@node ax_gcc_x86_avx_xgetbv
@unnumberedsec ax_gcc_x86_avx_xgetbv

@majorheading Synopsis

@smallexample
AX_GCC_X86_AVX_XGETBV
@end smallexample

@majorheading Description

On later x86 processors with AVX SIMD support, with gcc or a compiler
that has a compatible syntax for inline assembly instructions, run a
small program that executes the xgetbv instruction with input OP. This
can be used to detect if the OS supports AVX instruction usage.

On output, the values of the eax and edx registers are stored as
hexadecimal strings as "eax:edx" in the cache variable
ax_cv_gcc_x86_avx_xgetbv.

If the xgetbv instruction fails (because you are running a
cross-compiler, or because you are not using gcc, or because you are on
a processor that doesn't have this instruction),
ax_cv_gcc_x86_avx_xgetbv_OP is set to the string "unknown".

This macro mainly exists to be used in AX_EXT.

@majorheading Source Code

Download the
@uref{http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=blob_plain;f=m4/ax_gcc_x86_avx_xgetbv.m4,latest
version of @file{ax_gcc_x86_avx_xgetbv.m4}} or browse
@uref{http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=history;f=m4/ax_gcc_x86_avx_xgetbv.m4,the
macro's revision history}.

@majorheading License

@w{Copyright @copyright{} 2013 Michael Petch @email{mpetch@@capp-sysware.com}}

This program is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation, either version 3 of the License, or (at your
option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
Public License for more details.

You should have received a copy of the GNU General Public License along
with this program. If not, see <https://www.gnu.org/licenses/>.

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