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 
28 using namespace brw;
29 
30 bool
31 fs_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