Re: [GOLD][PATCH] Fix a sort order breakage of the zero-length script output sections.

[Ian Lance Taylor <iant@google.com>]

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Viktor Kutuzov <vkutuzov@accesssoftek.com> writes:

>     * configure.ac: Add NATIVE_OR_CROSS_LINKER condition macro.
>     * configure: Regenerate.
>     * testsuite/Makefile.am: Wrap the cross linker tests and the common
>       tests into NATIVE_OR_CROSS_LINKER; 
>       Add the script section order test.
>     * testsuite/Makefile.in: Regenerate.
>     * testsuite/script_test_10.sh: New test. Test script section
>       order.
>     * testsuite/script_test_10.t: Likewise.
>     * testsuite/script_test_10.s: Likewise.
>     * script-sections.h (Script_sections): Sections_elements as public;
>       Add a new member to save a list of the section elements.
>       (Sort_output_sections::ctor): Add new parameter to pass a list
>       of the section elements.
>     * script-sections.cc (Sort_output_sections::swap): New method.

Approved and applied with some changes to script-sections.cc and
testsuite/Makefile.am, as follows.

Thanks.

Ian


2010-10-12  Viktor Kutuzov  <vkutuzov@accesssoftek.com>

	* script-sections.h (class Script_sections): Make
	Sections_elements typedef public.
	* script-sections.cc (class Sort_output_sections): Add elements_
	field.  Add constructor which sets it; change all callers.
	(Sort_output_sections::is_before): New function.
	(Sort_output_sections::operator()): Call is_before.
	* configure.ac (NATIVE_OR_CROSS_LINKER): New automake
	conditional.
	* testsuite/script_test_10.sh: New test. Test script section
	order.
	* testsuite/script_test_10.t: Likewise.
	* testsuite/script_test_10.s: Likewise.
	* testsuite/Makefile.am: Wrap the cross linker tests and the
	common tests into NATIVE_OR_CROSS_LINKER.
	(check_SCRIPTS): Add script_test_10.sh.
	(check_DATA): Add script_test_10.stdout.
	(script_test_10.o, script_test_10): New targets.
	(script_test_10.stdout): New target.
	* configure, testsuite/Makefile.in: Regenerate.



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Index: script-sections.cc
===================================================================
RCS file: /cvs/src/src/gold/script-sections.cc,v
retrieving revision 1.44
diff -p -u -r1.44 script-sections.cc
--- script-sections.cc	6 Oct 2010 08:58:57 -0000	1.44
+++ script-sections.cc	12 Oct 2010 19:21:23 -0000
@@ -3552,8 +3552,19 @@ Script_sections::set_section_addresses(S
 class Sort_output_sections
 {
  public:
+  Sort_output_sections(const Script_sections::Sections_elements* elements)
+   : elements_(elements)
+  { }
+
   bool
   operator()(const Output_section* os1, const Output_section* os2) const;
+
+ private:
+  bool
+  is_before(const Output_section* os1, const Output_section* os2) const;
+
+ private:
+  const Script_sections::Sections_elements* elements_;
 };
 
 bool
@@ -3592,7 +3603,36 @@ Sort_output_sections::operator()(const O
   if (!os1->is_noload() && os2->is_noload())
     return true;
   
-  // Otherwise we don't care.
+  // The sections have the same address. Check the section positions 
+  // in accordance with the linker script.
+  return this->is_before(os1, os2);
+}
+
+// Return true if OS1 comes before OS2 in ELEMENTS_.  This ensures
+// that we keep empty sections in the order in which they appear in a
+// linker script.
+
+bool
+Sort_output_sections::is_before(const Output_section* os1,
+				const Output_section* os2) const
+{
+  if (this->elements_ == NULL)
+    return false;
+
+  for (Script_sections::Sections_elements::const_iterator
+	 p = this->elements_->begin();
+       p != this->elements_->end();
+       ++p)
+    {
+      if (os1 == (*p)->get_output_section())
+	{
+	  for (++p; p != this->elements_->end(); ++p)
+	    if (os2 == (*p)->get_output_section())
+	      return true;
+	  break;
+	}
+    }
+
   return false;
 }
 
@@ -3666,7 +3706,8 @@ Script_sections::create_segments(Layout*
   layout->get_allocated_sections(&sections);
 
   // Sort the sections by address.
-  std::stable_sort(sections.begin(), sections.end(), Sort_output_sections());
+  std::stable_sort(sections.begin(), sections.end(), 
+		   Sort_output_sections(this->sections_elements_));
 
   this->create_note_and_tls_segments(layout, &sections);
 
Index: testsuite/Makefile.am
===================================================================
RCS file: /cvs/src/src/gold/testsuite/Makefile.am,v
retrieving revision 1.148
diff -p -u -r1.148 Makefile.am
--- testsuite/Makefile.am	18 Sep 2010 00:34:58 -0000	1.148
+++ testsuite/Makefile.am	12 Oct 2010 19:21:23 -0000
@@ -70,12 +70,14 @@ LDADD = libgoldtest.a ../libgold.a ../..
 
 
 # The unittests themselves
+if NATIVE_OR_CROSS_LINKER
 check_PROGRAMS += object_unittest
 object_unittest_SOURCES = object_unittest.cc
 
 check_PROGRAMS += binary_unittest
 binary_unittest_SOURCES = binary_unittest.cc
 
+endif NATIVE_OR_CROSS_LINKER
 
 # ---------------------------------------------------------------------
 # These tests test the output of gold (end-to-end tests).  In
@@ -1798,7 +1800,21 @@ memory_test.stdout: memory_test
 endif GCC
 endif NATIVE_LINKER
 
-# These tests work with cross linkers.
+# These tests work with native and cross linkers.
+
+if NATIVE_OR_CROSS_LINKER
+
+# Test script section order.
+check_SCRIPTS += script_test_10.sh
+check_DATA += script_test_10.stdout
+script_test_10.o: script_test_10.s
+	$(TEST_AS) -o $@ $<
+script_test_10: $(srcdir)/script_test_10.t script_test_10.o gcctestdir/ld
+	gcctestdir/ld -o $@ script_test_10.o -T $(srcdir)/script_test_10.t
+script_test_10.stdout: script_test_10
+	$(TEST_READELF) -SW script_test_10 > $@
+
+# These tests work with cross linkers only.
 
 if DEFAULT_TARGET_I386
 
@@ -2131,3 +2147,6 @@ MOSTLYCLEANFILES += arm_cortex_a8_b_cond
 	arm_cortex_a8_blx arm_cortex_a8_local arm_cortex_a8_local_reloc
 
 endif DEFAULT_TARGET_ARM
+
+endif NATIVE_OR_CROSS_LINKER
+