[Support] Import SipHash c reference implementation. (#94393)

This brings the unmodified SipHash reference implementation:
  https://github.com/veorq/SipHash
which has been very graciously licensed under our llvm license
(Apache-2.0 WITH LLVM-exception) by Jean-Philippe Aumasson.

SipHash is a lightweight hash function optimized for speed on short
messages. We use it as part of the AArch64 ptrauth ABI (in arm64e and
ELF PAuth) to generate discriminators based on language identifiers and
mangled names.

This commit brings the unmodified reference implementation and tests
as of f26d35e, specifically siphash.c and vectors.h, as SipHash.cpp and
SipHashTest.cpp.

Next, we will integrate it properly into libSupport, with a wrapping API
suited for the ptrauth use-case.

Author: ahmedbougacha

llvm/lib/Support/CMakeLists.txt

@@ -127,6 +127,9 @@ endif()
 
 add_subdirectory(BLAKE3)
 
+# Temporarily ignore SipHash.cpp before we fully integrate it into LLVMSupport.
+set(LLVM_OPTIONAL_SOURCES SipHash.cpp)
+
 add_llvm_component_library(LLVMSupport
   ABIBreak.cpp
   AMDGPUMetadata.cpp

llvm/lib/Support/SipHash.cpp

@@ -0,0 +1,185 @@
+/*
+   SipHash reference C implementation
+
+   Copyright (c) 2012-2022 Jean-Philippe Aumasson
+   <[email protected]>
+   Copyright (c) 2012-2014 Daniel J. Bernstein <[email protected]>
+
+   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
+
+#define ROTL(x, b) (uint64_t)(((x) << (b)) | ((x) >> (64 - (b))))
+
+#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);
+
+#define U64TO8_LE(p, v)                                                        \
+    U32TO8_LE((p), (uint32_t)((v)));                                           \
+    U32TO8_LE((p) + 4, (uint32_t)((v) >> 32));
+
+#define U8TO64_LE(p)                                                           \
+    (((uint64_t)((p)[0])) | ((uint64_t)((p)[1]) << 8) |                        \
+     ((uint64_t)((p)[2]) << 16) | ((uint64_t)((p)[3]) << 24) |                 \
+     ((uint64_t)((p)[4]) << 32) | ((uint64_t)((p)[5]) << 40) |                 \
+     ((uint64_t)((p)[6]) << 48) | ((uint64_t)((p)[7]) << 56))
+
+#define SIPROUND                                                               \
+    do {                                                                       \
+        v0 += v1;                                                              \
+        v1 = ROTL(v1, 13);                                                     \
+        v1 ^= v0;                                                              \
+        v0 = ROTL(v0, 32);                                                     \
+        v2 += v3;                                                              \
+        v3 = ROTL(v3, 16);                                                     \
+        v3 ^= v2;                                                              \
+        v0 += v3;                                                              \
+        v3 = ROTL(v3, 21);                                                     \
+        v3 ^= v0;                                                              \
+        v2 += v1;                                                              \
+        v1 = ROTL(v1, 17);                                                     \
+        v1 ^= v2;                                                              \
+        v2 = ROTL(v2, 32);                                                     \
+    } while (0)
+
+#ifdef DEBUG_SIPHASH
+#include <stdio.h>
+
+#define TRACE                                                                  \
+    do {                                                                       \
+        printf("(%3zu) v0 %016" PRIx64 "\n", inlen, v0);                       \
+        printf("(%3zu) v1 %016" PRIx64 "\n", inlen, v1);                       \
+        printf("(%3zu) v2 %016" PRIx64 "\n", inlen, v2);                       \
+        printf("(%3zu) v3 %016" PRIx64 "\n", inlen, v3);                       \
+    } while (0)
+#else
+#define TRACE
+#endif
+
+/*
+    Computes a SipHash value
+    *in: pointer to input data (read-only)
+    inlen: input data length in bytes (any size_t value)
+    *k: pointer to the key data (read-only), must be 16 bytes 
+    *out: pointer to output data (write-only), outlen bytes must be allocated
+    outlen: length of the output in bytes, must be 8 or 16
+*/
+int siphash(const void *in, const size_t inlen, const void *k, uint8_t *out,
+            const size_t outlen) {
+
+    const unsigned char *ni = (const unsigned char *)in;
+    const unsigned char *kk = (const unsigned char *)k;
+
+    assert((outlen == 8) || (outlen == 16));
+    uint64_t v0 = UINT64_C(0x736f6d6570736575);
+    uint64_t v1 = UINT64_C(0x646f72616e646f6d);
+    uint64_t v2 = UINT64_C(0x6c7967656e657261);
+    uint64_t v3 = UINT64_C(0x7465646279746573);
+    uint64_t k0 = U8TO64_LE(kk);
+    uint64_t k1 = U8TO64_LE(kk + 8);
+    uint64_t m;
+    int i;
+    const unsigned char *end = ni + inlen - (inlen % sizeof(uint64_t));
+    const int left = inlen & 7;
+    uint64_t b = ((uint64_t)inlen) << 56;
+    v3 ^= k1;
+    v2 ^= k0;
+    v1 ^= k1;
+    v0 ^= k0;
+
+    if (outlen == 16)
+        v1 ^= 0xee;
+
+    for (; ni != end; ni += 8) {
+        m = U8TO64_LE(ni);
+        v3 ^= m;
+
+        TRACE;
+        for (i = 0; i < cROUNDS; ++i)
+            SIPROUND;
+
+        v0 ^= m;
+    }
+
+    switch (left) {
+    case 7:
+        b |= ((uint64_t)ni[6]) << 48;
+        /* FALLTHRU */
+    case 6:
+        b |= ((uint64_t)ni[5]) << 40;
+        /* FALLTHRU */
+    case 5:
+        b |= ((uint64_t)ni[4]) << 32;
+        /* FALLTHRU */
+    case 4:
+        b |= ((uint64_t)ni[3]) << 24;
+        /* FALLTHRU */
+    case 3:
+        b |= ((uint64_t)ni[2]) << 16;
+        /* FALLTHRU */
+    case 2:
+        b |= ((uint64_t)ni[1]) << 8;
+        /* FALLTHRU */
+    case 1:
+        b |= ((uint64_t)ni[0]);
+        break;
+    case 0:
+        break;
+    }
+
+    v3 ^= b;
+
+    TRACE;
+    for (i = 0; i < cROUNDS; ++i)
+        SIPROUND;
+
+    v0 ^= b;
+
+    if (outlen == 16)
+        v2 ^= 0xee;
+    else
+        v2 ^= 0xff;
+
+    TRACE;
+    for (i = 0; i < dROUNDS; ++i)
+        SIPROUND;
+
+    b = v0 ^ v1 ^ v2 ^ v3;
+    U64TO8_LE(out, b);
+
+    if (outlen == 8)
+        return 0;
+
+    v1 ^= 0xdd;
+
+    TRACE;
+    for (i = 0; i < dROUNDS; ++i)
+        SIPROUND;
+
+    b = v0 ^ v1 ^ v2 ^ v3;
+    U64TO8_LE(out + 8, b);
+
+    return 0;
+}

llvm/unittests/Support/CMakeLists.txt

@@ -3,6 +3,9 @@ set(LLVM_LINK_COMPONENTS
   TargetParser
   )
 
+# Temporarily ignore SipHashTest.cpp before we fully integrate it.
+set(LLVM_OPTIONAL_SOURCES SipHashTest.cpp)
+
 add_llvm_unittest(SupportTests
   AddressRangeTest.cpp
   AlignmentTest.cpp