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https://github.com/KhronosGroup/SPIRV-Tools
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8013d477ae
This adds a new kind of fact to the fact manager that knows whether a
block is dead - i.e. guaranteed to be statically unreachable - and a
new transformation for adding a selection construct to a CFG that
conditionally branches to a fresh, dead block, such that the branch
will never be dynamically taken. Transformations that may create new
blocks ('split block' and 'outline function') are updated to propagate
dead block facts to newly-created blocks where appropriate. A fuzzer
pass randomly adds dead blocks to the module.
Future transformations will be able to exploit the fact that such
blocks are known to be dead.
64 lines
2.5 KiB
C++
64 lines
2.5 KiB
C++
// Copyright (c) 2019 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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#ifndef SOURCE_FUZZ_TRANSFORMATION_ADD_DEAD_BLOCK_H_
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#define SOURCE_FUZZ_TRANSFORMATION_ADD_DEAD_BLOCK_H_
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#include "source/fuzz/fact_manager.h"
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#include "source/fuzz/protobufs/spirvfuzz_protobufs.h"
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#include "source/fuzz/transformation.h"
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#include "source/opt/ir_context.h"
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namespace spvtools {
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namespace fuzz {
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class TransformationAddDeadBlock : public Transformation {
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public:
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explicit TransformationAddDeadBlock(
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const protobufs::TransformationAddDeadBlock& message);
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TransformationAddDeadBlock(uint32_t fresh_id, uint32_t existing_block,
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bool condition_value);
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// - |message_.fresh_id| must be a fresh id
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// - A constant with the same value as |message_.condition_value| must be
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// available
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// - |message_.existing_block| must be a block that is not a loop header,
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// and that ends with OpBranch to a block that is not a merge block nor
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// continue target - this is because the successor will become the merge
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// block of a selection construct headed at |message_.existing_block|
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// - |message_.existing_block| must not be a back-edge block, since in this
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// case the newly-added block would lead to another back-edge to the
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// associated loop header
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bool IsApplicable(opt::IRContext* context,
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const FactManager& fact_manager) const override;
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// Changes the OpBranch from |message_.existing_block| to its successor 's'
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// to an OpBranchConditional to either 's' or a new block,
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// |message_.fresh_id|, which itself unconditionally branches to 's'. The
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// conditional branch uses |message.condition_value| as its condition, and is
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// arranged so that control will pass to 's' at runtime.
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void Apply(opt::IRContext* context, FactManager* fact_manager) const override;
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protobufs::Transformation ToMessage() const override;
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private:
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protobufs::TransformationAddDeadBlock message_;
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};
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} // namespace fuzz
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} // namespace spvtools
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#endif // SOURCE_FUZZ_TRANSFORMATION_ADD_DEAD_BLOCK_H_
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