2012-04-12  Cary Coutant  <ccoutant@google.com>

	* archive.cc (Library_base::should_include_member): Check for
	--export-dynamic-symbol.
	* options.h (class General_options): Add --export-dynamic-symbol.
	* symtab.cc (Symbol::should_add_dynsym_entry): Check for
	--export-dynamic-symbol.
	(Symbol_table::gc_mark_undef_symbols): Likewise.
	(Symbol_table::do_add_undefined_symbols_from_command_line): Likewise.


commit 0d5b3ac553d8f1cbd8bdeaa58f0e063881c8fbc4
Author: Cary Coutant <ccoutant@google.com>
Date:   Thu Apr 12 17:52:13 2012 -0700

    Add --export-dynamic-symbol option.

diff --git a/gold/archive.cc b/gold/archive.cc
index c2e6ff6..4db813d 100644
--- a/gold/archive.cc
+++ b/gold/archive.cc
@@ -104,6 +104,11 @@ Library_base::should_include_member(Symbol_table* symtab, Layout* layout,
           *why = "-u ";
           *why += sym_name;
         }
+      else if (parameters->options().is_export_dynamic_symbol(sym_name))
+        {
+          *why = "--export-dynamic-symbol ";
+          *why += sym_name;
+        }
       else if (layout->script_options()->is_referenced(sym_name))
 	{
 	  size_t alc = 100 + strlen(sym_name);
diff --git a/gold/options.h b/gold/options.h
index b5df3eb..b244bd5 100644
--- a/gold/options.h
+++ b/gold/options.h
@@ -739,6 +739,9 @@ class General_options
               N_("Export all dynamic symbols"),
 	      N_("Do not export all dynamic symbols (default)"));
 
+  DEFINE_set(export_dynamic_symbol, options::TWO_DASHES, '\0',
+	     N_("Export SYMBOL to dynamic symbol table"), N_("SYMBOL"));
+
   DEFINE_special(EB, options::ONE_DASH, '\0',
 		 N_("Link big-endian objects."), NULL);
 
diff --git a/gold/symtab.cc b/gold/symtab.cc
index f0ba1d5..1edb88d 100644
--- a/gold/symtab.cc
+++ b/gold/symtab.cc
@@ -363,14 +363,22 @@ Symbol::should_add_dynsym_entry(Symbol_table* symtab) const
         return false;
     }
 
+  // If the symbol was forced dynamic in a --dynamic-list file
+  // or an --export-dynamic-symbol option, add it.
+  if (parameters->options().in_dynamic_list(this->name())
+      || parameters->options().is_export_dynamic_symbol(this->name()))
+    {
+      if (!this->is_forced_local())
+        return true;
+      gold_warning(_("Cannot export local symbol '%s'"),
+		   this->demangled_name().c_str());
+      return false;
+    }
+
   // If the symbol was forced local in a version script, do not add it.
   if (this->is_forced_local())
     return false;
 
-  // If the symbol was forced dynamic in a --dynamic-list file, add it.
-  if (parameters->options().in_dynamic_list(this->name()))
-    return true;
-
   // If dynamic-list-data was specified, add any STT_OBJECT.
   if (parameters->options().dynamic_list_data()
       && !this->is_from_dynobj()
@@ -551,8 +559,8 @@ Symbol_table::is_section_folded(Object* obj, unsigned int shndx) const
           && this->icf_->is_section_folded(obj, shndx));
 }
 
-// For symbols that have been listed with -u option, add them to the
-// work list to avoid gc'ing them.
+// For symbols that have been listed with a -u or --export-dynamic-symbol
+// option, add them to the work list to avoid gc'ing them.
 
 void 
 Symbol_table::gc_mark_undef_symbols(Layout* layout)
@@ -579,6 +587,28 @@ Symbol_table::gc_mark_undef_symbols(Layout* layout)
         }
     }
 
+  for (options::String_set::const_iterator p =
+	 parameters->options().export_dynamic_symbol_begin();
+       p != parameters->options().export_dynamic_symbol_end();
+       ++p)
+    {
+      const char* name = p->c_str();
+      Symbol* sym = this->lookup(name);
+      gold_assert(sym != NULL);
+      if (sym->source() == Symbol::FROM_OBJECT 
+          && !sym->object()->is_dynamic())
+        {
+          Relobj* obj = static_cast<Relobj*>(sym->object());
+          bool is_ordinary;
+          unsigned int shndx = sym->shndx(&is_ordinary);
+          if (is_ordinary)
+            {
+              gold_assert(this->gc_ != NULL);
+              this->gc_->worklist().push(Section_id(obj, shndx));
+            }
+        }
+    }
+
   for (Script_options::referenced_const_iterator p =
 	 layout->script_options()->referenced_begin();
        p != layout->script_options()->referenced_end();
@@ -2291,6 +2321,12 @@ Symbol_table::do_add_undefined_symbols_from_command_line(Layout* layout)
        ++p)
     this->add_undefined_symbol_from_command_line<size>(p->c_str());
 
+  for (options::String_set::const_iterator p =
+	 parameters->options().export_dynamic_symbol_begin();
+       p != parameters->options().export_dynamic_symbol_end();
+       ++p)
+    this->add_undefined_symbol_from_command_line<size>(p->c_str());
+
   for (Script_options::referenced_const_iterator p =
 	 layout->script_options()->referenced_begin();
        p != layout->script_options()->referenced_end();