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.
   6  *
   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.
  22  * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
  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_scan.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 const unsigned char quad_offset_x[4] = {0, 1, 0, 1};
  79 static const unsigned char quad_offset_y[4] = {0, 0, 1, 1};
  80
  81
  82 static void
  83 attrib_name(LLVMValueRef val, unsigned attrib, unsigned chan, const char *suffix)
  84 {
  85    if(attrib == 0)
  86       lp_build_name(val, "pos.%c%s", "xyzw"[chan], suffix);
  87    else
  88       lp_build_name(val, "input%u.%c%s", attrib - 1, "xyzw"[chan], suffix);
  89 }
  90
  91
  92 /**
  93  * Initialize the bld->a0, dadx, dady fields.  This involves fetching
  94  * those values from the arrays which are passed into the JIT function.
  95  */
  96 static void
  97 coeffs_init(struct lp_build_interp_soa_context *bld,
  98             LLVMValueRef a0_ptr,
  99             LLVMValueRef dadx_ptr,
 100             LLVMValueRef dady_ptr)
 101 {
 102    struct lp_build_context *coeff_bld = &bld->coeff_bld;
 103    LLVMBuilderRef builder = coeff_bld->builder;
 104    unsigned attrib;
 105    unsigned chan;
 106
 107    for(attrib = 0; attrib < bld->num_attribs; ++attrib) {
 108       const unsigned mask = bld->mask[attrib];
 109       const unsigned interp = bld->interp[attrib];
 110       for(chan = 0; chan < NUM_CHANNELS; ++chan) {
 111          if(mask & (1 << chan)) {
 112             LLVMValueRef index = LLVMConstInt(LLVMInt32Type(), attrib*NUM_CHANNELS + chan, 0);
 113             LLVMValueRef a0 = coeff_bld->undef;
 114             LLVMValueRef dadx = coeff_bld->undef;
 115             LLVMValueRef dady = coeff_bld->undef;
 116
 117             switch( interp ) {
 118             case LP_INTERP_PERSPECTIVE:
 119                /* fall-through */
 120
 121             case LP_INTERP_LINEAR:
 122                dadx = LLVMBuildLoad(builder, LLVMBuildGEP(builder, dadx_ptr, &index, 1, ""), "");
 123                dady = LLVMBuildLoad(builder, LLVMBuildGEP(builder, dady_ptr, &index, 1, ""), "");
 124                dadx = lp_build_broadcast_scalar(coeff_bld, dadx);
 125                dady = lp_build_broadcast_scalar(coeff_bld, dady);
 126                attrib_name(dadx, attrib, chan, ".dadx");
 127                attrib_name(dady, attrib, chan, ".dady");
 128                /* fall-through */
 129
 130             case LP_INTERP_CONSTANT:
 131             case LP_INTERP_FACING:
 132                a0 = LLVMBuildLoad(builder, LLVMBuildGEP(builder, a0_ptr, &index, 1, ""), "");
 133                a0 = lp_build_broadcast_scalar(coeff_bld, a0);
 134                attrib_name(a0, attrib, chan, ".a0");
 135                break;
 136
 137             case LP_INTERP_POSITION:
 138                /* Nothing to do as the position coeffs are already setup in slot 0 */
 139                break;
 140
 141             default:
 142                assert(0);
 143                break;
 144             }
 145
 146             bld->a0  [attrib][chan] = a0;
 147             bld->dadx[attrib][chan] = dadx;
 148             bld->dady[attrib][chan] = dady;
 149          }
 150       }
 151    }
 152 }
 153
 154
 155 /**
 156  * Emit LLVM code to compute the fragment shader input attribute values.
 157  * For example, for a color input, we'll compute red, green, blue and alpha
 158  * values for the four pixels in a quad.
 159  * Recall that we're operating on 4-element vectors so each arithmetic
 160  * operation is operating on the four pixels in a quad.
 161  */
 162 static void
 163 attribs_init(struct lp_build_interp_soa_context *bld)
 164 {
 165    struct lp_build_context *coeff_bld = &bld->coeff_bld;
 166    LLVMValueRef x = bld->pos[0];
 167    LLVMValueRef y = bld->pos[1];
 168    LLVMValueRef oow = NULL;
 169    unsigned attrib;
 170    unsigned chan;
 171
 172    for(attrib = 0; attrib < bld->num_attribs; ++attrib) {
 173       const unsigned mask = bld->mask[attrib];
 174       const unsigned interp = bld->interp[attrib];
 175       for(chan = 0; chan < NUM_CHANNELS; ++chan) {
 176          if(mask & (1 << chan)) {
 177             if (interp == LP_INTERP_POSITION) {
 178                assert(attrib > 0);
 179                bld->attribs[attrib][chan] = bld->attribs[0][chan];
 180             }
 181             else {
 182                LLVMValueRef a0   = bld->a0  [attrib][chan];
 183                LLVMValueRef dadx = bld->dadx[attrib][chan];
 184                LLVMValueRef dady = bld->dady[attrib][chan];
 185                LLVMValueRef res;
 186
 187                res = a0;
 188
 189                if (interp != LP_INTERP_CONSTANT &&
 190                    interp != LP_INTERP_FACING) {
 191                   /* res = res + x * dadx */
 192                   res = lp_build_add(coeff_bld, res, lp_build_mul(coeff_bld, x, dadx));
 193                   /* res = res + y * dady */
 194                   res = lp_build_add(coeff_bld, res, lp_build_mul(coeff_bld, y, dady));
 195                }
 196
 197                /* Keep the value of the attribute before perspective divide
 198                 * for faster updates.
 199                 */
 200                bld->attribs_pre[attrib][chan] = res;
 201
 202                if (interp == LP_INTERP_PERSPECTIVE) {
 203                   LLVMValueRef w = bld->pos[3];
 204                   assert(attrib != 0);
 205                   assert(bld->mask[0] & TGSI_WRITEMASK_W);
 206                   if(!oow)
 207                      oow = lp_build_rcp(coeff_bld, w);
 208                   res = lp_build_mul(coeff_bld, res, oow);
 209                }
 210
 211                attrib_name(res, attrib, chan, "");
 212
 213                bld->attribs[attrib][chan] = res;
 214             }
 215          }
 216       }
 217    }
 218 }
 219
 220
 221 /**
 222  * Increment the shader input attribute values.
 223  * This is called when we move from one quad to the next.
 224  */
 225 static void
 226 attribs_update(struct lp_build_interp_soa_context *bld, int quad_index)
 227 {
 228    struct lp_build_context *coeff_bld = &bld->coeff_bld;
 229    LLVMValueRef oow = NULL;
 230    unsigned attrib;
 231    unsigned chan;
 232
 233    assert(quad_index < 4);
 234
 235    for(attrib = 0; attrib < bld->num_attribs; ++attrib) {
 236       const unsigned mask = bld->mask[attrib];
 237       const unsigned interp = bld->interp[attrib];
 238
 239       if (interp != LP_INTERP_CONSTANT &&
 240           interp != LP_INTERP_FACING) {
 241          for(chan = 0; chan < NUM_CHANNELS; ++chan) {
 242             if(mask & (1 << chan)) {
 243                if (interp == LP_INTERP_POSITION) {
 244                   assert(attrib > 0);
 245                   bld->attribs[attrib][chan] = bld->attribs[0][chan];
 246                }
 247                else {
 248                   LLVMValueRef dadx = bld->dadx[attrib][chan];
 249                   LLVMValueRef dady = bld->dady[attrib][chan];
 250                   LLVMValueRef res;
 251
 252                   res = bld->attribs_pre[attrib][chan];
 253
 254                   if (quad_index == 1 || quad_index == 3) {
 255                      /* top-right or bottom-right quad */
 256                      /* build res = res + dadx + dadx */
 257                      res = lp_build_add(coeff_bld, res, dadx);
 258                      res = lp_build_add(coeff_bld, res, dadx);
 259                   }
 260
 261                   if (quad_index == 2 || quad_index == 3) {
 262                      /* bottom-left or bottom-right quad */
 263                      /* build res = res + dady + dady */
 264                      res = lp_build_add(coeff_bld, res, dady);
 265                      res = lp_build_add(coeff_bld, res, dady);
 266                   }
 267
 268                   if (interp == LP_INTERP_PERSPECTIVE) {
 269                      LLVMValueRef w = bld->pos[3];
 270                      assert(attrib != 0);
 271                      assert(bld->mask[0] & TGSI_WRITEMASK_W);
 272                      if(!oow)
 273                         oow = lp_build_rcp(coeff_bld, w);
 274                      res = lp_build_mul(coeff_bld, res, oow);
 275                   }
 276
 277                   attrib_name(res, attrib, chan, "");
 278
 279                   bld->attribs[attrib][chan] = res;
 280                }
 281             }
 282          }
 283       }
 284    }
 285 }
 286
 287
 288 /**
 289  * Generate the position vectors.
 290  *
 291  * Parameter x0, y0 are the integer values with upper left coordinates.
 292  */
 293 static void
 294 pos_init(struct lp_build_interp_soa_context *bld,
 295          LLVMValueRef x0,
 296          LLVMValueRef y0)
 297 {
 298    struct lp_build_context *coeff_bld = &bld->coeff_bld;
 299    LLVMValueRef x_offsets[QUAD_SIZE];
 300    LLVMValueRef y_offsets[QUAD_SIZE];
 301    unsigned i;
 302
 303    /*
 304     * Derive from the quad's upper left scalar coordinates the coordinates for
 305     * all other quad pixels
 306     */
 307
 308    x0 = lp_build_broadcast(coeff_bld->builder, coeff_bld->int_vec_type, x0);
 309    y0 = lp_build_broadcast(coeff_bld->builder, coeff_bld->int_vec_type, y0);
 310
 311    for(i = 0; i < QUAD_SIZE; ++i) {
 312       x_offsets[i] = LLVMConstInt(coeff_bld->int_elem_type, quad_offset_x[i], 0);
 313       y_offsets[i] = LLVMConstInt(coeff_bld->int_elem_type, quad_offset_y[i], 0);
 314    }
 315
 316    x0 = LLVMBuildAdd(coeff_bld->builder, x0, LLVMConstVector(x_offsets, QUAD_SIZE), "");
 317    y0 = LLVMBuildAdd(coeff_bld->builder, y0, LLVMConstVector(y_offsets, QUAD_SIZE), "");
 318
 319    x0 = LLVMBuildSIToFP(coeff_bld->builder, x0, coeff_bld->vec_type, "");
 320    y0 = LLVMBuildSIToFP(coeff_bld->builder, y0, coeff_bld->vec_type, "");
 321
 322    lp_build_name(x0, "pos.x");
 323    lp_build_name(y0, "pos.y");
 324
 325    bld->attribs[0][0] = x0;
 326    bld->attribs[0][1] = y0;
 327 }
 328
 329
 330 /**
 331  * Update quad position values when moving to the next quad.
 332  */
 333 static void
 334 pos_update(struct lp_build_interp_soa_context *bld, int quad_index)
 335 {
 336    struct lp_build_context *coeff_bld = &bld->coeff_bld;
 337    LLVMValueRef x = bld->attribs[0][0];
 338    LLVMValueRef y = bld->attribs[0][1];
 339    const int xstep = 2, ystep = 2;
 340
 341    if (quad_index == 1 || quad_index == 3) {
 342       /* top-right or bottom-right quad in block */
 343       /* build x += xstep */
 344       x = lp_build_add(coeff_bld, x,
 345                        lp_build_const_vec(coeff_bld->type, xstep));
 346    }
 347
 348    if (quad_index == 2) {
 349       /* bottom-left quad in block */
 350       /* build y += ystep */
 351       y = lp_build_add(coeff_bld, y,
 352                        lp_build_const_vec(coeff_bld->type, ystep));
 353       /* build x -= xstep */
 354       x = lp_build_sub(coeff_bld, x,
 355                        lp_build_const_vec(coeff_bld->type, xstep));
 356    }
 357
 358    lp_build_name(x, "pos.x");
 359    lp_build_name(y, "pos.y");
 360
 361    bld->attribs[0][0] = x;
 362    bld->attribs[0][1] = y;
 363 }
 364
 365
 366 /**
 367  * Initialize fragment shader input attribute info.
 368  */
 369 void
 370 lp_build_interp_soa_init(struct lp_build_interp_soa_context *bld,
 371                          unsigned num_inputs,
 372                          const struct lp_shader_input *inputs,
 373                          LLVMBuilderRef builder,
 374                          struct lp_type type,
 375                          LLVMValueRef a0_ptr,
 376                          LLVMValueRef dadx_ptr,
 377                          LLVMValueRef dady_ptr,
 378                          LLVMValueRef x0,
 379                          LLVMValueRef y0)
 380 {
 381    struct lp_type coeff_type;
 382    unsigned attrib;
 383    unsigned chan;
 384
 385    memset(bld, 0, sizeof *bld);
 386
 387    memset(&coeff_type, 0, sizeof coeff_type);
 388    coeff_type.floating = TRUE;
 389    coeff_type.sign = TRUE;
 390    coeff_type.width = 32;
 391    coeff_type.length = QUAD_SIZE;
 392
 393    /* XXX: we don't support interpolating into any other types */
 394    assert(memcmp(&coeff_type, &type, sizeof &coeff_type) == 0);
 395
 396    lp_build_context_init(&bld->coeff_bld, builder, coeff_type);
 397
 398    /* For convenience */
 399    bld->pos = bld->attribs[0];
 400    bld->inputs = (const LLVMValueRef (*)[NUM_CHANNELS]) bld->attribs[1];
 401
 402    /* Position */
 403    bld->num_attribs = 1;
 404    bld->mask[0] = TGSI_WRITEMASK_ZW;
 405    bld->interp[0] = LP_INTERP_LINEAR;
 406
 407    /* Inputs */
 408    for (attrib = 0; attrib < num_inputs; ++attrib) {
 409       bld->mask[1 + attrib] = inputs[attrib].usage_mask;
 410       bld->interp[1 + attrib] = inputs[attrib].interp;
 411    }
 412    bld->num_attribs = 1 + num_inputs;
 413
 414    /* Ensure all masked out input channels have a valid value */
 415    for (attrib = 0; attrib < bld->num_attribs; ++attrib) {
 416       for (chan = 0; chan < NUM_CHANNELS; ++chan) {
 417          bld->attribs[attrib][chan] = bld->coeff_bld.undef;
 418       }
 419    }
 420
 421    coeffs_init(bld, a0_ptr, dadx_ptr, dady_ptr);
 422
 423    pos_init(bld, x0, y0);
 424
 425    attribs_init(bld);
 426 }
 427
 428
 429 /**
 430  * Advance the position and inputs to the given quad within the block.
 431  */
 432 void
 433 lp_build_interp_soa_update(struct lp_build_interp_soa_context *bld,
 434                            int quad_index)
 435 {
 436    assert(quad_index < 4);
 437
 438    pos_update(bld, quad_index);
 439
 440    attribs_update(bld, quad_index);
 441 }