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https://github.com/KhronosGroup/SPIRV-Tools
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7ee8f443ea
The implementation of these passes had overlooked the fact that adding a new edge to a control flow graph can change dominance information. Adding a dead break/continue risks causing uses to no longer be dominated by their definitions. This change introduces various tests to expose such scenarios, and augments the preconditions for these transformations with checks to guard against the situation.
77 lines
3.2 KiB
C++
77 lines
3.2 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_BREAK_H_
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#define SOURCE_FUZZ_TRANSFORMATION_ADD_DEAD_BREAK_H_
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#include <vector>
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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 TransformationAddDeadBreak : public Transformation {
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public:
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explicit TransformationAddDeadBreak(
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const protobufs::TransformationAddDeadBreak& message);
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TransformationAddDeadBreak(uint32_t from_block, uint32_t to_block,
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bool break_condition_value,
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std::vector<uint32_t> phi_id);
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// - |message_.from_block| must be the id of a block a in the given module.
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// - |message_.to_block| must be the id of a block b in the given module.
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// - if |message_.break_condition_value| holds (does not hold) then
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// OpConstantTrue (OpConstantFalse) must be present in the module
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// - |message_.phi_ids| must be a list of ids that are all available at
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// |message_.from_block|
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// - a and b must be in the same function.
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// - b must be a merge block.
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// - a must end with an unconditional branch to some block c.
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// - replacing this branch with a conditional branch to b or c, with
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// the boolean constant associated with |message_.break_condition_value| as
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// the condition, and the ids in |message_.phi_ids| used to extend
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// any OpPhi instructions at b as a result of the edge from a, must
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// maintain validity of the module.
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// In particular, the new branch must not lead to violations of the rule
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// that a use must be dominated by its definition.
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bool IsApplicable(opt::IRContext* context,
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const FactManager& fact_manager) const override;
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// Replaces the terminator of a with a conditional branch to b or c.
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// The boolean constant associated with |message_.break_condition_value| is
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// used as the condition, and the order of b and c is arranged such that
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// control is guaranteed to jump to c.
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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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// Returns true if and only if adding an edge from |bb_from| to
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// |message_.to_block| respects structured control flow.
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bool AddingBreakRespectsStructuredControlFlow(opt::IRContext* context,
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opt::BasicBlock* bb_from) const;
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protobufs::TransformationAddDeadBreak 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_BREAK_H_
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