[PATCH] R600/SI: implement range reduction for sin/cos

[Tom Stellard]

On Fri, Jun 20, 2014 at 07:27:11PM +0200, Grigori Goronzy wrote:
> These instructions can only take a limited input range, and return
> the constant value 1 out of range. We should do range reduction to
> be able to process arbitrary values. Use a FRACT instruction after
> normalization to achieve this.

There is code in R600ISelLowering.cpp that does something similar:
R600TargetLowering::LowerTrig().  Could we re-use that code here, or
implement something similar is SIISelLowering.cpp?

- Tom
> ---
>  lib/Target/R600/SIInstructions.td | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/Target/R600/SIInstructions.td b/lib/Target/R600/SIInstructions.td
> index f888b8e..2bdcfd2 100644
> --- a/lib/Target/R600/SIInstructions.td
> +++ b/lib/Target/R600/SIInstructions.td
> @@ -2253,12 +2253,12 @@ def : Pat<
>  
>  def : Pat <
>    (fcos f32:$src0),
> -  (V_COS_F32_e32 (V_MUL_F32_e32 $src0, (V_MOV_B32_e32 CONST.TWO_PI_INV)))
> +  (V_COS_F32_e32 (V_FRACT_F32_e32(V_MUL_F32_e32 $src0, (V_MOV_B32_e32 CONST.TWO_PI_INV))))
>  >;
>  
>  def : Pat <
>    (fsin f32:$src0),
> -  (V_SIN_F32_e32 (V_MUL_F32_e32 $src0, (V_MOV_B32_e32 CONST.TWO_PI_INV)))
> +  (V_SIN_F32_e32 (V_FRACT_F32_e32(V_MUL_F32_e32 $src0, (V_MOV_B32_e32 CONST.TWO_PI_INV))))
>  >;
>  
>  def : Pat <
> -- 
> 1.8.3.2
> 
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