src/gallium/drivers/llvmpipe/lp_bld_interp.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2009 VMware, Inc.
   4  * Copyright 2007-2008 Tungsten Graphics, Inc., Cedar Park, Texas.
   5  * All Rights Reserved.
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   7  * Permission is hereby granted, free of charge, to any person obtaining a
   8  * copy of this software and associated documentation files (the
   9  * "Software"), to deal in the Software without restriction, including
  10  * without limitation the rights to use, copy, modify, merge, publish,
  11  * distribute, sub license, and/or sell copies of the Software, and to
  12  * permit persons to whom the Software is furnished to do so, subject to
  13  * the following conditions:
  14  *
  15  * The above copyright notice and this permission notice (including the
  16  * next paragraph) shall be included in all copies or substantial portions
  17  * of the Software.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  20  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  21  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
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  23  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  24  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  25  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  26  *
  27  **************************************************************************/
  28
  29 /**
  30  * @file
  31  * Position and shader input interpolation.
  32  *
  33  * @author Jose Fonseca <jfonseca@vmware.com>
  34  */
  35
  36 #include "pipe/p_shader_tokens.h"
  37 #include "util/u_debug.h"
  38 #include "util/u_memory.h"
  39 #include "util/u_math.h"
  40 #include "tgsi/tgsi_parse.h"
  41 #include "gallivm/lp_bld_debug.h"
  42 #include "gallivm/lp_bld_const.h"
  43 #include "gallivm/lp_bld_arit.h"
  44 #include "gallivm/lp_bld_swizzle.h"
  45 #include "lp_bld_interp.h"
  46
  47
  48 /*
  49  * The shader JIT function operates on blocks of quads.
  50  * Each block has 2x2 quads and each quad has 2x2 pixels.
  51  *
  52  * We iterate over the quads in order 0, 1, 2, 3:
  53  *
  54  * #################
  55  * #   |   #   |   #
  56  * #---0---#---1---#
  57  * #   |   #   |   #
  58  * #################
  59  * #   |   #   |   #
  60  * #---2---#---3---#
  61  * #   |   #   |   #
  62  * #################
  63  *
  64  * Within each quad, we have four pixels which are represented in SOA
  65  * order:
  66  *
  67  * #########
  68  * # 0 | 1 #
  69  * #---+---#
  70  * # 2 | 3 #
  71  * #########
  72  *
  73  * So the green channel (for example) of the four pixels is stored in
  74  * a single vector register: {g0, g1, g2, g3}.
  75  */
  76
  77
  78 static void
  79 attrib_name(LLVMValueRef val, unsigned attrib, unsigned chan, const char *suffix)
  80 {
  81    if(attrib == 0)
  82       lp_build_name(val, "pos.%c%s", "xyzw"[chan], suffix);
  83    else
  84       lp_build_name(val, "input%u.%c%s", attrib - 1, "xyzw"[chan], suffix);
  85 }
  86
  87
  88 /**
  89  * Initialize the bld->a0, dadx, dady fields.  This involves fetching
  90  * those values from the arrays which are passed into the JIT function.
  91  */
  92 static void
  93 coeffs_init(struct lp_build_interp_soa_context *bld,
  94             LLVMValueRef a0_ptr,
  95             LLVMValueRef dadx_ptr,
  96             LLVMValueRef dady_ptr)
  97 {
  98    LLVMBuilderRef builder = bld->base.builder;
  99    unsigned attrib;
 100    unsigned chan;
 101
 102    for(attrib = 0; attrib < bld->num_attribs; ++attrib) {
 103       const unsigned mask = bld->mask[attrib];
 104       const unsigned interp = bld->interp[attrib];
 105       for(chan = 0; chan < NUM_CHANNELS; ++chan) {
 106          if(mask & (1 << chan)) {
 107             LLVMValueRef index = LLVMConstInt(LLVMInt32Type(), attrib*NUM_CHANNELS + chan, 0);
 108             LLVMValueRef a0 = NULL;
 109             LLVMValueRef dadx = NULL;
 110             LLVMValueRef dady = NULL;
 111
 112             switch( interp ) {
 113             case TGSI_INTERPOLATE_PERSPECTIVE:
 114                /* fall-through */
 115
 116             case TGSI_INTERPOLATE_LINEAR:
 117                dadx = LLVMBuildLoad(builder, LLVMBuildGEP(builder, dadx_ptr, &index, 1, ""), "");
 118                dady = LLVMBuildLoad(builder, LLVMBuildGEP(builder, dady_ptr, &index, 1, ""), "");
 119                dadx = lp_build_broadcast_scalar(&bld->base, dadx);
 120                dady = lp_build_broadcast_scalar(&bld->base, dady);
 121                attrib_name(dadx, attrib, chan, ".dadx");
 122                attrib_name(dady, attrib, chan, ".dady");
 123                /* fall-through */
 124
 125             case TGSI_INTERPOLATE_CONSTANT:
 126                a0 = LLVMBuildLoad(builder, LLVMBuildGEP(builder, a0_ptr, &index, 1, ""), "");
 127                a0 = lp_build_broadcast_scalar(&bld->base, a0);
 128                attrib_name(a0, attrib, chan, ".a0");
 129                break;
 130
 131             default:
 132                assert(0);
 133                break;
 134             }
 135
 136             bld->a0  [attrib][chan] = a0;
 137             bld->dadx[attrib][chan] = dadx;
 138             bld->dady[attrib][chan] = dady;
 139          }
 140       }
 141    }
 142 }
 143
 144
 145 /**
 146  * Emit LLVM code to compute the fragment shader input attribute values.
 147  * For example, for a color input, we'll compute red, green, blue and alpha
 148  * values for the four pixels in a quad.
 149  * Recall that we're operating on 4-element vectors so each arithmetic
 150  * operation is operating on the four pixels in a quad.
 151  */
 152 static void
 153 attribs_init(struct lp_build_interp_soa_context *bld)
 154 {
 155    LLVMValueRef x = bld->pos[0];
 156    LLVMValueRef y = bld->pos[1];
 157    LLVMValueRef oow = NULL;
 158    unsigned attrib;
 159    unsigned chan;
 160
 161    for(attrib = 0; attrib < bld->num_attribs; ++attrib) {
 162       const unsigned mask = bld->mask[attrib];
 163       const unsigned interp = bld->interp[attrib];
 164       for(chan = 0; chan < NUM_CHANNELS; ++chan) {
 165          if(mask & (1 << chan)) {
 166             LLVMValueRef a0   = bld->a0  [attrib][chan];
 167             LLVMValueRef dadx = bld->dadx[attrib][chan];
 168             LLVMValueRef dady = bld->dady[attrib][chan];
 169             LLVMValueRef res;
 170
 171             res = a0;
 172
 173             if (interp != TGSI_INTERPOLATE_CONSTANT) {
 174                /* res = res + x * dadx */
 175                res = lp_build_add(&bld->base, res, lp_build_mul(&bld->base, x, dadx));
 176                /* res = res + y * dady */
 177                res = lp_build_add(&bld->base, res, lp_build_mul(&bld->base, y, dady));
 178             }
 179
 180             /* Keep the value of the attribute before perspective divide
 181              * for faster updates.
 182              */
 183             bld->attribs_pre[attrib][chan] = res;
 184
 185             if (interp == TGSI_INTERPOLATE_PERSPECTIVE) {
 186                LLVMValueRef w = bld->pos[3];
 187                assert(attrib != 0);
 188                if(!oow)
 189                   oow = lp_build_rcp(&bld->base, w);
 190                res = lp_build_mul(&bld->base, res, oow);
 191             }
 192
 193             attrib_name(res, attrib, chan, "");
 194
 195             bld->attribs[attrib][chan] = res;
 196          }
 197       }
 198    }
 199 }
 200
 201
 202 /**
 203  * Increment the shader input attribute values.
 204  * This is called when we move from one quad to the next.
 205  */
 206 static void
 207 attribs_update(struct lp_build_interp_soa_context *bld, int quad_index)
 208 {
 209    LLVMValueRef oow = NULL;
 210    unsigned attrib;
 211    unsigned chan;
 212
 213    assert(quad_index < 4);
 214
 215    for(attrib = 0; attrib < bld->num_attribs; ++attrib) {
 216       const unsigned mask = bld->mask[attrib];
 217       const unsigned interp = bld->interp[attrib];
 218
 219       if (interp != TGSI_INTERPOLATE_CONSTANT) {
 220          for(chan = 0; chan < NUM_CHANNELS; ++chan) {
 221             if(mask & (1 << chan)) {
 222                LLVMValueRef dadx = bld->dadx[attrib][chan];
 223                LLVMValueRef dady = bld->dady[attrib][chan];
 224                LLVMValueRef res;
 225
 226                res = bld->attribs_pre[attrib][chan];
 227
 228                if (quad_index == 1 || quad_index == 3) {
 229                   /* top-right or bottom-right quad */
 230                   /* build res = res + dadx + dadx */
 231                   res = lp_build_add(&bld->base, res, dadx);
 232                   res = lp_build_add(&bld->base, res, dadx);
 233                }
 234
 235                if (quad_index == 2 || quad_index == 3) {
 236                   /* bottom-left or bottom-right quad */
 237                   /* build res = res + dady + dady */
 238                   res = lp_build_add(&bld->base, res, dady);
 239                   res = lp_build_add(&bld->base, res, dady);
 240                }
 241
 242                if (interp == TGSI_INTERPOLATE_PERSPECTIVE) {
 243                   LLVMValueRef w = bld->pos[3];
 244                   assert(attrib != 0);
 245                   if(!oow)
 246                      oow = lp_build_rcp(&bld->base, w);
 247                   res = lp_build_mul(&bld->base, res, oow);
 248                }
 249
 250                attrib_name(res, attrib, chan, "");
 251
 252                bld->attribs[attrib][chan] = res;
 253             }
 254          }
 255       }
 256    }
 257 }
 258
 259
 260 /**
 261  * Generate the position vectors.
 262  *
 263  * Parameter x0, y0 are the integer values with the quad upper left coordinates.
 264  */
 265 static void
 266 pos_init(struct lp_build_interp_soa_context *bld,
 267          LLVMValueRef x0,
 268          LLVMValueRef y0)
 269 {
 270    lp_build_name(x0, "pos.x");
 271    lp_build_name(y0, "pos.y");
 272
 273    bld->attribs[0][0] = x0;
 274    bld->attribs[0][1] = y0;
 275 }
 276
 277
 278 /**
 279  * Update quad position values when moving to the next quad.
 280  */
 281 static void
 282 pos_update(struct lp_build_interp_soa_context *bld, int quad_index)
 283 {
 284    LLVMValueRef x = bld->attribs[0][0];
 285    LLVMValueRef y = bld->attribs[0][1];
 286    const int xstep = 2, ystep = 2;
 287
 288    if (quad_index == 1 || quad_index == 3) {
 289       /* top-right or bottom-right quad in block */
 290       /* build x += xstep */
 291       x = lp_build_add(&bld->base, x,
 292                        lp_build_const_vec(bld->base.type, xstep));
 293    }
 294
 295    if (quad_index == 2) {
 296       /* bottom-left quad in block */
 297       /* build y += ystep */
 298       y = lp_build_add(&bld->base, y,
 299                        lp_build_const_vec(bld->base.type, ystep));
 300       /* build x -= xstep */
 301       x = lp_build_sub(&bld->base, x,
 302                        lp_build_const_vec(bld->base.type, xstep));
 303    }
 304
 305    lp_build_name(x, "pos.x");
 306    lp_build_name(y, "pos.y");
 307
 308    bld->attribs[0][0] = x;
 309    bld->attribs[0][1] = y;
 310 }
 311
 312
 313 /**
 314  * Initialize fragment shader input attribute info.
 315  */
 316 void
 317 lp_build_interp_soa_init(struct lp_build_interp_soa_context *bld,
 318                          const struct tgsi_token *tokens,
 319                          boolean flatshade,
 320                          LLVMBuilderRef builder,
 321                          struct lp_type type,
 322                          LLVMValueRef a0_ptr,
 323                          LLVMValueRef dadx_ptr,
 324                          LLVMValueRef dady_ptr,
 325                          LLVMValueRef x0,
 326                          LLVMValueRef y0)
 327 {
 328    struct tgsi_parse_context parse;
 329    struct tgsi_full_declaration *decl;
 330
 331    memset(bld, 0, sizeof *bld);
 332
 333    lp_build_context_init(&bld->base, builder, type);
 334
 335    /* For convenience */
 336    bld->pos = bld->attribs[0];
 337    bld->inputs = (const LLVMValueRef (*)[NUM_CHANNELS]) bld->attribs[1];
 338
 339    /* Position */
 340    bld->num_attribs = 1;
 341    bld->mask[0] = TGSI_WRITEMASK_ZW;
 342    bld->interp[0] = TGSI_INTERPOLATE_LINEAR;
 343
 344    /* Inputs */
 345    tgsi_parse_init( &parse, tokens );
 346    while( !tgsi_parse_end_of_tokens( &parse ) ) {
 347       tgsi_parse_token( &parse );
 348
 349       switch( parse.FullToken.Token.Type ) {
 350       case TGSI_TOKEN_TYPE_DECLARATION:
 351          decl = &parse.FullToken.FullDeclaration;
 352          if( decl->Declaration.File == TGSI_FILE_INPUT ) {
 353             unsigned first, last, mask;
 354             unsigned attrib;
 355
 356             first = decl->Range.First;
 357             last = decl->Range.Last;
 358             mask = decl->Declaration.UsageMask;
 359
 360             for( attrib = first; attrib <= last; ++attrib ) {
 361                bld->mask[1 + attrib] = mask;
 362
 363                /* XXX: have mesa set INTERP_CONSTANT in the fragment
 364                 * shader.
 365                 */
 366                if (decl->Semantic.Name == TGSI_SEMANTIC_COLOR &&
 367                    flatshade)
 368                   bld->interp[1 + attrib] = TGSI_INTERPOLATE_CONSTANT;
 369                else
 370                   bld->interp[1 + attrib] = decl->Declaration.Interpolate;
 371             }
 372
 373             bld->num_attribs = MAX2(bld->num_attribs, 1 + last + 1);
 374          }
 375          break;
 376
 377       case TGSI_TOKEN_TYPE_INSTRUCTION:
 378       case TGSI_TOKEN_TYPE_IMMEDIATE:
 379       case TGSI_TOKEN_TYPE_PROPERTY:
 380          break;
 381
 382       default:
 383          assert( 0 );
 384       }
 385    }
 386    tgsi_parse_free( &parse );
 387
 388    coeffs_init(bld, a0_ptr, dadx_ptr, dady_ptr);
 389
 390    pos_init(bld, x0, y0);
 391
 392    attribs_init(bld);
 393 }
 394
 395
 396 /**
 397  * Advance the position and inputs to the given quad within the block.
 398  */
 399 void
 400 lp_build_interp_soa_update(struct lp_build_interp_soa_context *bld,
 401                            int quad_index)
 402 {
 403    assert(quad_index < 4);
 404
 405    pos_update(bld, quad_index);
 406
 407    attribs_update(bld, quad_index);
 408 }