70 lines
2.2 KiB
C++
70 lines
2.2 KiB
C++
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// Copyright (c) 2018 Google LLC.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "source/opt/loop_fusion_pass.h"
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#include "source/opt/ir_context.h"
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#include "source/opt/loop_descriptor.h"
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#include "source/opt/loop_fusion.h"
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#include "source/opt/register_pressure.h"
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namespace spvtools {
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namespace opt {
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Pass::Status LoopFusionPass::Process() {
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bool modified = false;
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Module* module = context()->module();
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// Process each function in the module
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for (Function& f : *module) {
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modified |= ProcessFunction(&f);
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}
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return modified ? Status::SuccessWithChange : Status::SuccessWithoutChange;
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}
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bool LoopFusionPass::ProcessFunction(Function* function) {
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LoopDescriptor& ld = *context()->GetLoopDescriptor(function);
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// If a loop doesn't have a preheader needs then it needs to be created. Make
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// sure to return Status::SuccessWithChange in that case.
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auto modified = ld.CreatePreHeaderBlocksIfMissing();
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// TODO(tremmelg): Could the only loop that |loop| could possibly be fused be
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// picked out so don't have to check every loop
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for (auto& loop_0 : ld) {
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for (auto& loop_1 : ld) {
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LoopFusion fusion(context(), &loop_0, &loop_1);
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if (fusion.AreCompatible() && fusion.IsLegal()) {
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RegisterLiveness liveness(context(), function);
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RegisterLiveness::RegionRegisterLiveness reg_pressure{};
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liveness.SimulateFusion(loop_0, loop_1, ®_pressure);
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if (reg_pressure.used_registers_ <= max_registers_per_loop_) {
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fusion.Fuse();
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// Recurse, as the current iterators will have been invalidated.
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ProcessFunction(function);
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return true;
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}
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}
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}
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}
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return modified;
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}
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} // namespace opt
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} // namespace spvtools
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