1/*******************************************************************************
2* Copyright 2017-2018 Intel Corporation
3*
4* Licensed under the Apache License, Version 2.0 (the "License");
5* you may not use this file except in compliance with the License.
6* You may obtain a copy of the License at
7*
8* http://www.apache.org/licenses/LICENSE-2.0
9*
10* Unless required by applicable law or agreed to in writing, software
11* distributed under the License is distributed on an "AS IS" BASIS,
12* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13* See the License for the specific language governing permissions and
14* limitations under the License.
15*******************************************************************************/
16
17#include <assert.h>
18
19#include "cpu_barrier.hpp"
20
21namespace mkldnn {
22namespace impl {
23namespace cpu {
24
25namespace simple_barrier {
26
27void generate(jit_generator &code, Xbyak::Reg64 reg_ctx,
28 Xbyak::Reg64 reg_nthr) {
29# define BAR_CTR_OFF offsetof(ctx_t, ctr)
30# define BAR_SENSE_OFF offsetof(ctx_t, sense)
31 using namespace Xbyak;
32
33 Xbyak::Reg64 reg_tmp = [&]() {
34 /* returns register which is neither reg_ctx nor reg_nthr */
35 Xbyak::Reg64 regs[] = { util::rax, util::rbx, util::rcx };
36 for (size_t i = 0; i < sizeof(regs) / sizeof(regs[0]); ++i)
37 if (!utils::one_of(regs[i], reg_ctx, reg_nthr))
38 return regs[i];
39 return regs[0]; /* should not happen */
40 }();
41
42 Label barrier_exit_label, barrier_exit_restore_label, spin_label;
43
44 code.cmp(reg_nthr, 1);
45 code.jbe(barrier_exit_label);
46
47 code.push(reg_tmp);
48
49 /* take and save current sense */
50 code.mov(reg_tmp, code.ptr[reg_ctx + BAR_SENSE_OFF]);
51 code.push(reg_tmp);
52 code.mov(reg_tmp, 1);
53
54 if (mayiuse(avx512_mic)) {
55 code.prefetchwt1(code.ptr[reg_ctx + BAR_CTR_OFF]);
56 code.prefetchwt1(code.ptr[reg_ctx + BAR_CTR_OFF]);
57 }
58
59 code.lock(); code.xadd(code.ptr[reg_ctx + BAR_CTR_OFF], reg_tmp);
60 code.add(reg_tmp, 1);
61 code.cmp(reg_tmp, reg_nthr);
62 code.pop(reg_tmp); /* restore previous sense */
63 code.jne(spin_label);
64
65 /* the last thread {{{ */
66 code.mov(code.qword[reg_ctx + BAR_CTR_OFF], 0); // reset ctx
67
68 // notify waiting threads
69 code.not_(reg_tmp);
70 code.mov(code.ptr[reg_ctx + BAR_SENSE_OFF], reg_tmp);
71 code.jmp(barrier_exit_restore_label);
72 /* }}} the last thread */
73
74 code.CodeGenerator::L(spin_label);
75 code.pause();
76 code.cmp(reg_tmp, code.ptr[reg_ctx + BAR_SENSE_OFF]);
77 code.je(spin_label);
78
79 code.CodeGenerator::L(barrier_exit_restore_label);
80 code.pop(reg_tmp);
81
82 code.CodeGenerator::L(barrier_exit_label);
83# undef BAR_CTR_OFF
84# undef BAR_SENSE_OFF
85}
86
87/** jit barrier generator */
88struct jit_t: public jit_generator {
89 void (*barrier)(ctx_t *ctx, size_t nthr);
90
91 jit_t() {
92 generate(*this, abi_param1, abi_param2);
93 ret();
94 barrier = reinterpret_cast<decltype(barrier)>(const_cast<uint8_t*>(
95 this->getCode()));
96 }
97
98 DECLARE_CPU_JIT_AUX_FUNCTIONS(jit_t)
99};
100
101void barrier(ctx_t *ctx, int nthr) {
102 static jit_t j; /* XXX: constructed on load ... */
103 j.barrier(ctx, nthr);
104}
105
106}
107
108}
109}
110}
111
112// vim: et ts=4 sw=4 cindent cino^=l0,\:0,N-s
113