build: Restrict check for CRC32C intrinsic to aarch64

laanwj · fanquake · commit efb9f00f07c7 · 2022-06-09T12:53:50.000+01:00
`crc32c`'s hardware accelerated code doesn't handle ARM 32-bit at all. Make the check in `configure.ac` check for this architecture explicitly. For the release binaries, the current `configure.ac` check happens to work: it enables it on aarch64 but disables it for armhf. However some combination of compiler version and settings might ostensibly cause this check to succeed on armhf (as reported on IRC). So make the 64-bit platform requirement explicit. Github-Pull: #23045 Rebased-From: f2747d1
diff --git a/configure.ac b/configure.ac
@@ -535,13 +535,17 @@ AX_CHECK_COMPILE_FLAG([-march=armv8-a+crc+crypto],[[ARM_CRC_CXXFLAGS="-march=arm
 
 TEMP_CXXFLAGS="$CXXFLAGS"
 CXXFLAGS="$CXXFLAGS $ARM_CRC_CXXFLAGS"
-AC_MSG_CHECKING(for ARM CRC32 intrinsics)
+AC_MSG_CHECKING(for AArch64 CRC32 intrinsics)
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
     #include <arm_acle.h>
     #include <arm_neon.h>
   ]],[[
+#ifdef __aarch64__
     __crc32cb(0, 0); __crc32ch(0, 0); __crc32cw(0, 0); __crc32cd(0, 0);
     vmull_p64(0, 0);
+#else
+#error "crc32c library does not support hardware acceleration on 32-bit ARM"
+#endif
   ]])],
  [ AC_MSG_RESULT(yes); enable_arm_crc=yes; ],
  [ AC_MSG_RESULT(no)]
