SPIRV-Tools/source/reduce/remove_block_reduction_opportunity.cpp

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// Copyright (c) 2019 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/remove_block_reduction_opportunity.h"
#include "source/opt/ir_context.h"
namespace spvtools {
namespace reduce {
using opt::BasicBlock;
using opt::Function;
RemoveBlockReductionOpportunity::RemoveBlockReductionOpportunity(
Function* function, BasicBlock* block)
: function_(function), block_(block) {
// precondition:
assert(block_->begin() != block_->end() &&
block_->begin()->context()->get_def_use_mgr()->NumUsers(
block_->id()) == 0 &&
"RemoveBlockReductionOpportunity block must have 0 references");
}
bool RemoveBlockReductionOpportunity::PreconditionHolds() {
// Removing other blocks cannot disable this opportunity.
return true;
}
void RemoveBlockReductionOpportunity::Apply() {
// We need an iterator pointing to the block, hence the loop.
for (auto bi = function_->begin(); bi != function_->end(); ++bi) {
if (bi->id() == block_->id()) {
bi->KillAllInsts(true);
bi.Erase();
// Block removal changes the function, but we don't use analyses, so no
// need to invalidate them.
return;
}
}
assert(false &&
"Unreachable: we should have found a block with the desired id.");
}
} // namespace reduce
} // namespace spvtools