1 /*
2 * Copyright © 2024 Collabora, Ltd.
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 /* Adapted from intel_nir_lower_conversions.c */
25
26 #include "nak_private.h"
27 #include "nir_builder.h"
28
29 static nir_rounding_mode
op_rounding_mode(nir_op op)30 op_rounding_mode(nir_op op)
31 {
32 switch (op) {
33 case nir_op_f2f16_rtne: return nir_rounding_mode_rtne;
34 case nir_op_f2f16_rtz: return nir_rounding_mode_rtz;
35 default: return nir_rounding_mode_undef;
36 }
37 }
38
39 static bool
split_64bit_conversion(nir_builder * b,nir_instr * instr,UNUSED void * _data)40 split_64bit_conversion(nir_builder *b, nir_instr *instr, UNUSED void *_data)
41 {
42 if (instr->type != nir_instr_type_alu)
43 return false;
44
45 nir_alu_instr *alu = nir_instr_as_alu(instr);
46
47 if (!nir_op_infos[alu->op].is_conversion)
48 return false;
49
50 unsigned src_bit_size = nir_src_bit_size(alu->src[0].src);
51 nir_alu_type src_type = nir_op_infos[alu->op].input_types[0];
52 nir_alu_type src_full_type = (nir_alu_type) (src_type | src_bit_size);
53
54 unsigned dst_bit_size = alu->def.bit_size;
55 nir_alu_type dst_full_type = nir_op_infos[alu->op].output_type;
56 assert(nir_alu_type_get_type_size(dst_full_type) == dst_bit_size);
57 nir_alu_type dst_type = nir_alu_type_get_base_type(dst_full_type);
58
59 /* We can't cross the 64-bit boundary in one conversion */
60 if ((src_bit_size <= 32 && dst_bit_size <= 32) ||
61 (src_bit_size >= 32 && dst_bit_size >= 32))
62 return false;
63
64 nir_alu_type tmp_type;
65 if ((src_full_type == nir_type_float16 && dst_bit_size == 64) ||
66 (src_bit_size == 64 && dst_full_type == nir_type_float16)) {
67 /* It is important that the intermediate conversion happens through a
68 * 32-bit float type so we don't lose range when we convert to/from
69 * a 64-bit integer.
70 */
71 tmp_type = nir_type_float32;
72 } else {
73 /* For fp64 to integer conversions, using an integer intermediate type
74 * ensures that rounding happens as part of the first conversion,
75 * avoiding any chance of rtne rounding happening before the conversion
76 * to integer (which is expected to round towards zero).
77 *
78 * NOTE: NVIDIA hardware saturates conversions by default and the second
79 * conversion will not saturate in this case. However, GLSL makes OOB
80 * values in conversions undefiend.
81 *
82 * For all other conversions, the conversion from int to int is either
83 * lossless or just as lossy as the final conversion.
84 */
85 tmp_type = dst_type | 32;
86 }
87
88 b->cursor = nir_before_instr(&alu->instr);
89 nir_def *src = nir_ssa_for_alu_src(b, alu, 0);
90 nir_def *tmp = nir_type_convert(b, src, src_type, tmp_type,
91 nir_rounding_mode_undef);
92 nir_def *res = nir_type_convert(b, tmp, tmp_type, dst_full_type,
93 op_rounding_mode(alu->op));
94 nir_def_replace(&alu->def, res);
95
96 return true;
97 }
98
99 bool
nak_nir_split_64bit_conversions(nir_shader * nir)100 nak_nir_split_64bit_conversions(nir_shader *nir)
101 {
102 return nir_shader_instructions_pass(nir, split_64bit_conversion,
103 nir_metadata_control_flow,
104 NULL);
105 }
106