[Mesa-dev] [PATCH 2/2] R600: Add a pattern for fma (fused multiply add)

[Michel Dänzer]

On Don, 2013-02-07 at 17:23 -0500, Tom Stellard wrote: 
> From: Tom Stellard <thomas.stellard at amd.com>
> 
> NOTE: This is a candidate for the Mesa stable branches
> ---
>  lib/Target/R600/R600Instructions.td |    7 +++++++
>  1 files changed, 7 insertions(+), 0 deletions(-)
> 
> diff --git a/lib/Target/R600/R600Instructions.td b/lib/Target/R600/R600Instructions.td
> index d307ed2..07ee6f0 100644
> --- a/lib/Target/R600/R600Instructions.td
> +++ b/lib/Target/R600/R600Instructions.td
> @@ -1109,6 +1109,11 @@ class TGSI_LIT_Z_Common <InstR600 mul_lit, InstR600 log_clamped, InstR600 exp_ie
>    (exp_ieee (mul_lit (log_clamped (MAX R600_Reg32:$src_y, (f32 ZERO))), R600_Reg32:$src_w, R600_Reg32:$src_x))
>  >;
>  
> +class FMAPat <InstR600 muladd> : Pat<
> +  (fma R600_Reg32:$src0, R600_Reg32:$src1, R600_Reg32:$src2),
> +  (muladd R600_Reg32:$src0, R600_Reg32:$src1, R600_Reg32:$src2)
> +>;
> +
>  //===----------------------------------------------------------------------===//
>  // R600 / R700 Instructions
>  //===----------------------------------------------------------------------===//
> @@ -1167,6 +1172,7 @@ let Predicates = [isR600] in {
>      let Word1{31} = 1; // BARRIER
>    }
>    defm : SteamOutputExportPattern<R600_ExportBuf, 0x20, 0x21, 0x22, 0x23>;
> +  def : FMAPat <MULADD_r600>;
>  }
>  
>  // Helper pattern for normalizing inputs to triginomic instructions for R700+
> @@ -1320,6 +1326,7 @@ let hasSideEffects = 1 in {
>      let Word1{31} = 1; // BARRIER
>    }
>    defm : SteamOutputExportPattern<EG_ExportBuf, 0x40, 0x41, 0x42, 0x43>;
> +  def : FMAPat <MULADD_eg>;
>  
>  //===----------------------------------------------------------------------===//
>  // Memory read/write instructions

Do the MULADD instructions match the FMA semantics, i.e. they don't
round/truncate the intermediate product but only the final sum?


Patch 1 looks nice and is

Reviewed-by: Michel Dänzer <michel.daenzer at amd.com>


-- 
Earthling Michel Dänzer           |                   http://www.amd.com
Libre software enthusiast         |          Debian, X and DRI developer