src/compiler/nir/nir_gather_xfb_info.c

   1 /*
   2  * Copyright © 2018 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_xfb_info.h"
  25
  26 #include <util/u_math.h>
  27
  28 static void
  29 add_var_xfb_outputs(nir_xfb_info *xfb,
  30                     nir_variable *var,
  31                     unsigned buffer,
  32                     unsigned *location,
  33                     unsigned *offset,
  34                     const struct glsl_type *type)
  35 {
  36    /* If this type contains a 64-bit value, align to 8 bytes */
  37    if (glsl_type_contains_64bit(type))
  38       *offset = ALIGN_POT(*offset, 8);
  39
  40    if (glsl_type_is_array(type) || glsl_type_is_matrix(type)) {
  41       unsigned length = glsl_get_length(type);
  42       const struct glsl_type *child_type = glsl_get_array_element(type);
  43       for (unsigned i = 0; i < length; i++)
  44          add_var_xfb_outputs(xfb, var, buffer, location, offset, child_type);
  45    } else if (glsl_type_is_struct(type)) {
  46       unsigned length = glsl_get_length(type);
  47       for (unsigned i = 0; i < length; i++) {
  48          const struct glsl_type *child_type = glsl_get_struct_field(type, i);
  49          add_var_xfb_outputs(xfb, var, buffer, location, offset, child_type);
  50       }
  51    } else {
  52       assert(buffer < NIR_MAX_XFB_BUFFERS);
  53       if (xfb->buffers_written & (1 << buffer)) {
  54          assert(xfb->strides[buffer] == var->data.xfb_stride);
  55          assert(xfb->buffer_to_stream[buffer] == var->data.stream);
  56       } else {
  57          xfb->buffers_written |= (1 << buffer);
  58          xfb->strides[buffer] = var->data.xfb_stride;
  59          xfb->buffer_to_stream[buffer] = var->data.stream;
  60       }
  61
  62       assert(var->data.stream < NIR_MAX_XFB_STREAMS);
  63       xfb->streams_written |= (1 << var->data.stream);
  64
  65       unsigned comp_slots = glsl_get_component_slots(type);
  66       unsigned attrib_slots = DIV_ROUND_UP(comp_slots, 4);
  67       assert(attrib_slots == glsl_count_attribute_slots(type, false));
  68
  69       /* Ensure that we don't have, for instance, a dvec2 with a location_frac
  70        * of 2 which would make it crass a location boundary even though it
  71        * fits in a single slot.  However, you can have a dvec3 which crosses
  72        * the slot boundary with a location_frac of 2.
  73        */
  74       assert(DIV_ROUND_UP(var->data.location_frac + comp_slots, 4) == attrib_slots);
  75
  76       assert(var->data.location_frac + comp_slots <= 8);
  77       uint8_t comp_mask = ((1 << comp_slots) - 1) << var->data.location_frac;
  78
  79       while (comp_mask) {
  80          nir_xfb_output_info *output = &xfb->outputs[xfb->output_count++];
  81
  82          output->buffer = buffer;
  83          output->offset = *offset;
  84          output->location = *location;
  85          output->component_mask = comp_mask & 0xf;
  86
  87          *offset += util_bitcount(output->component_mask) * 4;
  88          (*location)++;
  89          comp_mask >>= 4;
  90       }
  91    }
  92 }
  93
  94 static int
  95 compare_xfb_output_offsets(const void *_a, const void *_b)
  96 {
  97    const nir_xfb_output_info *a = _a, *b = _b;
  98    return a->offset - b->offset;
  99 }
 100
 101 nir_xfb_info *
 102 nir_gather_xfb_info(const nir_shader *shader, void *mem_ctx)
 103 {
 104    assert(shader->info.stage == MESA_SHADER_VERTEX ||
 105           shader->info.stage == MESA_SHADER_TESS_EVAL ||
 106           shader->info.stage == MESA_SHADER_GEOMETRY);
 107
 108    /* Compute the number of outputs we have.  This is simply the number of
 109     * cumulative locations consumed by all the variables.  If a location is
 110     * represented by multiple variables, then they each count separately in
 111     * number of outputs.  This is only an estimate as some variables may have
 112     * an xfb_buffer but not an output so it may end up larger than we need but
 113     * it should be good enough for allocation.
 114     */
 115    unsigned num_outputs = 0;
 116    nir_foreach_variable(var, &shader->outputs) {
 117       if (var->data.explicit_xfb_buffer)
 118          num_outputs += glsl_count_attribute_slots(var->type, false);
 119    }
 120    if (num_outputs == 0)
 121       return NULL;
 122
 123    nir_xfb_info *xfb = rzalloc_size(mem_ctx, nir_xfb_info_size(num_outputs));
 124
 125    /* Walk the list of outputs and add them to the array */
 126    nir_foreach_variable(var, &shader->outputs) {
 127       if (!var->data.explicit_xfb_buffer)
 128          continue;
 129
 130       unsigned location = var->data.location;
 131
 132       /* In order to know if we have a array of blocks can't be done just by
 133        * checking if we have an interface type and is an array, because due
 134        * splitting we could end on a case were we received a split struct
 135        * that contains an array.
 136        */
 137       bool is_array_block = var->interface_type != NULL &&
 138          glsl_type_is_array(var->type) &&
 139          glsl_without_array(var->type) == glsl_get_bare_type(var->interface_type);
 140
 141       if (var->data.explicit_offset && !is_array_block) {
 142          unsigned offset = var->data.offset;
 143          add_var_xfb_outputs(xfb, var, var->data.xfb_buffer,
 144                              &location, &offset, var->type);
 145       } else if (is_array_block) {
 146          assert(glsl_type_is_struct(var->interface_type));
 147
 148          unsigned aoa_size = glsl_get_aoa_size(var->type);
 149          const struct glsl_type *itype = var->interface_type;
 150          unsigned nfields = glsl_get_length(itype);
 151          for (unsigned b = 0; b < aoa_size; b++) {
 152             for (unsigned f = 0; f < nfields; f++) {
 153                int foffset = glsl_get_struct_field_offset(itype, f);
 154                const struct glsl_type *ftype = glsl_get_struct_field(itype, f);
 155                if (foffset < 0) {
 156                   location += glsl_count_attribute_slots(ftype, false);
 157                   continue;
 158                }
 159
 160                unsigned offset = foffset;
 161                add_var_xfb_outputs(xfb, var, var->data.xfb_buffer + b,
 162                                    &location, &offset, ftype);
 163             }
 164          }
 165       }
 166    }
 167
 168    /* Everything is easier in the state setup code if the list is sorted in
 169     * order of output offset.
 170     */
 171    qsort(xfb->outputs, xfb->output_count, sizeof(xfb->outputs[0]),
 172          compare_xfb_output_offsets);
 173
 174 #ifndef NDEBUG
 175    /* Finally, do a sanity check */
 176    unsigned max_offset[NIR_MAX_XFB_BUFFERS] = {0};
 177    for (unsigned i = 0; i < xfb->output_count; i++) {
 178       assert(xfb->outputs[i].offset >= max_offset[xfb->outputs[i].buffer]);
 179       assert(xfb->outputs[i].component_mask != 0);
 180       unsigned slots = util_bitcount(xfb->outputs[i].component_mask);
 181       max_offset[xfb->outputs[i].buffer] = xfb->outputs[i].offset + slots * 4;
 182    }
 183 #endif
 184
 185    return xfb;
 186 }