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Patch for ICF string inline bug for SHT_REL sections.

Doug Kwan (關振德) dougkwan@google.com
Mon Jul 19 06:12:00 GMT 2010 
That affects all targets, including ARM, I guess?

-Doug

在 2010年7月18日下午5:43，Sriraman Tallam <tmsriram@google.com> 寫道：
> Hi,
>
>    I found a bug in ICF where it incorrectly inlines strings pointed
> to by SHT_REL relocation types. These relocation types encode the
> addend info at the relocation offset in the text section and ICF
> simply ignores them. Here is a simple example showing the bug.
>
> test_1.cc
> ----------
>
>
> #include <string>
> std::string name1() { return "Name1"; }
> std::string bar()
> {
>  return "AAAAAA";
> }
>
> int main()
> {
>  return 0;
> }
>
> test_2.cc
> ----------
>
>
> #include <string>
> std::string name2() { return "Name2"; }
> std::string foo()
> {
>  return "AAAAAA";
> }
>
> $ gcc -ffunction-sections -fdata-sections -Wl,--print-icf-sections,--icf=all -O2
> ld: ICF folding section '.text._Z5name2v' in file 'test_2.o'into
> '.text._Z5name1v' in file 'test_1.o
>
> Function name1() is folded into name2() which is wrong. This happens
> because the addend is ignored and the wrong string "AAAAAA" is
> inlined. The attached patch fixes it.
>
> 2010-07-18  Sriraman Tallam  <tmsriram@google.com>
>
>        * gc.h (gc_process_relocs): Save the section header type for use by
>        ICF.
>        * icf.cc (get_section_contents): Get the addend from the text section
>        for SHT_REL relocation sections.
>        * icf.h (Icf::Sh_type_info): New typedef.
>        (Icf::Reloc_info): Add new member sh_type_info.
>
> Is this ok to submit ?
>
> Thanks,
> -Sri.
>
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