1# =========================================================================== 2# http://www.gnu.org/software/autoconf-archive/ax_cc_maxopt.html 3# =========================================================================== 4# 5# SYNOPSIS 6# 7# AX_CC_MAXOPT 8# 9# DESCRIPTION 10# 11# Try to turn on "good" C optimization flags for various compilers and 12# architectures, for some definition of "good". (In our case, good for 13# FFTW and hopefully for other scientific codes. Modify as needed.) 14# 15# The user can override the flags by setting the CFLAGS environment 16# variable. The user can also specify --enable-portable-binary in order to 17# disable any optimization flags that might result in a binary that only 18# runs on the host architecture. 19# 20# Note also that the flags assume that ANSI C aliasing rules are followed 21# by the code (e.g. for gcc's -fstrict-aliasing), and that floating-point 22# computations can be re-ordered as needed. 23# 24# Requires macros: AX_CHECK_COMPILE_FLAG, AX_COMPILER_VENDOR, 25# AX_GCC_ARCHFLAG, AX_GCC_X86_CPUID. 26# 27# LICENSE 28# 29# Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu> 30# Copyright (c) 2008 Matteo Frigo 31# 32# This program is free software: you can redistribute it and/or modify it 33# under the terms of the GNU General Public License as published by the 34# Free Software Foundation, either version 3 of the License, or (at your 35# option) any later version. 36# 37# This program is distributed in the hope that it will be useful, but 38# WITHOUT ANY WARRANTY; without even the implied warranty of 39# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General 40# Public License for more details. 41# 42# You should have received a copy of the GNU General Public License along 43# with this program. If not, see <http://www.gnu.org/licenses/>. 44# 45# As a special exception, the respective Autoconf Macro's copyright owner 46# gives unlimited permission to copy, distribute and modify the configure 47# scripts that are the output of Autoconf when processing the Macro. You 48# need not follow the terms of the GNU General Public License when using 49# or distributing such scripts, even though portions of the text of the 50# Macro appear in them. The GNU General Public License (GPL) does govern 51# all other use of the material that constitutes the Autoconf Macro. 52# 53# This special exception to the GPL applies to versions of the Autoconf 54# Macro released by the Autoconf Archive. When you make and distribute a 55# modified version of the Autoconf Macro, you may extend this special 56# exception to the GPL to apply to your modified version as well. 57 58#serial 13 59 60AC_DEFUN([AX_CC_MAXOPT], 61[ 62AC_REQUIRE([AC_PROG_CC]) 63AC_REQUIRE([AX_COMPILER_VENDOR]) 64AC_REQUIRE([AC_CANONICAL_HOST]) 65 66AC_ARG_ENABLE(portable-binary, [AS_HELP_STRING([--enable-portable-binary], [disable compiler optimizations that would produce unportable binaries])], 67 acx_maxopt_portable=$enableval, acx_maxopt_portable=no) 68 69# Try to determine "good" native compiler flags if none specified via CFLAGS 70if test "$ac_test_CFLAGS" != "set"; then 71 CFLAGS="" 72 case $ax_cv_c_compiler_vendor in 73 dec) CFLAGS="-newc -w0 -O5 -ansi_alias -ansi_args -fp_reorder -tune host" 74 if test "x$acx_maxopt_portable" = xno; then 75 CFLAGS="$CFLAGS -arch host" 76 fi;; 77 78 sun) CFLAGS="-native -fast -xO5 -dalign" 79 if test "x$acx_maxopt_portable" = xyes; then 80 CFLAGS="$CFLAGS -xarch=generic" 81 fi;; 82 83 hp) CFLAGS="+Oall +Optrs_ansi +DSnative" 84 if test "x$acx_maxopt_portable" = xyes; then 85 CFLAGS="$CFLAGS +DAportable" 86 fi;; 87 88 ibm) if test "x$acx_maxopt_portable" = xno; then 89 xlc_opt="-qarch=auto -qtune=auto" 90 else 91 xlc_opt="-qtune=auto" 92 fi 93 AX_CHECK_COMPILE_FLAG($xlc_opt, 94 CFLAGS="-O3 -qansialias -w $xlc_opt", 95 [CFLAGS="-O3 -qansialias -w" 96 echo "******************************************************" 97 echo "* You seem to have the IBM C compiler. It is *" 98 echo "* recommended for best performance that you use: *" 99 echo "* *" 100 echo "* CFLAGS=-O3 -qarch=xxx -qtune=xxx -qansialias -w *" 101 echo "* ^^^ ^^^ *" 102 echo "* where xxx is pwr2, pwr3, 604, or whatever kind of *" 103 echo "* CPU you have. (Set the CFLAGS environment var. *" 104 echo "* and re-run configure.) For more info, man cc. *" 105 echo "******************************************************"]) 106 ;; 107 108 intel) CFLAGS="-O3 -ansi_alias" 109 if test "x$acx_maxopt_portable" = xno; then 110 icc_archflag=unknown 111 icc_flags="" 112 case $host_cpu in 113 i686*|x86_64*) 114 # icc accepts gcc assembly syntax, so these should work: 115 AX_GCC_X86_CPUID(0) 116 AX_GCC_X86_CPUID(1) 117 case $ax_cv_gcc_x86_cpuid_0 in # see AX_GCC_ARCHFLAG 118 *:756e6547:*:*) # Intel 119 case $ax_cv_gcc_x86_cpuid_1 in 120 *6a?:*[[234]]:*:*|*6[[789b]]?:*:*:*) icc_flags="-xK";; 121 *f3[[347]]:*:*:*|*f4[1347]:*:*:*) icc_flags="-xP -xN -xW -xK";; 122 *f??:*:*:*) icc_flags="-xN -xW -xK";; 123 esac ;; 124 esac ;; 125 esac 126 if test "x$icc_flags" != x; then 127 for flag in $icc_flags; do 128 AX_CHECK_COMPILE_FLAG($flag, [icc_archflag=$flag; break]) 129 done 130 fi 131 AC_MSG_CHECKING([for icc architecture flag]) 132 AC_MSG_RESULT($icc_archflag) 133 if test "x$icc_archflag" != xunknown; then 134 CFLAGS="$CFLAGS $icc_archflag" 135 fi 136 fi 137 ;; 138 139 gnu) 140 # default optimization flags for gcc on all systems 141 CFLAGS="-O3 -fomit-frame-pointer" 142 143 # -malign-double for x86 systems 144 # LIBFFI -- DON'T DO THIS - CHANGES ABI 145 # AX_CHECK_COMPILE_FLAG(-malign-double, CFLAGS="$CFLAGS -malign-double") 146 147 # -fstrict-aliasing for gcc-2.95+ 148 AX_CHECK_COMPILE_FLAG(-fstrict-aliasing, 149 CFLAGS="$CFLAGS -fstrict-aliasing") 150 151 # note that we enable "unsafe" fp optimization with other compilers, too 152 AX_CHECK_COMPILE_FLAG(-ffast-math, CFLAGS="$CFLAGS -ffast-math") 153 154 AX_GCC_ARCHFLAG($acx_maxopt_portable) 155 ;; 156 esac 157 158 if test -z "$CFLAGS"; then 159 echo "" 160 echo "********************************************************" 161 echo "* WARNING: Don't know the best CFLAGS for this system *" 162 echo "* Use ./configure CFLAGS=... to specify your own flags *" 163 echo "* (otherwise, a default of CFLAGS=-O3 will be used) *" 164 echo "********************************************************" 165 echo "" 166 CFLAGS="-O3" 167 fi 168 169 AX_CHECK_COMPILE_FLAG($CFLAGS, [], [ 170 echo "" 171 echo "********************************************************" 172 echo "* WARNING: The guessed CFLAGS don't seem to work with *" 173 echo "* your compiler. *" 174 echo "* Use ./configure CFLAGS=... to specify your own flags *" 175 echo "********************************************************" 176 echo "" 177 CFLAGS="" 178 ]) 179 180fi 181]) 182