[RFC][PATCH v6 6/6] Implement and document -z unique / -z nounique handling in gold

[Vivek Das Mohapatra]

---
 gold/ChangeLog | 6 ++++++
 gold/layout.cc | 6 ++++++
 gold/options.h | 3 +++
 3 files changed, 15 insertions(+)

diff --git a/gold/ChangeLog b/gold/ChangeLog
index e152e1ed69..4a08e35efc 100644
--- a/gold/ChangeLog
+++ b/gold/ChangeLog
@@ -1,3 +1,9 @@
+2020-12-09  Vivek Das Mohapatra  <vivek@collabora.com>
+
+	Implement -z unique / -z nounique options.
+	* layout.cc (Layout::finish_dynamic_section): Set DF_GNU_1_UNIQUE.
+	* options.h (class General_options): Handle -z unique, -z nounique.
+
 2020-12-07  Alan Modra  <amodra@gmail.com>
 
 	* plugin.cc (Plugin_recorder::init): Replace strncpy with memcpy.
diff --git a/gold/layout.cc b/gold/layout.cc
index 8563f11099..5cbef4d566 100644
--- a/gold/layout.cc
+++ b/gold/layout.cc
@@ -5371,6 +5371,12 @@ Layout::finish_dynamic_section(const Input_objects* input_objects,
     flags |= elfcpp::DF_1_PIE;
   if (flags != 0)
     odyn->add_constant(elfcpp::DT_FLAGS_1, flags);
+
+  flags = 0;
+  if (parameters->options().unique())
+    flags |= elfcpp::DF_GNU_1_UNIQUE;
+  if (flags != 0)
+    odyn->add_constant(elfcpp::DT_GNU_FLAGS_1, flags);
 }
 
 // Set the size of the _DYNAMIC symbol table to be the size of the
diff --git a/gold/options.h b/gold/options.h
index 51d3614e6b..5a487106d5 100644
--- a/gold/options.h
+++ b/gold/options.h
@@ -1469,6 +1469,9 @@ class General_options
   DEFINE_bool(interpose, options::DASH_Z, '\0', false,
 	      N_("Mark object to interpose all DSOs but executable"),
 	      NULL);
+  DEFINE_bool(unique, options::DASH_Z, '\0', false,
+              N_("Mark DSO to be loaded at most once, and only in the main namespace"),
+              N_("Do not mark the DSO as one to be loaded only in the main namespace"));
   DEFINE_bool_alias(lazy, now, options::DASH_Z, '\0',
 		    N_("Mark object for lazy runtime binding"),
 		    NULL, true);
-- 
2.20.1