == SIZE_MAX) {
n = 0;
while (s[n]) {
n++;
}
}
out.put("\"");
for (size_t i = 0; i < n; i++) {
char16_t c = s[i];
if (c == '\n') {
out.put("\\n");
} else if (c == '\t') {
out.put("\\t");
} else if (c >= 32 && c < 127) {
out.putChar((char)s[i]);
} else if (c <= 255) {
out.printf("\\x%02x", unsigned(c));
} else {
out.printf("\\u%04x", unsigned(c));
}
}
out.putChar('"');
}
template void JSString::dumpChars(const Latin1Char* s, size_t n,
js::GenericPrinter& out);
template void JSString::dumpChars(const char16_t* s, size_t n,
js::GenericPrinter& out);
void JSString::dumpCharsNoNewline(js::GenericPrinter& out) {
if (JSLinearString* linear = ensureLinear(nullptr)) {
AutoCheckCannotGC nogc;
if (hasLatin1Chars()) {
out.put("[Latin 1]");
dumpChars(linear->latin1Chars(nogc), length(), out);
} else {
out.put("[2 byte]");
dumpChars(linear->twoByteChars(nogc), length(), out);
}
} else {
out.put("(oom in JSString::dumpCharsNoNewline)");
}
}
void JSString::dump() {
js::Fprinter out(stderr);
dump(out);
}
void JSString::dump(js::GenericPrinter& out) {
dumpNoNewline(out);
out.putChar('\n');
}
void JSString::dumpNoNewline(js::GenericPrinter& out) {
if (JSLinearString* linear = ensureLinear(nullptr)) {
AutoCheckCannotGC nogc;
if (hasLatin1Chars()) {
const Latin1Char* chars = linear->latin1Chars(nogc);
out.printf("JSString* (%p) = Latin1Char * (%p) = ", (void*)this,
(void*)chars);
dumpChars(chars, length(), out);
} else {
const char16_t* chars = linear->twoByteChars(nogc);
out.printf("JSString* (%p) = char16_t * (%p) = ", (void*)this,
(void*)chars);
dumpChars(chars, length(), out);
}
} else {
out.put("(oom in JSString::dump)");
}
}
void JSString::dumpRepresentation(js::GenericPrinter& out, int indent) const {
if (isRope()) {
asRope().dumpRepresentation(out, indent);
} else if (isDependent()) {
asDependent().dumpRepresentation(out, indent);
} else if (isExternal()) {
asExternal().dumpRepresentation(out, indent);
} else if (isExtensible()) {
asExtensible().dumpRepresentation(out, indent);
} else if (isInline()) {
asInline().dumpRepresentation(out, indent);
} else if (isLinear()) {
asLinear().dumpRepresentation(out, indent);
} else {
MOZ_CRASH("Unexpected JSString representation");
}
}
void JSString::dumpRepresentationHeader(js::GenericPrinter& out,
const char* subclass) const {
uint32_t flags = JSString::flags();
// Print the string's address as an actual C++ expression, to facilitate
// copy-and-paste into a debugger.
out.printf("((%s*) %p) length: %zu flags: 0x%x", subclass, this, length(),
flags);
if (flags & LINEAR_BIT) out.put(" LINEAR");
if (flags & DEPENDENT_BIT) out.put(" DEPENDENT");
if (flags & INLINE_CHARS_BIT) out.put(" INLINE_CHARS");
if (flags & NON_ATOM_BIT)
out.put(" NON_ATOM");
else
out.put(" (ATOM)");
if (isPermanentAtom()) out.put(" PERMANENT");
if (flags & LATIN1_CHARS_BIT) out.put(" LATIN1");
if (flags & INDEX_VALUE_BIT) out.printf(" INDEX_VALUE(%u)", getIndexValue());
if (!isTenured()) out.put(" NURSERY");
out.putChar('\n');
}
void JSLinearString::dumpRepresentationChars(js::GenericPrinter& out,
int indent) const {
if (hasLatin1Chars()) {
out.printf("%*schars: ((Latin1Char*) %p) ", indent, "", rawLatin1Chars());
dumpChars(rawLatin1Chars(), length(), out);
} else {
out.printf("%*schars: ((char16_t*) %p) ", indent, "", rawTwoByteChars());
dumpChars(rawTwoByteChars(), length(), out);
}
out.putChar('\n');
}
bool JSString::equals(const char* s) {
JSLinearString* linear = ensureLinear(nullptr);
if (!linear) {
// This is DEBUG-only code.
fprintf(stderr, "OOM in JSString::equals!\n");
return false;
}
return StringEqualsAscii(linear, s);
}
#endif /* defined(DEBUG) || defined(JS_JITSPEW) */
template <typename CharT>
static MOZ_ALWAYS_INLINE bool AllocChars(JSString* str, size_t length,
CharT** chars, size_t* capacity) {
/*
* Grow by 12.5% if the buffer is very large. Otherwise, round up to the
* next power of 2. This is similar to what we do with arrays; see
* JSObject::ensureDenseArrayElements.
*/
static const size_t DOUBLING_MAX = 1024 * 1024;
*capacity =
length > DOUBLING_MAX ? length + (length / 8) : RoundUpPow2(length);
static_assert(JSString::MAX_LENGTH * sizeof(CharT) <= UINT32_MAX);
*chars =
str->zone()->pod_arena_malloc<CharT>(js::StringBufferArena, *capacity);
return *chars != nullptr;
}
UniqueLatin1Chars JSRope::copyLatin1Chars(JSContext* maybecx,
arena_id_t destArenaId) const {
return copyCharsInternal<Latin1Char>(maybecx, destArenaId);
}
UniqueTwoByteChars JSRope::copyTwoByteChars(JSContext* maybecx,
arena_id_t destArenaId) const {
return copyCharsInternal<char16_t>(maybecx, destArenaId);
}
template <typename CharT>
UniquePtr<CharT[], JS::FreePolicy> JSRope::copyCharsInternal(
JSContext* maybecx, arena_id_t destArenaId) const {
// Left-leaning ropes are far more common than right-leaning ropes, so
// perform a non-destructive traversal of the rope, right node first,
// splatting each node's characters into a contiguous buffer.
size_t n = length();
UniquePtr<CharT[], JS::FreePolicy> out;
if (maybecx) {
out.reset(maybecx->pod_arena_malloc<CharT>(destArenaId, n));
} else {
out.reset(js_pod_arena_malloc<CharT>(destArenaId, n));
}
if (!out) {
return nullptr;
}
Vector<const JSString*, 8, SystemAllocPolicy> nodeStack;
const JSString* str = this;
CharT* end = out.get() + str->length();
while (true) {
if (str->isRope()) {
if (!nodeStack.append(str->asRope().leftChild())) {
if (maybecx) {
ReportOutOfMemory(maybecx);
}
return nullptr;
}
str = str->asRope().rightChild();
} else {
end -= str->length();
CopyChars(end, str->asLinear());
if (nodeStack.empty()) {
break;
}
str = nodeStack.popCopy();
}
}
MOZ_ASSERT(end == out.get());
return out;
}
template <typename CharT>
void AddStringToHash(uint32_t* hash, const CharT* chars, size_t len) {
// It's tempting to use |HashString| instead of this loop, but that's
// slightly different than our existing implementation for non-ropes. We
// want to pretend we have a contiguous set of chars so we need to
// accumulate char by char rather than generate a new hash for substring
// and then accumulate that.
for (size_t i = 0; i < len; i++) {
*hash = mozilla::AddToHash(*hash, chars[i]);
}
}
void AddStringToHash(uint32_t* hash, const JSString* str) {
AutoCheckCannotGC nogc;
const auto& s = str->asLinear();
if (s.hasLatin1Chars()) {
AddStringToHash(hash, s.latin1Chars(nogc), s.length());
} else {
AddStringToHash(hash, s.twoByteChars(nogc), s.length());
}
}
bool JSRope::hash(uint32_t* outHash) const {
Vector<const JSString*, 8, SystemAllocPolicy> nodeStack;
const JSString* str = this;
*outHash = 0;
while (true) {
if (str->isRope()) {
if (!nodeStack.append(str->asRope().rightChild())) {
return false;
}
str = str->asRope().leftChild();
} else {
AddStringToHash(outHash, str);
if (nodeStack.empty()) {
break;
}
str = nodeStack.popCopy();
}
}
return true;
}
#if defined(DEBUG) || defined(JS_JITSPEW)
void JSRope::dumpRepresentation(js::GenericPrinter& out, int indent) const {
dumpRepresentationHeader(out, "JSRope");
indent += 2;
out.printf("%*sleft: ", indent, "");
leftChild()->dumpRepresentation(out, indent);
out.printf("%*sright: ", indent, "");
rightChild()->dumpRepresentation(out, indent);
}
#endif
namespace js {
template <>
void CopyChars(char16_t* dest, const JSLinearString& str) {
AutoCheckCannotGC nogc;
if (str.hasTwoByteChars()) {
PodCopy(dest, str.twoByteChars(nogc), str.length());
} else {
CopyAndInflateChars(dest, str.latin1Chars(nogc), str.length());
}
}
template <>
void CopyChars(Latin1Char* dest, const JSLinearString& str) {
AutoCheckCannotGC nogc;
if (str.hasLatin1Chars()) {
PodCopy(dest, str.latin1Chars(nogc), str.length());
} else {
/*
* When we flatten a TwoByte rope, we turn child ropes (including Latin1
* ropes) into TwoByte dependent strings. If one of these strings is
* also part of another Latin1 rope tree, we can have a Latin1 rope with
* a TwoByte descendent and we end up here when we flatten it. Although
* the chars are stored as TwoByte, we know they must be in the Latin1
* range, so we can safely deflate here.
*/
size_t len = str.length();
const char16_t* chars = str.twoByteChars(nogc);
auto src = MakeSpan(chars, len);
MOZ_ASSERT(IsUtf16Latin1(src));
LossyConvertUtf16toLatin1(src, AsWritableChars(MakeSpan(dest, len)));
}
}
} /* namespace js */
template <JSRope::UsingBarrier b, typename CharT>
JSLinearString* JSRope::flattenInternal(JSContext* maybecx) {
/*
* Consider the DAG of JSRopes rooted at this JSRope, with non-JSRopes as
* its leaves. Mutate the root JSRope into a JSExtensibleString containing
* the full flattened text that the root represents, and mutate all other
* JSRopes in the interior of the DAG into JSDependentStrings that refer to
* this new JSExtensibleString.
*
* If the leftmost leaf of our DAG is a JSExtensibleString, consider
* stealing its buffer for use in our new root, and transforming it into a
* JSDependentString too. Do not mutate any of the other leaves.
*
* Perform a depth-first dag traversal, splatting each node's characters
* into a contiguous buffer. Visit each rope node three times:
* 1. record position in the buffer and recurse into left child;
* 2. recurse into the right child;
* 3. transform the node into a dependent string.
* To avoid maintaining a stack, tree nodes are mutated to indicate how many
* times they have been visited. Since ropes can be dags, a node may be
* encountered multiple times during traversal. However, step 3 above leaves
* a valid dependent string, so everything works out.
*
* While ropes avoid all sorts of quadratic cases with string concatenation,
* they can't help when ropes are immediately flattened. One idiomatic case
* that we'd like to keep linear (and has traditionally been linear in SM
* and other JS engines) is:
*
* while (...) {
* s += ...
* s.flatten
* }
*
* Two behaviors accomplish this:
*
* - When the leftmost non-rope in the DAG we're flattening is a
* JSExtensibleString with sufficient capacity to hold the entire
* flattened string, we just flatten the DAG into its buffer. Then, when
* we transform the root of the DAG from a JSRope into a
* JSExtensibleString, we steal that buffer, and change the victim from a
* JSExtensibleString to a JSDependentString. In this case, the left-hand
* side of the string never needs to be copied.
*
* - Otherwise, we round up the total flattened size and create a fresh
* JSExtensibleString with that much capacity. If this in turn becomes the
* leftmost leaf of a subsequent flatten, we will hopefully be able to
* fill it, as in the case above.
*
* Note that, even though the code for creating JSDependentStrings avoids
* creating dependents of dependents, we can create that situation here: the
* JSExtensibleStrings we transform into JSDependentStrings might have
* JSDependentStrings pointing to them already. Stealing the buffer doesn't
* change its address, only its owning JSExtensibleString, so all chars()
* pointers in the JSDependentStrings are still valid.
*/
const size_t wholeLength = length();
size_t wholeCapacity;
CharT* wholeChars;
JSString* str = this;
CharT* pos;
// JSString::setFlattenData() is used to store a tagged pointer to the
// parent node. The tag indicates what to do when we return to the parent.
static const uintptr_t Tag_Mask = 0x3;
static const uintptr_t Tag_FinishNode = 0x0;
static const uintptr_t Tag_VisitRightChild = 0x1;
AutoCheckCannotGC nogc;
gc::StoreBuffer* bufferIfNursery = storeBuffer();
/* Find the left most string, containing the first string. */
JSRope* leftMostRope = this;
while (leftMostRope->leftChild()->isRope()) {
leftMostRope = &leftMostRope->leftChild()->asRope();
}
if (leftMostRope->leftChild()->isExtensible()) {
JSExtensibleString& left = leftMostRope->leftChild()->asExtensible();
size_t capacity = left.capacity();
if (capacity >= wholeLength &&
left.hasTwoByteChars() == std::is_same_v<CharT, char16_t>) {
wholeChars = const_cast<CharT*>(left.nonInlineChars<CharT>(nogc));
wholeCapacity = capacity;
// registerMallocedBuffer is fallible, so attempt it first before doing
// anything irreversible.
Nursery& nursery = runtimeFromMainThread()->gc.nursery();
bool inTenured = !bufferIfNursery;
if (!inTenured && left.isTenured()) {
// tenured leftmost child is giving its chars buffer to the
// nursery-allocated root node.
if (!nursery.registerMallocedBuffer(wholeChars)) {
if (maybecx) {
ReportOutOfMemory(maybecx);
}
return nullptr;
}
// leftmost child -> root is a tenured -> nursery edge.
bufferIfNursery->putWholeCell(&left);
} else if (inTenured && !left.isTenured()) {
// leftmost child is giving its nursery-held chars buffer to a
// tenured string.
nursery.removeMallocedBuffer(wholeChars);
}
/*
* Simulate a left-most traversal from the root to leftMost->leftChild()
* via first_visit_node
*/
MOZ_ASSERT(str->isRope());
while (str != leftMostRope) {
if (b == WithIncrementalBarrier) {
JSString::writeBarrierPre(str->d.s.u2.left);
JSString::writeBarrierPre(str->d.s.u3.right);
}
JSString* child = str->d.s.u2.left;
// 'child' will be post-barriered during the later traversal.
MOZ_ASSERT(child->isRope());
str->setNonInlineChars(wholeChars);
child->setFlattenData(uintptr_t(str) | Tag_VisitRightChild);
str = child;
}
if (b == WithIncrementalBarrier) {
JSString::writeBarrierPre(str->d.s.u2.left);
JSString::writeBarrierPre(str->d.s.u3.right);
}
str->setNonInlineChars(wholeChars);
uint32_t left_len = left.length();
pos = wholeChars + left_len;
// Remove memory association for left node we're about to make into a
// dependent string.
if (left.isTenured()) {
RemoveCellMemory(&left, left.allocSize(), MemoryUse::StringContents);
}
if constexpr (std::is_same_v<CharT, char16_t>) {
left.setLengthAndFlags(left_len, INIT_DEPENDENT_FLAGS);
} else {
left.setLengthAndFlags(left_len,
INIT_DEPENDENT_FLAGS | LATIN1_CHARS_BIT);
}
left.d.s.u3.base = (JSLinearString*)this; /* will be true on exit */
goto visit_right_child;
}
}
if (!AllocChars(this, wholeLength, &wholeChars, &wholeCapacity)) {
if (maybecx) {
ReportOutOfMemory(maybecx);
}
return nullptr;
}
if (!isTenured()) {
Nursery& nursery = runtimeFromMainThread()->gc.nursery();
if (!nursery.registerMallocedBuffer(wholeChars)) {
js_free(wholeChars);
if (maybecx) {
ReportOutOfMemory(maybecx);
}
return nullptr;
}
}
pos = wholeChars;
first_visit_node : {
if (b == WithIncrementalBarrier) {
JSString::writeBarrierPre(str->d.s.u2.left);
JSString::writeBarrierPre(str->d.s.u3.right);
}
JSString& left = *str->d.s.u2.left;
str->setNonInlineChars(pos);
if (left.isRope()) {
/* Return to this node when 'left' done, then goto visit_right_child. */
left.setFlattenData(uintptr_t(str) | Tag_VisitRightChild);
str = &left;
goto first_visit_node;
}
CopyChars(pos, left.asLinear());
pos += left.length();
}
visit_right_child : {
JSString& right = *str->d.s.u3.right;
if (right.isRope()) {
/* Return to this node when 'right' done, then goto finish_node. */
right.setFlattenData(uintptr_t(str) | Tag_FinishNode);
str = &right;
goto first_visit_node;
}
CopyChars(pos, right.asLinear());
pos += right.length();
}
finish_node : {
if (str == this) {
MOZ_ASSERT(pos == wholeChars + wholeLength);
if constexpr (std::is_same_v<CharT, char16_t>) {
str->setLengthAndFlags(wholeLength, EXTENSIBLE_FLAGS);
} else {
str->setLengthAndFlags(wholeLength, EXTENSIBLE_FLAGS | LATIN1_CHARS_BIT);
}
str->setNonInlineChars(wholeChars);
str->d.s.u3.capacity = wholeCapacity;
if (str->isTenured()) {
AddCellMemory(str, str->asLinear().allocSize(),
MemoryUse::StringContents);
}
return &this->asLinear();
}
uintptr_t flattenData;
uint32_t len = pos - str->nonInlineCharsRaw<CharT>();
if constexpr (std::is_same_v<CharT, char16_t>) {
flattenData = str->unsetFlattenData(len, INIT_DEPENDENT_FLAGS);
} else {
flattenData =
str->unsetFlattenData(len, INIT_DEPENDENT_FLAGS | LATIN1_CHARS_BIT);
}
str->d.s.u3.base = (JSLinearString*)this; /* will be true on exit */
// Every interior (rope) node in the rope's tree will be visited during
// the traversal and post-barriered here, so earlier additions of
// dependent.base -> root pointers are handled by this barrier as well.
//
// The only time post-barriers need do anything is when the root is in
// the nursery. Note that the root was a rope but will be an extensible
// string when we return, so it will not point to any strings and need
// not be barriered.
gc::StoreBuffer* bufferIfNursery = storeBuffer();
if (bufferIfNursery && str->isTenured()) {
bufferIfNursery->putWholeCell(str);
}
str = (JSString*)(flattenData & ~Tag_Mask);
if ((flattenData & Tag_Mask) == Tag_VisitRightChild) {
goto visit_right_child;
}
MOZ_ASSERT((flattenData & Tag_Mask) == Tag_FinishNode);
goto finish_node;
}
}
template <JSRope::UsingBarrier b>
JSLinearString* JSRope::flattenInternal(JSContext* maybecx) {
if (hasTwoByteChars()) {
return flattenInternal<b, char16_t>(maybecx);
}
return flattenInternal<b, Latin1Char>(maybecx);
}
JSLinearString* JSRope::flatten(JSContext* maybecx) {
mozilla::Maybe<AutoGeckoProfilerEntry> entry;
if (maybecx && !maybecx->isHelperThreadContext()) {
entry.emplace(maybecx, "JSRope::flatten");
}
if (zone()->needsIncrementalBarrier()) {
return flattenInternal<WithIncrementalBarrier>(maybecx);
}
return flattenInternal<NoBarrier>(maybecx);
}
template <AllowGC allowGC>
static JSLinearString* EnsureLinear(
JSContext* cx,
typename MaybeRooted<JSString*, allowGC>::HandleType string) {
JSLinearString* linear = string->ensureLinear(cx);
// Don't report an exception if GC is not allowed, just return nullptr.
if (!linear && !allowGC) {
cx->recoverFromOutOfMemory();
}
return linear;
}
template <AllowGC allowGC>
JSString* js::ConcatStrings(
JSContext* cx, typename MaybeRooted<JSString*, allowGC>::HandleType left,
typename MaybeRooted<JSString*, allowGC>::HandleType right) {
MOZ_ASSERT_IF(!left->isAtom(), cx->isInsideCurrentZone(left));
MOZ_ASSERT_IF(!right->isAtom(), cx->isInsideCurrentZone(right));
size_t leftLen = left->length();
if (leftLen == 0) {
return right;
}
size_t rightLen = right->length();
if (rightLen == 0) {
return left;
}
size_t wholeLength = leftLen + rightLen;
if (MOZ_UNLIKELY(wholeLength > JSString::MAX_LENGTH)) {
// Don't report an exception if GC is not allowed, just return nullptr.
if (allowGC) {
js::ReportAllocationOverflow(cx);
}
return nullptr;
}
bool isLatin1 = left->hasLatin1Chars() && right->hasLatin1Chars();
bool canUseInline = isLatin1
? JSInlineString::lengthFits<Latin1Char>(wholeLength)
: JSInlineString::lengthFits<char16_t>(wholeLength);
if (canUseInline) {
Latin1Char* latin1Buf = nullptr; // initialize to silence GCC warning
char16_t* twoByteBuf = nullptr; // initialize to silence GCC warning
JSInlineString* str =
isLatin1 ? AllocateInlineString<allowGC>(cx, wholeLength, &latin1Buf)
: AllocateInlineString<allowGC>(cx, wholeLength, &twoByteBuf);
if (!str) {
return nullptr;
}
AutoCheckCannotGC nogc;
JSLinearString* leftLinear = EnsureLinear<allowGC>(cx, left);
if (!leftLinear) {
return nullptr;
}
JSLinearString* rightLinear = EnsureLinear<allowGC>(cx, right);
if (!rightLinear) {
return nullptr;
}
if (isLatin1) {
PodCopy(latin1Buf, leftLinear->latin1Chars(nogc), leftLen);
PodCopy(latin1Buf + leftLen, rightLinear->latin1Chars(nogc), rightLen);
} else {
if (leftLinear->hasTwoByteChars()) {
PodCopy(twoByteBuf, leftLinear->twoByteChars(nogc), leftLen);
} else {
CopyAndInflateChars(twoByteBuf, leftLinear->latin1Chars(nogc), leftLen);
}
if (rightLinear->hasTwoByteChars()) {
PodCopy(twoByteBuf + leftLen, rightLinear->twoByteChars(nogc),
rightLen);
} else {
CopyAndInflateChars(twoByteBuf + leftLen,
rightLinear->latin1Chars(nogc), rightLen);
}
}
return str;
}
return JSRope::new_<allowGC>(cx, left, right, wholeLength);
}
template JSString* js::ConcatStrings<CanGC>(JSContext* cx, HandleString left,
HandleString right);
template JSString* js::ConcatStrings<NoGC>(JSContext* cx, JSString* const& left,
JSString* const& right);
/**
* Copy |src[0..length]| to |dest[0..length]| when copying doesn't narrow and
* therefore can't lose information.
*/
static inline void FillChars(char16_t* dest, const unsigned char* src,
size_t length) {
ConvertLatin1toUtf16(AsChars(MakeSpan(src, length)), MakeSpan(dest, length));
}
static inline void FillChars(char16_t* dest, const char16_t* src,
size_t length) {
PodCopy(dest, src, length);
}
static inline void FillChars(unsigned char* dest, const unsigned char* src,
size_t length) {
PodCopy(dest, src, length);
}
static inline void FillChars(char16_t* dest, LittleEndianChars src,
size_t length) {
#if MOZ_LITTLE_ENDIAN()
memcpy(dest, src.get(), length * sizeof(char16_t));
#else
for (size_t i = 0; i < length; ++i) {
dest[i] = src[i];
}
#endif
}
/**
* Copy |src[0..length]| to |dest[0..length]| when copying *does* narrow, but
* the user guarantees every runtime |src[i]| value can be stored without change
* of value in |dest[i]|.
*/
static inline void FillFromCompatible(unsigned char* dest, const char16_t* src,
size_t length) {
LossyConvertUtf16toLatin1(MakeSpan(src, length),
AsWritableChars(MakeSpan(dest, length)));
}
static inline void FillFromCompatible(unsigned char* dest,
LittleEndianChars src, size_t length) {
for (size_t i = 0; i < length; ++i) {
dest[i] = AssertedCast<unsigned char>(src[i]);
}
}
#if defined(DEBUG) || defined(JS_JITSPEW)
void JSDependentString::dumpRepresentation(js::GenericPrinter& out,
int indent) const {
dumpRepresentationHeader(out, "JSDependentString");
indent += 2;
out.printf("%*soffset: %zu\n", indent, "", baseOffset());
out.printf("%*sbase: ", indent, "");
base()->dumpRepresentation(out, indent);
}
#endif
bool js::EqualChars(JSLinearString* str1, JSLinearString* str2) {
MOZ_ASSERT(str1->length() == str2->length());
size_t len = str1->length();
AutoCheckCannotGC nogc;
if (str1->hasTwoByteChars()) {
if (str2->hasTwoByteChars()) {
return ArrayEqual(str1->twoByteChars(nogc), str2->twoByteChars(nogc),
len);
}
return EqualChars(str2->latin1Chars(nogc), str1->twoByteChars(nogc), len);
}
if (str2->hasLatin1Chars()) {
return ArrayEqual(str1->latin1Chars(nogc), str2->latin1Chars(nogc), len);
}
return EqualChars(str1->latin1Chars(nogc), str2->twoByteChars(nogc), len);
}