1/*
2 * Copyright © 2015 Connor Abbott
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 "brw_fs.h"
25#include "brw_cfg.h"
26#include "brw_fs_builder.h"
27
28using namespace brw;
29
30bool
31fs_visitor::lower_d2x()
32{
33   bool progress = false;
34
35   foreach_block_and_inst_safe(block, fs_inst, inst, cfg) {
36      if (inst->opcode != BRW_OPCODE_MOV)
37         continue;
38
39      if (inst->dst.type != BRW_REGISTER_TYPE_F &&
40          inst->dst.type != BRW_REGISTER_TYPE_D &&
41          inst->dst.type != BRW_REGISTER_TYPE_UD)
42         continue;
43
44      if (inst->src[0].type != BRW_REGISTER_TYPE_DF)
45         continue;
46
47      assert(inst->dst.file == VGRF);
48      assert(inst->saturate == false);
49      fs_reg dst = inst->dst;
50
51      const fs_builder ibld(this, block, inst);
52
53      /* From the Broadwell PRM, 3D Media GPGPU, "Double Precision Float to
54       * Single Precision Float":
55       *
56       *    The upper Dword of every Qword will be written with undefined
57       *    value when converting DF to F.
58       *
59       * So we need to allocate a temporary that's two registers, and then do
60       * a strided MOV to get the lower DWord of every Qword that has the
61       * result.
62       */
63      fs_reg temp = ibld.vgrf(inst->src[0].type, 1);
64      fs_reg strided_temp = subscript(temp, inst->dst.type, 0);
65      ibld.MOV(strided_temp, inst->src[0]);
66      ibld.MOV(dst, strided_temp);
67
68      inst->remove(block);
69      progress = true;
70   }
71
72   if (progress)
73      invalidate_live_intervals();
74
75   return progress;
76}
77