SPIRV-Tools/source/opt/block_merge_pass.cpp
Alastair Donaldson b8587c984a
spirv-reduce: Allow merging unreachable blocks (#4303)
This change allows the reducer to merge together blocks even when they
are unreachable, but keeps the restriction of reachability in place
for the optimizer.

Fixes #4302.
2021-06-28 23:05:30 +01:00

55 lines
1.7 KiB
C++

// Copyright (c) 2017 The Khronos Group Inc.
// Copyright (c) 2017 Valve Corporation
// Copyright (c) 2017 LunarG Inc.
//
// 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/opt/block_merge_pass.h"
#include <vector>
#include "source/opt/block_merge_util.h"
#include "source/opt/ir_context.h"
#include "source/opt/iterator.h"
namespace spvtools {
namespace opt {
bool BlockMergePass::MergeBlocks(Function* func) {
bool modified = false;
for (auto bi = func->begin(); bi != func->end();) {
// Don't bother trying to merge unreachable blocks.
if (context()->IsReachable(*bi) &&
blockmergeutil::CanMergeWithSuccessor(context(), &*bi)) {
blockmergeutil::MergeWithSuccessor(context(), func, bi);
// Reprocess block.
modified = true;
} else {
++bi;
}
}
return modified;
}
Pass::Status BlockMergePass::Process() {
// Process all entry point functions.
ProcessFunction pfn = [this](Function* fp) { return MergeBlocks(fp); };
bool modified = context()->ProcessEntryPointCallTree(pfn);
return modified ? Status::SuccessWithChange : Status::SuccessWithoutChange;
}
BlockMergePass::BlockMergePass() = default;
} // namespace opt
} // namespace spvtools