[Mesa-dev] [PATCH] r300/compiler: simplify code in peephole_add_presub_add

[Tom Stellard]

This looks good, I'll test it when I get a chance.

-Tom

On Mon, Jul 18, 2011 at 07:14:06AM +0200, Tobias Droste wrote:
> Signed-off-by: Tobias Droste <tdroste at gmx.de>
> ---
>  .../drivers/dri/r300/compiler/radeon_optimize.c    |   35 ++++++++++---------
>  1 files changed, 18 insertions(+), 17 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/r300/compiler/radeon_optimize.c b/src/mesa/drivers/dri/r300/compiler/radeon_optimize.c
> index b242742..39dcb21 100644
> --- a/src/mesa/drivers/dri/r300/compiler/radeon_optimize.c
> +++ b/src/mesa/drivers/dri/r300/compiler/radeon_optimize.c
> @@ -561,28 +561,29 @@ static int peephole_add_presub_add(
>  	struct rc_instruction * inst_add)
>  {
>  	unsigned dstmask = inst_add->U.I.DstReg.WriteMask;
> -	struct rc_src_register * src1 = NULL;
> -	unsigned int i;
> -
> -	if (!is_presub_candidate(c, inst_add))
> -		return 0;
> +        unsigned src0_neg = inst_add->U.I.SrcReg[0].Negate & dstmask;
> +        unsigned src1_neg = inst_add->U.I.SrcReg[1].Negate & dstmask;
>  
>  	if (inst_add->U.I.SrcReg[0].Swizzle != inst_add->U.I.SrcReg[1].Swizzle)
>  		return 0;
>  
> -	/* XXX This isn't fully implemented, is it? */
> -	/*   src0 and src1 can't have absolute values only one can be negative and they must be all negative or all positive. */
> -	for (i = 0; i < 2; i++) {
> -		if (inst_add->U.I.SrcReg[i].Abs)
> -			return 0;
> +	/* src0 and src1 can't have absolute values */
> +	if (inst_add->U.I.SrcReg[0].Abs || inst_add->U.I.SrcReg[1].Abs)
> +	        return 0;
>  
> -		/* XXX This looks weird, but it's basically what was here before this commit (see git blame): */
> -		if ((inst_add->U.I.SrcReg[i].Negate & dstmask) != dstmask && !src1) {
> -			src1 = &inst_add->U.I.SrcReg[i];
> -		}
> -	}
> +	/* presub_replace_add() assumes only one is negative */
> +	if (inst_add->U.I.SrcReg[0].Negate && inst_add->U.I.SrcReg[1].Negate)
> +	        return 0;
> +
> +        /* if src0 is negative, at least all bits of dstmask have to be set */
> +        if (inst_add->U.I.SrcReg[0].Negate && src0_neg != dstmask)
> +	        return 0;
>  
> -	if (!src1)
> +        /* if src1 is negative, at least all bits of dstmask have to be set */
> +        if (inst_add->U.I.SrcReg[1].Negate && src1_neg != dstmask)
> +	        return 0;
> +
> +	if (!is_presub_candidate(c, inst_add))
>  		return 0;
>  
>  	if (presub_helper(c, inst_add, RC_PRESUB_ADD, presub_replace_add)) {
> @@ -615,7 +616,7 @@ static void presub_replace_inv(
>   * of the add instruction must have the constatnt 1 swizzle.  This function
>   * does not check const registers to see if their value is 1.0, so it should
>   * be called after the constant_folding optimization.
> - * @return 
> + * @return
>   * 	0 if the ADD instruction is still part of the program.
>   * 	1 if the ADD instruction is no longer part of the program.
>   */
> -- 
> 1.7.3.4
> 
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