Re: [PATCH] Support libcall __float{,un}sibf by SF when it is not supported for _bf16

[Jeff Law <jeffreyalaw@gmail.com>]

On 12/20/23 4:17 AM, Jin Ma wrote:
> We don't have SI -> BF library functions, use SI -> SF -> BF
> instead. Although this can also be implemented in a target
> machine description, it is more appropriate to move
> into target independent code.
> 
> gcc/ChangeLog:
> 
> 	* optabs.cc (expand_float): Split SI -> BF into SI -> SF -> BF.
> ---
>   gcc/optabs.cc | 13 +++++++++++++
>   1 file changed, 13 insertions(+)
> 
> diff --git a/gcc/optabs.cc b/gcc/optabs.cc
> index 6a34276c239..c58a0321bbd 100644
> --- a/gcc/optabs.cc
> +++ b/gcc/optabs.cc
> @@ -5727,6 +5727,19 @@ expand_float (rtx to, rtx from, int unsignedp)
>         if (is_narrower_int_mode (GET_MODE (from), SImode))
>   	from = convert_to_mode (SImode, from, unsignedp);
>   
> +#ifdef HAVE_SFmode
> +      if (REAL_MODE_FORMAT (GET_MODE (to)) == &arm_bfloat_half_format
> +	  && REAL_MODE_FORMAT (SFmode) == &ieee_single_format
> +	  && GET_MODE (from) == SImode)
> +	/* We don't have SI -> BF library functions, use SI -> SF -> BF
> +	   instead.  */
> +	{
> +	  target = gen_reg_rtx (SFmode);
> +	  expand_float (target, from, unsignedp);
> +	  goto done;
> +	}
> +#endif
Why do you have the #ifdef HAVE_SFmode?  That seems odd, I think the 
only place we do anything like that is in targhooks.  Why did you add 
those cpp conditionals?

Bring the comment "We don't have SI -> BF ..." inside the open curly and 
indent it two more spaces.  That should be more consistent with GCC style.

So generally OK.  I suspect this can move forward once we figure out why 
you added those cpp conditionals and fix the formatting nit.

jeff