[Mesa-dev] [PATCH] llvmpipe: get rid of barycentric calculation of a0

[Jose Fonseca]

----- Original Message -----
> From: Roland Scheidegger <sroland at vmware.com>
> 
> Didn't really work as well as hoped (in particular it was not generally
> more accurate), will solve this differently.
> ---
>  src/gallium/drivers/llvmpipe/lp_state_setup.c |   70
>  ++-----------------------
>  1 file changed, 4 insertions(+), 66 deletions(-)
> 
> diff --git a/src/gallium/drivers/llvmpipe/lp_state_setup.c
> b/src/gallium/drivers/llvmpipe/lp_state_setup.c
> index 9c17d76..1d79a4a 100644
> --- a/src/gallium/drivers/llvmpipe/lp_state_setup.c
> +++ b/src/gallium/drivers/llvmpipe/lp_state_setup.c
> @@ -49,16 +49,6 @@
>  #include "lp_state_fs.h"
>  #include "lp_state_setup.h"
>  
> -/*
> - * Set if the start point for interpolation should be calculated with a
> - * more accurate method (barycentric interpolation).
> - * Unfortunately, actual interpolation results of small tris with steep
> - * gradients far away from the origin are still very busted, this does
> - * nothing to change that (in fact it may make it worse), but some tests
> - * (don't ask) really want accurate values at origin (and ONLY origin).
> - */
> -#define ACCURATE_A0 0
> -
>  
>  /* currently organized to interpolate full float[4] attributes even
>   * when some elements are unused.  Later, can pack vertex data more
> @@ -86,9 +76,6 @@ struct lp_setup_args
>     LLVMValueRef dy01_ooa;
>     LLVMValueRef dx20_ooa;
>     LLVMValueRef dx01_ooa;
> -   LLVMValueRef e01o;
> -   LLVMValueRef e20o;
> -   LLVMValueRef e12o;
>     struct lp_build_context bld;
>  };
>  
> @@ -410,7 +397,6 @@ emit_coef4( struct gallivm_state *gallivm,
>              LLVMValueRef a2)
>  {
>     LLVMBuilderRef b = gallivm->builder;
> -   bool accurate_a0 = ACCURATE_A0;
>     LLVMValueRef attr_0;
>     LLVMValueRef dy20_ooa = args->dy20_ooa;
>     LLVMValueRef dy01_ooa = args->dy01_ooa;
> @@ -435,19 +421,10 @@ emit_coef4( struct gallivm_state *gallivm,
>  
>     /* Calculate a0 - the attribute value at the origin
>      */
> -   if (!accurate_a0) {
> -      LLVMValueRef dadx_x0    = LLVMBuildFMul(b, dadx, x0_center,
> "dadx_x0");
> -      LLVMValueRef dady_y0    = LLVMBuildFMul(b, dady, y0_center,
> "dady_y0");
> -      LLVMValueRef attr_v0    = LLVMBuildFAdd(b, dadx_x0, dady_y0,
> "attr_v0");
> -      attr_0                  = LLVMBuildFSub(b, a0, attr_v0, "attr_0");
> -   }
> -   else {
> -      LLVMValueRef ao2 = LLVMBuildFMul(b, args->e01o, a2, "");
> -      LLVMValueRef ao1 = LLVMBuildFMul(b, args->e20o, a1, "");
> -      LLVMValueRef ao0 = LLVMBuildFMul(b, args->e12o, a0, "");
> -      attr_0 = LLVMBuildFAdd(b, ao0, ao1, "");
> -      attr_0 = LLVMBuildFAdd(b, attr_0, ao2, "");
> -   }
> +   LLVMValueRef dadx_x0    = LLVMBuildFMul(b, dadx, x0_center, "dadx_x0");
> +   LLVMValueRef dady_y0    = LLVMBuildFMul(b, dady, y0_center, "dady_y0");
> +   LLVMValueRef attr_v0    = LLVMBuildFAdd(b, dadx_x0, dady_y0, "attr_v0");
> +   attr_0                  = LLVMBuildFSub(b, a0, attr_v0, "attr_0");
>  
>     store_coef(gallivm, args, slot, attr_0, dadx, dady);
>  }
> @@ -663,7 +640,6 @@ init_args(struct gallivm_state *gallivm,
>     LLVMValueRef attr_pos[3];
>     struct lp_type typef4 = lp_type_float_vec(32, 128);
>     struct lp_build_context bld;
> -   bool accurate_a0 = ACCURATE_A0;
>  
>     lp_build_context_init(&bld, gallivm, typef4);
>     args->bld = bld;
> @@ -708,44 +684,6 @@ init_args(struct gallivm_state *gallivm,
>     dxy20 = LLVMBuildFMul(b, dxy20, ooa, "");
>     dxy01 = LLVMBuildFMul(b, dxy01, ooa, "");
>  
> -   if (accurate_a0) {
> -      LLVMValueRef xy1xy2, xy1xy2_center, dxy12, dyx01, dyx12yx20;
> -      LLVMValueRef p0, p1p2, tmp0, tmp1, shuf0145, shuf1054, shuf1u3u;
> -
> -      shuffles[0] = zeroi;
> -      shuffles[1] = onei;
> -      shuffles[2] = lp_build_const_int32(gallivm, 4);
> -      shuffles[3] = lp_build_const_int32(gallivm, 5);
> -      shuf0145 = LLVMConstVector(shuffles, 4);
> -      shuffles[0] = onei;
> -      shuffles[1] = zeroi;
> -      shuffles[2] = lp_build_const_int32(gallivm, 5);
> -      shuffles[3] = lp_build_const_int32(gallivm, 4);
> -      shuf1054 = LLVMConstVector(shuffles, 4);
> -      shuffles[0] = onei;
> -      shuffles[1] = LLVMGetUndef(shuf_type);
> -      shuffles[2] = lp_build_const_int32(gallivm, 3);
> -      shuffles[3] = LLVMGetUndef(shuf_type);
> -      shuf1u3u = LLVMConstVector(shuffles, 4);
> -
> -      xy1xy2 = LLVMBuildShuffleVector(b, attr_pos[1], attr_pos[2], shuf0145,
> "");
> -      xy1xy2_center = LLVMBuildFSub(b, xy1xy2, pixel_center, "");
> -      dxy12 = LLVMBuildFSub(b, attr_pos[1], attr_pos[2], "dxy12");
> -      dxy12 = LLVMBuildFMul(b, dxy12, ooa, "");
> -      dyx12yx20 = LLVMBuildShuffleVector(b, dxy12, dxy20, shuf1054,
> "dyx12yx20");
> -      dyx01 = LLVMBuildShuffleVector(b, dxy01, dxy01, shuf10, "");
> -      p0 = LLVMBuildFMul(b, dyx01, xy0_center, "");
> -      p1p2 = LLVMBuildFMul(b, dyx12yx20, xy1xy2_center, "");
> -      tmp0 = LLVMBuildExtractElement(b, p0, zeroi, "");
> -      tmp1 = LLVMBuildExtractElement(b, p0, onei, "");
> -      args->e01o = lp_build_broadcast_scalar(&bld, LLVMBuildFSub(b, tmp0,
> tmp1, "e01o"));
> -      tmp1 = LLVMBuildShuffleVector(b, p1p2, p1p2, shuf1u3u, "");
> -      tmp0 = LLVMBuildFSub(b, p1p2, tmp1, "e12o20o");
> -      args->e12o = lp_build_extract_broadcast(gallivm, typef4, typef4, tmp0,
> zeroi);
> -      args->e20o = lp_build_extract_broadcast(gallivm, typef4, typef4, tmp0,
> -                                              lp_build_const_int32(gallivm,
> 2));
> -   }
> -
>     args->dy20_ooa  = lp_build_extract_broadcast(gallivm, typef4, typef4,
>     dxy20, onei);
>     args->dy01_ooa  = lp_build_extract_broadcast(gallivm, typef4, typef4,
>     dxy01, onei);
>  
> --
> 1.7.9.5
> 


Reviewed-by: Jose Fonseca <jfonseca at vmware.com>