config/gcc-plugin.m4

   1 # gcc-plugin.m4 -*- Autoconf -*-
   2 # Check whether GCC is able to be built with plugin support.
   3
   4 dnl Copyright (C) 2014 Free Software Foundation, Inc.
   5 dnl This file is free software, distributed under the terms of the GNU
   6 dnl General Public License.  As a special exception to the GNU General
   7 dnl Public License, this file may be distributed as part of a program
   8 dnl that contains a configuration script generated by Autoconf, under
   9 dnl the same distribution terms as the rest of that program.
  10
  11 # Check for plugin support.
  12 # Respects --enable-plugin.
  13 # Sets the shell variables enable_plugin and pluginlibs.
  14 AC_DEFUN([GCC_ENABLE_PLUGINS],
  15   [# Check for plugin support
  16    AC_ARG_ENABLE(plugin,
  17    [AS_HELP_STRING([--enable-plugin], [enable plugin support])],
  18    enable_plugin=$enableval,
  19    enable_plugin=yes; default_plugin=yes)
  20
  21    pluginlibs=
  22
  23    case "${host}" in
  24      *-*-darwin*)
  25        if test x$build = x$host; then
  26          export_sym_check="nm${exeext} -g"
  27        elif test x$host = x$target; then
  28          export_sym_check="$gcc_cv_nm -g"
  29        else
  30          export_sym_check=
  31        fi
  32      ;;
  33      *)
  34        if test x$build = x$host; then
  35          export_sym_check="objdump${exeext} -T"
  36        elif test x$host = x$target; then
  37          export_sym_check="$gcc_cv_objdump -T"
  38        else
  39          export_sym_check=
  40        fi
  41      ;;
  42    esac
  43
  44    if test x"$enable_plugin" = x"yes"; then
  45
  46      AC_MSG_CHECKING([for exported symbols])
  47      if test "x$export_sym_check" != x; then
  48        echo "int main() {return 0;} int foobar() {return 0;}" > conftest.c
  49        ${CC} ${CFLAGS} ${LDFLAGS} conftest.c -o conftest$ac_exeext > /dev/null 2>&1
  50        if $export_sym_check conftest$ac_exeext | grep -q foobar > /dev/null; then
  51          : # No need to use a flag
  52          AC_MSG_RESULT([yes])
  53        else
  54          AC_MSG_RESULT([yes])
  55          AC_MSG_CHECKING([for -rdynamic])
  56          ${CC} ${CFLAGS} ${LDFLAGS} -rdynamic conftest.c -o conftest$ac_exeext > /dev/null 2>&1
  57          if $export_sym_check conftest$ac_exeext | grep -q foobar > /dev/null; then
  58            plugin_rdynamic=yes
  59            pluginlibs="-rdynamic"
  60          else
  61            plugin_rdynamic=no
  62            enable_plugin=no
  63          fi
  64          AC_MSG_RESULT([$plugin_rdynamic])
  65        fi
  66      else
  67        AC_MSG_RESULT([unable to check])
  68      fi
  69
  70      # Check -ldl
  71      saved_LIBS="$LIBS"
  72      AC_SEARCH_LIBS([dlopen], [dl])
  73      if test x"$ac_cv_search_dlopen" = x"-ldl"; then
  74        pluginlibs="$pluginlibs -ldl"
  75      fi
  76      LIBS="$saved_LIBS"
  77
  78      # Check that we can build shared objects with -fPIC -shared
  79      saved_LDFLAGS="$LDFLAGS"
  80      saved_CFLAGS="$CFLAGS"
  81      case "${host}" in
  82        *-*-darwin*)
  83          CFLAGS=`echo $CFLAGS | sed s/-mdynamic-no-pic//g`
  84          CFLAGS="$CFLAGS -fPIC"
  85          LDFLAGS="$LDFLAGS -shared -undefined dynamic_lookup"
  86        ;;
  87        *)
  88          CFLAGS="$CFLAGS -fPIC"
  89          LDFLAGS="$LDFLAGS -fPIC -shared"
  90        ;;
  91      esac
  92      AC_MSG_CHECKING([for -fPIC -shared])
  93      AC_TRY_LINK(
  94        [extern int X;],[return X == 0;],
  95        [AC_MSG_RESULT([yes]); have_pic_shared=yes],
  96        [AC_MSG_RESULT([no]); have_pic_shared=no])
  97      if test x"$have_pic_shared" != x"yes" -o x"$ac_cv_search_dlopen" = x"no"; then
  98        pluginlibs=
  99        enable_plugin=no
 100      fi
 101      LDFLAGS="$saved_LDFLAGS"
 102      CFLAGS="$saved_CFLAGS"
 103
 104      # If plugin support had been requested but not available, fail.
 105      if test x"$enable_plugin" = x"no" ; then
 106        if test x"$default_plugin" != x"yes"; then
 107          AC_MSG_ERROR([
 108    Building GCC with plugin support requires a host that supports
 109    -fPIC, -shared, -ldl and -rdynamic.])
 110        fi
 111      fi
 112    fi
 113 ])