@node ax_cc_maxopt
@unnumberedsec ax_cc_maxopt

@majorheading Synopsis

@smallexample
AX_CC_MAXOPT
@end smallexample

@majorheading Description

Try to turn on "good" C optimization flags for various compilers and
architectures, for some definition of "good". (In our case, good for
FFTW and hopefully for other scientific codes. Modify as needed.)

The user can override the flags by setting the CFLAGS environment
variable. The user can also specify --enable-portable-binary in order to
disable any optimization flags that might result in a binary that only
runs on the host architecture.

Note also that the flags assume that ANSI C aliasing rules are followed
by the code (e.g. for gcc's -fstrict-aliasing), and that floating-point
computations can be re-ordered as needed.

Requires macros: AX_CHECK_COMPILE_FLAG, AX_COMPILER_VENDOR,
AX_GCC_ARCHFLAG, AX_GCC_X86_CPUID.

@majorheading Source Code

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

@majorheading License

@w{Copyright @copyright{} 2008 Steven G. Johnson @email{stevenj@@alum.mit.edu}} @* @w{Copyright @copyright{} 2008 Matteo Frigo}

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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