[gold commit] Fix problem where -u is ignored when a weak undef is seen

[ccoutant at google dot com (Cary Coutant)]

Fix problem where -u is ignored when a weak undef is seen.

When the linker has a weak undefined symbol, it normally does not
select an archive library member just to satisfy the reference.
If the same symbol is also listed in a -u option, however, we
should select the archive library member.  This patch reorders
the code in Library_base::should_include_member so that the
additional checks are performed in the case of a weak undef.

Tested on x86-64 and committed.

-cary

gold/

2014-02-06  Cary Coutant  <ccoutant@google.com>

	* archive.cc (Library_base::should_include_member): Reorder
	code to check for -u option if a weak undef has already been seen.
	* testsuite/Makefile.am (weak_undef_test_2): New test case.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/weak_undef_file3.cc: New file.
	* testsuite/weak_undef_file4.cc: New file.
	* testsuite/weak_undef_test_2.cc: New file.


diff --git a/gold/archive.cc b/gold/archive.cc
index 53d88a2..b52ebd3 100644
--- a/gold/archive.cc
+++ b/gold/archive.cc
@@ -97,46 +97,56 @@ Library_base::should_include_member(Symbol_table* symtab, Layout* layout,
 
   *symp = sym;
 
-  if (sym == NULL)
+  if (sym != NULL)
     {
-      // Check whether the symbol was named in a -u option.
-      if (parameters->options().is_undefined(sym_name))
-        {
-          *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);
-	  char* buf = new char[alc];
-	  snprintf(buf, alc, _("script or expression reference to %s"),
-		   sym_name);
-	  *why = buf;
-	  delete[] buf;
-	}
-      else if (strcmp(sym_name, parameters->entry()) == 0)
-	{
-	  *why = "entry symbol ";
-	  *why += sym_name;
-	}
-      else
-	return Library_base::SHOULD_INCLUDE_UNKNOWN;
+      if (!sym->is_undefined())
+	return Library_base::SHOULD_INCLUDE_NO;
+
+      // PR 12001: Do not include an archive when the undefined
+      // symbol has actually been defined on the command line.
+      if (layout->script_options()->is_pending_assignment(sym_name))
+	return Library_base::SHOULD_INCLUDE_NO;
+
+      // If the symbol is weak undefined, we still need to check
+      // for other reasons (like a -u option).
+      if (sym->binding() != elfcpp::STB_WEAK)
+	return Library_base::SHOULD_INCLUDE_YES;
+    }
+
+  // Check whether the symbol was named in a -u option.
+  if (parameters->options().is_undefined(sym_name))
+    {
+      *why = "-u ";
+      *why += sym_name;
+      return Library_base::SHOULD_INCLUDE_YES;
+    }
+
+  if (parameters->options().is_export_dynamic_symbol(sym_name))
+    {
+      *why = "--export-dynamic-symbol ";
+      *why += sym_name;
+      return Library_base::SHOULD_INCLUDE_YES;
     }
-  else if (!sym->is_undefined())
-    return Library_base::SHOULD_INCLUDE_NO;
-  // PR 12001: Do not include an archive when the undefined
-  // symbol has actually been defined on the command line.
-  else if (layout->script_options()->is_pending_assignment(sym_name))
-    return Library_base::SHOULD_INCLUDE_NO;
-  else if (sym->binding() == elfcpp::STB_WEAK)
-    return Library_base::SHOULD_INCLUDE_UNKNOWN;
-
-  return Library_base::SHOULD_INCLUDE_YES;
+
+  if (layout->script_options()->is_referenced(sym_name))
+    {
+      size_t alc = 100 + strlen(sym_name);
+      char* buf = new char[alc];
+      snprintf(buf, alc, _("script or expression reference to %s"),
+	       sym_name);
+      *why = buf;
+      delete[] buf;
+      return Library_base::SHOULD_INCLUDE_YES;
+    }
+
+  if (strcmp(sym_name, parameters->entry()) == 0)
+    {
+      *why = "entry symbol ";
+      *why += sym_name;
+      return Library_base::SHOULD_INCLUDE_YES;
+    }
+
+  return Library_base::SHOULD_INCLUDE_UNKNOWN;
 }
 
 // The header of an entry in the archive.  This is all readable text,
diff --git a/gold/testsuite/Makefile.am b/gold/testsuite/Makefile.am
index 0b22c13..aa41290 100644
--- a/gold/testsuite/Makefile.am
+++ b/gold/testsuite/Makefile.am
@@ -710,6 +710,18 @@ alt/weak_undef_lib.so: weak_undef_file2.o
 	test -d alt || mkdir -p alt
 	$(CXXLINK) -Bgcctestdir/ -shared weak_undef_file2.o
 
+check_PROGRAMS += weak_undef_test_2
+weak_undef_test_2_SOURCES = weak_undef_test_2.cc
+weak_undef_test_2_DEPENDENCIES = gcctestdir/ld libweak_undef_2.a
+weak_undef_test_2_LDFLAGS = -Bgcctestdir/ -u weak_undef_2
+weak_undef_test_2_LDADD = -L . -lweak_undef_2
+libweak_undef_2.a: weak_undef_file3.o weak_undef_file4.o
+	$(TEST_AR) rc $@ $^
+weak_undef_file3.o: weak_undef_file3.cc
+	$(CXXCOMPILE) -c -o $@ $<
+weak_undef_file4.o: weak_undef_file4.cc
+	$(CXXCOMPILE) -c -o $@ $<
+
 if FN_PTRS_IN_SO_WITHOUT_PIC
 check_PROGRAMS += weak_undef_nonpic_test
 MOSTLYCLEANFILES += alt/weak_undef_lib_nonpic.so
diff --git a/gold/testsuite/weak_undef_file3.cc b/gold/testsuite/weak_undef_file3.cc
new file mode 100644
index 0000000..7c96d3a
--- /dev/null
+++ b/gold/testsuite/weak_undef_file3.cc
@@ -0,0 +1,29 @@
+// weak_undef_file3.cc -- test handling of weak undefined symbols for gold
+
+// Copyright 2014 Free Software Foundation, Inc.
+// Written by Cary Coutant <ccoutant@google.com>.
+
+// This file is part of gold.
+
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+// MA 02110-1301, USA.
+
+// This file tests that we correctly deal with weak undefined symbols
+// when searching archive libraries.  If we have a weak undefined symbol,
+// it should not cause us to link an archive library member that defines
+// that symbol.  However, if the symbol is also listed in a -u option on
+// the command line, it should cause the archive member to be linked.
+
+int weak_undef_1 = 1;
diff --git a/gold/testsuite/weak_undef_file4.cc b/gold/testsuite/weak_undef_file4.cc
new file mode 100644
index 0000000..3f3cc14
--- /dev/null
+++ b/gold/testsuite/weak_undef_file4.cc
@@ -0,0 +1,29 @@
+// weak_undef_file4.cc -- test handling of weak undefined symbols for gold
+
+// Copyright 2014 Free Software Foundation, Inc.
+// Written by Cary Coutant <ccoutant@google.com>.
+
+// This file is part of gold.
+
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+// MA 02110-1301, USA.
+
+// This file tests that we correctly deal with weak undefined symbols
+// when searching archive libraries.  If we have a weak undefined symbol,
+// it should not cause us to link an archive library member that defines
+// that symbol.  However, if the symbol is also listed in a -u option on
+// the command line, it should cause the archive member to be linked.
+
+int weak_undef_2 = 2;
diff --git a/gold/testsuite/weak_undef_test_2.cc b/gold/testsuite/weak_undef_test_2.cc
new file mode 100644
index 0000000..fc9bbab
--- /dev/null
+++ b/gold/testsuite/weak_undef_test_2.cc
@@ -0,0 +1,79 @@
+// weak_undef_test_2.cc -- test handling of weak undefined symbols for gold
+
+// Copyright 2014 Free Software Foundation, Inc.
+// Written by Cary Coutant <ccoutant@google.com>.
+
+// This file is part of gold.
+
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+// MA 02110-1301, USA.
+
+// This file tests that we correctly deal with weak undefined symbols
+// when searching archive libraries.  If we have a weak undefined symbol,
+// it should not cause us to link an archive library member that defines
+// that symbol.  However, if the symbol is also listed in a -u option on
+// the command line, it should cause the archive member to be linked.
+
+
+#include <cstdio>
+
+// This symbol is defined in weak_undef_file3.cc, but we should
+// not load it from the library.
+extern int weak_undef_1 __attribute__ ((weak));
+
+// This symbol is defined in weak_undef_file4.cc, but is also
+// listed in a -u option on the link command, so we should
+// load it from the library.
+extern int weak_undef_2 __attribute__ ((weak));
+
+int *p1 = &weak_undef_1;
+
+int *p2 = &weak_undef_2;
+
+int
+main()
+{
+  int status = 0;
+
+  if (&weak_undef_1 != NULL)
+    {
+      fprintf(stderr, "FAILED weak undef test 1: %s\n",
+              "&weak_undef_1 is not NULL");
+      status = 1;
+    }
+
+  if (&weak_undef_2 == NULL)
+    {
+      fprintf(stderr, "FAILED weak undef test 2: %s\n",
+              "&weak_undef_2 is NULL");
+      status = 1;
+    }
+
+  if (p1 != NULL)
+    {
+      fprintf(stderr, "FAILED weak undef test 3: %s\n",
+              "p1 is not NULL");
+      status = 1;
+    }
+
+  if (p2 == NULL)
+    {
+      fprintf(stderr, "FAILED weak undef test 4: %s\n",
+              "p2 is NULL");
+      status = 1;
+    }
+
+  return status;
+}