Switch 64-bit hashes to xxhash3 (#8721)

Context: https://xxhash.com/

XXH3 is an improved  xxHash algorithm for 64-bit machines, which offers around twice
as much performance over the XXH2 variant (see the link above), especially when processing
small data, at the same time keeping the hash quality intact.

In our case, the processing speed up isn't that dramatic, of course, because we're running 
real world applications and not synthetic tests, but we do see startup time improvements.

Performance improvements compared to `main`, tests  on Pixel 6 Pro  running Android 14:

   * **Displayed time**: 2.17% faster
   * **Native-to-managed init**: 1.4% faster
   * **Total native init**: 1.15% faster

.gitmodules

@@ -22,3 +22,9 @@
     path = external/xamarin-android-tools
     url = /~https://github.com/xamarin/xamarin-android-tools
     branch = main
+[submodule "external/xxHash"]
+	path = external/xxHash
+	url = /~https://github.com/Cyan4973/xxHash.git
+[submodule "external/constexpr-xxh3"]
+	path = external/constexpr-xxh3
+	url = /~https://github.com/chys87/constexpr-xxh3.git

THIRD-PARTY-NOTICES.TXT

@@ -516,3 +516,68 @@ SOFTWARE.
 ======================================================
 END OF tessil/robin-map NOTICES AND INFORMATION
 
+%% chys87/constexpr-xxh3 NOTICES AND INFORMATION BEGIN HERE
+===========================================================
+
+BSD 2-Clause License
+
+constexpr-xxh3 - C++20 constexpr implementation of the XXH3 64-bit variant of xxHash
+Copyright (c) 2021-2023, chys <admin@chys.info> <chys87@github>
+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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDER 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.
+
+======================================================
+END OF chys87/constexpr-xxh3 NOTICES AND INFORMATION
+
+%% Cyan4973/xxHash NOTICES AND INFORMATION BEGIN HERE
+=====================================================
+
+xxHash Library
+Copyright (c) 2012-2021 Yann Collet
+All rights reserved.
+
+BSD 2-Clause License (https://www.opensource.org/licenses/bsd-license.php)
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+* 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDER 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.
+
+%% END OF Cyan4973/xxHash NOTICES AND INFORMATION
+=================================================

build-tools/scripts/generate-pinvoke-tables.sh

@@ -8,6 +8,7 @@ GENERATOR_BINARY="${MONODROID_SOURCE_DIR}/generate-pinvoke-tables"
 TARGET_FILE="${MONODROID_SOURCE_DIR}/pinvoke-tables.include"
 GENERATED_FILE="${TARGET_FILE}.generated"
 DIFF_FILE="${TARGET_FILE}.diff"
+EXTERNAL_DIR="${MY_DIR}/../../external/"
 
 function die()
 {
@@ -62,7 +63,7 @@ case ${HOST} in
 	*) die Unsupported OS ;;
 esac
 
-${COMPILER} -O2 -std=c++20 "${GENERATOR_SOURCE}" -o "${GENERATOR_BINARY}"
+${COMPILER} -O2 -std=c++20 -I${EXTERNAL_DIR} -I${EXTERNAL_DIR}/constexpr-xxh3 "${GENERATOR_SOURCE}" -o "${GENERATOR_BINARY}"
 "${GENERATOR_BINARY}" "${GENERATED_FILE}"
 
 FILES_DIFFER="no"

src/Xamarin.Android.Build.Tasks/Utilities/MonoAndroidHelper.Basic.cs

@@ -223,7 +223,7 @@ public static ulong GetMangledAssemblyNameSizeOverhead ()
 	public static ulong GetXxHash (byte[] stringBytes, bool is64Bit)
 	{
 		if (is64Bit) {
-			return XxHash64.HashToUInt64 (stringBytes);
+			return XxHash3.HashToUInt64 (stringBytes);
 		}
 
 		return (ulong)XxHash32.HashToUInt32 (stringBytes);

src/Xamarin.Android.Build.Tasks/Utilities/TypeMapHelper.cs

@@ -23,7 +23,7 @@ public static ulong HashJavaName (string name, bool is64Bit)
 	static ulong HashBytes (byte[] bytes, bool is64Bit)
 	{
 		if (is64Bit) {
-			return XxHash64.HashToUInt64 (bytes);
+			return XxHash3.HashToUInt64 (bytes);
 		}
 
 		return (ulong)XxHash32.HashToUInt32 (bytes);

src/monodroid/CMakeLists.txt

@@ -142,6 +142,8 @@ set(LZ4_INCLUDE_DIR ${LZ4_SRC_DIR})
 set(XA_BIN_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../../bin/${XA_BUILD_CONFIGURATION}")
 set(XA_BUILD_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../../bin/Build${XA_BUILD_CONFIGURATION}")
 set(ROBIN_MAP_DIR "${EXTERNAL_DIR}/robin-map")
+set(XXHASH_DIR "${EXTERNAL_DIR}/xxHash")
+set(CONSTEXPR_XXH3_DIR "${EXTERNAL_DIR}/constexpr-xxh3")
 
 include("${XA_BUILD_DIR}/xa_build_configuration.cmake")
 
@@ -163,9 +165,11 @@ set(LZ4_SOURCES
 
 # Include directories
 include_directories(${CMAKE_CURRENT_BINARY_DIR}/include/ ${CMAKE_SOURCE_DIR}/include)
+include_directories(${EXTERNAL_DIR})
 
 # The SYSTEM which will make clang skip warnings for the headers there. Since we can't do
 # much about them, we can just as well avoid cluttered build output.
+include_directories(SYSTEM ${CONSTEXPR_XXH3_DIR})
 include_directories(SYSTEM ${ROBIN_MAP_DIR}/include)
 include_directories(SYSTEM ${CMAKE_SYSROOT}/usr/include/c++/v1/)
 include_directories(SYSTEM ${LZ4_INCLUDE_DIR})

src/monodroid/jni/generate-pinvoke-tables.cc

@@ -688,9 +688,9 @@ struct constexpr_test {
 
 constexpr_test<xxhash32::hash<0> ("", 0), 0x2CC5D05U> constexprTest_1;
 constexpr_test<xxhash32::hash<2654435761U> ("", 0), 0x36B78AE7U> constexprTest_2;
-constexpr_test<xxhash64::hash<0> ("", 0), 0xEF46DB3751D8E999ULL> constexprTest_3;
-constexpr_test<xxhash64::hash<2654435761U> ("", 0), 0xAC75FDA2929B17EFULL> constexprTest_4;
+//constexpr_test<xxhash64::hash<0> ("", 0), 0xEF46DB3751D8E999ULL> constexprTest_3;
+//constexpr_test<xxhash64::hash<2654435761U> ("", 0), 0xAC75FDA2929B17EFULL> constexprTest_4;
 constexpr_test<xxhash32::hash<0> ("test", 4), 0x3E2023CFU> constexprTest32_5;
 constexpr_test<xxhash32::hash<2654435761U> ("test", 4), 0xA9C14438U> constexprTest32_6;
-constexpr_test<xxhash64::hash<0> ("test", 4), 0x4fdcca5ddb678139ULL> constexprTest64_7;
-constexpr_test<xxhash64::hash<2654435761U> ("test", 4), 0x5A183B8150E2F651ULL> constexprTest64_8;
+//constexpr_test<xxhash64::hash<0> ("test", 4), 0x4fdcca5ddb678139ULL> constexprTest64_7;
+//constexpr_test<xxhash64::hash<2654435761U> ("test", 4), 0x5A183B8150E2F651ULL> constexprTest64_8;