summaryrefslogtreecommitdiff
path: root/src/compiler/nir/nir_lower_helper_writes.c
blob: cb828569f5a22960e1e5df9f9c5eb132734c1b18 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
/*
 * Copyright (C) 2020-2021 Collabora, Ltd.
 * Copyright © 2020 Valve Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#include "compiler/nir/nir.h"
#include "compiler/nir/nir_builder.h"

static bool
lower(nir_builder *b, nir_instr *instr, void *data)
{
   if (instr->type != nir_instr_type_intrinsic)
      return false;

   nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
   bool *lower_plain_stores = data;

   switch (intr->intrinsic) {
   case nir_intrinsic_global_atomic:
   case nir_intrinsic_global_atomic_swap:
   case nir_intrinsic_global_atomic_add:
   case nir_intrinsic_global_atomic_and:
   case nir_intrinsic_global_atomic_comp_swap:
   case nir_intrinsic_global_atomic_exchange:
   case nir_intrinsic_global_atomic_fadd:
   case nir_intrinsic_global_atomic_fcomp_swap:
   case nir_intrinsic_global_atomic_fmax:
   case nir_intrinsic_global_atomic_fmin:
   case nir_intrinsic_global_atomic_imax:
   case nir_intrinsic_global_atomic_imin:
   case nir_intrinsic_global_atomic_or:
   case nir_intrinsic_global_atomic_umax:
   case nir_intrinsic_global_atomic_umin:
   case nir_intrinsic_global_atomic_xor:
   case nir_intrinsic_image_atomic:
   case nir_intrinsic_image_atomic_swap:
   case nir_intrinsic_image_atomic_add:
   case nir_intrinsic_image_atomic_and:
   case nir_intrinsic_image_atomic_comp_swap:
   case nir_intrinsic_image_atomic_dec_wrap:
   case nir_intrinsic_image_atomic_exchange:
   case nir_intrinsic_image_atomic_fadd:
   case nir_intrinsic_image_atomic_imax:
   case nir_intrinsic_image_atomic_imin:
   case nir_intrinsic_image_atomic_inc_wrap:
   case nir_intrinsic_image_atomic_or:
   case nir_intrinsic_image_atomic_umax:
   case nir_intrinsic_image_atomic_umin:
   case nir_intrinsic_image_atomic_xor:
      break;
   case nir_intrinsic_store_global:
   case nir_intrinsic_image_store:
      if (!(*lower_plain_stores))
         return false;
      else
         break;
   default:
      return false;
   }

   b->cursor = nir_before_instr(instr);
   bool has_dest = nir_intrinsic_infos[intr->intrinsic].has_dest;
   nir_ssa_def *undef = NULL;

   nir_ssa_def *helper = nir_load_helper_invocation(b, 1);
   nir_push_if(b, nir_inot(b, helper));
   nir_instr_remove(instr);
   nir_builder_instr_insert(b, instr);

   /* Per the spec, it does not matter what we return for helper threads.
    * Represent this by an ssa_undef in the hopes the backend will be clever
    * enough to optimize out the phi.
    *
    *    Fragment shader helper invocations execute the same shader code as
    *    non-helper invocations, but will not have side effects that modify the
    *    framebuffer or other shader-accessible memory. In particular:
    *
    *       ...
    *
    *       Atomic operations to image, buffer, or atomic counter variables
    *       performed by helper invocations have no effect on the underlying
    *       image or buffer memory. The values returned by such atomic
    *       operations are undefined.
    */
   if (has_dest) {
      nir_push_else(b, NULL);
      undef = nir_ssa_undef(b, nir_dest_num_components(intr->dest),
                            nir_dest_bit_size(intr->dest));
   }

   nir_pop_if(b, NULL);

   if (has_dest) {
      assert(intr->dest.is_ssa);
      nir_ssa_def *phi = nir_if_phi(b, &intr->dest.ssa, undef);

      /* We can't use nir_ssa_def_rewrite_uses_after on phis, so use the global
       * version and fixup the phi manually
       */
      nir_ssa_def_rewrite_uses(&intr->dest.ssa, phi);

      nir_instr *phi_instr = phi->parent_instr;
      nir_phi_instr *phi_as_phi = nir_instr_as_phi(phi_instr);
      nir_phi_src *phi_src = nir_phi_get_src_from_block(phi_as_phi,
                                                        instr->block);
      nir_instr_rewrite_src_ssa(phi->parent_instr, &phi_src->src,
                                &intr->dest.ssa);
   }

   return true;
}

bool
nir_lower_helper_writes(nir_shader *shader, bool lower_plain_stores)
{
   assert(shader->info.stage == MESA_SHADER_FRAGMENT);
   return nir_shader_instructions_pass(shader, lower, nir_metadata_none,
                                       &lower_plain_stores);
}