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[PATCH] x86: Expand Broadcast to 3 bits

Jan Beulich JBeulich@suse.com
Thu Jul 26 15:02:00 GMT 2018 
>>> 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.

Also, wouldn't you better clear ->bytes again in case the function later
returns an error, leading to the next template to be looked at?

Jan
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