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_uniform(struct v3d_compile *c, nir_builder *b,
  56                       nir_intrinsic_instr *intr)
  57 {
  58         b->cursor = nir_before_instr(&intr->instr);
  59
  60         /* Generate scalar loads equivalent to the original vector. */
  61         nir_ssa_def *dests[4];
  62         for (unsigned i = 0; i < intr->num_components; i++) {
  63                 nir_intrinsic_instr *intr_comp =
  64                         nir_intrinsic_instr_create(c->s, intr->intrinsic);
  65                 intr_comp->num_components = 1;
  66                 nir_ssa_dest_init(&intr_comp->instr, &intr_comp->dest, 1,
  67                                   intr->dest.ssa.bit_size, NULL);
  68
  69                 /* Convert the uniform offset to bytes.  If it happens
  70                  * to be a constant, constant-folding will clean up
  71                  * the shift for us.
  72                  */
  73                 nir_intrinsic_set_base(intr_comp,
  74                                        nir_intrinsic_base(intr) * 16 +
  75                                        i * 4);
  76
  77                 intr_comp->src[0] =
  78                         nir_src_for_ssa(nir_ishl(b, intr->src[0].ssa,
  79                                                  nir_imm_int(b, 4)));
  80
  81                 dests[i] = &intr_comp->dest.ssa;
  82
  83                 nir_builder_instr_insert(b, &intr_comp->instr);
  84         }
  85
  86         replace_intrinsic_with_vec(b, intr, dests);
  87 }
  88
  89 static void
  90 v3d_nir_lower_io_instr(struct v3d_compile *c, nir_builder *b,
  91                        struct nir_instr *instr)
  92 {
  93         if (instr->type != nir_instr_type_intrinsic)
  94                 return;
  95         nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
  96
  97         switch (intr->intrinsic) {
  98         case nir_intrinsic_load_input:
  99                 break;
 100
 101         case nir_intrinsic_load_uniform:
 102                 v3d_nir_lower_uniform(c, b, intr);
 103                 break;
 104
 105         case nir_intrinsic_load_user_clip_plane:
 106         default:
 107                 break;
 108         }
 109 }
 110
 111 static bool
 112 v3d_nir_lower_io_impl(struct v3d_compile *c, nir_function_impl *impl)
 113 {
 114         nir_builder b;
 115         nir_builder_init(&b, impl);
 116
 117         nir_foreach_block(block, impl) {
 118                 nir_foreach_instr_safe(instr, block)
 119                         v3d_nir_lower_io_instr(c, &b, instr);
 120         }
 121
 122         nir_metadata_preserve(impl, nir_metadata_block_index |
 123                               nir_metadata_dominance);
 124
 125         return true;
 126 }
 127
 128 void
 129 v3d_nir_lower_io(nir_shader *s, struct v3d_compile *c)
 130 {
 131         nir_foreach_function(function, s) {
 132                 if (function->impl)
 133                         v3d_nir_lower_io_impl(c, function->impl);
 134         }
 135 }