2010-02-12 Sriraman Tallam <tmsriram@google.com>

	* arm.cc (Scan::local_reloc_may_be_function_pointer): New function.
	(Scan::global_reloc_may_be_function_pointer): New function.
	* sparc.cc (Scan::local_reloc_may_be_function_pointer): New function.
	(Scan::global_reloc_may_be_function_pointer): New function.
	* powerpc.cc (Scan::local_reloc_may_be_function_pointer): New function.
	(Scan::global_reloc_may_be_function_pointer): New function.
	* i386.cc (Scan::local_reloc_may_be_function_pointer): New function.
	(Scan::global_reloc_may_be_function_pointer): New function.
	* x86_64.cc (Scan::local_reloc_may_be_function_pointer): New function.
	(Scan::global_reloc_may_be_function_pointer): New function.
	(Scan::possible_function_pointer_reloc): New function.
	(Target_x86_64::can_check_for_function_pointers): New function.
	* gc.h (gc_process_relocs): Scan relocation types to determine if
	function pointers were taken for targets that support it.
	* icf.cc (Icf::find_identical_sections): Include functions for
	folding in safe ICF whose pointer is not taken.
	* icf.h (Secn_fptr_taken_set): New typedef.
	(fptr_section_id_): New member.
	(section_has_function_pointers): New function.
	(set_section_has_function_pointers): New function.
	(check_section_for_function_pointers): New function.
	* options.h: Fix comment for safe ICF option.
	* target.h (can_check_for_function_pointers): New function.
	* testsuite/Makefile.am: Add icf_safe_so_test test case.
	Modify icf_safe_test for X86-64.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/icf_safe_so_test.cc: New file.
	* testsuite/icf_safe_so_test.sh: New file.
	* testsuite/icf_safe_test.cc (kept_func_3): New function.
	(main): Change to take pointer to function kept_func_3.
	* testsuite/icf_safe_test.sh (arch_specific_safe_fold): Check if safe
	folding is done correctly for X86-64.

1 files changed, 37 insertions, 1 deletions

diff --git a/gold/icf.h b/gold/icf.h
index e336572105..76e491c094 100644
--- a/gold/icf.h
+++ b/gold/icf.h
@@ -50,9 +50,11 @@ class Icf
   typedef Unordered_map<Section_id,
                         unsigned int,
                         Section_id_hash> Uniq_secn_id_map;
+  typedef Unordered_set<Section_id, Section_id_hash> Secn_fptr_taken_set;
 
   Icf()
   : id_section_(), section_id_(), kept_section_id_(),
+    fptr_section_id_(),
     num_tracked_relocs(NULL), icf_ready_(false),
     section_reloc_list_(), symbol_reloc_list_(),
     addend_reloc_list_()
@@ -88,7 +90,37 @@ class Icf
   // given section.
   bool
   is_section_folded(Object* obj, unsigned int shndx);
-    
+
+  // Given an object and a section index, this returns true if the
+  // pointer of the function defined in this section is taken.
+  bool
+  section_has_function_pointers(Object *obj, unsigned int shndx)
+  {
+    return (this->fptr_section_id_.find(Section_id(obj, shndx))
+            != this->fptr_section_id_.end());
+  }
+
+  // Records that a pointer of the function defined in this section
+  // is taken.
+  void
+  set_section_has_function_pointers(Object *obj, unsigned int shndx)
+  {
+    this->fptr_section_id_.insert(Section_id(obj, shndx));
+  }
+
+  // Checks if the section_name should be searched for relocs
+  // corresponding to taken function pointers.  Ignores eh_frame
+  // and vtable sections.
+  inline bool
+  check_section_for_function_pointers(std::string section_name,
+                                      Target* target)
+  {
+    return (parameters->options().icf_safe_folding()
+	    && target->can_check_for_function_pointers()
+            && !is_prefix_of(".rodata._ZTV", section_name.c_str())
+            && !is_prefix_of(".eh_frame", section_name.c_str()));
+  }
+
   // Returns a map of a section to a list of all sections referenced
   // by its relocations.
   Section_list&
@@ -122,6 +154,10 @@ class Icf
   // section.  If the id's are the same then this section is
   // not folded.
   std::vector<unsigned int> kept_section_id_;
+  // Given a section id, this says if the pointer to this
+  // function is taken in which case it is dangerous to fold
+  // this function.
+  Secn_fptr_taken_set fptr_section_id_;
   unsigned int* num_tracked_relocs;
   // Flag to indicate if ICF has been run.
   bool icf_ready_;