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// Copyright (c) 2018 Google LLC
//
// 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 "source/reduce/operand_to_const_reduction_opportunity_finder.h"
#include "source/opt/instruction.h"
#include "source/reduce/change_operand_reduction_opportunity.h"
namespace spvtools {
namespace reduce {
std::vector<std::unique_ptr<ReductionOpportunity>>
OperandToConstReductionOpportunityFinder::GetAvailableOpportunities(
opt::IRContext* context, uint32_t target_function) const {
std::vector<std::unique_ptr<ReductionOpportunity>> result;
assert(result.empty());
// We first loop over all constants. This means that all the reduction
// opportunities to replace an operand with a particular constant will be
// contiguous, and in particular it means that multiple, incompatible
// reduction opportunities that try to replace the same operand with distinct
// constants are likely to be discontiguous. This is good because the
// reducer works in the spirit of delta debugging and tries applying large
// contiguous blocks of opportunities early on, and we want to avoid having a
// large block of incompatible opportunities if possible.
for (const auto& constant : context->GetConstants()) {
for (auto* function : GetTargetFunctions(context, target_function)) {
for (auto& block : *function) {
for (auto& inst : block) {
// We iterate through the operands using an explicit index (rather
// than using a lambda) so that we use said index in the construction
// of a ChangeOperandReductionOpportunity
for (uint32_t index = 0; index < inst.NumOperands(); index++) {
const auto& operand = inst.GetOperand(index);
if (spvIsInIdType(operand.type)) {
const auto id = operand.words[0];
auto def = context->get_def_use_mgr()->GetDef(id);
if (spvOpcodeIsConstant(def->opcode())) {
// The argument is already a constant.
continue;
}
if (def->opcode() == spv::Op::OpFunction) {
// The argument refers to a function, e.g. the function called
// by OpFunctionCall; avoid replacing this with a constant of
// the function's return type.
continue;
}
auto type_id = def->type_id();
if (type_id) {
if (constant->type_id() == type_id) {
result.push_back(
MakeUnique<ChangeOperandReductionOpportunity>(
&inst, index, constant->result_id()));
}
}
}
}
}
}
}
}
return result;
}
std::string OperandToConstReductionOpportunityFinder::GetName() const {
return "OperandToConstReductionOpportunityFinder";
}
} // namespace reduce
} // namespace spvtools