try building a sample SVE program

When configure'd with --enable-sve, try to build a sample SVE program
and abort on failure, otherwise configure successes but make will fail.

configure.ac

@@ -237,11 +237,10 @@ AM_CONDITIONAL(HAVE_GENERIC_SIMD256, test "$have_generic_simd256" = "yes")
 
 AC_ARG_ENABLE(sve, [AC_HELP_STRING([--enable-sve],[enable ARM SVE optimizations])], have_sve=$enableval, have_sve=no)
 if test "$have_sve" = "yes"; then
-        AC_DEFINE(HAVE_SVE,1,[Define to enable ARM SVE optimizations.])
+   AC_DEFINE(HAVE_SVE,1,[Define to enable ARM SVE optimizations])
 fi
 AM_CONDITIONAL(HAVE_SVE, test "$have_sve" = "yes")
 
-
 dnl FIXME:
 dnl AC_ARG_ENABLE(mips-ps, [AS_HELP_STRING([--enable-mips-ps],[enable MIPS pair-single optimizations])], have_mips_ps=$enableval, have_mips_ps=no)
 dnl if test "$have_mips_ps" = "yes"; then
@@ -683,6 +682,13 @@ if test "$enable_openmp" = "yes"; then
    AX_OPENMP([], [AC_MSG_ERROR([don't know how to enable OpenMP])])
 fi
 
+if test "$have_sve" = "yes"; then
+   ACX_SVE([sve_ok=yes], [sve_ok=no])
+   if test "$sve_ok" != "yes"; then
+      AC_MSG_ERROR([Cannot build a SVE program, aborting])
+   fi
+fi
+
 AC_ARG_ENABLE(threads, [AS_HELP_STRING([--enable-threads],[compile FFTW SMP threads library])], enable_threads=$enableval, enable_threads=no)
 
 if test "$enable_threads" = "yes"; then

m4/acx_sve.m4

@@ -0,0 +1,26 @@
+dnl @synopsis ACX_SVE([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
+dnl @summary figure out whether a simple SVE program can be compiled
+dnl @category InstalledPackages
+dnl
+dnl This macro tries to compile a simple SVE program that uses
+dnl the ACLE SVE extensions.
+dnl
+dnl ACTION-IF-FOUND is a list of shell commands to run if a SVE
+dnl program can be compiled, and ACTION-IF-NOT-FOUND is a list of commands
+dnl to run it cannot.
+dnl
+dnl @version 2024-04-15
+dnl @license GPLWithACException
+dnl @author Gilles Gouaillardet <[email protected]>
+
+AC_DEFUN([ACX_SVE], [
+
+   AC_MSG_CHECKING([whether a SVE program can be compiled])
+   AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <arm_sve.h>]],
+      [[#if defined(__GNUC__) && !defined(__ARM_FEATURE_SVE)
+#error compiling without SVE support
+#endif]])],[AC_MSG_RESULT([yes])
+            $1],
+       [AC_MSG_RESULT([no])
+        $2])
+])dnl ACX_SVE