Merging upstream version 5.6.2.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 140 insertions, 18 deletions

diff --git a/src/liblzma/check/crc32_fast.c b/src/liblzma/check/crc32_fast.c
index eed7350..16dbb74 100644
--- a/src/liblzma/check/crc32_fast.c
+++ b/src/liblzma/check/crc32_fast.c
@@ -1,35 +1,40 @@
+// SPDX-License-Identifier: 0BSD
+
 ///////////////////////////////////////////////////////////////////////////////
 //
 /// \file       crc32.c
 /// \brief      CRC32 calculation
-///
-/// Calculate the CRC32 using the slice-by-eight algorithm.
-/// It is explained in this document:
-/// http://www.intel.com/technology/comms/perfnet/download/CRC_generators.pdf
-/// The code in this file is not the same as in Intel's paper, but
-/// the basic principle is identical.
-//
-//  Author:     Lasse Collin
 //
-//  This file has been put into the public domain.
-//  You can do whatever you want with this file.
+//  Authors:    Lasse Collin
+//              Ilya Kurdyukov
+//              Hans Jansen
 //
 ///////////////////////////////////////////////////////////////////////////////
 
 #include "check.h"
-#include "crc_macros.h"
+#include "crc_common.h"
+
+#if defined(CRC_X86_CLMUL)
+#	define BUILDING_CRC32_CLMUL
+#	include "crc_x86_clmul.h"
+#elif defined(CRC32_ARM64)
+#	include "crc32_arm64.h"
+#endif
 
 
-// If you make any changes, do some benchmarking! Seemingly unrelated
-// changes can very easily ruin the performance (and very probably is
-// very compiler dependent).
-extern LZMA_API(uint32_t)
-lzma_crc32(const uint8_t *buf, size_t size, uint32_t crc)
+#ifdef CRC32_GENERIC
+
+///////////////////
+// Generic CRC32 //
+///////////////////
+
+static uint32_t
+crc32_generic(const uint8_t *buf, size_t size, uint32_t crc)
 {
 	crc = ~crc;
 
 #ifdef WORDS_BIGENDIAN
-	crc = bswap32(crc);
+	crc = byteswap32(crc);
 #endif
 
 	if (size > 8) {
@@ -75,8 +80,125 @@ lzma_crc32(const uint8_t *buf, size_t size, uint32_t crc)
 		crc = lzma_crc32_table[0][*buf++ ^ A(crc)] ^ S8(crc);
 
 #ifdef WORDS_BIGENDIAN
-	crc = bswap32(crc);
+	crc = byteswap32(crc);
 #endif
 
 	return ~crc;
 }
+#endif
+
+
+#if defined(CRC32_GENERIC) && defined(CRC32_ARCH_OPTIMIZED)
+
+//////////////////////////
+// Function dispatching //
+//////////////////////////
+
+// If both the generic and arch-optimized implementations are built, then
+// the function to use is selected at runtime because the system running
+// the binary might not have the arch-specific instruction set extension(s)
+// available. The dispatch methods in order of priority:
+//
+// 1. Constructor. This method uses __attribute__((__constructor__)) to
+//    set crc32_func at load time. This avoids extra computation (and any
+//    unlikely threading bugs) on the first call to lzma_crc32() to decide
+//    which implementation should be used.
+//
+// 2. First Call Resolution. On the very first call to lzma_crc32(), the
+//    call will be directed to crc32_dispatch() instead. This will set the
+//    appropriate implementation function and will not be called again.
+//    This method does not use any kind of locking but is safe because if
+//    multiple threads run the dispatcher simultaneously then they will all
+//    set crc32_func to the same value.
+
+typedef uint32_t (*crc32_func_type)(
+		const uint8_t *buf, size_t size, uint32_t crc);
+
+// This resolver is shared between all dispatch methods.
+static crc32_func_type
+crc32_resolve(void)
+{
+	return is_arch_extension_supported()
+			? &crc32_arch_optimized : &crc32_generic;
+}
+
+
+#ifdef HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR
+// Constructor method.
+#	define CRC32_SET_FUNC_ATTR __attribute__((__constructor__))
+static crc32_func_type crc32_func;
+#else
+// First Call Resolution method.
+#	define CRC32_SET_FUNC_ATTR
+static uint32_t crc32_dispatch(const uint8_t *buf, size_t size, uint32_t crc);
+static crc32_func_type crc32_func = &crc32_dispatch;
+#endif
+
+CRC32_SET_FUNC_ATTR
+static void
+crc32_set_func(void)
+{
+	crc32_func = crc32_resolve();
+	return;
+}
+
+#ifndef HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR
+static uint32_t
+crc32_dispatch(const uint8_t *buf, size_t size, uint32_t crc)
+{
+	// When __attribute__((__constructor__)) isn't supported, set the
+	// function pointer without any locking. If multiple threads run
+	// the detection code in parallel, they will all end up setting
+	// the pointer to the same value. This avoids the use of
+	// mythread_once() on every call to lzma_crc32() but this likely
+	// isn't strictly standards compliant. Let's change it if it breaks.
+	crc32_set_func();
+	return crc32_func(buf, size, crc);
+}
+
+#endif
+#endif
+
+
+extern LZMA_API(uint32_t)
+lzma_crc32(const uint8_t *buf, size_t size, uint32_t crc)
+{
+#if defined(CRC32_GENERIC) && defined(CRC32_ARCH_OPTIMIZED)
+	// On x86-64, if CLMUL is available, it is the best for non-tiny
+	// inputs, being over twice as fast as the generic slice-by-four
+	// version. However, for size <= 16 it's different. In the extreme
+	// case of size == 1 the generic version can be five times faster.
+	// At size >= 8 the CLMUL starts to become reasonable. It
+	// varies depending on the alignment of buf too.
+	//
+	// The above doesn't include the overhead of mythread_once().
+	// At least on x86-64 GNU/Linux, pthread_once() is very fast but
+	// it still makes lzma_crc32(buf, 1, crc) 50-100 % slower. When
+	// size reaches 12-16 bytes the overhead becomes negligible.
+	//
+	// So using the generic version for size <= 16 may give better
+	// performance with tiny inputs but if such inputs happen rarely
+	// it's not so obvious because then the lookup table of the
+	// generic version may not be in the processor cache.
+#ifdef CRC_USE_GENERIC_FOR_SMALL_INPUTS
+	if (size <= 16)
+		return crc32_generic(buf, size, crc);
+#endif
+
+/*
+#ifndef HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR
+	// See crc32_dispatch(). This would be the alternative which uses
+	// locking and doesn't use crc32_dispatch(). Note that on Windows
+	// this method needs Vista threads.
+	mythread_once(crc64_set_func);
+#endif
+*/
+	return crc32_func(buf, size, crc);
+
+#elif defined(CRC32_ARCH_OPTIMIZED)
+	return crc32_arch_optimized(buf, size, crc);
+
+#else
+	return crc32_generic(buf, size, crc);
+#endif
+}