Re: detection and support of OpenMP

[Paul Eggert]

Noah Misch <address@hidden> writes:

> 2007-05-21  Noah Misch  <address@hidden>
>
>       * lib/autoconf/c.m4 (AC_OPENMP): Simplify use of AC_ARG_ENABLE. 
>       * tests/local.at (AT_CHECK_ENV): Exempt OPENMP_CFLAGS.

Thanks.  I discovered one more problem: the output looks weird when
$enable_openmp is empty.  Also, the indenting didn't work with Emacs.
I installed this:

2007-05-21  Paul Eggert  <address@hidden>

        * lib/autoconf/c.m4 (AC_OPENMP): Don't echo --enable-openmp
        choice, since that's what we do with --enable-largefile etc.
        Redo indenting and assignments to simplify things a bit, and make
        the parens work with Emacs.

Index: lib/autoconf/c.m4
===================================================================
RCS file: /cvsroot/autoconf/autoconf/lib/autoconf/c.m4,v
retrieving revision 1.250
diff -u -p -r1.250 c.m4
--- lib/autoconf/c.m4   21 May 2007 22:31:18 -0000      1.250
+++ lib/autoconf/c.m4   21 May 2007 23:10:07 -0000
@@ -1887,74 +1887,71 @@ m4_copy([_AC_LANG_OPENMP(Fortran 77)], [
 # an output file called 'penmp' rather than activating OpenMP support.
 AC_DEFUN([AC_OPENMP],
 [
-  AC_MSG_CHECKING([whether to use OpenMP])
-  AC_ARG_ENABLE(openmp,
-    [AS_HELP_STRING([--disable-openmp], [do not use OpenMP])])
-  AC_MSG_RESULT([$enable_openmp])
   OPENMP_[]_AC_LANG_PREFIX[]FLAGS=
+  AC_ARG_ENABLE([openmp],
+    [AS_HELP_STRING([--disable-openmp], [do not use OpenMP])])
   if test "$enable_openmp" != no; then
-    AC_MSG_CHECKING([for $CC option to support OpenMP])
-    AC_CACHE_VAL([ac_cv_prog_[]_AC_LANG_ABBREV[]_openmp], [
-      ac_cv_prog_[]_AC_LANG_ABBREV[]_openmp=unsupported
-      AC_LINK_IFELSE([_AC_LANG_OPENMP],
-        [ac_cv_prog_[]_AC_LANG_ABBREV[]_openmp="none needed"])
-      if test "$ac_cv_prog_[]_AC_LANG_ABBREV[]_openmp" = unsupported; then
-        dnl Try these flags:
-        dnl   GCC >= 4.2           -fopenmp
-        dnl   SunPRO C             -xopenmp
-        dnl   Intel C              -openmp
-        dnl   SGI C, PGI C         -mp
-        dnl   Tru64 Compaq C       -omp
-        dnl   IBM C (AIX, Linux)   -qsmp=omp
-        for ac_brand in GCC SunPRO Intel SGI/PGI Compaq IBM; do
-          case $ac_brand in
-            GCC)
-              ac_conditional='defined __GNUC__'
-              ac_option='-fopenmp' ;;
-            SunPRO)
-              ac_conditional='defined __SUNPRO_C || defined __SUNPRO_CC'
-              ac_option='-xopenmp' ;;
-            Intel)
-              ac_conditional='defined __INTEL_COMPILER'
-              ac_option='-openmp' ;;
-            SGI/PGI)
-              ac_conditional='defined __sgi || defined __PGI || defined 
__PGIC__'
-              ac_option='-mp' ;;
-            Compaq)
-              ac_conditional='defined __DECC || defined __DECCXX'
-              ac_option='-omp' ;;
-            IBM)
-              ac_conditional='defined __xlc__ || defined __xlC__'
-              ac_option='-qsmp=omp' ;;
-          esac
-          if test $ac_brand = GCC; then
-            if test "$ac_compiler_gnu" = yes; then
-              ac_openmp_result=yes
-            else
-              ac_openmp_result=no
-            fi
-          else
-            AC_EGREP_CPP([Brand], [
-              #if $ac_conditional
-               Brand
-              #endif
-              ], [ac_openmp_result=yes], [ac_openmp_result=no])
-          fi
-          if test $ac_openmp_result = yes; then
-            ac_save_[]_AC_LANG_PREFIX[]FLAGS=$[]_AC_LANG_PREFIX[]FLAGS
-            _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $ac_option"
-            AC_LINK_IFELSE([_AC_LANG_OPENMP],
-              [ac_cv_prog_[]_AC_LANG_ABBREV[]_openmp=$ac_option])
-            _AC_LANG_PREFIX[]FLAGS=$ac_save_[]_AC_LANG_PREFIX[]FLAGS
-            break
-          fi
-        done
-      fi
-      ])
-    AC_MSG_RESULT([$ac_cv_prog_[]_AC_LANG_ABBREV[]_openmp])
-    case $ac_cv_prog_[]_AC_LANG_ABBREV[]_openmp in
+    AC_CACHE_CHECK([for $CC option to support OpenMP],
+      [ac_cv_prog_[]_AC_LANG_ABBREV[]_openmp],
+      [AC_LINK_IFELSE([_AC_LANG_OPENMP],
+        [ac_cv_prog_[]_AC_LANG_ABBREV[]_openmp='none needed'],
+        [ac_cv_prog_[]_AC_LANG_ABBREV[]_openmp='unsupported'
+         dnl Try these flags:
+         dnl   GCC >= 4.2           -fopenmp
+         dnl   SunPRO C             -xopenmp
+         dnl   Intel C              -openmp
+         dnl   SGI C, PGI C         -mp
+         dnl   Tru64 Compaq C       -omp
+         dnl   IBM C (AIX, Linux)   -qsmp=omp
+         for ac_brand in GCC SunPRO Intel SGI/PGI Compaq IBM; do
+           case $ac_brand in #(
+             GCC)
+               ac_conditional='defined __GNUC__'
+               ac_option='-fopenmp' ;; #(
+             SunPRO)
+               ac_conditional='defined __SUNPRO_C || defined __SUNPRO_CC'
+               ac_option='-xopenmp' ;; #(
+             Intel)
+               ac_conditional='defined __INTEL_COMPILER'
+               ac_option='-openmp' ;; #(
+             SGI/PGI)
+               ac_conditional='defined __sgi || defined __PGI || defined 
__PGIC__'
+               ac_option='-mp' ;; #(
+             Compaq)
+               ac_conditional='defined __DECC || defined __DECCXX'
+               ac_option='-omp' ;; #(
+             IBM)
+               ac_conditional='defined __xlc__ || defined __xlC__'
+               ac_option='-qsmp=omp' ;;
+           esac
+           if test $ac_brand = GCC; then
+             if test "$ac_compiler_gnu" = yes; then
+               ac_openmp_result=yes
+             else
+               ac_openmp_result=no
+             fi
+           else
+             AC_EGREP_CPP([Brand],
+               [
+                 #if $ac_conditional
+                  Brand
+                 #endif
+               ],
+               [ac_openmp_result=yes],
+               [ac_openmp_result=no])
+           fi
+           if test $ac_openmp_result = yes; then
+             ac_save_[]_AC_LANG_PREFIX[]FLAGS=$[]_AC_LANG_PREFIX[]FLAGS
+             _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $ac_option"
+             AC_LINK_IFELSE([_AC_LANG_OPENMP],
+               [ac_cv_prog_[]_AC_LANG_ABBREV[]_openmp=$ac_option])
+             _AC_LANG_PREFIX[]FLAGS=$ac_save_[]_AC_LANG_PREFIX[]FLAGS
+             break
+           fi
+         done])])
+    case $ac_cv_prog_[]_AC_LANG_ABBREV[]_openmp in #(
       "none needed" | unsupported)
-        OPENMP_[]_AC_LANG_PREFIX[]FLAGS= ;;
+        ;; #(
       *)
         OPENMP_[]_AC_LANG_PREFIX[]FLAGS=$ac_cv_prog_[]_AC_LANG_ABBREV[]_openmp 
;;
     esac