Enable EBX for x86 in 32bits PIC code

[Ilya Enkovich]

2014-08-28 1:39 GMT+04:00 Jeff Law <law@redhat.com>:
> On 08/26/14 15:42, Ilya Enkovich wrote:
>>
>> diff --git a/gcc/calls.c b/gcc/calls.c
>> index 4285ec1..85dae6b 100644
>> --- a/gcc/calls.c
>> +++ b/gcc/calls.c
>> @@ -1122,6 +1122,14 @@ initialize_argument_information (int num_actuals
>> ATTRIBUTE_UNUSED,
>>       call_expr_arg_iterator iter;
>>       tree arg;
>>
>> +    if (targetm.calls.implicit_pic_arg (fndecl ? fndecl : fntype))
>> +      {
>> +       gcc_assert (pic_offset_table_rtx);
>> +       args[j].tree_value = make_tree (ptr_type_node,
>> +                                       pic_offset_table_rtx);
>> +       j--;
>> +      }
>> +
>>       if (struct_value_addr_value)
>>         {
>>         args[j].tree_value = struct_value_addr_value;
>
> So why do you need this?  Can't this be handled in the call/call_value
> expanders or what about attaching the use to CALL_INSN_FUNCTION_USAGE from
> inside ix86_expand_call?  Basically I'm not seeing the need for another
> target hook here.  I think that would significantly simply the patch as
> well.

GOT base address become an additional implicit arg with EBX relaxed
and I handled it as all other args. I can move EBX initialization into
ix86_expand_call. Would still need some hint from target to init
pic_offset_table_rtx with proper value in the beginning of function
expand.

Thanks,
Ilya

>
>
> Jeff