liblzma: Speed up CRC32 calculation on 64-bit LoongArch

The crc.w.{b/h/w/d}.w instructions in LoongArch can calculate the CRC32
result for 1/2/4/8 bytes in a single operation. Using these is much
faster compared to the generic method.

Optimized CRC32 is enabled unconditionally on 64-bit LoongArch because
the LoongArch specification says that CRC32 instructions shall be
implemented for 64-bit processors. Optimized CRC32 isn't enabled for
32-bit LoongArch processors because not enough information is available
about them.

Co-authored-by: Lasse Collin <lasse.collin@tukaani.org>

Closes: https://github.com/tukaani-project/xz/pull/86

CMakeLists.txt

@@ -548,6 +548,7 @@ add_library(liblzma
     src/liblzma/check/crc_common.h
     src/liblzma/check/crc_x86_clmul.h
     src/liblzma/check/crc32_arm64.h
+    src/liblzma/check/crc32_loongarch.h
     src/liblzma/common/block_util.c
     src/liblzma/common/common.c
     src/liblzma/common/common.h
@@ -1341,6 +1342,30 @@ if(XZ_ARM64_CRC32)
     endif()
 endif()
 
+option(XZ_LOONGARCH_CRC32
+       "Use LoongArch CRC32 instructions if supported by the compiler" ON)
+
+if(XZ_LOONGARCH_CRC32)
+    # LoongArch CRC32 intrinsics are in larchintrin.h.
+    # These are supported by at least GCC and Clang.
+    #
+    # Only 64-bit LoongArch is currently supported.
+    # It doesn't need runtime detection.
+    check_c_source_compiles("
+            #if !(defined(__loongarch__) && __loongarch_grlen >= 64)
+            #   error
+            #endif
+
+            #include <larchintrin.h>
+            int main(void)
+            {
+                return __crc_w_w_w(1, 2);
+            }
+        "
+        HAVE_LOONGARCH_CRC32)
+    tuklib_add_definition_if(liblzma HAVE_LOONGARCH_CRC32)
+endif()
+
 
 # Symbol visibility support:
 #

configure.ac

@@ -394,6 +394,16 @@ AC_ARG_ENABLE([arm64-crc32], AS_HELP_STRING([--disable-arm64-crc32],
 	[], [enable_arm64_crc32=yes])
 
 
+################################
+# LoongArch CRC32 instructions #
+################################
+
+AC_ARG_ENABLE([loongarch-crc32], AS_HELP_STRING([--disable-loongarch-crc32],
+		[Do not use LoongArch CRC32 instructions even if support for
+		them is detected.]),
+	[], [enable_loongarch_crc32=yes])
+
+
 #####################
 # Size optimization #
 #####################
@@ -1106,6 +1116,36 @@ AS_IF([test "x$enable_arm64_crc32" = xyes], [
 ])
 
 
+# LoongArch CRC32 intrinsics are in larchintrin.h.
+# These are supported by at least GCC and Clang.
+#
+# Only 64-bit LoongArch is currently supported.
+# It doesn't need runtime detection.
+AC_MSG_CHECKING([if LoongArch CRC32 instructions are usable])
+AS_IF([test "x$enable_loongarch_crc32" = xno], [
+	AC_MSG_RESULT([no, --disable-loongarch-crc32 was used])
+], [
+	AC_LINK_IFELSE([AC_LANG_SOURCE([[
+#if !(defined(__loongarch__) && __loongarch_grlen >= 64)
+#	error
+#endif
+
+#include <larchintrin.h>
+int main(void)
+{
+	return __crc_w_w_w(1, 2);
+}
+	]])], [
+		AC_DEFINE([HAVE_LOONGARCH_CRC32], [1], [Define to 1 if
+			64-bit LoongArch CRC32 instructions are supported.])
+		enable_loongarch_crc32=yes
+	], [
+		enable_loongarch_crc32=no
+	])
+	AC_MSG_RESULT([$enable_loongarch_crc32])
+])
+
+
 # Check for sandbox support. If one is found, set enable_sandbox=found.
 #
 # About -fsanitize: Of our three sandbox methods, only Landlock is

src/liblzma/check/Makefile.inc

@@ -14,7 +14,8 @@ liblzma_la_SOURCES += \
 	check/check.h \
 	check/crc_common.h \
 	check/crc_x86_clmul.h \
-	check/crc32_arm64.h
+	check/crc32_arm64.h \
+	check/crc32_loongarch.h
 
 if COND_SMALL
 liblzma_la_SOURCES += check/crc32_small.c

src/liblzma/check/crc32_fast.c

@@ -19,6 +19,8 @@
 #	include "crc_x86_clmul.h"
 #elif defined(CRC32_ARM64)
 #	include "crc32_arm64.h"
+#elif defined(CRC32_LOONGARCH)
+#	include "crc32_loongarch.h"
 #endif
 
 

src/liblzma/check/crc32_loongarch.h

@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: 0BSD
+
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       crc32_loongarch.h
+/// \brief      CRC32 calculation with LoongArch optimization
+//
+//  Authors:    Xi Ruoyao
+//              Lasse Collin
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef LZMA_CRC32_LOONGARCH_H
+#define LZMA_CRC32_LOONGARCH_H
+
+#include <larchintrin.h>
+
+
+static uint32_t
+crc32_arch_optimized(const uint8_t *buf, size_t size, uint32_t crc_unsigned)
+{
+	int32_t crc = (int32_t)~crc_unsigned;
+
+	if (size >= 8) {
+		const size_t align = (0 - (uintptr_t)buf) & 7;
+
+		if (align & 1)
+			crc = __crc_w_b_w((int8_t)*buf++, crc);
+
+		if (align & 2) {
+			crc = __crc_w_h_w((int16_t)aligned_read16le(buf), crc);
+			buf += 2;
+		}
+
+		if (align & 4) {
+			crc = __crc_w_w_w((int32_t)aligned_read32le(buf), crc);
+			buf += 4;
+		}
+
+		size -= align;
+
+		for (const uint8_t *limit = buf + (size & ~(size_t)7);
+				buf < limit; buf += 8)
+			crc = __crc_w_d_w((int64_t)aligned_read64le(buf), crc);
+
+		size &= 7;
+	}
+
+	if (size & 4) {
+		crc = __crc_w_w_w((int32_t)aligned_read32le(buf), crc);
+		buf += 4;
+	}
+
+	if (size & 2) {
+		crc = __crc_w_h_w((int16_t)aligned_read16le(buf), crc);
+		buf += 2;
+	}
+
+	if (size & 1)
+		crc = __crc_w_b_w((int8_t)*buf, crc);
+
+	return (uint32_t)~crc;
+}
+
+#endif // LZMA_CRC32_LOONGARCH_H

src/liblzma/check/crc_common.h

@@ -83,6 +83,9 @@ extern const uint64_t lzma_crc64_table[4][256];
 // CRC64 could be done with CLMUL but it's not implemented yet.
 #undef CRC32_ARM64
 
+// 64-bit LoongArch has CRC32 instructions.
+#undef CRC32_LOONGARCH
+
 
 // ARM64
 //
@@ -112,6 +115,18 @@ extern const uint64_t lzma_crc64_table[4][256];
 #endif
 
 
+// LoongArch
+//
+// Only 64-bit LoongArch is supported for now. No runtime detection
+// is needed because the LoongArch specification says that the CRC32
+// instructions are a part of the Basic Integer Instructions and
+// they shall be implemented by 64-bit LoongArch implementations.
+#ifdef HAVE_LOONGARCH_CRC32
+#	define CRC32_ARCH_OPTIMIZED 1
+#	define CRC32_LOONGARCH 1
+#endif
+
+
 // x86 and E2K
 #if defined(HAVE_USABLE_CLMUL)
 	// If CLMUL is allowed unconditionally in the compiler options then