Re: [PATCH, middle-end/RTL, i386]: Simplify nested VEC_SELECT RTX

[Uros Bizjak <ubizjak at gmail dot com>]

Andrew Pinski wrote:

> > This patch optimizes VEC_SELECT nested RTL expressions (with optional
> > VEC_CONCAT), when top VEC_SELECT extracts scalar operand.
>
> One comment, could you add a comment before:
> +      if (GET_CODE (trueop0) == VEC_SELECT)
>
> Explaining what is going to be tried to be folded?

Sure. Something like this?

     /* Extract a scalar element from a nested VEC_SELECT expression
        (with optional nested VEC_CONCAT expression).  Some targets
        (i386) extract scalar element from a vector using chain of
        nested VEC_SELECT expressions.  When input operand is a memory
        operand, this operation can be simplified to a simple scalar
        load from an offseted memory address.  */
     if (GET_CODE (trueop0) == VEC_SELECT)

Uros.