gold patch for fixing ICF bugs.

[Sriraman Tallam <tmsriram at google dot com>]

Hi,

       I have attached a gold patch to fix a couple of bugs in ICF.

1) String merge :  I fixed gold to ignore the addend when it is a
negative value as that is used for PC offset in PC relative
computations.
2) Check for section folding when section is not included : When the
section is absent ICF should explicitly check if the section is not
folded.
3) Preemptible functions : ICF must be careful when folding functions
that call preemptible functions.
4) Exported functions in shared objects : Safe ICF assumed that the
address of an exported function in shared objects is always the PLT
and hence unique. This is not always true. Hence, I must use
relocation type disambiguation for exported functions too.



       2010-04-18  Sriraman Tallam  <tmsriram@google.com>

	* icf.cc (get_section_contents): Check for preemptible functions.
	Ignore addend when appropriate.
	* symtab.cc (should_add_dynsym_entry): Add new parameter.  Check for
	section folded.
	(add_from_relobj): Check for section folded.
	(set_dynsym_indexes): Fix call to should_add_dynsym_entry.
	* symtab.h (should_add_dynsym_entry): Add new parameter.
	* target-reloc.h (scan_relocs): Check for section folded.
	* x86_64.cc (Target_x86_64::Scan::possible_function_pointer_reloc):
	Check reloc types for function pointers in shared objects.
	* testsuite/Makefile.am (icf_virtual_function_folding_test): New test
	case.
	(icf_preemptible_functions_test): New test case.
	(icf_string_merge_test): New test case.
	* testsuite.Makefile.in: Regenerate.
	* testsuite/icf_safe_so_test.sh: Change to not fold foo_glob and
	bar_glob.  Refactor code.
	* testsuite/icf_preemptible_functions_test.cc: New file.
	* testsuite/icf_preemptible_functions_test.sh: New file.
	* testsuite/icf_string_merge_test.cc: New file.
	* testsuite/icf_string_merge_test.sh: New file.
	* testsuite/icf_virtual_function_folding_test.cc: New file.
	* testsuite/icf_virtual_function_folding_test.sh: New file.


Thanks,
-Sriraman.

Attachment: icf_bug_fixes_patch.txt
Description: Text document