Re: [PATCH] i386, expand: Optimize also 256-bit and 512-bit permutatations as vpmovzx if possible [PR95905]

[Jakub Jelinek via Gcc-patches]

On Wed, Jan 13, 2021 at 08:26:49AM +0100, Richard Biener wrote:
> +  if (op1 && op0 != op1)
> +    op1 = force_reg (vmode, op1);
> 
> code (presumably to handle RTX sharing here)?

That could be actually simplified, incrementally e.g. to:
   if (op0)
     {
       rtx nop0 = force_reg (vmode, op0);
       if (op0 == op1)
         op1 = nop0;
       op0 = nop0;
     }
-  if (op1 && op0 != op1)
+  if (op1)
     op1 = force_reg (vmode, op1);

(because the outer force_reg in force_reg (vmode, force_reg (vmode, X))
just returns its argument).

        Jakub