MDEV-23585: Fix HAVE_CLMUL_INSTRUCTION

MDEV-22641 in commit dec3f8ca
refactored a SIMD implementation of CRC-32 for the ISO 3309 polynomial
that uses the IA-32/AMD64 carry-less multiplication (pclmul)
instructions. The code was previously only available in Mariabackup;
it was changed to be a general replacement of the zlib crc32().

There exist AMD64 systems where CMAKE_SYSTEM_PROCESSOR matches
the pattern i[36]86 but not x86_64 or amd64. This would cause a
link failure, because mysys/checksum.c would basically assume that
the compiler support for instruction is always available on GCC-compatible
compilers on AMD64.

Furthermore, we were unnecessarily disabling the SIMD acceleration
for 32-bit executables.

Note: Until MDEV-22749 has been implemented, the PCLMUL instruction
will not be used on Microsoft Windows.

Closes: #1660

config.h.cmake

@@ -102,6 +102,8 @@
 /* Libraries */
 #cmakedefine HAVE_LIBWRAP 1
 #cmakedefine HAVE_SYSTEMD 1
+
+#cmakedefine HAVE_CLMUL_INSTRUCTION 1
 #cmakedefine HAVE_CRC32_VPMSUM 1
 
 /* Support ARMv8 crc + crypto  */

mysys/CMakeLists.txt

@@ -58,7 +58,7 @@ IF (WIN32)
     my_win_popen.cc)
 ENDIF()
 
-IF(NOT MSVC AND CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64|amd64")
+IF(NOT MSVC AND CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64|amd64|i[36]86")
   #Check for PCLMUL instruction (x86)
   CHECK_C_SOURCE_COMPILES("
   int main()

mysys/checksum.c

@@ -30,8 +30,7 @@ static unsigned int my_crc32_zlib(unsigned int crc, const void *data,
 my_crc32_t my_checksum= my_crc32_zlib;
 #endif
 
-#if __GNUC__ >= 4 && defined(__x86_64__)
-
+#ifdef HAVE_CLMUL_INSTRUCTION
 extern int crc32_pclmul_enabled();
 extern unsigned int crc32_pclmul(unsigned int, const void *, size_t);
 

mysys/crc32/crc32_x86.c

@@ -57,8 +57,6 @@ typedef uint8_t byte;
 
 # define _gcry_bswap32 __builtin_bswap32
 
-#if __GNUC__ >= 4 && defined(__x86_64__)
-
 #if defined(_GCRY_GCC_VERSION) && _GCRY_GCC_VERSION >= 40400 /* 4.4 */
 /* Prevent compiler from issuing SSE instructions between asm blocks. */
 #  pragma GCC target("no-sse")
@@ -542,4 +540,3 @@ unsigned int crc32_pclmul(unsigned int crc32, const void *buf, size_t len)
   crc32_intel_pclmul(&crc32, buf, len);
   return ~crc32;
 }
-#endif