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dnl --------------------------------------------------------------------
dnl
dnl Copyright (C) 2022-2025 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 $LIBS"
AC_LANG_PUSH(Fortran 77)
# Check if BLAS functions with single precision return value work
# correctly
AC_CACHE_CHECK([whether BLAS functions with single precision return value work correctly],
[octave_cv_working_blas_single_precision],
[AC_RUN_IFELSE([AC_LANG_PROGRAM(,[[
implicit none
real d
real x(2), y(2)
real sdot
data x /1.0, 2.0/
data y /3.0, 4.0/
d = sdot (2, x, 1, y, 1)
* print *, 'result: ', d
c Some implementations of BLAS (e.g., the one from Apple Accelerate)
c erroneously return a *double*-precision floating point value for functions
c that should be returning a single-precision floating point value.
c Check if the result for SDOT is correct if we (correctly) assume that it
c returns a single-precision floating point value.
if (d .ne. 11.0) then
stop 1
endif
]])],
octave_cv_working_blas_single_precision=yes,
octave_cv_working_blas_single_precision=no)
])
if test "$octave_cv_working_blas_single_precision" != yes; then
AC_MSG_ERROR([The function SDOT does not work correctly with the selected BLAS library. Use a different implementation of BLAS.])
fi
## 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
])
|
