Re: ICF on PowerPC Bug

[Sriraman Tallam <tmsriram@google.com>]

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Attached patch to fix the PPC ICF problem by using references to the
reloc info vectors. Ok to commit?

Thanks
Sri

On Wed, Apr 2, 2014 at 9:49 AM, Sriraman Tallam <tmsriram@google.com> wrote:
> On Tue, Apr 1, 2014 at 11:54 PM, Alan Modra <amodra@gmail.com> wrote:
>> On Tue, Apr 01, 2014 at 03:06:37PM -0700, Sriraman Tallam wrote:
>>> because fold2 is folded onto fold1.    The only way to differentiate
>>> fold1 and fold2 which have the same object code is via the relocation
>>> type and the Info value is different.  However, with powerpc this is
>>> rewritten here in icf.cc:
>>>
>>> // Look through function descriptors
>>> parameters->target().function_location(&loc);
>>>  if (loc.shndx != it_v->second)
>>> {
>>>  it_v->second = loc.shndx;
>>>  // Modify symvalue/addend to the code entry.
>>>  it_a->first = loc.offset;
>>>  it_a->second = 0;
>>> }
>>>
>>> I am not sure how to fix it.
>>
>> The following patch fixes the problem, but did you really mean to copy
>> all the vectors here?
>
> Yikes!, no did not intend that. I will make these references and send a patch.
>
> Thanks
> Sri
>
>>
>>       Icf::Sections_reachable_info v =
>>         (it_reloc_info_list->second).section_info;
>>       // Stores the information of the symbol pointed to by the reloc.
>>       Icf::Symbol_info s = (it_reloc_info_list->second).symbol_info;
>>       // Stores the addend and the symbol value.
>>       Icf::Addend_info a = (it_reloc_info_list->second).addend_info;
>>       // Stores the offset of the reloc.
>>       Icf::Offset_info o = (it_reloc_info_list->second).offset_info;
>>       Icf::Reloc_addend_size_info reloc_addend_size_info =
>>         (it_reloc_info_list->second).reloc_addend_size_info;
>>
>>
>> diff --git a/gold/icf.cc b/gold/icf.cc
>> index f30eb41..920514c 100644
>> --- a/gold/icf.cc
>> +++ b/gold/icf.cc
>> @@ -288,8 +288,7 @@ get_section_contents(bool first_iteration,
>>
>>        for (; it_v != v.end(); ++it_v, ++it_s, ++it_a, ++it_o, ++it_addend_size)
>>          {
>> -         if (first_iteration
>> -             && it_v->first != NULL)
>> +         if (it_v->first != NULL)
>>             {
>>               Symbol_location loc;
>>               loc.object = it_v->first;
>>
>> --
>> Alan Modra
>> Australia Development Lab, IBM

[-- Attachment #2: icf_fix.txt --]
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	* icf.cc (get_section_contents): Use references to reloc_info
	vectors to avoid copies.

Index: icf.cc
===================================================================
RCS file: /cvs/src/src/gold/icf.cc,v
retrieving revision 1.21
diff -u -p -r1.21 icf.cc
--- icf.cc	15 Mar 2013 07:51:32 -0000	1.21
+++ icf.cc	2 Apr 2014 19:08:28 -0000
@@ -269,15 +269,15 @@ get_section_contents(bool first_iteratio
 
   if (it_reloc_info_list != reloc_info_list.end())
     {
-      Icf::Sections_reachable_info v =
+      Icf::Sections_reachable_info &v =
         (it_reloc_info_list->second).section_info;
       // Stores the information of the symbol pointed to by the reloc.
-      Icf::Symbol_info s = (it_reloc_info_list->second).symbol_info;
+      Icf::Symbol_info &s = (it_reloc_info_list->second).symbol_info;
       // Stores the addend and the symbol value.
-      Icf::Addend_info a = (it_reloc_info_list->second).addend_info;
+      Icf::Addend_info &a = (it_reloc_info_list->second).addend_info;
       // Stores the offset of the reloc.
-      Icf::Offset_info o = (it_reloc_info_list->second).offset_info;
-      Icf::Reloc_addend_size_info reloc_addend_size_info =
+      Icf::Offset_info &o = (it_reloc_info_list->second).offset_info;
+      Icf::Reloc_addend_size_info &reloc_addend_size_info =
         (it_reloc_info_list->second).reloc_addend_size_info;
       Icf::Sections_reachable_info::iterator it_v = v.begin();
       Icf::Symbol_info::iterator it_s = s.begin();