Implement -z dynamic-undefined-weak

-z nodynamic-undefined-weak is only implemented for x86.  (The sparc
backend has some support code but doesn't enable the option by
including ld/emulparams/dynamic_undefined_weak.sh, and since the
support looks like it may be broken I haven't enabled it.)  This patch
adds the complementary -z dynamic-undefined-weak, extends both options
to affect building of shared libraries as well as executables, and
adds support for the option on powerpc.

include/
	* bfdlink.h (struct bfd_link_info <dynamic_undefined_weak>):
	Revise comment.
bfd/
	* elflink.c (_bfd_elf_adjust_dynamic_symbol): Hide undefweak
	or make dynamic for info->dynamic_undefined_weak 0 and 1.
	* elf32-ppc.c:Formatting.
	(ensure_undefweak_dynamic): Don't make dynamic when
	info->dynamic_undefined_weak is zero.
	(allocate_dynrelocs): Discard undefweak dyn_relocs for
	info->dynamic_undefined_weak.  Discard undef dyn_relocs when
	not default visibility.  Discard undef and undefweak
	dyn_relocs earlier.
	(ppc_elf_relocate_section): Adjust to suit.
	* elf64-ppc.c: Formatting.
	(ensure_undefweak_dynamic): Don't make dynamic when
	info->dynamic_undefined_weak is zero.
	(allocate_dynrelocs): Discard undefweak dyn_relocs for
	info->dynamic_undefined_weak.  Discard them earlier.
ld/
	* ld.texinfo (dynamic-undefined-weak): Document.
	(nodynamic-undefined-weak): Document that this option now can
	be used with shared libs.
	* emulparams/dynamic_undefined_weak.sh: Support -z
	dynamic-undefined-weak.
	* emulparams/elf32ppccommon.sh: Include dynamic_undefined_weak.sh.
	* testsuite/ld-undefined/weak-undef.exp (undef_weak_so),
	(undef_weak_exe): New.  Use them.  Add -z dynamic-undefined-weak
	and -z nodynamic-undefined-weak tests.
	* Makefile.am: Update powerpc dependencies.
	* Makefile.in: Regenerate.

7 files changed, 144 insertions, 45 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index a5732a5..c20ed75 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,17 @@
+2017-04-19  Alan Modra  <amodra@gmail.com>
+
+	* ld.texinfo (dynamic-undefined-weak): Document.
+	(nodynamic-undefined-weak): Document that this option now can
+	be used with shared libs.
+	* emulparams/dynamic_undefined_weak.sh: Support -z
+	dynamic-undefined-weak.
+	* emulparams/elf32ppccommon.sh: Include dynamic_undefined_weak.sh.
+	* testsuite/ld-undefined/weak-undef.exp (undef_weak_so),
+	(undef_weak_exe): New.  Use them.  Add -z dynamic-undefined-weak
+	and -z nodynamic-undefined-weak tests.
+	* Makefile.am: Update powerpc dependencies.
+	* Makefile.in: Regenerate.
+
 2017-04-17  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR ld/21389
diff --git a/ld/Makefile.am b/ld/Makefile.am
index 9dd31ff..3aa7e80 100644
--- a/ld/Makefile.am
+++ b/ld/Makefile.am
@@ -1157,23 +1157,27 @@ eelf32lmip.c: $(srcdir)/emulparams/elf32lmip.sh \
 eelf32lppc.c: $(srcdir)/emulparams/elf32lppc.sh \
   $(srcdir)/emulparams/elf32ppccommon.sh \
   $(srcdir)/emulparams/elf32ppc.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf32lppclinux.c: $(srcdir)/emulparams/elf32lppclinux.sh \
   $(srcdir)/emulparams/elf32lppc.sh $(srcdir)/emulparams/elf32ppc.sh \
   $(srcdir)/emulparams/elf32ppccommon.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf32lppcnto.c: $(srcdir)/emulparams/elf32lppcnto.sh \
   $(srcdir)/emulparams/elf32ppc.sh $(srcdir)/emulparams/elf32ppccommon.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf32lppcsim.c: $(srcdir)/emulparams/elf32lppcsim.sh \
   $(srcdir)/emulparams/elf32lppc.sh $(srcdir)/emulparams/elf32ppc.sh \
   $(srcdir)/emulparams/elf32ppccommon.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
@@ -1253,31 +1257,37 @@ eelf32or1k_linux.c: $(srcdir)/emulparams/elf32or1k_linux.sh \
 
 eelf32ppc.c: $(srcdir)/emulparams/elf32ppc.sh \
   $(srcdir)/emulparams/elf32ppccommon.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf32ppc_fbsd.c: $(srcdir)/emulparams/elf32ppc_fbsd.sh \
   $(srcdir)/emulparams/elf32ppc.sh $(srcdir)/emulparams/elf32ppccommon.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf32ppclinux.c: $(srcdir)/emulparams/elf32ppclinux.sh \
   $(srcdir)/emulparams/elf32ppc.sh $(srcdir)/emulparams/elf32ppccommon.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf32ppcnto.c: $(srcdir)/emulparams/elf32ppcnto.sh \
   $(srcdir)/emulparams/elf32ppc.sh $(srcdir)/emulparams/elf32ppccommon.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf32ppcsim.c: $(srcdir)/emulparams/elf32ppcsim.sh \
   $(srcdir)/emulparams/elf32ppc.sh $(srcdir)/emulparams/elf32ppccommon.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf32ppcvxworks.c: $(srcdir)/emulparams/elf32ppcvxworks.sh \
   $(srcdir)/emulparams/elf32ppccommon.sh $(srcdir)/emulparams/vxworks.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(srcdir)/emultempl/vxworks.em \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
@@ -1976,8 +1986,9 @@ eelf64hppa.c: $(srcdir)/emulparams/elf64hppa.sh \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf64hppa.sc ${GEN_DEPENDS}
 
 eelf64lppc.c: $(srcdir)/emulparams/elf64lppc.sh \
-  $(srcdir)/emulparams/elf64ppc.sh $(srcdir)/emultempl/ppc64elf.em \
-  ldemul-list.h \
+  $(srcdir)/emulparams/elf64ppc.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
+  $(srcdir)/emultempl/ppc64elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf64lriscv.c: $(srcdir)/emulparams/elf64lriscv.sh \
@@ -2000,11 +2011,13 @@ eelf64mmix.c: $(srcdir)/emulparams/elf64mmix.sh \
   $(ELF_DEPS) $(srcdir)/emultempl/mmix-elfnmmo.em \
   $(srcdir)/emultempl/mmixelf.em $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
-eelf64ppc.c: $(srcdir)/emulparams/elf64ppc.sh $(srcdir)/emultempl/ppc64elf.em \
-  ldemul-list.h \
+eelf64ppc.c: $(srcdir)/emulparams/elf64ppc.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
+  $(srcdir)/emultempl/ppc64elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf64ppc_fbsd.c: $(srcdir)/emulparams/elf64ppc_fbsd.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc64elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
diff --git a/ld/Makefile.in b/ld/Makefile.in
index c464302..f485f4f 100644
--- a/ld/Makefile.in
+++ b/ld/Makefile.in
@@ -2721,23 +2721,27 @@ eelf32lmip.c: $(srcdir)/emulparams/elf32lmip.sh \
 eelf32lppc.c: $(srcdir)/emulparams/elf32lppc.sh \
   $(srcdir)/emulparams/elf32ppccommon.sh \
   $(srcdir)/emulparams/elf32ppc.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf32lppclinux.c: $(srcdir)/emulparams/elf32lppclinux.sh \
   $(srcdir)/emulparams/elf32lppc.sh $(srcdir)/emulparams/elf32ppc.sh \
   $(srcdir)/emulparams/elf32ppccommon.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf32lppcnto.c: $(srcdir)/emulparams/elf32lppcnto.sh \
   $(srcdir)/emulparams/elf32ppc.sh $(srcdir)/emulparams/elf32ppccommon.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf32lppcsim.c: $(srcdir)/emulparams/elf32lppcsim.sh \
   $(srcdir)/emulparams/elf32lppc.sh $(srcdir)/emulparams/elf32ppc.sh \
   $(srcdir)/emulparams/elf32ppccommon.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
@@ -2817,31 +2821,37 @@ eelf32or1k_linux.c: $(srcdir)/emulparams/elf32or1k_linux.sh \
 
 eelf32ppc.c: $(srcdir)/emulparams/elf32ppc.sh \
   $(srcdir)/emulparams/elf32ppccommon.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf32ppc_fbsd.c: $(srcdir)/emulparams/elf32ppc_fbsd.sh \
   $(srcdir)/emulparams/elf32ppc.sh $(srcdir)/emulparams/elf32ppccommon.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf32ppclinux.c: $(srcdir)/emulparams/elf32ppclinux.sh \
   $(srcdir)/emulparams/elf32ppc.sh $(srcdir)/emulparams/elf32ppccommon.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf32ppcnto.c: $(srcdir)/emulparams/elf32ppcnto.sh \
   $(srcdir)/emulparams/elf32ppc.sh $(srcdir)/emulparams/elf32ppccommon.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf32ppcsim.c: $(srcdir)/emulparams/elf32ppcsim.sh \
   $(srcdir)/emulparams/elf32ppc.sh $(srcdir)/emulparams/elf32ppccommon.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf32ppcvxworks.c: $(srcdir)/emulparams/elf32ppcvxworks.sh \
   $(srcdir)/emulparams/elf32ppccommon.sh $(srcdir)/emulparams/vxworks.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc32elf.em ldemul-list.h \
   $(srcdir)/emultempl/vxworks.em \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
@@ -3540,8 +3550,9 @@ eelf64hppa.c: $(srcdir)/emulparams/elf64hppa.sh \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf64hppa.sc ${GEN_DEPENDS}
 
 eelf64lppc.c: $(srcdir)/emulparams/elf64lppc.sh \
-  $(srcdir)/emulparams/elf64ppc.sh $(srcdir)/emultempl/ppc64elf.em \
-  ldemul-list.h \
+  $(srcdir)/emulparams/elf64ppc.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
+  $(srcdir)/emultempl/ppc64elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf64lriscv.c: $(srcdir)/emulparams/elf64lriscv.sh \
@@ -3564,11 +3575,13 @@ eelf64mmix.c: $(srcdir)/emulparams/elf64mmix.sh \
   $(ELF_DEPS) $(srcdir)/emultempl/mmix-elfnmmo.em \
   $(srcdir)/emultempl/mmixelf.em $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
-eelf64ppc.c: $(srcdir)/emulparams/elf64ppc.sh $(srcdir)/emultempl/ppc64elf.em \
-  ldemul-list.h \
+eelf64ppc.c: $(srcdir)/emulparams/elf64ppc.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
+  $(srcdir)/emultempl/ppc64elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf64ppc_fbsd.c: $(srcdir)/emulparams/elf64ppc_fbsd.sh \
+  $(srcdir)/emulparams/dynamic_undefined_weak.sh \
   $(srcdir)/emultempl/ppc64elf.em ldemul-list.h \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
diff --git a/ld/emulparams/dynamic_undefined_weak.sh b/ld/emulparams/dynamic_undefined_weak.sh
index 82d88d6..a20bbd4 100644
--- a/ld/emulparams/dynamic_undefined_weak.sh
+++ b/ld/emulparams/dynamic_undefined_weak.sh
@@ -1,12 +1,15 @@
-PARSE_AND_LIST_OPTIONS_NODYNAMIC_UNDEFINED_WEAK='
+PARSE_AND_LIST_OPTIONS_DYNAMIC_UNDEFINED_WEAK='
   fprintf (file, _("\
-  -z nodynamic-undefined-weak Do not treat undefined weak symbol as dynamic\n"));
+  -z dynamic-undefined-weak   Make undefined weak symbols dynamic\n\
+  -z nodynamic-undefined-weak Do not make undefined weak symbols dynamic\n"));
 '
 
-PARSE_AND_LIST_ARGS_CASE_Z_NODYNAMIC_UNDEFINED_WEAK='
+PARSE_AND_LIST_ARGS_CASE_Z_DYNAMIC_UNDEFINED_WEAK='
+      else if (strcmp (optarg, "dynamic-undefined-weak") == 0)
+	link_info.dynamic_undefined_weak = TRUE;
       else if (strcmp (optarg, "nodynamic-undefined-weak") == 0)
 	link_info.dynamic_undefined_weak = FALSE;
 '
 
-PARSE_AND_LIST_OPTIONS="$PARSE_AND_LIST_OPTIONS $PARSE_AND_LIST_OPTIONS_NODYNAMIC_UNDEFINED_WEAK"
-PARSE_AND_LIST_ARGS_CASE_Z="$PARSE_AND_LIST_ARGS_CASE_Z $PARSE_AND_LIST_ARGS_CASE_Z_NODYNAMIC_UNDEFINED_WEAK"
+PARSE_AND_LIST_OPTIONS="$PARSE_AND_LIST_OPTIONS $PARSE_AND_LIST_OPTIONS_DYNAMIC_UNDEFINED_WEAK"
+PARSE_AND_LIST_ARGS_CASE_Z="$PARSE_AND_LIST_ARGS_CASE_Z $PARSE_AND_LIST_ARGS_CASE_Z_DYNAMIC_UNDEFINED_WEAK"
diff --git a/ld/emulparams/elf32ppccommon.sh b/ld/emulparams/elf32ppccommon.sh
index d00cf68..44edbd0 100644
--- a/ld/emulparams/elf32ppccommon.sh
+++ b/ld/emulparams/elf32ppccommon.sh
@@ -1,5 +1,7 @@
 # The PLT-agnostic parts of a generic 32-bit ELF PowerPC target.  Included by:
 # elf32ppc.sh elf32ppcvxworks.sh elf64ppc.sh
+. ${srcdir}/emulparams/dynamic_undefined_weak.sh
+
 TEMPLATE_NAME=elf32
 GENERATE_SHLIB_SCRIPT=yes
 GENERATE_PIE_SCRIPT=yes
diff --git a/ld/ld.texinfo b/ld/ld.texinfo
index 909342c..2626b5d 100644
--- a/ld/ld.texinfo
+++ b/ld/ld.texinfo
@@ -1231,11 +1231,18 @@ generated by compiler.  Updates on protected data symbols by another
 module aren't visible to the resulting shared library.  Supported for
 i386 and x86-64.
 
+@item dynamic-undefined-weak
+Make undefined weak symbols dynamic when building a dynamic object,
+if they are referenced from a regular object file and not forced local
+by symbol visibility or versioning.  Not all targets support this
+option.
+
 @item nodynamic-undefined-weak
-Don't treat undefined weak symbols as dynamic when building executable.
-This option overrides linker backend default.  It can be used to avoid
-dynamic relocations against undefined weak symbols in executable.
-Supported for i386 and x86-64.
+Do not make undefined weak symbols dynamic when building a dynamic
+object.  Not all targets support this option.  If neither
+@option{-z nodynamic-undefined-weak} nor @option{-z dynamic-undefined-weak}
+are given, a target may default to either option being in force, or
+make some other selection of undefined weak symbols dynamic.
 
 @item noreloc-overflow
 Disable relocation overflow check.  This can be used to disable
diff --git a/ld/testsuite/ld-undefined/weak-undef.exp b/ld/testsuite/ld-undefined/weak-undef.exp
index eb28c2c..4ae22cf 100644
--- a/ld/testsuite/ld-undefined/weak-undef.exp
+++ b/ld/testsuite/ld-undefined/weak-undef.exp
@@ -53,6 +53,52 @@ if { ![is_elf_format] && ![is_pecoff_format] } then {
     }
 }
 
+proc undef_weak_so { testname opts passval } {
+    global ld
+    global nm
+
+    if {![ld_link $ld tmpdir/weak-fundef.so \
+	  "$opts tmpdir/weak-fundef.o"]} then {
+	fail $testname
+    } elseif {![is_remote host] && [which $nm] == 0} then {
+	unresolved $testname
+    } else {
+	set exec_output [run_host_cmd "$nm" "-D tmpdir/weak-fundef.so"]
+	set exec_output [prune_warnings $exec_output]
+
+	set output_regexp ".*w undef_weak_fun.*"
+	if {[regexp $output_regexp $exec_output] == $passval} then {
+	    pass $testname
+	} else {
+	    fail $testname
+	}
+	return 1
+    }
+    return 0
+}
+
+proc undef_weak_exe { testname opts passval } {
+    global ld
+    global nm
+
+    if {![ld_link $ld tmpdir/weak-fundef \
+	  "$opts tmpdir/weak-fundef.o tmpdir/weak-fundef.so"]} then {
+	fail $testname
+    } elseif {![is_remote host] && [which $nm] == 0} then {
+	unresolved $testname
+    } else {
+	set exec_output [run_host_cmd "$nm" "-D tmpdir/weak-fundef"]
+	set exec_output [prune_warnings $exec_output]
+
+	set output_regexp ".*w undef_weak_fun.*"
+	if {[regexp $output_regexp $exec_output] == $passval} then {
+	    pass $testname
+	} else {
+	    fail $testname
+	}
+    }
+}
+
 # When linking a shared lib, weak undefined symbols should become dynamic.
 set testname "weak undefined function symbols in shared lib"
 
@@ -71,39 +117,40 @@ if { $asflags == "" || ![is_elf_format] || ![check_shared_lib_support]} then {
 } elseif {![ld_assemble $as "$asflags $srcdir/$subdir/weak-fundef.s" \
 		tmpdir/weak-fundef.o]} then {
     fail $testname
-} elseif {![ld_link $ld tmpdir/weak-fundef.so \
-	    "--shared tmpdir/weak-fundef.o"]} then {
-    fail $testname
-} elseif {![is_remote host] && [which $nm] == 0} then {
-    unresolved $testname
-} else {
-    set exec_output [run_host_cmd "$nm" "-D tmpdir/weak-fundef.so"]
-    set exec_output [prune_warnings $exec_output]
-    verbose -log $exec_output
+} elseif { [undef_weak_so $testname "--shared" 1] } then {
 
-    set output_regexp ".*w undef_weak_fun.*"
+    # When linking a dynamic executable, weak undefined symbols become dynamic.
+    set testname "weak undefined function symbols in dynamic exe"
+    undef_weak_exe $testname "--no-as-needed" 1
 
-    if {[regexp $output_regexp $exec_output]} then {
-	pass $testname
-    } else {
-	fail $testname
+    # Find -z options supported by the default emulation
+    set emul [get_target_emul]
+    set cmd [list "$ld --help 2>&1 | sed -e '1,/^$emul:/d;/^\[^ \]*:/,\$d'"]
+    set status [remote_exec host [concat sh -c $cmd]]
+    if { [lindex $status 0] != 0 } {
+	verbose -log "$cmd exited with status [lindex $status 0]"
     }
+    set emulopt [lindex $status 1]
 
-    # When linking a dynamic executable, weak undefined symbols become dynamic.
-    set testname "weak undefined function symbols in dynamic exe"
+    if { [string first "dynamic-undefined-weak" $emulopt] >= 0 } {
+	# -z dynamic-undefined-weak is supported.  Let's see if it works.
 
-    if {![ld_link $ld tmpdir/weak-fundef \
-	  "--no-as-needed tmpdir/weak-fundef.o tmpdir/weak-fundef.so"]} then {
-	fail $testname
-    } else {
-	set exec_output [run_host_cmd "$nm" "-D tmpdir/weak-fundef"]
-	set exec_output [prune_warnings $exec_output]
-	verbose -log $exec_output
+	set testname "weak undefined functions in shared lib, no dyn undef weak"
+	undef_weak_so $testname "--shared -z nodynamic-undefined-weak" 0
 
-	if {[regexp $output_regexp $exec_output]} then {
-	    pass $testname
-	} else {
-	    fail $testname
-	}
+	set testname "weak undefined functions in shared lib, dyn undef weak"
+	undef_weak_so $testname "--shared -z dynamic-undefined-weak" 1
+
+	set testname "weak undefined functions in dynamic exe, no dyn undef weak"
+	undef_weak_exe $testname "-z nodynamic-undefined-weak" 0
+
+	set testname "weak undefined functions in dynamic exe, dyn undef weak"
+	undef_weak_exe $testname "-z dynamic-undefined-weak" 1
+
+	set testname "weak undefined functions in pie, no dyn undef weak"
+	undef_weak_exe $testname "-pie -z nodynamic-undefined-weak" 0
+
+	set testname "weak undefined functions in pie, dyn undef weak"
+	undef_weak_exe $testname "-pie -z dynamic-undefined-weak" 1
     }
 }