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
|
/*
* Copyright © 2020 Valve Corporation
* SPDX-License-Identifier: MIT
*/
#include "tu_private.h"
#include "nir_builder.h"
/* Some a6xx variants cannot support a non-contiguous multiview mask. Instead,
* inside the shader something like this needs to be inserted:
*
* gl_Position = ((1ull << gl_ViewIndex) & view_mask) ? gl_Position : vec4(0.);
*
* Scan backwards until we find the gl_Position write (there should only be
* one).
*/
static bool
lower_multiview_mask(nir_shader *nir, uint32_t *mask)
{
nir_function_impl *impl = nir_shader_get_entrypoint(nir);
if (util_is_power_of_two_or_zero(*mask + 1)) {
nir_metadata_preserve(impl, nir_metadata_all);
return false;
}
nir_builder b;
nir_builder_init(&b, impl);
uint32_t old_mask = *mask;
*mask = BIT(util_logbase2(old_mask) + 1) - 1;
nir_foreach_block_reverse(block, impl) {
nir_foreach_instr_reverse(instr, block) {
if (instr->type != nir_instr_type_intrinsic)
continue;
nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
if (intrin->intrinsic != nir_intrinsic_store_deref)
continue;
nir_deref_instr *deref = nir_src_as_deref(intrin->src[0]);
if (!nir_deref_mode_is(deref, nir_var_shader_out))
continue;
nir_variable *var = nir_deref_instr_get_variable(deref);
if (var->data.location != VARYING_SLOT_POS)
continue;
assert(intrin->src[1].is_ssa);
nir_ssa_def *orig_src = intrin->src[1].ssa;
b.cursor = nir_before_instr(instr);
/* ((1ull << gl_ViewIndex) & mask) != 0 */
nir_ssa_def *cmp =
nir_i2b(&b, nir_iand(&b, nir_imm_int(&b, old_mask),
nir_ishl(&b, nir_imm_int(&b, 1),
nir_load_view_index(&b))));
nir_ssa_def *src = nir_bcsel(&b, cmp, orig_src, nir_imm_float(&b, 0.));
nir_instr_rewrite_src(instr, &intrin->src[1], nir_src_for_ssa(src));
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
return true;
}
}
nir_metadata_preserve(impl, nir_metadata_all);
return false;
}
bool
tu_nir_lower_multiview(nir_shader *nir, uint32_t mask, bool *multi_pos_output,
struct tu_device *dev)
{
*multi_pos_output = false;
bool progress = false;
if (!dev->physical_device->info.a6xx.supports_multiview_mask)
NIR_PASS(progress, nir, lower_multiview_mask, &mask);
unsigned num_views = util_logbase2(mask) + 1;
/* Speculatively assign output locations so that we know num_outputs. We
* will assign output locations for real after this pass.
*/
unsigned num_outputs;
nir_assign_io_var_locations(nir, nir_var_shader_out, &num_outputs, MESA_SHADER_VERTEX);
/* In addition to the generic checks done by NIR, check that we don't
* overflow VPC with the extra copies of gl_Position.
*/
if (likely(!(dev->physical_device->instance->debug_flags & TU_DEBUG_NOMULTIPOS)) &&
num_outputs + (num_views - 1) <= 32 && nir_can_lower_multiview(nir)) {
*multi_pos_output = true;
/* It appears that the multiview mask is ignored when multi-position
* output is enabled, so we have to write 0 to inactive views ourselves.
*/
NIR_PASS(progress, nir, lower_multiview_mask, &mask);
NIR_PASS_V(nir, nir_lower_multiview, mask);
progress = true;
}
return progress;
}
|
