liblzma: Remove CRC_USE_GENERIC_FOR_SMALL_INPUTS

It was already commented out.

src/liblzma/check/crc32_fast.c

@@ -164,27 +164,6 @@ 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

src/liblzma/check/crc64_fast.c

@@ -134,11 +134,6 @@ extern LZMA_API(uint64_t)
 lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
 {
 #if defined(CRC64_GENERIC) && defined(CRC64_ARCH_OPTIMIZED)
-
-#ifdef CRC_USE_GENERIC_FOR_SMALL_INPUTS
-	if (size <= 16)
-		return crc64_generic(buf, size, crc);
-#endif
 	return crc64_func(buf, size, crc);
 
 #elif defined(CRC64_ARCH_OPTIMIZED)

src/liblzma/check/crc_common.h

@@ -59,8 +59,6 @@
 #undef CRC32_ARM64
 #undef CRC64_ARM64_CLMUL
 
-#undef CRC_USE_GENERIC_FOR_SMALL_INPUTS
-
 // ARM64 CRC32 instruction is only useful for CRC32. Currently, only
 // little endian is supported since we were unable to test on a big
 // endian machine.
@@ -99,18 +97,6 @@
 #		define CRC32_ARCH_OPTIMIZED 1
 #		define CRC64_ARCH_OPTIMIZED 1
 #		define CRC_X86_CLMUL 1
-
-/*
-		// The generic code is much faster with 1-8-byte inputs and
-		// has similar performance up to 16 bytes  at least in
-		// microbenchmarks (it depends on input buffer alignment
-		// too). If both versions are built, this #define will use
-		// the generic version for inputs up to 16 bytes and CLMUL
-		// for bigger inputs. It saves a little in code size since
-		// the special cases for 0-16-byte inputs will be omitted
-		// from the CLMUL code.
-#		define CRC_USE_GENERIC_FOR_SMALL_INPUTS 1
-*/
 #	endif
 #endif
 

src/liblzma/check/crc_x86_clmul.h

@@ -130,7 +130,6 @@ crc_simd_body(const uint8_t *buf, const size_t size, __m128i *v0, __m128i *v1,
 
 	__m128i v2, v3;
 
-#ifndef CRC_USE_GENERIC_FOR_SMALL_INPUTS
 	if (size <= 16) {
 		// Right-shift initial_crc by 1-16 bytes based on "size"
 		// and store the result in v1 (high bytes) and v0 (low bytes).
@@ -173,9 +172,7 @@ crc_simd_body(const uint8_t *buf, const size_t size, __m128i *v0, __m128i *v1,
 
 		*v0 = _mm_xor_si128(*v0, v3);
 		*v1 = _mm_alignr_epi8(*v1, *v0, 8);
-	} else
+	} else {
-#endif
-	{
 		// There is more than 16 bytes of input.
 		const __m128i data1 = _mm_load_si128(aligned_buf);
 		const __m128i *end = (const __m128i*)(
@@ -245,11 +242,9 @@ crc_attr_target
 static uint32_t
 crc32_arch_optimized(const uint8_t *buf, size_t size, uint32_t crc)
 {
-#ifndef CRC_USE_GENERIC_FOR_SMALL_INPUTS
 	// The code assumes that there is at least one byte of input.
 	if (size == 0)
 		return crc;
-#endif
 
 	// uint32_t poly = 0xedb88320;
 	const int64_t p = 0x1db710640; // p << 1
@@ -334,11 +329,9 @@ crc_attr_target
 static uint64_t
 crc64_arch_optimized(const uint8_t *buf, size_t size, uint64_t crc)
 {
-#ifndef CRC_USE_GENERIC_FOR_SMALL_INPUTS
 	// The code assumes that there is at least one byte of input.
 	if (size == 0)
 		return crc;
-#endif
 
 	// const uint64_t poly = 0xc96c5795d7870f42; // CRC polynomial
 	const uint64_t p  = 0x92d8af2baf0e1e85; // (poly << 1) | 1