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      1 /*
      2  * Copyright  2015 Intel Corporation
      3  *
      4  * Permission is hereby granted, free of charge, to any person obtaining a
      5  * copy of this software and associated documentation files (the "Software"),
      6  * to deal in the Software without restriction, including without limitation
      7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
      8  * and/or sell copies of the Software, and to permit persons to whom the
      9  * Software is furnished to do so, subject to the following conditions:
     10  *
     11  * The above copyright notice and this permission notice (including the next
     12  * paragraph) shall be included in all copies or substantial portions of the
     13  * Software.
     14  *
     15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
     18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
     20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
     21  * IN THE SOFTWARE.
     22  */
     23 
     24 #include "nir.h"
     25 #include "nir_builder.h"
     26 
     27 /**
     28  * @file
     29  *
     30  * This pass combines separate clip and cull distance arrays into a
     31  * single array that contains both.  Clip distances come first, then
     32  * cull distances.  It also populates nir_shader_info with the size
     33  * of the original arrays so the driver knows which are which.
     34  */
     35 
     36 /**
     37  * Get the length of the clip/cull distance array, looking past
     38  * any interface block arrays.
     39  */
     40 static unsigned
     41 get_unwrapped_array_length(nir_shader *nir, nir_variable *var)
     42 {
     43    if (!var)
     44       return 0;
     45 
     46    /* Unwrap GS input and TCS input/output interfaces.  We want the
     47     * underlying clip/cull distance array length, not the per-vertex
     48     * array length.
     49     */
     50    const struct glsl_type *type = var->type;
     51    if (nir_is_per_vertex_io(var, nir->stage))
     52       type = glsl_get_array_element(type);
     53 
     54    assert(glsl_type_is_array(type));
     55 
     56    return glsl_get_length(type);
     57 }
     58 
     59 /**
     60  * Update the type of the combined array (including interface block nesting).
     61  */
     62 static void
     63 update_type(nir_variable *var, gl_shader_stage stage, unsigned length)
     64 {
     65    const struct glsl_type *type = glsl_array_type(glsl_float_type(), length);
     66 
     67    if (nir_is_per_vertex_io(var, stage))
     68       type = glsl_array_type(type, glsl_get_length(var->type));
     69 
     70    var->type = type;
     71 }
     72 
     73 /**
     74  * Rewrite any clip/cull distances to refer to the new combined array.
     75  */
     76 static void
     77 rewrite_references(nir_instr *instr,
     78                    nir_variable *combined,
     79                    unsigned cull_offset)
     80 {
     81    if (instr->type != nir_instr_type_intrinsic)
     82       return;
     83 
     84    nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
     85 
     86    /* copy_var needs to be lowered to load/store before calling this pass */
     87    assert(intrin->intrinsic != nir_intrinsic_copy_var);
     88 
     89    if (intrin->intrinsic != nir_intrinsic_load_var &&
     90        intrin->intrinsic != nir_intrinsic_store_var)
     91       return;
     92 
     93    nir_deref_var *var_ref = intrin->variables[0];
     94    if (var_ref->var->data.mode != combined->data.mode)
     95       return;
     96 
     97    if (var_ref->var->data.location != VARYING_SLOT_CLIP_DIST0 &&
     98        var_ref->var->data.location != VARYING_SLOT_CULL_DIST0)
     99       return;
    100 
    101    /* Update types along the deref chain */
    102    const struct glsl_type *type = combined->type;
    103    nir_deref *deref = &var_ref->deref;
    104    while (deref) {
    105       deref->type = type;
    106       deref = deref->child;
    107       type = glsl_get_array_element(type);
    108    }
    109 
    110    /* For cull distances, add an offset to the array index */
    111    if (var_ref->var->data.location == VARYING_SLOT_CULL_DIST0) {
    112       nir_deref *tail = nir_deref_tail(&intrin->variables[0]->deref);
    113       nir_deref_array *array_ref = nir_deref_as_array(tail);
    114 
    115       array_ref->base_offset += cull_offset;
    116    }
    117 
    118    /* Point the deref at the combined array */
    119    var_ref->var = combined;
    120 
    121    /* There's no need to update writemasks; it's a scalar array. */
    122 }
    123 
    124 static void
    125 combine_clip_cull(nir_shader *nir,
    126                   struct exec_list *vars,
    127                   bool store_info)
    128 {
    129    nir_variable *cull = NULL;
    130    nir_variable *clip = NULL;
    131 
    132    nir_foreach_variable(var, vars) {
    133       if (var->data.location == VARYING_SLOT_CLIP_DIST0)
    134          clip = var;
    135 
    136       if (var->data.location == VARYING_SLOT_CULL_DIST0)
    137          cull = var;
    138    }
    139 
    140    const unsigned clip_array_size = get_unwrapped_array_length(nir, clip);
    141    const unsigned cull_array_size = get_unwrapped_array_length(nir, cull);
    142 
    143    if (store_info) {
    144       nir->info->clip_distance_array_size = clip_array_size;
    145       nir->info->cull_distance_array_size = cull_array_size;
    146    }
    147 
    148    if (clip)
    149       clip->data.compact = true;
    150 
    151    if (cull)
    152       cull->data.compact = true;
    153 
    154    if (cull_array_size > 0) {
    155       if (clip_array_size == 0) {
    156          /* No clip distances, just change the cull distance location */
    157          cull->data.location = VARYING_SLOT_CLIP_DIST0;
    158       } else {
    159          /* Turn the ClipDistance array into a combined one */
    160          update_type(clip, nir->stage, clip_array_size + cull_array_size);
    161 
    162          /* Rewrite CullDistance to reference the combined array */
    163          nir_foreach_function(function, nir) {
    164             if (function->impl) {
    165                nir_foreach_block(block, function->impl) {
    166                   nir_foreach_instr(instr, block) {
    167                      rewrite_references(instr, clip, clip_array_size);
    168                   }
    169                }
    170             }
    171          }
    172 
    173          /* Delete the old CullDistance variable */
    174          exec_node_remove(&cull->node);
    175          ralloc_free(cull);
    176       }
    177    }
    178 }
    179 
    180 void
    181 nir_lower_clip_cull_distance_arrays(nir_shader *nir)
    182 {
    183    if (nir->stage <= MESA_SHADER_GEOMETRY)
    184       combine_clip_cull(nir, &nir->outputs, true);
    185 
    186    if (nir->stage > MESA_SHADER_VERTEX)
    187       combine_clip_cull(nir, &nir->inputs, false);
    188 }
    189