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      1 /**************************************************************************
      2  *
      3  * Copyright 2009 VMware, Inc.
      4  * All Rights Reserved.
      5  *
      6  * Permission is hereby granted, free of charge, to any person obtaining a
      7  * copy of this software and associated documentation files (the
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     11  * permit persons to whom the Software is furnished to do so, subject to
     12  * the following conditions:
     13  *
     14  * The above copyright notice and this permission notice (including the
     15  * next paragraph) shall be included in all copies or substantial portions
     16  * of the Software.
     17  *
     18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
     19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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     21  * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
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     23  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
     24  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
     25  *
     26  **************************************************************************/
     27 
     28 /**
     29  * @file
     30  * Texture sampling -- common code.
     31  *
     32  * @author Jose Fonseca <jfonseca (at) vmware.com>
     33  */
     34 
     35 #include "pipe/p_defines.h"
     36 #include "pipe/p_state.h"
     37 #include "util/u_format.h"
     38 #include "util/u_math.h"
     39 #include "lp_bld_arit.h"
     40 #include "lp_bld_const.h"
     41 #include "lp_bld_debug.h"
     42 #include "lp_bld_printf.h"
     43 #include "lp_bld_flow.h"
     44 #include "lp_bld_sample.h"
     45 #include "lp_bld_swizzle.h"
     46 #include "lp_bld_type.h"
     47 #include "lp_bld_logic.h"
     48 #include "lp_bld_pack.h"
     49 
     50 
     51 /*
     52  * Bri-linear factor. Should be greater than one.
     53  */
     54 #define BRILINEAR_FACTOR 2
     55 
     56 /**
     57  * Does the given texture wrap mode allow sampling the texture border color?
     58  * XXX maybe move this into gallium util code.
     59  */
     60 boolean
     61 lp_sampler_wrap_mode_uses_border_color(unsigned mode,
     62                                        unsigned min_img_filter,
     63                                        unsigned mag_img_filter)
     64 {
     65    switch (mode) {
     66    case PIPE_TEX_WRAP_REPEAT:
     67    case PIPE_TEX_WRAP_CLAMP_TO_EDGE:
     68    case PIPE_TEX_WRAP_MIRROR_REPEAT:
     69    case PIPE_TEX_WRAP_MIRROR_CLAMP_TO_EDGE:
     70       return FALSE;
     71    case PIPE_TEX_WRAP_CLAMP:
     72    case PIPE_TEX_WRAP_MIRROR_CLAMP:
     73       if (min_img_filter == PIPE_TEX_FILTER_NEAREST &&
     74           mag_img_filter == PIPE_TEX_FILTER_NEAREST) {
     75          return FALSE;
     76       } else {
     77          return TRUE;
     78       }
     79    case PIPE_TEX_WRAP_CLAMP_TO_BORDER:
     80    case PIPE_TEX_WRAP_MIRROR_CLAMP_TO_BORDER:
     81       return TRUE;
     82    default:
     83       assert(0 && "unexpected wrap mode");
     84       return FALSE;
     85    }
     86 }
     87 
     88 
     89 /**
     90  * Initialize lp_sampler_static_state object with the gallium sampler
     91  * and texture state.
     92  * The former is considered to be static and the later dynamic.
     93  */
     94 void
     95 lp_sampler_static_state(struct lp_sampler_static_state *state,
     96                         const struct pipe_sampler_view *view,
     97                         const struct pipe_sampler_state *sampler)
     98 {
     99    const struct pipe_resource *texture;
    100 
    101    memset(state, 0, sizeof *state);
    102 
    103    if (!sampler || !view || !view->texture)
    104       return;
    105 
    106    texture = view->texture;
    107 
    108    /*
    109     * We don't copy sampler state over unless it is actually enabled, to avoid
    110     * spurious recompiles, as the sampler static state is part of the shader
    111     * key.
    112     *
    113     * Ideally the state tracker or cso_cache module would make all state
    114     * canonical, but until that happens it's better to be safe than sorry here.
    115     *
    116     * XXX: Actually there's much more than can be done here, especially
    117     * regarding 1D/2D/3D/CUBE textures, wrap modes, etc.
    118     */
    119 
    120    state->format            = view->format;
    121    state->swizzle_r         = view->swizzle_r;
    122    state->swizzle_g         = view->swizzle_g;
    123    state->swizzle_b         = view->swizzle_b;
    124    state->swizzle_a         = view->swizzle_a;
    125 
    126    state->target            = texture->target;
    127    state->pot_width         = util_is_power_of_two(texture->width0);
    128    state->pot_height        = util_is_power_of_two(texture->height0);
    129    state->pot_depth         = util_is_power_of_two(texture->depth0);
    130 
    131    state->wrap_s            = sampler->wrap_s;
    132    state->wrap_t            = sampler->wrap_t;
    133    state->wrap_r            = sampler->wrap_r;
    134    state->min_img_filter    = sampler->min_img_filter;
    135    state->mag_img_filter    = sampler->mag_img_filter;
    136 
    137    if (view->u.tex.last_level && sampler->max_lod > 0.0f) {
    138       state->min_mip_filter = sampler->min_mip_filter;
    139    } else {
    140       state->min_mip_filter = PIPE_TEX_MIPFILTER_NONE;
    141    }
    142 
    143    if (state->min_mip_filter != PIPE_TEX_MIPFILTER_NONE) {
    144       if (sampler->lod_bias != 0.0f) {
    145          state->lod_bias_non_zero = 1;
    146       }
    147 
    148       /* If min_lod == max_lod we can greatly simplify mipmap selection.
    149        * This is a case that occurs during automatic mipmap generation.
    150        */
    151       if (sampler->min_lod == sampler->max_lod) {
    152          state->min_max_lod_equal = 1;
    153       } else {
    154          if (sampler->min_lod > 0.0f) {
    155             state->apply_min_lod = 1;
    156          }
    157 
    158          if (sampler->max_lod < (float)view->u.tex.last_level) {
    159             state->apply_max_lod = 1;
    160          }
    161       }
    162    }
    163 
    164    state->compare_mode      = sampler->compare_mode;
    165    if (sampler->compare_mode != PIPE_TEX_COMPARE_NONE) {
    166       state->compare_func   = sampler->compare_func;
    167    }
    168 
    169    state->normalized_coords = sampler->normalized_coords;
    170 
    171    /*
    172     * FIXME: Handle the remainder of pipe_sampler_view.
    173     */
    174 }
    175 
    176 
    177 /**
    178  * Generate code to compute coordinate gradient (rho).
    179  * \param derivs  partial derivatives of (s, t, r, q) with respect to X and Y
    180  *
    181  * The resulting rho is scalar per quad.
    182  */
    183 static LLVMValueRef
    184 lp_build_rho(struct lp_build_sample_context *bld,
    185              unsigned unit,
    186              const struct lp_derivatives *derivs)
    187 {
    188    struct gallivm_state *gallivm = bld->gallivm;
    189    struct lp_build_context *int_size_bld = &bld->int_size_bld;
    190    struct lp_build_context *float_size_bld = &bld->float_size_bld;
    191    struct lp_build_context *float_bld = &bld->float_bld;
    192    struct lp_build_context *coord_bld = &bld->coord_bld;
    193    struct lp_build_context *perquadf_bld = &bld->perquadf_bld;
    194    const LLVMValueRef *ddx_ddy = derivs->ddx_ddy;
    195    const unsigned dims = bld->dims;
    196    LLVMBuilderRef builder = bld->gallivm->builder;
    197    LLVMTypeRef i32t = LLVMInt32TypeInContext(bld->gallivm->context);
    198    LLVMValueRef index0 = LLVMConstInt(i32t, 0, 0);
    199    LLVMValueRef index1 = LLVMConstInt(i32t, 1, 0);
    200    LLVMValueRef index2 = LLVMConstInt(i32t, 2, 0);
    201    LLVMValueRef rho_vec;
    202    LLVMValueRef int_size, float_size;
    203    LLVMValueRef rho;
    204    LLVMValueRef first_level, first_level_vec;
    205    LLVMValueRef abs_ddx_ddy[2];
    206    unsigned length = coord_bld->type.length;
    207    unsigned num_quads = length / 4;
    208    unsigned i;
    209    LLVMValueRef i32undef = LLVMGetUndef(LLVMInt32TypeInContext(gallivm->context));
    210    LLVMValueRef rho_xvec, rho_yvec;
    211 
    212    abs_ddx_ddy[0] = lp_build_abs(coord_bld, ddx_ddy[0]);
    213    if (dims > 2) {
    214       abs_ddx_ddy[1] = lp_build_abs(coord_bld, ddx_ddy[1]);
    215    }
    216    else {
    217       abs_ddx_ddy[1] = NULL;
    218    }
    219 
    220    if (dims == 1) {
    221       static const unsigned char swizzle1[] = {
    222          0, LP_BLD_SWIZZLE_DONTCARE,
    223          LP_BLD_SWIZZLE_DONTCARE, LP_BLD_SWIZZLE_DONTCARE
    224       };
    225       static const unsigned char swizzle2[] = {
    226          1, LP_BLD_SWIZZLE_DONTCARE,
    227          LP_BLD_SWIZZLE_DONTCARE, LP_BLD_SWIZZLE_DONTCARE
    228       };
    229       rho_xvec = lp_build_swizzle_aos(coord_bld, abs_ddx_ddy[0], swizzle1);
    230       rho_yvec = lp_build_swizzle_aos(coord_bld, abs_ddx_ddy[0], swizzle2);
    231    }
    232    else if (dims == 2) {
    233       static const unsigned char swizzle1[] = {
    234          0, 2,
    235          LP_BLD_SWIZZLE_DONTCARE, LP_BLD_SWIZZLE_DONTCARE
    236       };
    237       static const unsigned char swizzle2[] = {
    238          1, 3,
    239          LP_BLD_SWIZZLE_DONTCARE, LP_BLD_SWIZZLE_DONTCARE
    240       };
    241       rho_xvec = lp_build_swizzle_aos(coord_bld, abs_ddx_ddy[0], swizzle1);
    242       rho_yvec = lp_build_swizzle_aos(coord_bld, abs_ddx_ddy[0], swizzle2);
    243    }
    244    else {
    245       LLVMValueRef shuffles1[LP_MAX_VECTOR_LENGTH];
    246       LLVMValueRef shuffles2[LP_MAX_VECTOR_LENGTH];
    247       assert(dims == 3);
    248       for (i = 0; i < num_quads; i++) {
    249          shuffles1[4*i + 0] = lp_build_const_int32(gallivm, 4*i);
    250          shuffles1[4*i + 1] = lp_build_const_int32(gallivm, 4*i + 2);
    251          shuffles1[4*i + 2] = lp_build_const_int32(gallivm, length + 4*i);
    252          shuffles1[4*i + 3] = i32undef;
    253          shuffles2[4*i + 0] = lp_build_const_int32(gallivm, 4*i + 1);
    254          shuffles2[4*i + 1] = lp_build_const_int32(gallivm, 4*i + 3);
    255          shuffles2[4*i + 2] = lp_build_const_int32(gallivm, length + 4*i + 1);
    256          shuffles2[4*i + 3] = i32undef;
    257       }
    258       rho_xvec = LLVMBuildShuffleVector(builder, abs_ddx_ddy[0], abs_ddx_ddy[1],
    259                                         LLVMConstVector(shuffles1, length), "");
    260       rho_yvec = LLVMBuildShuffleVector(builder, abs_ddx_ddy[0], abs_ddx_ddy[1],
    261                                         LLVMConstVector(shuffles2, length), "");
    262    }
    263 
    264    rho_vec = lp_build_max(coord_bld, rho_xvec, rho_yvec);
    265 
    266    first_level = bld->dynamic_state->first_level(bld->dynamic_state,
    267                                                  bld->gallivm, unit);
    268    first_level_vec = lp_build_broadcast_scalar(&bld->int_size_bld, first_level);
    269    int_size = lp_build_minify(int_size_bld, bld->int_size, first_level_vec);
    270    float_size = lp_build_int_to_float(float_size_bld, int_size);
    271 
    272    if (bld->coord_type.length > 4) {
    273       /* expand size to each quad */
    274       if (dims > 1) {
    275          /* could use some broadcast_vector helper for this? */
    276          int num_quads = bld->coord_type.length / 4;
    277          LLVMValueRef src[LP_MAX_VECTOR_LENGTH/4];
    278          for (i = 0; i < num_quads; i++) {
    279             src[i] = float_size;
    280          }
    281          float_size = lp_build_concat(bld->gallivm, src, float_size_bld->type, num_quads);
    282       }
    283       else {
    284          float_size = lp_build_broadcast_scalar(coord_bld, float_size);
    285       }
    286       rho_vec = lp_build_mul(coord_bld, rho_vec, float_size);
    287 
    288       if (dims <= 1) {
    289          rho = rho_vec;
    290       }
    291       else {
    292          if (dims >= 2) {
    293             static const unsigned char swizzle1[] = {
    294                0, LP_BLD_SWIZZLE_DONTCARE,
    295                LP_BLD_SWIZZLE_DONTCARE, LP_BLD_SWIZZLE_DONTCARE
    296             };
    297             static const unsigned char swizzle2[] = {
    298                1, LP_BLD_SWIZZLE_DONTCARE,
    299                LP_BLD_SWIZZLE_DONTCARE, LP_BLD_SWIZZLE_DONTCARE
    300             };
    301             LLVMValueRef rho_s, rho_t, rho_r;
    302 
    303             rho_s = lp_build_swizzle_aos(coord_bld, rho_vec, swizzle1);
    304             rho_t = lp_build_swizzle_aos(coord_bld, rho_vec, swizzle2);
    305 
    306             rho = lp_build_max(coord_bld, rho_s, rho_t);
    307 
    308             if (dims >= 3) {
    309                static const unsigned char swizzle3[] = {
    310                   2, LP_BLD_SWIZZLE_DONTCARE,
    311                   LP_BLD_SWIZZLE_DONTCARE, LP_BLD_SWIZZLE_DONTCARE
    312                };
    313                rho_r = lp_build_swizzle_aos(coord_bld, rho_vec, swizzle3);
    314                rho = lp_build_max(coord_bld, rho, rho_r);
    315             }
    316          }
    317       }
    318       rho = lp_build_pack_aos_scalars(bld->gallivm, coord_bld->type,
    319                                       perquadf_bld->type, rho);
    320    }
    321    else {
    322       if (dims <= 1) {
    323          rho_vec = LLVMBuildExtractElement(builder, rho_vec, index0, "");
    324       }
    325       rho_vec = lp_build_mul(float_size_bld, rho_vec, float_size);
    326 
    327       if (dims <= 1) {
    328          rho = rho_vec;
    329       }
    330       else {
    331          if (dims >= 2) {
    332             LLVMValueRef rho_s, rho_t, rho_r;
    333 
    334             rho_s = LLVMBuildExtractElement(builder, rho_vec, index0, "");
    335             rho_t = LLVMBuildExtractElement(builder, rho_vec, index1, "");
    336 
    337             rho = lp_build_max(float_bld, rho_s, rho_t);
    338 
    339             if (dims >= 3) {
    340                rho_r = LLVMBuildExtractElement(builder, rho_vec, index2, "");
    341                rho = lp_build_max(float_bld, rho, rho_r);
    342             }
    343          }
    344       }
    345    }
    346 
    347    return rho;
    348 }
    349 
    350 
    351 /*
    352  * Bri-linear lod computation
    353  *
    354  * Use a piece-wise linear approximation of log2 such that:
    355  * - round to nearest, for values in the neighborhood of -1, 0, 1, 2, etc.
    356  * - linear approximation for values in the neighborhood of 0.5, 1.5., etc,
    357  *   with the steepness specified in 'factor'
    358  * - exact result for 0.5, 1.5, etc.
    359  *
    360  *
    361  *   1.0 -              /----*
    362  *                     /
    363  *                    /
    364  *                   /
    365  *   0.5 -          *
    366  *                 /
    367  *                /
    368  *               /
    369  *   0.0 - *----/
    370  *
    371  *         |                 |
    372  *        2^0               2^1
    373  *
    374  * This is a technique also commonly used in hardware:
    375  * - http://ixbtlabs.com/articles2/gffx/nv40-rx800-3.html
    376  *
    377  * TODO: For correctness, this should only be applied when texture is known to
    378  * have regular mipmaps, i.e., mipmaps derived from the base level.
    379  *
    380  * TODO: This could be done in fixed point, where applicable.
    381  */
    382 static void
    383 lp_build_brilinear_lod(struct lp_build_context *bld,
    384                        LLVMValueRef lod,
    385                        double factor,
    386                        LLVMValueRef *out_lod_ipart,
    387                        LLVMValueRef *out_lod_fpart)
    388 {
    389    LLVMValueRef lod_fpart;
    390    double pre_offset = (factor - 0.5)/factor - 0.5;
    391    double post_offset = 1 - factor;
    392 
    393    if (0) {
    394       lp_build_printf(bld->gallivm, "lod = %f\n", lod);
    395    }
    396 
    397    lod = lp_build_add(bld, lod,
    398                       lp_build_const_vec(bld->gallivm, bld->type, pre_offset));
    399 
    400    lp_build_ifloor_fract(bld, lod, out_lod_ipart, &lod_fpart);
    401 
    402    lod_fpart = lp_build_mul(bld, lod_fpart,
    403                             lp_build_const_vec(bld->gallivm, bld->type, factor));
    404 
    405    lod_fpart = lp_build_add(bld, lod_fpart,
    406                             lp_build_const_vec(bld->gallivm, bld->type, post_offset));
    407 
    408    /*
    409     * It's not necessary to clamp lod_fpart since:
    410     * - the above expression will never produce numbers greater than one.
    411     * - the mip filtering branch is only taken if lod_fpart is positive
    412     */
    413 
    414    *out_lod_fpart = lod_fpart;
    415 
    416    if (0) {
    417       lp_build_printf(bld->gallivm, "lod_ipart = %i\n", *out_lod_ipart);
    418       lp_build_printf(bld->gallivm, "lod_fpart = %f\n\n", *out_lod_fpart);
    419    }
    420 }
    421 
    422 
    423 /*
    424  * Combined log2 and brilinear lod computation.
    425  *
    426  * It's in all identical to calling lp_build_fast_log2() and
    427  * lp_build_brilinear_lod() above, but by combining we can compute the integer
    428  * and fractional part independently.
    429  */
    430 static void
    431 lp_build_brilinear_rho(struct lp_build_context *bld,
    432                        LLVMValueRef rho,
    433                        double factor,
    434                        LLVMValueRef *out_lod_ipart,
    435                        LLVMValueRef *out_lod_fpart)
    436 {
    437    LLVMValueRef lod_ipart;
    438    LLVMValueRef lod_fpart;
    439 
    440    const double pre_factor = (2*factor - 0.5)/(M_SQRT2*factor);
    441    const double post_offset = 1 - 2*factor;
    442 
    443    assert(bld->type.floating);
    444 
    445    assert(lp_check_value(bld->type, rho));
    446 
    447    /*
    448     * The pre factor will make the intersections with the exact powers of two
    449     * happen precisely where we want then to be, which means that the integer
    450     * part will not need any post adjustments.
    451     */
    452    rho = lp_build_mul(bld, rho,
    453                       lp_build_const_vec(bld->gallivm, bld->type, pre_factor));
    454 
    455    /* ipart = ifloor(log2(rho)) */
    456    lod_ipart = lp_build_extract_exponent(bld, rho, 0);
    457 
    458    /* fpart = rho / 2**ipart */
    459    lod_fpart = lp_build_extract_mantissa(bld, rho);
    460 
    461    lod_fpart = lp_build_mul(bld, lod_fpart,
    462                             lp_build_const_vec(bld->gallivm, bld->type, factor));
    463 
    464    lod_fpart = lp_build_add(bld, lod_fpart,
    465                             lp_build_const_vec(bld->gallivm, bld->type, post_offset));
    466 
    467    /*
    468     * Like lp_build_brilinear_lod, it's not necessary to clamp lod_fpart since:
    469     * - the above expression will never produce numbers greater than one.
    470     * - the mip filtering branch is only taken if lod_fpart is positive
    471     */
    472 
    473    *out_lod_ipart = lod_ipart;
    474    *out_lod_fpart = lod_fpart;
    475 }
    476 
    477 
    478 /**
    479  * Generate code to compute texture level of detail (lambda).
    480  * \param derivs  partial derivatives of (s, t, r, q) with respect to X and Y
    481  * \param lod_bias  optional float vector with the shader lod bias
    482  * \param explicit_lod  optional float vector with the explicit lod
    483  * \param width  scalar int texture width
    484  * \param height  scalar int texture height
    485  * \param depth  scalar int texture depth
    486  *
    487  * The resulting lod is scalar per quad, so only the first value per quad
    488  * passed in from lod_bias, explicit_lod is used.
    489  */
    490 void
    491 lp_build_lod_selector(struct lp_build_sample_context *bld,
    492                       unsigned unit,
    493                       const struct lp_derivatives *derivs,
    494                       LLVMValueRef lod_bias, /* optional */
    495                       LLVMValueRef explicit_lod, /* optional */
    496                       unsigned mip_filter,
    497                       LLVMValueRef *out_lod_ipart,
    498                       LLVMValueRef *out_lod_fpart)
    499 
    500 {
    501    LLVMBuilderRef builder = bld->gallivm->builder;
    502    struct lp_build_context *perquadf_bld = &bld->perquadf_bld;
    503    LLVMValueRef lod;
    504 
    505    *out_lod_ipart = bld->perquadi_bld.zero;
    506    *out_lod_fpart = perquadf_bld->zero;
    507 
    508    if (bld->static_state->min_max_lod_equal) {
    509       /* User is forcing sampling from a particular mipmap level.
    510        * This is hit during mipmap generation.
    511        */
    512       LLVMValueRef min_lod =
    513          bld->dynamic_state->min_lod(bld->dynamic_state, bld->gallivm, unit);
    514 
    515       lod = lp_build_broadcast_scalar(perquadf_bld, min_lod);
    516    }
    517    else {
    518       if (explicit_lod) {
    519          lod = lp_build_pack_aos_scalars(bld->gallivm, bld->coord_bld.type,
    520                                          perquadf_bld->type, explicit_lod);
    521       }
    522       else {
    523          LLVMValueRef rho;
    524 
    525          rho = lp_build_rho(bld, unit, derivs);
    526 
    527          /*
    528           * Compute lod = log2(rho)
    529           */
    530 
    531          if (!lod_bias &&
    532              !bld->static_state->lod_bias_non_zero &&
    533              !bld->static_state->apply_max_lod &&
    534              !bld->static_state->apply_min_lod) {
    535             /*
    536              * Special case when there are no post-log2 adjustments, which
    537              * saves instructions but keeping the integer and fractional lod
    538              * computations separate from the start.
    539              */
    540 
    541             if (mip_filter == PIPE_TEX_MIPFILTER_NONE ||
    542                 mip_filter == PIPE_TEX_MIPFILTER_NEAREST) {
    543                *out_lod_ipart = lp_build_ilog2(perquadf_bld, rho);
    544                *out_lod_fpart = perquadf_bld->zero;
    545                return;
    546             }
    547             if (mip_filter == PIPE_TEX_MIPFILTER_LINEAR &&
    548                 !(gallivm_debug & GALLIVM_DEBUG_NO_BRILINEAR)) {
    549                lp_build_brilinear_rho(perquadf_bld, rho, BRILINEAR_FACTOR,
    550                                       out_lod_ipart, out_lod_fpart);
    551                return;
    552             }
    553          }
    554 
    555          if (0) {
    556             lod = lp_build_log2(perquadf_bld, rho);
    557          }
    558          else {
    559             lod = lp_build_fast_log2(perquadf_bld, rho);
    560          }
    561 
    562          /* add shader lod bias */
    563          if (lod_bias) {
    564             lod_bias = lp_build_pack_aos_scalars(bld->gallivm, bld->coord_bld.type,
    565                   perquadf_bld->type, lod_bias);
    566             lod = LLVMBuildFAdd(builder, lod, lod_bias, "shader_lod_bias");
    567          }
    568       }
    569 
    570       /* add sampler lod bias */
    571       if (bld->static_state->lod_bias_non_zero) {
    572          LLVMValueRef sampler_lod_bias =
    573             bld->dynamic_state->lod_bias(bld->dynamic_state, bld->gallivm, unit);
    574          sampler_lod_bias = lp_build_broadcast_scalar(perquadf_bld,
    575                                                       sampler_lod_bias);
    576          lod = LLVMBuildFAdd(builder, lod, sampler_lod_bias, "sampler_lod_bias");
    577       }
    578 
    579       /* clamp lod */
    580       if (bld->static_state->apply_max_lod) {
    581          LLVMValueRef max_lod =
    582             bld->dynamic_state->max_lod(bld->dynamic_state, bld->gallivm, unit);
    583          max_lod = lp_build_broadcast_scalar(perquadf_bld, max_lod);
    584 
    585          lod = lp_build_min(perquadf_bld, lod, max_lod);
    586       }
    587       if (bld->static_state->apply_min_lod) {
    588          LLVMValueRef min_lod =
    589             bld->dynamic_state->min_lod(bld->dynamic_state, bld->gallivm, unit);
    590          min_lod = lp_build_broadcast_scalar(perquadf_bld, min_lod);
    591 
    592          lod = lp_build_max(perquadf_bld, lod, min_lod);
    593       }
    594    }
    595 
    596    if (mip_filter == PIPE_TEX_MIPFILTER_LINEAR) {
    597       if (!(gallivm_debug & GALLIVM_DEBUG_NO_BRILINEAR)) {
    598          lp_build_brilinear_lod(perquadf_bld, lod, BRILINEAR_FACTOR,
    599                                 out_lod_ipart, out_lod_fpart);
    600       }
    601       else {
    602          lp_build_ifloor_fract(perquadf_bld, lod, out_lod_ipart, out_lod_fpart);
    603       }
    604 
    605       lp_build_name(*out_lod_fpart, "lod_fpart");
    606    }
    607    else {
    608       *out_lod_ipart = lp_build_iround(perquadf_bld, lod);
    609    }
    610 
    611    lp_build_name(*out_lod_ipart, "lod_ipart");
    612 
    613    return;
    614 }
    615 
    616 
    617 /**
    618  * For PIPE_TEX_MIPFILTER_NEAREST, convert float LOD to integer
    619  * mipmap level index.
    620  * Note: this is all scalar per quad code.
    621  * \param lod_ipart  int texture level of detail
    622  * \param level_out  returns integer
    623  */
    624 void
    625 lp_build_nearest_mip_level(struct lp_build_sample_context *bld,
    626                            unsigned unit,
    627                            LLVMValueRef lod_ipart,
    628                            LLVMValueRef *level_out)
    629 {
    630    struct lp_build_context *perquadi_bld = &bld->perquadi_bld;
    631    LLVMValueRef first_level, last_level, level;
    632 
    633    first_level = bld->dynamic_state->first_level(bld->dynamic_state,
    634                                                  bld->gallivm, unit);
    635    last_level = bld->dynamic_state->last_level(bld->dynamic_state,
    636                                                bld->gallivm, unit);
    637    first_level = lp_build_broadcast_scalar(perquadi_bld, first_level);
    638    last_level = lp_build_broadcast_scalar(perquadi_bld, last_level);
    639 
    640    level = lp_build_add(perquadi_bld, lod_ipart, first_level);
    641 
    642    /* clamp level to legal range of levels */
    643    *level_out = lp_build_clamp(perquadi_bld, level, first_level, last_level);
    644 }
    645 
    646 
    647 /**
    648  * For PIPE_TEX_MIPFILTER_LINEAR, convert per-quad int LOD(s) to two (per-quad)
    649  * (adjacent) mipmap level indexes, and fix up float lod part accordingly.
    650  * Later, we'll sample from those two mipmap levels and interpolate between them.
    651  */
    652 void
    653 lp_build_linear_mip_levels(struct lp_build_sample_context *bld,
    654                            unsigned unit,
    655                            LLVMValueRef lod_ipart,
    656                            LLVMValueRef *lod_fpart_inout,
    657                            LLVMValueRef *level0_out,
    658                            LLVMValueRef *level1_out)
    659 {
    660    LLVMBuilderRef builder = bld->gallivm->builder;
    661    struct lp_build_context *perquadi_bld = &bld->perquadi_bld;
    662    struct lp_build_context *perquadf_bld = &bld->perquadf_bld;
    663    LLVMValueRef first_level, last_level;
    664    LLVMValueRef clamp_min;
    665    LLVMValueRef clamp_max;
    666 
    667    first_level = bld->dynamic_state->first_level(bld->dynamic_state,
    668                                                  bld->gallivm, unit);
    669    last_level = bld->dynamic_state->last_level(bld->dynamic_state,
    670                                                bld->gallivm, unit);
    671    first_level = lp_build_broadcast_scalar(perquadi_bld, first_level);
    672    last_level = lp_build_broadcast_scalar(perquadi_bld, last_level);
    673 
    674    *level0_out = lp_build_add(perquadi_bld, lod_ipart, first_level);
    675    *level1_out = lp_build_add(perquadi_bld, *level0_out, perquadi_bld->one);
    676 
    677    /*
    678     * Clamp both *level0_out and *level1_out to [first_level, last_level], with
    679     * the minimum number of comparisons, and zeroing lod_fpart in the extreme
    680     * ends in the process.
    681     */
    682 
    683    /*
    684     * This code (vector select in particular) only works with llvm 3.1
    685     * (if there's more than one quad, with x86 backend). Might consider
    686     * converting to our lp_bld_logic helpers.
    687     */
    688 #if HAVE_LLVM < 0x0301
    689    assert(perquadi_bld->type.length == 1);
    690 #endif
    691 
    692    /* *level0_out < first_level */
    693    clamp_min = LLVMBuildICmp(builder, LLVMIntSLT,
    694                              *level0_out, first_level,
    695                              "clamp_lod_to_first");
    696 
    697    *level0_out = LLVMBuildSelect(builder, clamp_min,
    698                                  first_level, *level0_out, "");
    699 
    700    *level1_out = LLVMBuildSelect(builder, clamp_min,
    701                                  first_level, *level1_out, "");
    702 
    703    *lod_fpart_inout = LLVMBuildSelect(builder, clamp_min,
    704                                       perquadf_bld->zero, *lod_fpart_inout, "");
    705 
    706    /* *level0_out >= last_level */
    707    clamp_max = LLVMBuildICmp(builder, LLVMIntSGE,
    708                              *level0_out, last_level,
    709                              "clamp_lod_to_last");
    710 
    711    *level0_out = LLVMBuildSelect(builder, clamp_max,
    712                                  last_level, *level0_out, "");
    713 
    714    *level1_out = LLVMBuildSelect(builder, clamp_max,
    715                                  last_level, *level1_out, "");
    716 
    717    *lod_fpart_inout = LLVMBuildSelect(builder, clamp_max,
    718                                       perquadf_bld->zero, *lod_fpart_inout, "");
    719 
    720    lp_build_name(*level0_out, "sampler%u_miplevel0", unit);
    721    lp_build_name(*level1_out, "sampler%u_miplevel1", unit);
    722    lp_build_name(*lod_fpart_inout, "sampler%u_mipweight", unit);
    723 }
    724 
    725 
    726 /**
    727  * Return pointer to a single mipmap level.
    728  * \param data_array  array of pointers to mipmap levels
    729  * \param level  integer mipmap level
    730  */
    731 LLVMValueRef
    732 lp_build_get_mipmap_level(struct lp_build_sample_context *bld,
    733                           LLVMValueRef level)
    734 {
    735    LLVMBuilderRef builder = bld->gallivm->builder;
    736    LLVMValueRef indexes[2], data_ptr;
    737 
    738    indexes[0] = lp_build_const_int32(bld->gallivm, 0);
    739    indexes[1] = level;
    740    data_ptr = LLVMBuildGEP(builder, bld->data_array, indexes, 2, "");
    741    data_ptr = LLVMBuildLoad(builder, data_ptr, "");
    742    return data_ptr;
    743 }
    744 
    745 
    746 /**
    747  * Codegen equivalent for u_minify().
    748  * Return max(1, base_size >> level);
    749  */
    750 LLVMValueRef
    751 lp_build_minify(struct lp_build_context *bld,
    752                 LLVMValueRef base_size,
    753                 LLVMValueRef level)
    754 {
    755    LLVMBuilderRef builder = bld->gallivm->builder;
    756    assert(lp_check_value(bld->type, base_size));
    757    assert(lp_check_value(bld->type, level));
    758 
    759    if (level == bld->zero) {
    760       /* if we're using mipmap level zero, no minification is needed */
    761       return base_size;
    762    }
    763    else {
    764       LLVMValueRef size =
    765          LLVMBuildLShr(builder, base_size, level, "minify");
    766       assert(bld->type.sign);
    767       size = lp_build_max(bld, size, bld->one);
    768       return size;
    769    }
    770 }
    771 
    772 
    773 /**
    774  * Dereference stride_array[mipmap_level] array to get a stride.
    775  * Return stride as a vector.
    776  */
    777 static LLVMValueRef
    778 lp_build_get_level_stride_vec(struct lp_build_sample_context *bld,
    779                               LLVMValueRef stride_array, LLVMValueRef level)
    780 {
    781    LLVMBuilderRef builder = bld->gallivm->builder;
    782    LLVMValueRef indexes[2], stride;
    783    indexes[0] = lp_build_const_int32(bld->gallivm, 0);
    784    indexes[1] = level;
    785    stride = LLVMBuildGEP(builder, stride_array, indexes, 2, "");
    786    stride = LLVMBuildLoad(builder, stride, "");
    787    stride = lp_build_broadcast_scalar(&bld->int_coord_bld, stride);
    788    return stride;
    789 }
    790 
    791 
    792 /**
    793  * When sampling a mipmap, we need to compute the width, height, depth
    794  * of the source levels from the level indexes.  This helper function
    795  * does that.
    796  */
    797 void
    798 lp_build_mipmap_level_sizes(struct lp_build_sample_context *bld,
    799                             LLVMValueRef ilevel,
    800                             LLVMValueRef *out_size,
    801                             LLVMValueRef *row_stride_vec,
    802                             LLVMValueRef *img_stride_vec)
    803 {
    804    const unsigned dims = bld->dims;
    805    LLVMValueRef ilevel_vec;
    806 
    807    ilevel_vec = lp_build_broadcast_scalar(&bld->int_size_bld, ilevel);
    808 
    809    /*
    810     * Compute width, height, depth at mipmap level 'ilevel'
    811     */
    812    *out_size = lp_build_minify(&bld->int_size_bld, bld->int_size, ilevel_vec);
    813 
    814    if (dims >= 2) {
    815       *row_stride_vec = lp_build_get_level_stride_vec(bld,
    816                                                       bld->row_stride_array,
    817                                                       ilevel);
    818       if (dims == 3 || bld->static_state->target == PIPE_TEXTURE_CUBE) {
    819          *img_stride_vec = lp_build_get_level_stride_vec(bld,
    820                                                          bld->img_stride_array,
    821                                                          ilevel);
    822       }
    823    }
    824 }
    825 
    826 
    827 /**
    828  * Extract and broadcast texture size.
    829  *
    830  * @param size_type   type of the texture size vector (either
    831  *                    bld->int_size_type or bld->float_size_type)
    832  * @param coord_type  type of the texture size vector (either
    833  *                    bld->int_coord_type or bld->coord_type)
    834  * @param size        vector with the texture size (width, height, depth)
    835  */
    836 void
    837 lp_build_extract_image_sizes(struct lp_build_sample_context *bld,
    838                              struct lp_type size_type,
    839                              struct lp_type coord_type,
    840                              LLVMValueRef size,
    841                              LLVMValueRef *out_width,
    842                              LLVMValueRef *out_height,
    843                              LLVMValueRef *out_depth)
    844 {
    845    const unsigned dims = bld->dims;
    846    LLVMTypeRef i32t = LLVMInt32TypeInContext(bld->gallivm->context);
    847 
    848    *out_width = lp_build_extract_broadcast(bld->gallivm,
    849                                            size_type,
    850                                            coord_type,
    851                                            size,
    852                                            LLVMConstInt(i32t, 0, 0));
    853    if (dims >= 2) {
    854       *out_height = lp_build_extract_broadcast(bld->gallivm,
    855                                                size_type,
    856                                                coord_type,
    857                                                size,
    858                                                LLVMConstInt(i32t, 1, 0));
    859       if (dims == 3) {
    860          *out_depth = lp_build_extract_broadcast(bld->gallivm,
    861                                                  size_type,
    862                                                  coord_type,
    863                                                  size,
    864                                                  LLVMConstInt(i32t, 2, 0));
    865       }
    866    }
    867 }
    868 
    869 
    870 /**
    871  * Unnormalize coords.
    872  *
    873  * @param flt_size  vector with the integer texture size (width, height, depth)
    874  */
    875 void
    876 lp_build_unnormalized_coords(struct lp_build_sample_context *bld,
    877                              LLVMValueRef flt_size,
    878                              LLVMValueRef *s,
    879                              LLVMValueRef *t,
    880                              LLVMValueRef *r)
    881 {
    882    const unsigned dims = bld->dims;
    883    LLVMValueRef width;
    884    LLVMValueRef height;
    885    LLVMValueRef depth;
    886 
    887    lp_build_extract_image_sizes(bld,
    888                                 bld->float_size_type,
    889                                 bld->coord_type,
    890                                 flt_size,
    891                                 &width,
    892                                 &height,
    893                                 &depth);
    894 
    895    /* s = s * width, t = t * height */
    896    *s = lp_build_mul(&bld->coord_bld, *s, width);
    897    if (dims >= 2) {
    898       *t = lp_build_mul(&bld->coord_bld, *t, height);
    899       if (dims >= 3) {
    900          *r = lp_build_mul(&bld->coord_bld, *r, depth);
    901       }
    902    }
    903 }
    904 
    905 
    906 /** Helper used by lp_build_cube_lookup() */
    907 static LLVMValueRef
    908 lp_build_cube_imapos(struct lp_build_context *coord_bld, LLVMValueRef coord)
    909 {
    910    /* ima = +0.5 / abs(coord); */
    911    LLVMValueRef posHalf = lp_build_const_vec(coord_bld->gallivm, coord_bld->type, 0.5);
    912    LLVMValueRef absCoord = lp_build_abs(coord_bld, coord);
    913    LLVMValueRef ima = lp_build_div(coord_bld, posHalf, absCoord);
    914    return ima;
    915 }
    916 
    917 /** Helper used by lp_build_cube_lookup() */
    918 static LLVMValueRef
    919 lp_build_cube_imaneg(struct lp_build_context *coord_bld, LLVMValueRef coord)
    920 {
    921    /* ima = -0.5 / abs(coord); */
    922    LLVMValueRef negHalf = lp_build_const_vec(coord_bld->gallivm, coord_bld->type, -0.5);
    923    LLVMValueRef absCoord = lp_build_abs(coord_bld, coord);
    924    LLVMValueRef ima = lp_build_div(coord_bld, negHalf, absCoord);
    925    return ima;
    926 }
    927 
    928 /**
    929  * Helper used by lp_build_cube_lookup()
    930  * FIXME: the sign here can also be 0.
    931  * Arithmetically this could definitely make a difference. Either
    932  * fix the comment or use other (simpler) sign function, not sure
    933  * which one it should be.
    934  * \param sign  scalar +1 or -1
    935  * \param coord  float vector
    936  * \param ima  float vector
    937  */
    938 static LLVMValueRef
    939 lp_build_cube_coord(struct lp_build_context *coord_bld,
    940                     LLVMValueRef sign, int negate_coord,
    941                     LLVMValueRef coord, LLVMValueRef ima)
    942 {
    943    /* return negate(coord) * ima * sign + 0.5; */
    944    LLVMValueRef half = lp_build_const_vec(coord_bld->gallivm, coord_bld->type, 0.5);
    945    LLVMValueRef res;
    946 
    947    assert(negate_coord == +1 || negate_coord == -1);
    948 
    949    if (negate_coord == -1) {
    950       coord = lp_build_negate(coord_bld, coord);
    951    }
    952 
    953    res = lp_build_mul(coord_bld, coord, ima);
    954    if (sign) {
    955       sign = lp_build_broadcast_scalar(coord_bld, sign);
    956       res = lp_build_mul(coord_bld, res, sign);
    957    }
    958    res = lp_build_add(coord_bld, res, half);
    959 
    960    return res;
    961 }
    962 
    963 
    964 /** Helper used by lp_build_cube_lookup()
    965  * Return (major_coord >= 0) ? pos_face : neg_face;
    966  */
    967 static LLVMValueRef
    968 lp_build_cube_face(struct lp_build_sample_context *bld,
    969                    LLVMValueRef major_coord,
    970                    unsigned pos_face, unsigned neg_face)
    971 {
    972    struct gallivm_state *gallivm = bld->gallivm;
    973    LLVMBuilderRef builder = gallivm->builder;
    974    LLVMValueRef cmp = LLVMBuildFCmp(builder, LLVMRealUGE,
    975                                     major_coord,
    976                                     bld->float_bld.zero, "");
    977    LLVMValueRef pos = lp_build_const_int32(gallivm, pos_face);
    978    LLVMValueRef neg = lp_build_const_int32(gallivm, neg_face);
    979    LLVMValueRef res = LLVMBuildSelect(builder, cmp, pos, neg, "");
    980    return res;
    981 }
    982 
    983 
    984 
    985 /**
    986  * Generate code to do cube face selection and compute per-face texcoords.
    987  */
    988 void
    989 lp_build_cube_lookup(struct lp_build_sample_context *bld,
    990                      LLVMValueRef s,
    991                      LLVMValueRef t,
    992                      LLVMValueRef r,
    993                      LLVMValueRef *face,
    994                      LLVMValueRef *face_s,
    995                      LLVMValueRef *face_t)
    996 {
    997    struct lp_build_context *coord_bld = &bld->coord_bld;
    998    LLVMBuilderRef builder = bld->gallivm->builder;
    999    struct gallivm_state *gallivm = bld->gallivm;
   1000    LLVMValueRef rx, ry, rz;
   1001    LLVMValueRef tmp[4], rxyz, arxyz;
   1002 
   1003    /*
   1004     * Use the average of the four pixel's texcoords to choose the face.
   1005     * Slight simplification just calculate the sum, skip scaling.
   1006     */
   1007    tmp[0] = s;
   1008    tmp[1] = t;
   1009    tmp[2] = r;
   1010    rxyz = lp_build_hadd_partial4(&bld->coord_bld, tmp, 3);
   1011    arxyz = lp_build_abs(&bld->coord_bld, rxyz);
   1012 
   1013    if (coord_bld->type.length > 4) {
   1014       struct lp_build_context *cint_bld = &bld->int_coord_bld;
   1015       struct lp_type intctype = cint_bld->type;
   1016       LLVMValueRef signrxs, signrys, signrzs, signrxyz, sign;
   1017       LLVMValueRef arxs, arys, arzs;
   1018       LLVMValueRef arx_ge_ary, maxarxsarys, arz_ge_arx_ary;
   1019       LLVMValueRef snewx, tnewx, snewy, tnewy, snewz, tnewz;
   1020       LLVMValueRef ryneg, rzneg;
   1021       LLVMValueRef ma, ima;
   1022       LLVMValueRef posHalf = lp_build_const_vec(gallivm, coord_bld->type, 0.5);
   1023       LLVMValueRef signmask = lp_build_const_int_vec(gallivm, intctype,
   1024                                                      1 << (intctype.width - 1));
   1025       LLVMValueRef signshift = lp_build_const_int_vec(gallivm, intctype,
   1026                                                       intctype.width -1);
   1027       LLVMValueRef facex = lp_build_const_int_vec(gallivm, intctype, PIPE_TEX_FACE_POS_X);
   1028       LLVMValueRef facey = lp_build_const_int_vec(gallivm, intctype, PIPE_TEX_FACE_POS_Y);
   1029       LLVMValueRef facez = lp_build_const_int_vec(gallivm, intctype, PIPE_TEX_FACE_POS_Z);
   1030 
   1031       assert(PIPE_TEX_FACE_NEG_X == PIPE_TEX_FACE_POS_X + 1);
   1032       assert(PIPE_TEX_FACE_NEG_Y == PIPE_TEX_FACE_POS_Y + 1);
   1033       assert(PIPE_TEX_FACE_NEG_Z == PIPE_TEX_FACE_POS_Z + 1);
   1034 
   1035       rx = LLVMBuildBitCast(builder, s, lp_build_vec_type(gallivm, intctype), "");
   1036       ry = LLVMBuildBitCast(builder, t, lp_build_vec_type(gallivm, intctype), "");
   1037       rz = LLVMBuildBitCast(builder, r, lp_build_vec_type(gallivm, intctype), "");
   1038       ryneg = LLVMBuildXor(builder, ry, signmask, "");
   1039       rzneg = LLVMBuildXor(builder, rz, signmask, "");
   1040 
   1041       /* the sign bit comes from the averaged vector (per quad),
   1042        * as does the decision which face to use */
   1043       signrxyz = LLVMBuildBitCast(builder, rxyz, lp_build_vec_type(gallivm, intctype), "");
   1044       signrxyz = LLVMBuildAnd(builder, signrxyz, signmask, "");
   1045 
   1046       arxs = lp_build_swizzle_scalar_aos(coord_bld, arxyz, 0);
   1047       arys = lp_build_swizzle_scalar_aos(coord_bld, arxyz, 1);
   1048       arzs = lp_build_swizzle_scalar_aos(coord_bld, arxyz, 2);
   1049 
   1050       /*
   1051        * select x if x >= y else select y
   1052        * select previous result if y >= max(x,y) else select z
   1053        */
   1054       arx_ge_ary = lp_build_cmp(coord_bld, PIPE_FUNC_GEQUAL, arxs, arys);
   1055       maxarxsarys = lp_build_max(coord_bld, arxs, arys);
   1056       arz_ge_arx_ary = lp_build_cmp(coord_bld, PIPE_FUNC_GEQUAL, maxarxsarys, arzs);
   1057 
   1058       /*
   1059        * compute all possible new s/t coords
   1060        * snewx = signrx * -rz;
   1061        * tnewx = -ry;
   1062        * snewy = rx;
   1063        * tnewy = signry * rz;
   1064        * snewz = signrz * rx;
   1065        * tnewz = -ry;
   1066        */
   1067       signrxs = lp_build_swizzle_scalar_aos(cint_bld, signrxyz, 0);
   1068       snewx = LLVMBuildXor(builder, signrxs, rzneg, "");
   1069       tnewx = ryneg;
   1070 
   1071       signrys = lp_build_swizzle_scalar_aos(cint_bld, signrxyz, 1);
   1072       snewy = rx;
   1073       tnewy = LLVMBuildXor(builder, signrys, rz, "");
   1074 
   1075       signrzs = lp_build_swizzle_scalar_aos(cint_bld, signrxyz, 2);
   1076       snewz = LLVMBuildXor(builder, signrzs, rx, "");
   1077       tnewz = ryneg;
   1078 
   1079       /* XXX on x86 unclear if we should cast the values back to float
   1080        * or not - on some cpus (nehalem) pblendvb has twice the throughput
   1081        * of blendvps though on others there just might be domain
   1082        * transition penalties when using it (this depends on what llvm
   1083        * will chose for the bit ops above so there appears no "right way",
   1084        * but given the boatload of selects let's just use the int type).
   1085        *
   1086        * Unfortunately we also need the sign bit of the summed coords.
   1087        */
   1088       *face_s = lp_build_select(cint_bld, arx_ge_ary, snewx, snewy);
   1089       *face_t = lp_build_select(cint_bld, arx_ge_ary, tnewx, tnewy);
   1090       ma = lp_build_select(coord_bld, arx_ge_ary, s, t);
   1091       *face = lp_build_select(cint_bld, arx_ge_ary, facex, facey);
   1092       sign = lp_build_select(cint_bld, arx_ge_ary, signrxs, signrys);
   1093 
   1094       *face_s = lp_build_select(cint_bld, arz_ge_arx_ary, *face_s, snewz);
   1095       *face_t = lp_build_select(cint_bld, arz_ge_arx_ary, *face_t, tnewz);
   1096       ma = lp_build_select(coord_bld, arz_ge_arx_ary, ma, r);
   1097       *face = lp_build_select(cint_bld, arz_ge_arx_ary, *face, facez);
   1098       sign = lp_build_select(cint_bld, arz_ge_arx_ary, sign, signrzs);
   1099 
   1100       *face_s = LLVMBuildBitCast(builder, *face_s,
   1101                                lp_build_vec_type(gallivm, coord_bld->type), "");
   1102       *face_t = LLVMBuildBitCast(builder, *face_t,
   1103                                lp_build_vec_type(gallivm, coord_bld->type), "");
   1104 
   1105       /* add +1 for neg face */
   1106       /* XXX with AVX probably want to use another select here -
   1107        * as long as we ensure vblendvps gets used we can actually
   1108        * skip the comparison and just use sign as a "mask" directly.
   1109        */
   1110       sign = LLVMBuildLShr(builder, sign, signshift, "");
   1111       *face = LLVMBuildOr(builder, *face, sign, "face");
   1112 
   1113       ima = lp_build_cube_imapos(coord_bld, ma);
   1114 
   1115       *face_s = lp_build_mul(coord_bld, *face_s, ima);
   1116       *face_s = lp_build_add(coord_bld, *face_s, posHalf);
   1117       *face_t = lp_build_mul(coord_bld, *face_t, ima);
   1118       *face_t = lp_build_add(coord_bld, *face_t, posHalf);
   1119    }
   1120 
   1121    else {
   1122       struct lp_build_if_state if_ctx;
   1123       LLVMValueRef face_s_var;
   1124       LLVMValueRef face_t_var;
   1125       LLVMValueRef face_var;
   1126       LLVMValueRef arx_ge_ary_arz, ary_ge_arx_arz;
   1127       LLVMValueRef shuffles[4];
   1128       LLVMValueRef arxy_ge_aryx, arxy_ge_arzz, arxy_ge_arxy_arzz;
   1129       LLVMValueRef arxyxy, aryxzz, arxyxy_ge_aryxzz;
   1130       struct lp_build_context *float_bld = &bld->float_bld;
   1131 
   1132       assert(bld->coord_bld.type.length == 4);
   1133 
   1134       shuffles[0] = lp_build_const_int32(gallivm, 0);
   1135       shuffles[1] = lp_build_const_int32(gallivm, 1);
   1136       shuffles[2] = lp_build_const_int32(gallivm, 0);
   1137       shuffles[3] = lp_build_const_int32(gallivm, 1);
   1138       arxyxy = LLVMBuildShuffleVector(builder, arxyz, arxyz, LLVMConstVector(shuffles, 4), "");
   1139       shuffles[0] = lp_build_const_int32(gallivm, 1);
   1140       shuffles[1] = lp_build_const_int32(gallivm, 0);
   1141       shuffles[2] = lp_build_const_int32(gallivm, 2);
   1142       shuffles[3] = lp_build_const_int32(gallivm, 2);
   1143       aryxzz = LLVMBuildShuffleVector(builder, arxyz, arxyz, LLVMConstVector(shuffles, 4), "");
   1144       arxyxy_ge_aryxzz = lp_build_cmp(&bld->coord_bld, PIPE_FUNC_GEQUAL, arxyxy, aryxzz);
   1145 
   1146       shuffles[0] = lp_build_const_int32(gallivm, 0);
   1147       shuffles[1] = lp_build_const_int32(gallivm, 1);
   1148       arxy_ge_aryx = LLVMBuildShuffleVector(builder, arxyxy_ge_aryxzz, arxyxy_ge_aryxzz,
   1149                                             LLVMConstVector(shuffles, 2), "");
   1150       shuffles[0] = lp_build_const_int32(gallivm, 2);
   1151       shuffles[1] = lp_build_const_int32(gallivm, 3);
   1152       arxy_ge_arzz = LLVMBuildShuffleVector(builder, arxyxy_ge_aryxzz, arxyxy_ge_aryxzz,
   1153                                             LLVMConstVector(shuffles, 2), "");
   1154       arxy_ge_arxy_arzz = LLVMBuildAnd(builder, arxy_ge_aryx, arxy_ge_arzz, "");
   1155 
   1156       arx_ge_ary_arz = LLVMBuildExtractElement(builder, arxy_ge_arxy_arzz,
   1157                                                lp_build_const_int32(gallivm, 0), "");
   1158       arx_ge_ary_arz = LLVMBuildICmp(builder, LLVMIntNE, arx_ge_ary_arz,
   1159                                                lp_build_const_int32(gallivm, 0), "");
   1160       ary_ge_arx_arz = LLVMBuildExtractElement(builder, arxy_ge_arxy_arzz,
   1161                                                lp_build_const_int32(gallivm, 1), "");
   1162       ary_ge_arx_arz = LLVMBuildICmp(builder, LLVMIntNE, ary_ge_arx_arz,
   1163                                                lp_build_const_int32(gallivm, 0), "");
   1164       face_s_var = lp_build_alloca(gallivm, bld->coord_bld.vec_type, "face_s_var");
   1165       face_t_var = lp_build_alloca(gallivm, bld->coord_bld.vec_type, "face_t_var");
   1166       face_var = lp_build_alloca(gallivm, bld->int_bld.vec_type, "face_var");
   1167 
   1168       lp_build_if(&if_ctx, gallivm, arx_ge_ary_arz);
   1169       {
   1170          /* +/- X face */
   1171          LLVMValueRef sign, ima;
   1172          rx = LLVMBuildExtractElement(builder, rxyz,
   1173                                       lp_build_const_int32(gallivm, 0), "");
   1174          /* +/- X face */
   1175          sign = lp_build_sgn(float_bld, rx);
   1176          ima = lp_build_cube_imaneg(coord_bld, s);
   1177          *face_s = lp_build_cube_coord(coord_bld, sign, +1, r, ima);
   1178          *face_t = lp_build_cube_coord(coord_bld, NULL, +1, t, ima);
   1179          *face = lp_build_cube_face(bld, rx,
   1180                                     PIPE_TEX_FACE_POS_X,
   1181                                     PIPE_TEX_FACE_NEG_X);
   1182          LLVMBuildStore(builder, *face_s, face_s_var);
   1183          LLVMBuildStore(builder, *face_t, face_t_var);
   1184          LLVMBuildStore(builder, *face, face_var);
   1185       }
   1186       lp_build_else(&if_ctx);
   1187       {
   1188          struct lp_build_if_state if_ctx2;
   1189 
   1190          lp_build_if(&if_ctx2, gallivm, ary_ge_arx_arz);
   1191          {
   1192             LLVMValueRef sign, ima;
   1193             /* +/- Y face */
   1194             ry = LLVMBuildExtractElement(builder, rxyz,
   1195                                          lp_build_const_int32(gallivm, 1), "");
   1196             sign = lp_build_sgn(float_bld, ry);
   1197             ima = lp_build_cube_imaneg(coord_bld, t);
   1198             *face_s = lp_build_cube_coord(coord_bld, NULL, -1, s, ima);
   1199             *face_t = lp_build_cube_coord(coord_bld, sign, -1, r, ima);
   1200             *face = lp_build_cube_face(bld, ry,
   1201                                        PIPE_TEX_FACE_POS_Y,
   1202                                        PIPE_TEX_FACE_NEG_Y);
   1203             LLVMBuildStore(builder, *face_s, face_s_var);
   1204             LLVMBuildStore(builder, *face_t, face_t_var);
   1205             LLVMBuildStore(builder, *face, face_var);
   1206          }
   1207          lp_build_else(&if_ctx2);
   1208          {
   1209             /* +/- Z face */
   1210             LLVMValueRef sign, ima;
   1211             rz = LLVMBuildExtractElement(builder, rxyz,
   1212                                          lp_build_const_int32(gallivm, 2), "");
   1213             sign = lp_build_sgn(float_bld, rz);
   1214             ima = lp_build_cube_imaneg(coord_bld, r);
   1215             *face_s = lp_build_cube_coord(coord_bld, sign, -1, s, ima);
   1216             *face_t = lp_build_cube_coord(coord_bld, NULL, +1, t, ima);
   1217             *face = lp_build_cube_face(bld, rz,
   1218                                        PIPE_TEX_FACE_POS_Z,
   1219                                        PIPE_TEX_FACE_NEG_Z);
   1220             LLVMBuildStore(builder, *face_s, face_s_var);
   1221             LLVMBuildStore(builder, *face_t, face_t_var);
   1222             LLVMBuildStore(builder, *face, face_var);
   1223          }
   1224          lp_build_endif(&if_ctx2);
   1225       }
   1226 
   1227       lp_build_endif(&if_ctx);
   1228 
   1229       *face_s = LLVMBuildLoad(builder, face_s_var, "face_s");
   1230       *face_t = LLVMBuildLoad(builder, face_t_var, "face_t");
   1231       *face   = LLVMBuildLoad(builder, face_var, "face");
   1232       *face   = lp_build_broadcast_scalar(&bld->int_coord_bld, *face);
   1233    }
   1234 }
   1235 
   1236 
   1237 /**
   1238  * Compute the partial offset of a pixel block along an arbitrary axis.
   1239  *
   1240  * @param coord   coordinate in pixels
   1241  * @param stride  number of bytes between rows of successive pixel blocks
   1242  * @param block_length  number of pixels in a pixels block along the coordinate
   1243  *                      axis
   1244  * @param out_offset    resulting relative offset of the pixel block in bytes
   1245  * @param out_subcoord  resulting sub-block pixel coordinate
   1246  */
   1247 void
   1248 lp_build_sample_partial_offset(struct lp_build_context *bld,
   1249                                unsigned block_length,
   1250                                LLVMValueRef coord,
   1251                                LLVMValueRef stride,
   1252                                LLVMValueRef *out_offset,
   1253                                LLVMValueRef *out_subcoord)
   1254 {
   1255    LLVMBuilderRef builder = bld->gallivm->builder;
   1256    LLVMValueRef offset;
   1257    LLVMValueRef subcoord;
   1258 
   1259    if (block_length == 1) {
   1260       subcoord = bld->zero;
   1261    }
   1262    else {
   1263       /*
   1264        * Pixel blocks have power of two dimensions. LLVM should convert the
   1265        * rem/div to bit arithmetic.
   1266        * TODO: Verify this.
   1267        * It does indeed BUT it does transform it to scalar (and back) when doing so
   1268        * (using roughly extract, shift/and, mov, unpack) (llvm 2.7).
   1269        * The generated code looks seriously unfunny and is quite expensive.
   1270        */
   1271 #if 0
   1272       LLVMValueRef block_width = lp_build_const_int_vec(bld->type, block_length);
   1273       subcoord = LLVMBuildURem(builder, coord, block_width, "");
   1274       coord    = LLVMBuildUDiv(builder, coord, block_width, "");
   1275 #else
   1276       unsigned logbase2 = util_logbase2(block_length);
   1277       LLVMValueRef block_shift = lp_build_const_int_vec(bld->gallivm, bld->type, logbase2);
   1278       LLVMValueRef block_mask = lp_build_const_int_vec(bld->gallivm, bld->type, block_length - 1);
   1279       subcoord = LLVMBuildAnd(builder, coord, block_mask, "");
   1280       coord = LLVMBuildLShr(builder, coord, block_shift, "");
   1281 #endif
   1282    }
   1283 
   1284    offset = lp_build_mul(bld, coord, stride);
   1285 
   1286    assert(out_offset);
   1287    assert(out_subcoord);
   1288 
   1289    *out_offset = offset;
   1290    *out_subcoord = subcoord;
   1291 }
   1292 
   1293 
   1294 /**
   1295  * Compute the offset of a pixel block.
   1296  *
   1297  * x, y, z, y_stride, z_stride are vectors, and they refer to pixels.
   1298  *
   1299  * Returns the relative offset and i,j sub-block coordinates
   1300  */
   1301 void
   1302 lp_build_sample_offset(struct lp_build_context *bld,
   1303                        const struct util_format_description *format_desc,
   1304                        LLVMValueRef x,
   1305                        LLVMValueRef y,
   1306                        LLVMValueRef z,
   1307                        LLVMValueRef y_stride,
   1308                        LLVMValueRef z_stride,
   1309                        LLVMValueRef *out_offset,
   1310                        LLVMValueRef *out_i,
   1311                        LLVMValueRef *out_j)
   1312 {
   1313    LLVMValueRef x_stride;
   1314    LLVMValueRef offset;
   1315 
   1316    x_stride = lp_build_const_vec(bld->gallivm, bld->type,
   1317                                  format_desc->block.bits/8);
   1318 
   1319    lp_build_sample_partial_offset(bld,
   1320                                   format_desc->block.width,
   1321                                   x, x_stride,
   1322                                   &offset, out_i);
   1323 
   1324    if (y && y_stride) {
   1325       LLVMValueRef y_offset;
   1326       lp_build_sample_partial_offset(bld,
   1327                                      format_desc->block.height,
   1328                                      y, y_stride,
   1329                                      &y_offset, out_j);
   1330       offset = lp_build_add(bld, offset, y_offset);
   1331    }
   1332    else {
   1333       *out_j = bld->zero;
   1334    }
   1335 
   1336    if (z && z_stride) {
   1337       LLVMValueRef z_offset;
   1338       LLVMValueRef k;
   1339       lp_build_sample_partial_offset(bld,
   1340                                      1, /* pixel blocks are always 2D */
   1341                                      z, z_stride,
   1342                                      &z_offset, &k);
   1343       offset = lp_build_add(bld, offset, z_offset);
   1344    }
   1345 
   1346    *out_offset = offset;
   1347 }
   1348