On Thu, Aug 28, 2014 at 2:54 PM, Ilya Enkovich <enkovich....@gmail.com> 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.
>>
>> Maybe you can you use get_hard_reg_initial_val for this?
>
> Actually there is no input hard reg holding GOT address. Currently I
> use initialization with ebx with following ebx initialization in
> prolog_epilog pass. But this is a temporary workaround. It is
> inefficient because always uses callee save reg to get GOT address. I
> suppose we should generate pseudo reg for pic_offset_table_rtx and
> also set_got with this register as a destination in expand pass.
> After register allocation set_got may be transformed into get_pc_thunk
> call with proper hard reg. But some target hook has to be used for
> this.
Let me expand my idea a bit. IIRC, get_hard_reg_initial_val and
friends will automatically emit intialization of a pseudo from
pic_offset_table_rtx hard reg. After reload, real initialization of
pic_offset_table_rtx hard reg is emitted in pro_and_epilogue pass. I
don't know if this works with current implementation of dynamic
pic_offset_table_rtx selection, though.
Uros.
