Made one more change and New patch attached.

Thanks
Sri

On Fri, May 29, 2015 at 2:37 PM, Sriraman Tallam <tmsriram@google.com> wrote:
> On Fri, May 29, 2015 at 12:35 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
>>>       * config/i386/i386.c (avoid_plt_to_call): New function.
>>>       (ix86_output_call_insn): Generate indirect call for functions
>>>       marked with "noplt" attribute.
>>>       (attribute_spec ix86_attribute_): Define new attribute "noplt".
>>>       * doc/extend.texi: Document new attribute "noplt".
>>>       * gcc.target/i386/noplt-1.c: New testcase.
>>>       * gcc.target/i386/noplt-2.c: New testcase.
>>>
>>> Index: config/i386/i386.c
>>> ===================================================================
>>> --- config/i386/i386.c        (revision 223720)
>>> +++ config/i386/i386.c        (working copy)
>>> @@ -25599,6 +25599,24 @@ ix86_expand_call (rtx retval, rtx fnaddr, rtx call
>>>    return call;
>>>  }
>>>
>>> +/* Return true if the function being called was marked with attribute
>>> +   "noplt".  If this function is defined, this should return false.  */
>>> +static bool
>>> +avoid_plt_to_call (rtx call_op)
>>> +{
>>> +  if (SYMBOL_REF_LOCAL_P (call_op))
>>> +    return false;
>>> +
>>> +  tree symbol_decl = SYMBOL_REF_DECL (call_op);
>>> +
>>> +  if (symbol_decl != NULL_TREE
>>> +      && TREE_CODE (symbol_decl) == FUNCTION_DECL
>>> +      && lookup_attribute ("noplt", DECL_ATTRIBUTES (symbol_decl)))
>>> +    return true;
>>> +
>>> +  return false;
>>> +}
>>
>> OK, now we have __attribute__ (optimize("noplt")) which binds to the caller and makes
>> all calls in the function to skip PLT and __attribute__ ("noplt") which binds to callee
>> and makes all calls to function to not use PLT.
>>
>> That sort of makes sense to me, but why "noplt" attribute is not implemented at generic level
>> just like -fplt? Is it only because every target supporting PLT would need update in its
>> call expansion patterns?
>
> Yes, that is what I had in mind.
>
>>
>> Also I think the PLT calls have EBX in call fusage wich is added by ix86_expand_call.
>>   else
>>     {
>>       /* Static functions and indirect calls don't need the pic register.  */
>>       if (flag_pic
>>           && (!TARGET_64BIT
>>               || (ix86_cmodel == CM_LARGE_PIC
>>                   && DEFAULT_ABI != MS_ABI))
>>           && GET_CODE (XEXP (fnaddr, 0)) == SYMBOL_REF
>>           && ! SYMBOL_REF_LOCAL_P (XEXP (fnaddr, 0)))
>>         {
>>           use_reg (&use, gen_rtx_REG (Pmode, REAL_PIC_OFFSET_TABLE_REGNUM));
>>           if (ix86_use_pseudo_pic_reg ())
>>             emit_move_insn (gen_rtx_REG (Pmode, REAL_PIC_OFFSET_TABLE_REGNUM),
>>                             pic_offset_table_rtx);
>>         }
>>
>> I think you want to take that away from FUSAGE there just like we do for local calls
>> (and in fact the code should already check flag_pic && flag_plt I suppose.
>
> Done that now and patch attached.
>
> Thanks
> Sri
>
>>
>> Honza