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194c9f4ba1
Change the original algorithm so that it scales better when meeting very large bitcode where every instruction does not implies a global. The target query is "how to you get all the globals referenced by another global"? Before this patch, it was doing this by walking the body (or the initializer) and collecting the references. What this patch is doing, it precomputing the answer to this query for the whole module by walking the use-list of every global instead. Patch by: Serge Guelton <serge.guelton@telecom-bretagne.eu> Differential Revision: https://reviews.llvm.org/D28549 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293328 91177308-0d34-0410-b5e6-96231b3b80d8
58 lines
1.9 KiB
C++
58 lines
1.9 KiB
C++
//===-- GlobalDCE.h - DCE unreachable internal functions ------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This transform is designed to eliminate unreachable internal globals from the
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// program. It uses an aggressive algorithm, searching out globals that are
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// known to be alive. After it finds all of the globals which are needed, it
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// deletes whatever is left over. This allows it to delete recursive chunks of
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// the program which are unreachable.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TRANSFORMS_IPO_GLOBALDCE_H
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#define LLVM_TRANSFORMS_IPO_GLOBALDCE_H
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/SmallSet.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/PassManager.h"
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#include <unordered_map>
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namespace llvm {
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/// Pass to remove unused function declarations.
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class GlobalDCEPass : public PassInfoMixin<GlobalDCEPass> {
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public:
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PreservedAnalyses run(Module &M, ModuleAnalysisManager &);
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private:
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SmallPtrSet<GlobalValue*, 32> AliveGlobals;
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/// Global -> Global that uses this global.
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std::unordered_multimap<GlobalValue *, GlobalValue *> GVDependencies;
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/// Constant -> Globals that use this global cache.
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std::unordered_map<Constant *, SmallPtrSet<GlobalValue *, 8>>
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ConstantDependenciesCache;
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/// Comdat -> Globals in that Comdat section.
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std::unordered_multimap<Comdat *, GlobalValue *> ComdatMembers;
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void UpdateGVDependencies(GlobalValue &GV);
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void MarkLive(GlobalValue &GV,
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SmallVectorImpl<GlobalValue *> *Updates = nullptr);
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bool RemoveUnusedGlobalValue(GlobalValue &GV);
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void ComputeDependencies(Value *V, SmallPtrSetImpl<GlobalValue *> &U);
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};
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}
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#endif // LLVM_TRANSFORMS_IPO_GLOBALDCE_H
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