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CodeBlockHash.h
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102 lines (80 loc) · 3.65 KB
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/*
* Copyright (C) 2012 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <JavaScriptCore/CodeSpecializationKind.h>
#include <JavaScriptCore/JSExportMacros.h>
#include <wtf/PrintStream.h>
#include <wtf/SixCharacterHash.h>
#include <wtf/text/StringImpl.h>
// CodeBlock hashes are useful for informally identifying code blocks. They correspond
// to the low 32 bits of a SHA1 hash of the source code with two low bit flipped
// according to the role that the code block serves (call, construct). Additionally, the
// hashes are typically operated over using a string in which the hash is transformed
// into a 6-byte alphanumeric representation. This can be retrieved by using
// toString(const CodeBlockHash&). Finally, we support CodeBlockHashes for native
// functions, in which case the hash is replaced by the function address.
WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN
namespace JSC {
class SourceCode;
class CodeBlockHash {
public:
static constexpr size_t stringLength = 6;
CodeBlockHash() = default;
explicit CodeBlockHash(unsigned hash)
: m_hash(hash)
{
}
JS_EXPORT_PRIVATE CodeBlockHash(const SourceCode&, CodeSpecializationKind);
JS_EXPORT_PRIVATE CodeBlockHash(StringView codeBlockSourceCode, StringView entireSourceCode, CodeSpecializationKind);
explicit CodeBlockHash(std::span<const char, stringLength>);
bool isSet() const { return !!m_hash; }
explicit operator bool() const { return isSet(); }
unsigned hash() const { return m_hash; }
void dump(PrintStream&) const;
// Comparison methods useful for bisection.
friend auto operator<=>(const CodeBlockHash&, const CodeBlockHash&) = default;
private:
unsigned m_hash { };
};
} // namespace JSC
namespace WTF {
template<> class StringTypeAdapter<JSC::CodeBlockHash> {
public:
explicit StringTypeAdapter(const JSC::CodeBlockHash& hash)
: m_hash { hash }
{
}
unsigned length() const { return JSC::CodeBlockHash::stringLength; }
bool is8Bit() const { return true; }
template<typename CharacterType> void writeTo(std::span<CharacterType> destination) const
{
auto buffer = integerToSixCharacterHashString(m_hash.hash());
StringImpl::copyCharacters(destination, std::span<const Latin1Character>(std::bit_cast<const Latin1Character*>(buffer.data()), buffer.size()));
}
private:
JSC::CodeBlockHash m_hash;
};
} // namespace WTF
WTF_ALLOW_UNSAFE_BUFFER_USAGE_END