This is the mail archive of the binutils@sourceware.org mailing list for the binutils project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH] x86: Expand Broadcast to 3 bits


>>> On 26.07.18 at 17:52, <hjl.tools@gmail.com> wrote:
> On Thu, Jul 26, 2018 at 8:47 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>>> On 26.07.18 at 17:02, <hjl.tools@gmail.com> wrote:
>>> On Thu, Jul 26, 2018 at 7:58 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>>>>> On 26.07.18 at 00:05, <hongjiu.lu@intel.com> wrote:
>>>>> @@ -5008,6 +5010,22 @@ optimize_disp (void)
>>>>>        }
>>>>>  }
>>>>>
>>>>> +/* Return 1 if there is a match in broadcast bytes between operand
>>>>> +   GIVEN and instruction template T.   */
>>>>> +
>>>>> +static INLINE int
>>>>> +match_broadcast_size (const insn_template *t, unsigned int given)
>>>>> +{
>>>>> +  return ((t->opcode_modifier.broadcast == BYTE_BROADCAST
>>>>> +        && i.types[given].bitfield.byte)
>>>>> +       || (t->opcode_modifier.broadcast == WORD_BROADCAST
>>>>> +           && i.types[given].bitfield.word)
>>>>> +       || (t->opcode_modifier.broadcast == DWORD_BROADCAST
>>>>> +           && i.types[given].bitfield.dword)
>>>>> +       || (t->opcode_modifier.broadcast == QWORD_BROADCAST
>>>>> +           && i.types[given].bitfield.qword));
>>>>> +}
>>>>> +
>>>>>  /* Check if operands are valid for the instruction.  */
>>>>>
>>>>>  static int
>>>>> @@ -5126,23 +5144,29 @@ check_VecOperands (const insn_template *t)
>>>>>        i386_operand_type type, overlap;
>>>>>
>>>>>        /* Check if specified broadcast is supported in this instruction,
>>>>> -      and it's applied to memory operand of DWORD or QWORD type.  */
>>>>> +      and its broadcast bytes match the memory operand.  */
>>>>>        op = i.broadcast->operand;
>>>>>        if (!t->opcode_modifier.broadcast
>>>>>         || !i.types[op].bitfield.mem
>>>>>         || (!i.types[op].bitfield.unspecified
>>>>> -           && (t->operand_types[op].bitfield.dword
>>>>> -               ? !i.types[op].bitfield.dword
>>>>> -               : !i.types[op].bitfield.qword)))
>>>>> +           && !match_broadcast_size (t, op)))
>>>>>       {
>>>>>       bad_broadcast:
>>>>>         i.error = unsupported_broadcast;
>>>>>         return 1;
>>>>>       }
>>>>>
>>>>> +      i.broadcast->bytes = ((1 << (t->opcode_modifier.broadcast - 1))
>>>>> +                         * i.broadcast->type);
>>>>
>>>> So if you moved this up ahead of the earlier if(), and if you used
>>>> i.broadcast->bytes in place of t->opcode_modifier.broadcast in
>>>> match_broadcast_size(), I think you could get away without the
>>>> extension to 3 bits in the templates.
>>>
>>> i.broadcast->bytes is set from t->opcode_modifier.broadcast.
>>> I'd like to avoid check byte, word, dword, qword to compute
>>> i.broadcast->bytes.
>>
>> And this is because of what? This is exactly the kind of redundancy
>> I'm talking about. Or are there going to be cases where the
>> broadcast element size is not the smallest among multiple possible
>> ones for a single template (but then your logic in i386-gen would
>> be wrong too)?
> 
> By definition, the broadcast element size is the smalltest non-vector
> size.

In which case my question stands - what you've said in your earlier
reply is because of what?

Jan



Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]