On 09/18/2015 06:21 AM, Ilya Enkovich wrote:
>>> +machine_mode
>>> +default_get_mask_mode (unsigned nunits, unsigned vector_size)
>>> +{
>>> + unsigned elem_size = vector_size / nunits;
>>> + machine_mode elem_mode
>>> + = smallest_mode_for_size (elem_size * BITS_PER_UNIT, MODE_INT);
>>
>> Why these arguments as opposed to passing elem_size? It seems that every
>> hook
>> is going to have to do this division...
>
> Every target would have nunits = vector_size / elem_size because
> nunits is used to create a vector mode. Thus no difference.
I meant passing nunits and elem_size, but not vector_size. Thus no division
required. If the target does require the vector size, it could be obtained by
multiplication, which is cheaper. But in cases like this we'd not require
either mult or div.
>>> @@ -1885,7 +1885,9 @@ expand_MASK_LOAD (gcall *stmt)
>>> create_output_operand (&ops[0], target, TYPE_MODE (type));
>>> create_fixed_operand (&ops[1], mem);
>>> create_input_operand (&ops[2], mask, TYPE_MODE (TREE_TYPE (maskt)));
>>> - expand_insn (optab_handler (maskload_optab, TYPE_MODE (type)), 3, ops);
>>> + expand_insn (convert_optab_handler (maskload_optab, TYPE_MODE (type),
>>> + TYPE_MODE (TREE_TYPE (maskt))),
>>> + 3, ops);
>>
>> Why do we now need a conversion here?
>
> Mask mode was implicit for masked loads and stores. Now it becomes
> explicit because we may load the same value using different masks.
> E.g. for i386 we may load 256bit vector using both vector and scalar
> masks.
Ok, sure, the mask mode is needed, I get that. But that doesn't answer the
question regarding conversion. Why would convert_optab_handler be needed to
*change* the mode of the mask. I assume that's not actually possible, with the
target hook already having chosen the proper mode for the mask.
r~
