aboutsummaryrefslogtreecommitdiff
path: root/configure.ac
diff options
context:
space:
mode:
Diffstat (limited to 'configure.ac')
-rw-r--r--configure.ac52
1 files changed, 52 insertions, 0 deletions
diff --git a/configure.ac b/configure.ac
index bb2697f6..d2fa730c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -380,6 +380,16 @@ AC_ARG_ENABLE([clmul-crc], AS_HELP_STRING([--disable-clmul-crc],
[], [enable_clmul_crc=yes])
+############################
+# ARM64 CRC32 Instructions #
+############################
+
+AC_ARG_ENABLE([arm64-crc32], AS_HELP_STRING([--disable-arm64-crc32],
+ [Do not use ARM64 CRC32 instructions even if support for it
+ is detected.]),
+ [], [enable_arm64_crc32=yes])
+
+
#####################
# Size optimization #
#####################
@@ -1087,6 +1097,48 @@ __m128i my_clmul(__m128i a)
AC_MSG_RESULT([$enable_clmul_crc])
])
+# ARM64 C Language Extensions define CRC32 functions in arm_acle.h.
+# These are supported by at least GCC and Clang which both need
+# __attribute__((__target__("+crc"))), unless the needed compiler flags
+# are used to support the CRC instruction.
+AC_MSG_CHECKING([if ARM64 CRC32 instruction is usable])
+AS_IF([test "x$enable_arm64_crc32" = xno], [
+ AC_MSG_RESULT([no, --disable-arm64-crc32 was used])
+], [
+ AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+#include <arm_acle.h>
+#include <stdint.h>
+
+#if (defined(__GNUC__) || defined(__clang__)) && !defined(__EDG__)
+__attribute__((__target__("+crc")))
+#endif
+uint32_t my_crc(uint32_t a, uint64_t b)
+{
+ return __crc32d(a, b);
+}
+ ]])], [
+ AC_DEFINE([HAVE_ARM64_CRC32], [1],
+ [Define to 1 if ARM64 CRC32 instruction is supported.
+ See configure.ac for details.])
+ enable_arm64_crc32=yes
+ ], [
+ enable_arm64_crc32=no
+ ])
+ AC_MSG_RESULT([$enable_arm64_crc32])
+])
+
+# Check for ARM64 CRC32 instruction runtime detection.
+# getauxval() is supported on Linux, elf_aux_info() on FreeBSD, and
+# sysctlbyname("hw.optional.armv8_crc32", ...) is supported on Darwin
+# (macOS, iOS, etc.). Note that sysctlbyname() is supported on FreeBSD,
+# NetBSD, and possibly others too but the string is specific to Apple OSes.
+# The C code is responsible for checking defined(__APPLE__) before using
+# sysctlbyname("hw.optional.armv8_crc32", ...).
+AS_IF([test "x$enable_arm64_crc32" = xyes], [
+ AC_CHECK_FUNCS([getauxval elf_aux_info sysctlbyname])
+])
+
+
# Check for sandbox support. If one is found, set enable_sandbox=found.
#
# About -fsanitize: Of our three sandbox methods, only Landlock is