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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 static nir_intrinsic_instr *
     28 as_intrinsic(nir_instr *instr, nir_intrinsic_op op)
     29 {
     30    if (instr->type != nir_instr_type_intrinsic)
     31       return NULL;
     32 
     33    nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
     34    if (intrin->intrinsic != op)
     35       return NULL;
     36 
     37    return intrin;
     38 }
     39 
     40 static nir_intrinsic_instr *
     41 as_set_vertex_and_primitive_count(nir_instr *instr)
     42 {
     43    return as_intrinsic(instr, nir_intrinsic_set_vertex_and_primitive_count);
     44 }
     45 
     46 /**
     47  * Count the number of vertices/primitives emitted by a geometry shader per stream.
     48  * If a constant number of vertices is emitted, the output is set to
     49  * that number, otherwise it is unknown at compile time and the
     50  * result will be -1.
     51  *
     52  * This only works if you've used nir_lower_gs_intrinsics() to do vertex
     53  * counting at the NIR level.
     54  */
     55 void
     56 nir_gs_count_vertices_and_primitives(const nir_shader *shader,
     57                                      int *out_vtxcnt,
     58                                      int *out_prmcnt,
     59                                      unsigned num_streams)
     60 {
     61    assert(num_streams);
     62 
     63    int vtxcnt_arr[4] = {-1, -1, -1, -1};
     64    int prmcnt_arr[4] = {-1, -1, -1, -1};
     65    bool cnt_found[4] = {false, false, false, false};
     66 
     67    nir_foreach_function(function, shader) {
     68       if (!function->impl)
     69          continue;
     70 
     71       /* set_vertex_and_primitive_count intrinsics only appear in predecessors of the
     72        * end block.  So we don't need to walk all of them.
     73        */
     74       set_foreach(function->impl->end_block->predecessors, entry) {
     75          nir_block *block = (nir_block *) entry->key;
     76 
     77          nir_foreach_instr_reverse(instr, block) {
     78             nir_intrinsic_instr *intrin = as_set_vertex_and_primitive_count(instr);
     79             if (!intrin)
     80                continue;
     81 
     82             unsigned stream = nir_intrinsic_stream_id(intrin);
     83             if (stream >= num_streams)
     84                continue;
     85 
     86             int vtxcnt = -1;
     87             int prmcnt = -1;
     88 
     89             /* If the number of vertices/primitives is compile-time known, we use that,
     90              * otherwise we leave it at -1 which means that it's unknown.
     91              */
     92             if (nir_src_is_const(intrin->src[0]))
     93                vtxcnt = nir_src_as_int(intrin->src[0]);
     94             if (nir_src_is_const(intrin->src[1]))
     95                prmcnt = nir_src_as_int(intrin->src[1]);
     96 
     97             /* We've found contradictory set_vertex_and_primitive_count intrinsics.
     98              * This can happen if there are early-returns in main() and
     99              * different paths emit different numbers of vertices.
    100              */
    101             if (cnt_found[stream] && vtxcnt != vtxcnt_arr[stream])
    102                vtxcnt = -1;
    103             if (cnt_found[stream] && prmcnt != prmcnt_arr[stream])
    104                prmcnt = -1;
    105 
    106             vtxcnt_arr[stream] = vtxcnt;
    107             prmcnt_arr[stream] = prmcnt;
    108             cnt_found[stream] = true;
    109          }
    110       }
    111    }
    112 
    113    if (out_vtxcnt)
    114       memcpy(out_vtxcnt, vtxcnt_arr, num_streams * sizeof(int));
    115    if (out_prmcnt)
    116       memcpy(out_prmcnt, prmcnt_arr, num_streams * sizeof(int));
    117 }
    118