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/*******************************************************************************
* Copyright 2017 Intel Corporation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*******************************************************************************/
#include <assert.h>
#include "cpu/x64/cpu_barrier.hpp"
namespace dnnl {
namespace impl {
namespace cpu {
namespace x64 {
namespace simple_barrier {
void generate(
jit_generator_t &code, Xbyak::Reg64 reg_ctx, Xbyak::Reg64 reg_nthr) {
#define BAR_CTR_OFF offsetof(ctx_t, ctr)
#define BAR_SENSE_OFF offsetof(ctx_t, sense)
using namespace Xbyak;
Xbyak::Reg64 reg_tmp = [&]() {
/* returns register which is neither reg_ctx nor reg_nthr */
Xbyak::Reg64 regs[] = {util::rax, util::rbx, util::rcx};
for (size_t i = 0; i < sizeof(regs) / sizeof(regs[0]); ++i)
if (!utils::one_of(regs[i], reg_ctx, reg_nthr)) return regs[i];
return regs[0]; /* should not happen */
}();
Label barrier_exit_label, barrier_exit_restore_label, spin_label;
code.cmp(reg_nthr, 1);
code.jbe(barrier_exit_label);
code.push(reg_tmp);
/* take and save current sense */
code.mov(reg_tmp, code.ptr[reg_ctx + BAR_SENSE_OFF]);
code.push(reg_tmp);
code.mov(reg_tmp, 1);
code.lock();
code.xadd(code.ptr[reg_ctx + BAR_CTR_OFF], reg_tmp);
code.add(reg_tmp, 1);
code.cmp(reg_tmp, reg_nthr);
code.pop(reg_tmp); /* restore previous sense */
code.jne(spin_label);
/* the last thread {{{ */
code.mov(code.qword[reg_ctx + BAR_CTR_OFF], 0); // reset ctx
// notify waiting threads
code.not_(reg_tmp);
code.mov(code.ptr[reg_ctx + BAR_SENSE_OFF], reg_tmp);
code.jmp(barrier_exit_restore_label);
/* }}} the last thread */
code.CodeGenerator::L(spin_label);
code.pause();
code.cmp(reg_tmp, code.ptr[reg_ctx + BAR_SENSE_OFF]);
code.je(spin_label);
code.CodeGenerator::L(barrier_exit_restore_label);
code.pop(reg_tmp);
code.CodeGenerator::L(barrier_exit_label);
#undef BAR_CTR_OFF
#undef BAR_SENSE_OFF
}
/** jit barrier generator */
struct jit_t : public jit_generator_t {
void generate() override {
simple_barrier::generate(*this, abi_param1, abi_param2);
ret();
}
// TODO: Need to check status
jit_t() : jit_generator_t(jit_name()) { create_kernel(); }
DECLARE_CPU_JIT_AUX_FUNCTIONS(jit_t)
};
void barrier(ctx_t *ctx, int nthr) {
static jit_t j; /* XXX: constructed on load ... */
j(ctx, nthr);
}
} // namespace simple_barrier
} // namespace x64
} // namespace cpu
} // namespace impl
} // namespace dnnl
// vim: et ts=4 sw=4 cindent cino+=l0,\:4,N-s