Re: [PATCH] rs6000: Define movsf_from_si2 to extract high part SF element from DImode[PR89310]

[Segher Boessenkool <segher@kernel.crashing.org>]

On Mon, Jul 13, 2020 at 02:30:28PM +0800, luoxhu wrote:
> For extracting high part element from DImode register like:
> 
> {%1:SF=unspec[r122:DI>>0x20#0] 86;clobber scratch;}
> 
> split it before reload with "and mask" to avoid generating shift right
> 32 bit then shift left 32 bit.  This pattern also exists in PR42475 and
> PR67741, etc.
> 
> srdi 3,3,32
> sldi 9,3,32
> mtvsrd 1,9
> xscvspdpn 1,1
> 
> =>
> 
> rldicr 3,3,0,31
> mtvsrd 1,3
> xscvspdpn 1,1

> 	* config/rs6000/rs6000.md (movsf_from_si2): New
> 	define_insn_and_split.

(That fits on one line).

> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr89310.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2" } */

> +/* { dg-final { scan-assembler-not {\msrdi\M} } } */
> +/* { dg-final { scan-assembler-not {\msldi\M} } } */
> +/* { dg-final { scan-assembler-times {\mrldicr\M} 1 } } */

I'm not sure that works on older cpus?  Please test there, and add
-mdejagnu-cpu=power8 to the dg-options if needed.  Also test on BE please.

Okay for trunk with those last details taking care of.  Thank you!


Segher