77 lines
2.5 KiB
C
77 lines
2.5 KiB
C
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//===- llvm/Analysis/LegacyDivergenceAnalysis.h - KernelDivergence Analysis -*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// The kernel divergence analysis is an LLVM pass which can be used to find out
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// if a branch instruction in a GPU program (kernel) is divergent or not. It can help
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// branch optimizations such as jump threading and loop unswitching to make
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// better decisions.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_LEGACY_DIVERGENCE_ANALYSIS_H
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#define LLVM_ANALYSIS_LEGACY_DIVERGENCE_ANALYSIS_H
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#include "llvm/ADT/DenseSet.h"
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#include "llvm/Pass.h"
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#include <memory>
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namespace llvm {
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class Function;
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class GPUDivergenceAnalysis;
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class Module;
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class raw_ostream;
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class TargetTransformInfo;
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class Use;
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class Value;
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class LegacyDivergenceAnalysis : public FunctionPass {
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public:
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static char ID;
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LegacyDivergenceAnalysis();
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void getAnalysisUsage(AnalysisUsage &AU) const override;
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bool runOnFunction(Function &F) override;
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// Print all divergent branches in the function.
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void print(raw_ostream &OS, const Module *) const override;
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// Returns true if V is divergent at its definition.
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bool isDivergent(const Value *V) const;
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// Returns true if U is divergent. Uses of a uniform value can be divergent.
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bool isDivergentUse(const Use *U) const;
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// Returns true if V is uniform/non-divergent.
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bool isUniform(const Value *V) const { return !isDivergent(V); }
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// Returns true if U is uniform/non-divergent. Uses of a uniform value can be
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// divergent.
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bool isUniformUse(const Use *U) const { return !isDivergentUse(U); }
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// Keep the analysis results uptodate by removing an erased value.
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void removeValue(const Value *V) { DivergentValues.erase(V); }
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private:
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// Whether analysis should be performed by GPUDivergenceAnalysis.
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bool shouldUseGPUDivergenceAnalysis(const Function &F,
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const TargetTransformInfo &TTI) const;
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// (optional) handle to new DivergenceAnalysis
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std::unique_ptr<GPUDivergenceAnalysis> gpuDA;
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// Stores all divergent values.
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DenseSet<const Value *> DivergentValues;
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// Stores divergent uses of possibly uniform values.
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DenseSet<const Use *> DivergentUses;
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};
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} // End llvm namespace
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#endif //LLVM_ANALYSIS_LEGACY_DIVERGENCE_ANALYSIS_H
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