Mercurial > jwe > octave
view m4/octave_blas.m4 @ 31170:06c76eca5f95 default tip @
maint: merge stable to default
author | John W. Eaton <jwe@octave.org> |
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date | Fri, 29 Jul 2022 12:02:42 -0400 |
parents | 6308ce73bdca |
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dnl -------------------------------------------------------------------- dnl dnl Copyright (C) 2022 The Octave Project Developers dnl dnl See the file COPYRIGHT.md in the top-level directory of this dnl distribution or <https://octave.org/copyright/>. dnl dnl This file is part of Octave. dnl dnl Octave is free software: you can redistribute it and/or modify it dnl under the terms of the GNU General Public License as published by dnl the Free Software Foundation, either version 3 of the License, or dnl (at your option) any later version. dnl dnl Octave is distributed in the hope that it will be useful, but dnl WITHOUT ANY WARRANTY; without even the implied warranty of dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the dnl GNU General Public License for more details. dnl dnl You should have received a copy of the GNU General Public License dnl along with Octave; see the file COPYING. If not, see dnl <https://www.gnu.org/licenses/>. dnl dnl -------------------------------------------------------------------- dnl dnl Check for BLAS library and, if valid, determine integer size of library dnl AC_DEFUN([OCTAVE_BLAS], [ AC_PREREQ(2.50) dnl Call reference macro to find BLAS library AX_BLAS if test "$cross_compiling" = yes ; then dnl Assume BLAS library exists when cross compiling ax_blas_ok=yes AC_MSG_CHECKING([BLAS can be called from Fortran]) AC_MSG_RESULT([yes assumed for cross compilation]) dnl Assume generic 4-byte BLAS library if not specified AC_MSG_CHECKING([BLAS library integer size]) if test -z "$ax_cv_blas_integer_size" ; then ax_cv_blas_integer_size=4 fi AC_MSG_RESULT([$ax_cv_blas_integer_size assumed for cross compilation]) elif test $ax_blas_ok = yes; then ac_octave_save_LIBS="$LIBS" LIBS="$BLAS_LIBS $LIBS" AC_LANG_PUSH(Fortran 77) ## Check BLAS library integer size. ## If it does not appear to be 8 bytes, we assume it is 4 bytes. ## FIXME: this may fail with options like -ftrapping-math. AC_CACHE_CHECK([BLAS library integer size], [ax_cv_blas_integer_size], [AC_RUN_IFELSE([AC_LANG_PROGRAM(,[[ integer*8 two, n integer*4 n2(2) double precision d, a(1), b(1), ddot equivalence (n, n2) a(1) = 1.0 b(1) = 1.0 c Generate 2**32 + 1 in an 8-byte integer. Whether we have a big c endian or little endian system, both 4-byte words of this value c should be 1. two = 2 n = (two ** 32) + 1 c Check that our expectation about the type conversions are correct. if (n2(1) .ne. 1 .or. n2(2) .ne. 1) then print *, 'invalid assumption about integer type conversion' stop 2 endif * print *, n, n2(1), n2(2) * print *, a(1), b(1) c DDOT will either see 1 or a large value for N. Since INCX and INCY c are both 0, we will never increment the index, so A and B only need to c have a single element. If N is interpreted as 1 (BLAS compiled with c 4-byte integers) then the result will be 1. If N is interpreted as a c large value (BLAS compiled with 8-byte integers) then the result will c be the summation a(1)*b(1) 2^32+1 times. This will also take some c time to compute, but at least for now it is the unusual case so we are c much more likely to exit quickly after detecting that the BLAS library c was compiled with 4-byte integers. d = ddot (n, a, 0, b, 0) * print *, a(1), b(1), d c Success (0 exit status) means we detected BLAS compiled with c 8-byte integers. if (d .eq. 1.0) then stop 1 endif ]])], ax_cv_blas_integer_size=8, ax_cv_blas_integer_size=4) ]) AC_LANG_POP(Fortran 77) LIBS="$ac_octave_save_LIBS" fi ])