[llvm-branch-commits] [llvm] [Support] Integrate SipHash.cpp into libSupport. (PR #94394)

[Ahmed Bougacha via llvm-branch-commits]

================
@@ -1,185 +1,149 @@
-/*
-   SipHash reference C implementation
-
-   Copyright (c) 2012-2022 Jean-Philippe Aumasson
-   <jeanphilippe.aumasson at gmail.com>
-   Copyright (c) 2012-2014 Daniel J. Bernstein <djb at cr.yp.to>
-
-   To the extent possible under law, the author(s) have dedicated all copyright
-   and related and neighboring rights to this software to the public domain
-   worldwide. This software is distributed without any warranty.
-
-   You should have received a copy of the CC0 Public Domain Dedication along
-   with
-   this software. If not, see
-   <http://creativecommons.org/publicdomain/zero/1.0/>.
- */
-
-#include "siphash.h"
-#include <assert.h>
-#include <stddef.h>
-#include <stdint.h>
-
-/* default: SipHash-2-4 */
-#ifndef cROUNDS
-#define cROUNDS 2
-#endif
-#ifndef dROUNDS
-#define dROUNDS 4
-#endif
+//===--- SipHash.cpp - An ABI-stable string hash --------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
 
-#define ROTL(x, b) (uint64_t)(((x) << (b)) | ((x) >> (64 - (b))))
+#include "llvm/Support/Compiler.h"
+#include <cstdint>
 
-#define U32TO8_LE(p, v)                                                        \
-    (p)[0] = (uint8_t)((v));                                                   \
-    (p)[1] = (uint8_t)((v) >> 8);                                              \
-    (p)[2] = (uint8_t)((v) >> 16);                                             \
-    (p)[3] = (uint8_t)((v) >> 24);
+// Lightly adapted from the SipHash reference C implementation:
+//   https://github.com/veorq/SipHash
+// by Jean-Philippe Aumasson and Daniel J. Bernstein
 
-#define U64TO8_LE(p, v)                                                        \
-    U32TO8_LE((p), (uint32_t)((v)));                                           \
-    U32TO8_LE((p) + 4, (uint32_t)((v) >> 32));
+#define ROTL(x, b) (uint64_t)(((x) << (b)) | ((x) >> (64 - (b))))
----------------
ahmedbougacha wrote:

This, I'm a little more inclined to keep the macros as close to original as possible, it being the core of the function.  It could help to name the function `ROTL` to match the original;  we can turn the whole block into a function as well.  I don't feel strongly either way, let me know which you prefer.

https://github.com/llvm/llvm-project/pull/94394