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=$enableval,
  19    enable_plugin=yes; default_plugin=yes)
  20
  21    pluginlibs=
  22    plugin_check=yes
  23
  24    case "${host}" in
  25      *-*-mingw*)
  26        # Since plugin support under MinGW is not as straightforward as on
  27        # other platforms (e.g., we have to link import library, etc), we
  28        # only enable it if explicitly requested.
  29        if test x"$default_plugin" = x"yes"; then
  30          enable_plugin=no
  31        elif test x"$enable_plugin" = x"yes"; then
  32          # Use make's target variable to derive import library name.
  33          pluginlibs='-Wl,--export-all-symbols -Wl,--out-implib=[$]@.a'
  34          plugin_check=no
  35        fi
  36      ;;
  37      *-*-darwin*)
  38        if test x$build = x$host; then
  39          export_sym_check="nm${exeext} -g"
  40        elif test x$host = x$target; then
  41          export_sym_check="$gcc_cv_nm -g"
  42        else
  43          export_sym_check=
  44        fi
  45      ;;
  46      *)
  47        if test x$build = x$host; then
  48          export_sym_check="$ac_cv_prog_OBJDUMP -T"
  49        elif test x$host = x$target; then
  50          export_sym_check="$gcc_cv_objdump -T"
  51        else
  52          export_sym_check=
  53        fi
  54      ;;
  55    esac
  56
  57    if test x"$enable_plugin" = x"yes" -a x"$plugin_check" = x"yes"; then
  58
  59      AC_MSG_CHECKING([for exported symbols])
  60      if test "x$export_sym_check" != x; then
  61        echo "int main() {return 0;} int foobar() {return 0;}" > conftest.c
  62        ${CC} ${CFLAGS} ${LDFLAGS} conftest.c -o conftest$ac_exeext > /dev/null 2>&1
  63        if $export_sym_check conftest$ac_exeext | grep foobar > /dev/null; then
  64          : # No need to use a flag
  65          AC_MSG_RESULT([yes])
  66        else
  67          AC_MSG_RESULT([yes])
  68          AC_MSG_CHECKING([for -rdynamic])
  69          ${CC} ${CFLAGS} ${LDFLAGS} -rdynamic conftest.c -o conftest$ac_exeext > /dev/null 2>&1
  70          if $export_sym_check conftest$ac_exeext | grep foobar > /dev/null; then
  71            plugin_rdynamic=yes
  72            pluginlibs="-rdynamic"
  73          else
  74            plugin_rdynamic=no
  75            enable_plugin=no
  76          fi
  77          AC_MSG_RESULT([$plugin_rdynamic])
  78        fi
  79      else
  80        AC_MSG_RESULT([unable to check])
  81      fi
  82
  83      # Check -ldl
  84      saved_LIBS="$LIBS"
  85      AC_SEARCH_LIBS([dlopen], [dl])
  86      if test x"$ac_cv_search_dlopen" = x"-ldl"; then
  87        pluginlibs="$pluginlibs -ldl"
  88      fi
  89      LIBS="$saved_LIBS"
  90
  91      # Check that we can build shared objects with -fPIC -shared
  92      saved_LDFLAGS="$LDFLAGS"
  93      saved_CFLAGS="$CFLAGS"
  94      saved_CXXFLAGS="$CXXFLAGS"
  95      case "${host}" in
  96        *-*-darwin*)
  97          CFLAGS=`echo $CFLAGS | sed s/-mdynamic-no-pic//g`
  98          CFLAGS="$CFLAGS -fPIC"
  99          CXXFLAGS=`echo $CXXFLAGS | sed s/-mdynamic-no-pic//g`
 100          CXXFLAGS="$CXXFLAGS -fPIC"
 101          LDFLAGS="$LDFLAGS -shared -undefined dynamic_lookup"
 102        ;;
 103        *)
 104          CFLAGS="$CFLAGS -fPIC"
 105          CXXFLAGS="$CXXFLAGS -fPIC"
 106          LDFLAGS="$LDFLAGS -fPIC -shared"
 107        ;;
 108      esac
 109      AC_MSG_CHECKING([for -fPIC -shared])
 110      AC_TRY_LINK(
 111        [extern int X;],[return X == 0;],
 112        [AC_MSG_RESULT([yes]); have_pic_shared=yes],
 113        [AC_MSG_RESULT([no]); have_pic_shared=no])
 114      if test x"$have_pic_shared" != x"yes" -o x"$ac_cv_search_dlopen" = x"no"; then
 115        pluginlibs=
 116        enable_plugin=no
 117      fi
 118      LDFLAGS="$saved_LDFLAGS"
 119      CFLAGS="$saved_CFLAGS"
 120      CXXFLAGS="$saved_CXXFLAGS"
 121
 122      # If plugin support had been requested but not available, fail.
 123      if test x"$enable_plugin" = x"no" ; then
 124        if test x"$default_plugin" != x"yes"; then
 125          AC_MSG_ERROR([
 126    Building GCC with plugin support requires a host that supports
 127    -fPIC, -shared, -ldl and -rdynamic.])
 128        fi
 129      fi
 130    fi
 131 ])