change ifunc assembly test to a link test

The test currently tests the binutils frontend support which passes for
all versions of binutils we currently require (2.20+).  It doesn't test
the backend which is required for ifunc to actually work, and which most
targets don't yet support.

Change the assembly code so that when we link it, we get a file that has
ifunc relocations if the backend supports it.  That way we can test to
see if binutils supports everything we need.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

3 files changed, 144 insertions, 115 deletions

diff --git a/ChangeLog b/ChangeLog
index 0b34621859..3c9a31e2eb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 2012-10-24  Mike Frysinger  <vapier@gentoo.org>
 
+	* configure.in: Move READELF check to start of file.
+	(libc_cv_ld_gnu_indirect_function): Change to a link test. Rename from
+	libc_cv_asm_gnu_indirect_function in the process.
+	* configure: Regenerated.
+
+2012-10-24  Mike Frysinger  <vapier@gentoo.org>
+
 	* configure.in (libc_cv_gcc_static_libgcc): Drop -q flag to grep and
 	send the output to /dev/null.
 	(libc_cv_cc_with_libunwind): Likewise.
diff --git a/configure b/configure
index 2592022260..8cd403bf4e 100755
--- a/configure
+++ b/configure
@@ -631,7 +631,6 @@ CXX_SYSINCLUDES
 SYSINCLUDES
 AUTOCONF
 NM
-READELF
 AWK
 SED
 MAKEINFO
@@ -664,6 +663,7 @@ oldest_abi
 use_default_link
 sysheaders
 with_fp
+READELF
 ac_ct_CXX
 CXXFLAGS
 CXX
@@ -3397,6 +3397,98 @@ ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
 ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
+if test -n "$ac_tool_prefix"; then
+  # Extract the first word of "${ac_tool_prefix}readelf", so it can be a program name with args.
+set dummy ${ac_tool_prefix}readelf; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_prog_READELF+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -n "$READELF"; then
+  ac_cv_prog_READELF="$READELF" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if { test -f "$as_dir/$ac_word$ac_exec_ext" && $as_test_x "$as_dir/$ac_word$ac_exec_ext"; }; then
+    ac_cv_prog_READELF="${ac_tool_prefix}readelf"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+READELF=$ac_cv_prog_READELF
+if test -n "$READELF"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $READELF" >&5
+$as_echo "$READELF" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+fi
+if test -z "$ac_cv_prog_READELF"; then
+  ac_ct_READELF=$READELF
+  # Extract the first word of "readelf", so it can be a program name with args.
+set dummy readelf; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_prog_ac_ct_READELF+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -n "$ac_ct_READELF"; then
+  ac_cv_prog_ac_ct_READELF="$ac_ct_READELF" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if { test -f "$as_dir/$ac_word$ac_exec_ext" && $as_test_x "$as_dir/$ac_word$ac_exec_ext"; }; then
+    ac_cv_prog_ac_ct_READELF="readelf"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+ac_ct_READELF=$ac_cv_prog_ac_ct_READELF
+if test -n "$ac_ct_READELF"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_ct_READELF" >&5
+$as_echo "$ac_ct_READELF" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+  if test "x$ac_ct_READELF" = x; then
+    READELF="false"
+  else
+    case $cross_compiling:$ac_tool_warned in
+yes:)
+{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
+$as_echo "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
+ac_tool_warned=yes ;;
+esac
+    READELF=$ac_ct_READELF
+  fi
+else
+  READELF="$ac_cv_prog_READELF"
+fi
+
 
 if test "`cd $srcdir; /bin/pwd`" = "`/bin/pwd`"; then
   as_fn_error $? "you must configure in a separate build directory" "$LINENO" 5
@@ -4053,25 +4145,36 @@ if test "$base_machine" = "i386"; then
 
 fi
 
-# For the multi-arch option we need support in the assembler.
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for assembler gnu_indirect_function symbol type support" >&5
-$as_echo_n "checking for assembler gnu_indirect_function symbol type support... " >&6; }
-if ${libc_cv_asm_gnu_indirect_function+:} false; then :
+# For the multi-arch option we need support in the assembler & linker.
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for assembler and linker STT_GNU_IFUNC support" >&5
+$as_echo_n "checking for assembler and linker STT_GNU_IFUNC support... " >&6; }
+if ${libc_cv_ld_gnu_indirect_function+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   cat > conftest.s <<EOF
 .type foo,%gnu_indirect_function
+foo:
+.globl _start
+_start:
+.globl __start
+__start:
+.data
+.long foo
 EOF
-if ${CC-cc} -c $ASFLAGS conftest.s 1>&5 2>&5;
-then
-  libc_cv_asm_gnu_indirect_function=yes
-else
-  libc_cv_asm_gnu_indirect_function=no
+libc_cv_ld_gnu_indirect_function=no
+if ${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS \
+	    -nostartfiles -nostdlib \
+	    -o conftest conftest.s 1>&5 2>&5; then
+  # Do a link to see if the backend supports IFUNC relocs.
+  $READELF -r conftest 1>&5
+  LC_ALL=C $READELF -r conftest | grep 'no relocations' >/dev/null || {
+    libc_cv_ld_gnu_indirect_function=yes
+  }
 fi
 rm -f conftest*
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_asm_gnu_indirect_function" >&5
-$as_echo "$libc_cv_asm_gnu_indirect_function" >&6; }
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_ld_gnu_indirect_function" >&5
+$as_echo "$libc_cv_ld_gnu_indirect_function" >&6; }
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether .text pseudo-op must be used" >&5
 $as_echo_n "checking whether .text pseudo-op must be used... " >&6; }
@@ -4101,7 +4204,7 @@ else
 $as_echo "yes" >&6; }
 fi
 
-if test x"$libc_cv_asm_gnu_indirect_function" != xyes; then
+if test x"$libc_cv_ld_gnu_indirect_function" != xyes; then
   if test x"$multi_arch" = xyes; then
     as_fn_error $? "--enable-multi-arch support requires assembler and linker support" "$LINENO" 5
   else
@@ -5066,98 +5169,6 @@ fi
 
 
 if test -n "$ac_tool_prefix"; then
-  # Extract the first word of "${ac_tool_prefix}readelf", so it can be a program name with args.
-set dummy ${ac_tool_prefix}readelf; ac_word=$2
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-$as_echo_n "checking for $ac_word... " >&6; }
-if ${ac_cv_prog_READELF+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  if test -n "$READELF"; then
-  ac_cv_prog_READELF="$READELF" # Let the user override the test.
-else
-as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  test -z "$as_dir" && as_dir=.
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if { test -f "$as_dir/$ac_word$ac_exec_ext" && $as_test_x "$as_dir/$ac_word$ac_exec_ext"; }; then
-    ac_cv_prog_READELF="${ac_tool_prefix}readelf"
-    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-fi
-fi
-READELF=$ac_cv_prog_READELF
-if test -n "$READELF"; then
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $READELF" >&5
-$as_echo "$READELF" >&6; }
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-fi
-
-
-fi
-if test -z "$ac_cv_prog_READELF"; then
-  ac_ct_READELF=$READELF
-  # Extract the first word of "readelf", so it can be a program name with args.
-set dummy readelf; ac_word=$2
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-$as_echo_n "checking for $ac_word... " >&6; }
-if ${ac_cv_prog_ac_ct_READELF+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  if test -n "$ac_ct_READELF"; then
-  ac_cv_prog_ac_ct_READELF="$ac_ct_READELF" # Let the user override the test.
-else
-as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  test -z "$as_dir" && as_dir=.
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if { test -f "$as_dir/$ac_word$ac_exec_ext" && $as_test_x "$as_dir/$ac_word$ac_exec_ext"; }; then
-    ac_cv_prog_ac_ct_READELF="readelf"
-    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-fi
-fi
-ac_ct_READELF=$ac_cv_prog_ac_ct_READELF
-if test -n "$ac_ct_READELF"; then
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_ct_READELF" >&5
-$as_echo "$ac_ct_READELF" >&6; }
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-fi
-
-  if test "x$ac_ct_READELF" = x; then
-    READELF="false"
-  else
-    case $cross_compiling:$ac_tool_warned in
-yes:)
-{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
-$as_echo "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
-ac_tool_warned=yes ;;
-esac
-    READELF=$ac_ct_READELF
-  fi
-else
-  READELF="$ac_cv_prog_READELF"
-fi
-
-if test -n "$ac_tool_prefix"; then
   # Extract the first word of "${ac_tool_prefix}nm", so it can be a program name with args.
 set dummy ${ac_tool_prefix}nm; ac_word=$2
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
diff --git a/configure.in b/configure.in
index b3fab3772b..4f7bc09842 100644
--- a/configure.in
+++ b/configure.in
@@ -23,6 +23,7 @@ AC_SUBST(cross_compiling)
 AC_PROG_CPP
 # We need the C++ compiler only for testing.
 AC_PROG_CXX
+AC_CHECK_TOOL(READELF, readelf, false)
 
 if test "`cd $srcdir; /bin/pwd`" = "`/bin/pwd`"; then
   AC_MSG_ERROR([you must configure in a separate build directory])
@@ -566,17 +567,28 @@ if test "$base_machine" = "i386"; then
   AC_DEFINE(USE_REGPARMS)
 fi
 
-# For the multi-arch option we need support in the assembler.
-AC_CACHE_CHECK([for assembler gnu_indirect_function symbol type support],
-	       libc_cv_asm_gnu_indirect_function, [dnl
+# For the multi-arch option we need support in the assembler & linker.
+AC_CACHE_CHECK([for assembler and linker STT_GNU_IFUNC support],
+	       libc_cv_ld_gnu_indirect_function, [dnl
 cat > conftest.s <<EOF
 .type foo,%gnu_indirect_function
+foo:
+.globl _start
+_start:
+.globl __start
+__start:
+.data
+.long foo
 EOF
-if ${CC-cc} -c $ASFLAGS conftest.s 1>&AS_MESSAGE_LOG_FD 2>&AS_MESSAGE_LOG_FD;
-then
-  libc_cv_asm_gnu_indirect_function=yes
-else
-  libc_cv_asm_gnu_indirect_function=no
+libc_cv_ld_gnu_indirect_function=no
+if ${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS \
+	    -nostartfiles -nostdlib \
+	    -o conftest conftest.s 1>&AS_MESSAGE_LOG_FD 2>&AS_MESSAGE_LOG_FD; then
+  # Do a link to see if the backend supports IFUNC relocs.
+  $READELF -r conftest 1>&AS_MESSAGE_LOG_FD
+  LC_ALL=C $READELF -r conftest | grep 'no relocations' >/dev/null || {
+    libc_cv_ld_gnu_indirect_function=yes
+  }
 fi
 rm -f conftest*])
 
@@ -596,7 +608,7 @@ else
   AC_MSG_RESULT(yes)
 fi
 
-if test x"$libc_cv_asm_gnu_indirect_function" != xyes; then
+if test x"$libc_cv_ld_gnu_indirect_function" != xyes; then
   if test x"$multi_arch" = xyes; then
     AC_MSG_ERROR([--enable-multi-arch support requires assembler and linker support])
   else
@@ -930,7 +942,6 @@ AC_CHECK_PROG_VER(AWK, gawk, --version,
   [GNU Awk[^0-9]*\([0-9][0-9.]*\)],
   [[3-9].*], critic_missing="$critic_missing gawk")
 
-AC_CHECK_TOOL(READELF, readelf, false)
 AC_CHECK_TOOL(NM, nm, false)
 
 AC_CHECK_PROGS(AUTOCONF, autoconf, no)