[Mesa-dev] [PATCH 1/2] i965/fs: Constant-fold immediates in src0 of CMP instructions.

[Ian Romanick]

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On 04/09/2011 10:08 PM, Eric Anholt wrote:
> This is like what we do with add/mul, but we also have to flip the
> conditional test.

I assume this passes full piglit runs?  If so,

Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>

> ---
>  src/mesa/drivers/dri/i965/brw_eu.c   |   22 ++++++++++++++++++++++
>  src/mesa/drivers/dri/i965/brw_eu.h   |    2 ++
>  src/mesa/drivers/dri/i965/brw_fs.cpp |   21 +++++++++++++++++++++
>  3 files changed, 45 insertions(+), 0 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_eu.c b/src/mesa/drivers/dri/i965/brw_eu.c
> index 3b5c4c0..b59d6b2 100644
> --- a/src/mesa/drivers/dri/i965/brw_eu.c
> +++ b/src/mesa/drivers/dri/i965/brw_eu.c
> @@ -34,6 +34,28 @@
>  #include "brw_defines.h"
>  #include "brw_eu.h"
>  
> +/* Returns the corresponding conditional mod for swapping src0 and
> + * src1 in e.g. CMP.
> + */
> +uint32_t
> +brw_swap_cmod(uint32_t cmod)
> +{
> +   switch (cmod) {
> +   case BRW_CONDITIONAL_Z:
> +   case BRW_CONDITIONAL_NZ:
> +      return cmod;
> +   case BRW_CONDITIONAL_G:
> +      return BRW_CONDITIONAL_LE;
> +   case BRW_CONDITIONAL_GE:
> +      return BRW_CONDITIONAL_L;
> +   case BRW_CONDITIONAL_L:
> +      return BRW_CONDITIONAL_GE;
> +   case BRW_CONDITIONAL_LE:
> +      return BRW_CONDITIONAL_G;
> +   default:
> +      return ~0;
> +   }
> +}
>  
>  
>  /* How does predicate control work when execution_size != 8?  Do I
> diff --git a/src/mesa/drivers/dri/i965/brw_eu.h b/src/mesa/drivers/dri/i965/brw_eu.h
> index 2d2ed9d..c2e59c1 100644
> --- a/src/mesa/drivers/dri/i965/brw_eu.h
> +++ b/src/mesa/drivers/dri/i965/brw_eu.h
> @@ -1017,6 +1017,8 @@ void brw_set_src1( struct brw_instruction *insn,
>  
>  void brw_set_uip_jip(struct brw_compile *p);
>  
> +uint32_t brw_swap_cmod(uint32_t cmod);
> +
>  /* brw_optimize.c */
>  void brw_optimize(struct brw_compile *p);
>  void brw_remove_duplicate_mrf_moves(struct brw_compile *p);
> diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
> index 99cd8f8..128bbe9 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
> @@ -2938,12 +2938,33 @@ fs_visitor::propagate_constants()
>  		  progress = true;
>  	       }
>  	       break;
> +
>  	    case BRW_OPCODE_CMP:
> +	       if (i == 1) {
> +		  scan_inst->src[i] = inst->src[0];
> +		  progress = true;
> +	       } else if (i == 0 && scan_inst->src[1].file != IMM) {
> +		  uint32_t new_cmod;
> +
> +		  new_cmod = brw_swap_cmod(scan_inst->conditional_mod);
> +		  if (new_cmod != ~0u) {
> +		     /* Fit this constant in by swapping the operands and
> +		      * flipping the test
> +		      */
> +		     scan_inst->src[0] = scan_inst->src[1];
> +		     scan_inst->src[1] = inst->src[0];
> +		     scan_inst->conditional_mod = new_cmod;
> +		     progress = true;
> +		  }
> +	       }
> +	       break;
> +
>  	    case BRW_OPCODE_SEL:
>  	       if (i == 1) {
>  		  scan_inst->src[i] = inst->src[0];
>  		  progress = true;
>  	       }
> +	       break;
>  	    }
>  	 }
>  

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