src/gallium/drivers/llvmpipe/lp_bld_blend_aos.c

/**************************************************************************
 *
 * Copyright 2009 VMware, Inc.
 * All Rights Reserved.
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 *
 * The above copyright notice and this permission notice (including the
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 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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/**
 * @file
 * Blend LLVM IR generation -- AoS layout.
 *
 * AoS blending is in general much slower than SoA, but there are some cases
 * where it might be faster. In particular, if a pixel is rendered only once
 * then the overhead of tiling and untiling will dominate over the speedup that
 * SoA gives. So we might want to detect such cases and fallback to AoS in the
 * future, but for now this function is here for historical/benchmarking
 * purposes.
 *
 * Run lp_blend_test after any change to this file.
 *
 * @author Jose Fonseca <jfonseca@vmware.com>
 */


#include "pipe/p_state.h"

#include "lp_bld_type.h"
#include "lp_bld_const.h"
#include "lp_bld_arit.h"
#include "lp_bld_logic.h"
#include "lp_bld_swizzle.h"
#include "lp_bld_blend.h"
#include "lp_bld_debug.h"


/**
 * We may the same values several times, so we keep them here to avoid
 * recomputing them. Also reusing the values allows us to do simplifications
 * that LLVM optimization passes wouldn't normally be able to do.
 */
struct lp_build_blend_aos_context
{
   struct lp_build_context base;
   
   LLVMValueRef src;
   LLVMValueRef dst;
   LLVMValueRef const_;

   LLVMValueRef inv_src;
   LLVMValueRef inv_dst;
   LLVMValueRef inv_const;
   LLVMValueRef saturate;

   LLVMValueRef rgb_src_factor;
   LLVMValueRef alpha_src_factor;
   LLVMValueRef rgb_dst_factor;
   LLVMValueRef alpha_dst_factor;
};


static LLVMValueRef
lp_build_blend_factor_unswizzled(struct lp_build_blend_aos_context *bld,
                                 unsigned factor,
                                 boolean alpha)
{
   switch (factor) {
   case PIPE_BLENDFACTOR_ZERO:
      return bld->base.zero;
   case PIPE_BLENDFACTOR_ONE:
      return bld->base.one;
   case PIPE_BLENDFACTOR_SRC_COLOR:
   case PIPE_BLENDFACTOR_SRC_ALPHA:
      return bld->src;
   case PIPE_BLENDFACTOR_DST_COLOR:
   case PIPE_BLENDFACTOR_DST_ALPHA:
      return bld->dst;
   case PIPE_BLENDFACTOR_SRC_ALPHA_SATURATE:
      if(alpha)
         return bld->base.one;
      else {
         if(!bld->inv_dst)
            bld->inv_dst = lp_build_comp(&bld->base, bld->dst);
         if(!bld->saturate)
            bld->saturate = lp_build_min(&bld->base, bld->src, bld->inv_dst);
         return bld->saturate;
      }
   case PIPE_BLENDFACTOR_CONST_COLOR:
   case PIPE_BLENDFACTOR_CONST_ALPHA:
      return bld->const_;
   case PIPE_BLENDFACTOR_SRC1_COLOR:
   case PIPE_BLENDFACTOR_SRC1_ALPHA:
      /* TODO */
      assert(0);
      return bld->base.zero;
   case PIPE_BLENDFACTOR_INV_SRC_COLOR:
   case PIPE_BLENDFACTOR_INV_SRC_ALPHA:
      if(!bld->inv_src)
         bld->inv_src = lp_build_comp(&bld->base, bld->src);
      return bld->inv_src;
   case PIPE_BLENDFACTOR_INV_DST_COLOR:
   case PIPE_BLENDFACTOR_INV_DST_ALPHA:
      if(!bld->inv_dst)
         bld->inv_dst = lp_build_comp(&bld->base, bld->dst);
      return bld->inv_dst;
   case PIPE_BLENDFACTOR_INV_CONST_COLOR:
   case PIPE_BLENDFACTOR_INV_CONST_ALPHA:
      if(!bld->inv_const)
         bld->inv_const = lp_build_comp(&bld->base, bld->const_);
      return bld->inv_const;
   case PIPE_BLENDFACTOR_INV_SRC1_COLOR:
   case PIPE_BLENDFACTOR_INV_SRC1_ALPHA:
      /* TODO */
      assert(0);
      return bld->base.zero;
   default:
      assert(0);
      return bld->base.zero;
   }
}


enum lp_build_blend_swizzle {
   LP_BUILD_BLEND_SWIZZLE_RGBA = 0,
   LP_BUILD_BLEND_SWIZZLE_AAAA = 1,
};


/**
 * How should we shuffle the base factor.
 */
static enum lp_build_blend_swizzle
lp_build_blend_factor_swizzle(unsigned factor)
{
   switch (factor) {
   case PIPE_BLENDFACTOR_ONE:
   case PIPE_BLENDFACTOR_ZERO:
   case PIPE_BLENDFACTOR_SRC_COLOR:
   case PIPE_BLENDFACTOR_DST_COLOR:
   case PIPE_BLENDFACTOR_CONST_COLOR:
   case PIPE_BLENDFACTOR_SRC1_COLOR:
   case PIPE_BLENDFACTOR_INV_SRC_COLOR:
   case PIPE_BLENDFACTOR_INV_DST_COLOR:
   case PIPE_BLENDFACTOR_INV_CONST_COLOR:
   case PIPE_BLENDFACTOR_INV_SRC1_COLOR:
      return LP_BUILD_BLEND_SWIZZLE_RGBA;
   case PIPE_BLENDFACTOR_SRC_ALPHA:
   case PIPE_BLENDFACTOR_DST_ALPHA:
   case PIPE_BLENDFACTOR_SRC_ALPHA_SATURATE:
   case PIPE_BLENDFACTOR_SRC1_ALPHA:
   case PIPE_BLENDFACTOR_CONST_ALPHA:
   case PIPE_BLENDFACTOR_INV_SRC_ALPHA:
   case PIPE_BLENDFACTOR_INV_DST_ALPHA:
   case PIPE_BLENDFACTOR_INV_CONST_ALPHA:
   case PIPE_BLENDFACTOR_INV_SRC1_ALPHA:
      return LP_BUILD_BLEND_SWIZZLE_AAAA;
   default:
      assert(0);
      return LP_BUILD_BLEND_SWIZZLE_RGBA;
   }
}


static LLVMValueRef
lp_build_blend_swizzle(struct lp_build_blend_aos_context *bld,
                       LLVMValueRef rgb, 
                       LLVMValueRef alpha, 
                       enum lp_build_blend_swizzle rgb_swizzle,
                       unsigned alpha_swizzle)
{
   if(rgb == alpha) {
      if(rgb_swizzle == LP_BUILD_BLEND_SWIZZLE_RGBA)
         return rgb;
      if(rgb_swizzle == LP_BUILD_BLEND_SWIZZLE_AAAA)
         return lp_build_broadcast_aos(&bld->base, rgb, alpha_swizzle);
   }
   else {
      if(rgb_swizzle == LP_BUILD_BLEND_SWIZZLE_RGBA) {
         boolean cond[4] = {0, 0, 0, 0};
         cond[alpha_swizzle] = 1;
         return lp_build_select_aos(&bld->base, alpha, rgb, cond);
      }
      if(rgb_swizzle == LP_BUILD_BLEND_SWIZZLE_AAAA) {
         unsigned char swizzle[4];
         swizzle[0] = alpha_swizzle;
         swizzle[1] = alpha_swizzle;
         swizzle[2] = alpha_swizzle;
         swizzle[3] = alpha_swizzle;
         swizzle[alpha_swizzle] += 4;
         return lp_build_swizzle2_aos(&bld->base, rgb, alpha, swizzle);
      }
   }
   assert(0);
   return bld->base.undef;
}


/**
 * @sa http://www.opengl.org/sdk/docs/man/xhtml/glBlendFuncSeparate.xml
 */
static LLVMValueRef
lp_build_blend_factor(struct lp_build_blend_aos_context *bld,
                      LLVMValueRef factor1,
                      unsigned rgb_factor,
                      unsigned alpha_factor,
                      unsigned alpha_swizzle)
{
   LLVMValueRef rgb_factor_;
   LLVMValueRef alpha_factor_;
   LLVMValueRef factor2;
   enum lp_build_blend_swizzle rgb_swizzle;

   rgb_factor_   = lp_build_blend_factor_unswizzled(bld, rgb_factor,   FALSE);
   alpha_factor_ = lp_build_blend_factor_unswizzled(bld, alpha_factor, TRUE);

   rgb_swizzle = lp_build_blend_factor_swizzle(rgb_factor);

   factor2 = lp_build_blend_swizzle(bld, rgb_factor_, alpha_factor_, rgb_swizzle, alpha_swizzle);

   return lp_build_mul(&bld->base, factor1, factor2);
}


boolean
lp_build_blend_func_commutative(unsigned func)
{
   switch (func) {
   case PIPE_BLEND_ADD:
   case PIPE_BLEND_MIN:
   case PIPE_BLEND_MAX:
      return TRUE;
   case PIPE_BLEND_SUBTRACT:
   case PIPE_BLEND_REVERSE_SUBTRACT:
      return FALSE;
   default:
      assert(0);
      return TRUE;
   }
}


boolean
lp_build_blend_func_reverse(unsigned rgb_func, unsigned alpha_func)
{
   if(rgb_func == alpha_func)
      return FALSE;
   if(rgb_func == PIPE_BLEND_SUBTRACT && alpha_func == PIPE_BLEND_REVERSE_SUBTRACT)
      return TRUE;
   if(rgb_func == PIPE_BLEND_REVERSE_SUBTRACT && alpha_func == PIPE_BLEND_SUBTRACT)
      return TRUE;
   return FALSE;
}


/**
 * @sa http://www.opengl.org/sdk/docs/man/xhtml/glBlendEquationSeparate.xml
 */
LLVMValueRef
lp_build_blend_func(struct lp_build_context *bld,
                    unsigned func,
                    LLVMValueRef term1, 
                    LLVMValueRef term2)
{
   switch (func) {
   case PIPE_BLEND_ADD:
      return lp_build_add(bld, term1, term2);
      break;
   case PIPE_BLEND_SUBTRACT:
      return lp_build_sub(bld, term1, term2);
   case PIPE_BLEND_REVERSE_SUBTRACT:
      return lp_build_sub(bld, term2, term1);
   case PIPE_BLEND_MIN:
      return lp_build_min(bld, term1, term2);
   case PIPE_BLEND_MAX:
      return lp_build_max(bld, term1, term2);
   default:
      assert(0);
      return bld->zero;
   }
}


LLVMValueRef
lp_build_blend_aos(LLVMBuilderRef builder,
                   const struct pipe_blend_state *blend,
                   struct lp_type type,
                   LLVMValueRef src,
                   LLVMValueRef dst,
                   LLVMValueRef const_,
                   unsigned alpha_swizzle)
{
   struct lp_build_blend_aos_context bld;
   LLVMValueRef src_term;
   LLVMValueRef dst_term;

   /* FIXME */
   assert(blend->colormask == 0xf);

   if(!blend->blend_enable)
      return src;

   /* It makes no sense to blend unless values are normalized */
   assert(type.norm);

   /* Setup build context */
   memset(&bld, 0, sizeof bld);
   lp_build_context_init(&bld.base, builder, type);
   bld.src = src;
   bld.dst = dst;
   bld.const_ = const_;

   /* TODO: There are still a few optimization opportunities here. For certain
    * combinations it is possible to reorder the operations and therefore saving
    * some instructions. */

   src_term = lp_build_blend_factor(&bld, src, blend->rgb_src_factor, blend->alpha_src_factor, alpha_swizzle);
   dst_term = lp_build_blend_factor(&bld, dst, blend->rgb_dst_factor, blend->alpha_dst_factor, alpha_swizzle);

   lp_build_name(src_term, "src_term");
   lp_build_name(dst_term, "dst_term");

   if(blend->rgb_func == blend->alpha_func) {
      return lp_build_blend_func(&bld.base, blend->rgb_func, src_term, dst_term);
   }
   else {
      /* Seperate RGB / A functions */

      LLVMValueRef rgb;
      LLVMValueRef alpha;

      rgb   = lp_build_blend_func(&bld.base, blend->rgb_func,   src_term, dst_term);
      alpha = lp_build_blend_func(&bld.base, blend->alpha_func, src_term, dst_term);

      return lp_build_blend_swizzle(&bld, rgb, alpha, LP_BUILD_BLEND_SWIZZLE_RGBA, alpha_swizzle);
   }
}