src/broadcom/compiler/v3d_nir_lower_io.c

   1 /*
   2  * Copyright © 2015 Broadcom
   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 "compiler/v3d_compiler.h"
  25 #include "compiler/nir/nir_builder.h"
  26
  27 /**
  28  * Walks the NIR generated by TGSI-to-NIR or GLSL-to-NIR to lower its io
  29  * intrinsics into something amenable to the V3D architecture.
  30  *
  31  * Currently, it splits VS inputs and uniforms into scalars, drops any
  32  * non-position outputs in coordinate shaders, and fixes up the addressing on
  33  * indirect uniform loads.  FS input and VS output scalarization is handled by
  34  * nir_lower_io_to_scalar().
  35  */
  36
  37 static void
  38 replace_intrinsic_with_vec(nir_builder *b, nir_intrinsic_instr *intr,
  39                            nir_ssa_def **comps)
  40 {
  41
  42         /* Batch things back together into a vector.  This will get split by
  43          * the later ALU scalarization pass.
  44          */
  45         nir_ssa_def *vec = nir_vec(b, comps, intr->num_components);
  46
  47         /* Replace the old intrinsic with a reference to our reconstructed
  48          * vector.
  49          */
  50         nir_ssa_def_rewrite_uses(&intr->dest.ssa, nir_src_for_ssa(vec));
  51         nir_instr_remove(&intr->instr);
  52 }
  53
  54 static void
  55 v3d_nir_lower_output(struct v3d_compile *c, nir_builder *b,
  56                      nir_intrinsic_instr *intr)
  57 {
  58         nir_variable *output_var = NULL;
  59         nir_foreach_variable(var, &c->s->outputs) {
  60                 if (var->data.driver_location == nir_intrinsic_base(intr)) {
  61                         output_var = var;
  62                         break;
  63                 }
  64         }
  65         assert(output_var);
  66
  67         if (c->vs_key) {
  68                 int slot = output_var->data.location;
  69                 bool used = false;
  70
  71                 switch (slot) {
  72                 case VARYING_SLOT_PSIZ:
  73                 case VARYING_SLOT_POS:
  74                         used = true;
  75                         break;
  76
  77                 default:
  78                         for (int i = 0; i < c->vs_key->num_fs_inputs; i++) {
  79                                 if (v3d_slot_get_slot(c->vs_key->fs_inputs[i]) == slot) {
  80                                         used = true;
  81                                         break;
  82                                 }
  83                         }
  84                         break;
  85                 }
  86
  87                 if (!used)
  88                         nir_instr_remove(&intr->instr);
  89         }
  90 }
  91
  92 static void
  93 v3d_nir_lower_uniform(struct v3d_compile *c, nir_builder *b,
  94                       nir_intrinsic_instr *intr)
  95 {
  96         b->cursor = nir_before_instr(&intr->instr);
  97
  98         /* Generate scalar loads equivalent to the original vector. */
  99         nir_ssa_def *dests[4];
 100         for (unsigned i = 0; i < intr->num_components; i++) {
 101                 nir_intrinsic_instr *intr_comp =
 102                         nir_intrinsic_instr_create(c->s, intr->intrinsic);
 103                 intr_comp->num_components = 1;
 104                 nir_ssa_dest_init(&intr_comp->instr, &intr_comp->dest, 1, 32, NULL);
 105
 106                 /* Convert the uniform offset to bytes.  If it happens
 107                  * to be a constant, constant-folding will clean up
 108                  * the shift for us.
 109                  */
 110                 nir_intrinsic_set_base(intr_comp,
 111                                        nir_intrinsic_base(intr) * 16 +
 112                                        i * 4);
 113
 114                 intr_comp->src[0] =
 115                         nir_src_for_ssa(nir_ishl(b, intr->src[0].ssa,
 116                                                  nir_imm_int(b, 4)));
 117
 118                 dests[i] = &intr_comp->dest.ssa;
 119
 120                 nir_builder_instr_insert(b, &intr_comp->instr);
 121         }
 122
 123         replace_intrinsic_with_vec(b, intr, dests);
 124 }
 125
 126 static void
 127 v3d_nir_lower_io_instr(struct v3d_compile *c, nir_builder *b,
 128                        struct nir_instr *instr)
 129 {
 130         if (instr->type != nir_instr_type_intrinsic)
 131                 return;
 132         nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
 133
 134         switch (intr->intrinsic) {
 135         case nir_intrinsic_load_input:
 136                 break;
 137
 138         case nir_intrinsic_store_output:
 139                 v3d_nir_lower_output(c, b, intr);
 140                 break;
 141
 142         case nir_intrinsic_load_uniform:
 143                 v3d_nir_lower_uniform(c, b, intr);
 144                 break;
 145
 146         case nir_intrinsic_load_user_clip_plane:
 147         default:
 148                 break;
 149         }
 150 }
 151
 152 static bool
 153 v3d_nir_lower_io_impl(struct v3d_compile *c, nir_function_impl *impl)
 154 {
 155         nir_builder b;
 156         nir_builder_init(&b, impl);
 157
 158         nir_foreach_block(block, impl) {
 159                 nir_foreach_instr_safe(instr, block)
 160                         v3d_nir_lower_io_instr(c, &b, instr);
 161         }
 162
 163         nir_metadata_preserve(impl, nir_metadata_block_index |
 164                               nir_metadata_dominance);
 165
 166         return true;
 167 }
 168
 169 void
 170 v3d_nir_lower_io(nir_shader *s, struct v3d_compile *c)
 171 {
 172         nir_foreach_function(function, s) {
 173                 if (function->impl)
 174                         v3d_nir_lower_io_impl(c, function->impl);
 175         }
 176 }