llvm/llvm/include/llvm/ADT/StableHashing.h

//===- llvm/ADT/StableHashing.h - Utilities for stable hashing * C++ *-----===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file provides types and functions for computing and combining stable
// hashes. Stable hashes can be useful for hashing across different modules,
// processes, machines, or compiler runs for a specific compiler version. It
// currently employs the xxh3_64bits hashing algorithm. Be aware that this
// implementation may be adjusted or updated as improvements to the compiler are
// made.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_ADT_STABLEHASHING_H
#define LLVM_ADT_STABLEHASHING_H

#include "llvm/ADT/StringRef.h"
#include "llvm/Support/xxhash.h"

namespace llvm {

/// An opaque object representing a stable hash code. It can be serialized,
/// deserialized, and is stable across processes and executions.
stable_hash;

inline stable_hash stable_hash_combine(ArrayRef<stable_hash> Buffer) { … }

inline stable_hash stable_hash_combine(stable_hash A, stable_hash B) { … }

inline stable_hash stable_hash_combine(stable_hash A, stable_hash B,
                                       stable_hash C) { … }

inline stable_hash stable_hash_combine(stable_hash A, stable_hash B,
                                       stable_hash C, stable_hash D) { … }

// Removes suffixes introduced by LLVM from the name to enhance stability and
// maintain closeness to the original name across different builds.
inline StringRef get_stable_name(StringRef Name) { … }

// Generates a consistent hash value for a given input name across different
// program executions and environments. This function first converts the input
// name into a stable form using the `get_stable_name` function, and then
// computes a hash of this stable name. For instance, `foo.llvm.1234` would have
// the same hash as `foo.llvm.5678.
inline stable_hash stable_hash_name(StringRef Name) { … }

} // namespace llvm

#endif