Coverage Report

Created: 2019-07-24 05:18

/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/include/llvm/Transforms/IPO/DeadArgumentElimination.h
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//===- DeadArgumentElimination.h - Eliminate Dead Args ----------*- 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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// This pass deletes dead arguments from internal functions.  Dead argument
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// elimination removes arguments which are directly dead, as well as arguments
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// only passed into function calls as dead arguments of other functions.  This
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// pass also deletes dead return values in a similar way.
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//
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// This pass is often useful as a cleanup pass to run after aggressive
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// interprocedural passes, which add possibly-dead arguments or return values.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TRANSFORMS_IPO_DEADARGUMENTELIMINATION_H
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#define LLVM_TRANSFORMS_IPO_DEADARGUMENTELIMINATION_H
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/PassManager.h"
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#include <map>
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#include <set>
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#include <string>
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#include <tuple>
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namespace llvm {
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class Module;
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class Use;
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class Value;
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/// Eliminate dead arguments (and return values) from functions.
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class DeadArgumentEliminationPass
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    : public PassInfoMixin<DeadArgumentEliminationPass> {
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public:
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  /// Struct that represents (part of) either a return value or a function
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  /// argument.  Used so that arguments and return values can be used
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  /// interchangeably.
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  struct RetOrArg {
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    const Function *F;
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    unsigned Idx;
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    bool IsArg;
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    RetOrArg(const Function *F, unsigned Idx, bool IsArg)
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1.84M
        : F(F), Idx(Idx), IsArg(IsArg) {}
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    /// Make RetOrArg comparable, so we can put it into a map.
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2.66M
    bool operator<(const RetOrArg &O) const {
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      return std::tie(F, Idx, IsArg) < std::tie(O.F, O.Idx, O.IsArg);
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    }
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    /// Make RetOrArg comparable, so we can easily iterate the multimap.
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    bool operator==(const RetOrArg &O) const {
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      return F == O.F && 
Idx == O.Idx29.0k
&&
IsArg == O.IsArg20.5k
;
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    }
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    std::string getDescription() const {
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      return (Twine(IsArg ? "Argument #" : "Return value #") + Twine(Idx) +
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              " of function " + F->getName())
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          .str();
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    }
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  };
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  /// Liveness enum - During our initial pass over the program, we determine
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  /// that things are either alive or maybe alive. We don't mark anything
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  /// explicitly dead (even if we know they are), since anything not alive
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  /// with no registered uses (in Uses) will never be marked alive and will
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  /// thus become dead in the end.
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  enum Liveness { Live, MaybeLive };
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  DeadArgumentEliminationPass(bool ShouldHackArguments_ = false)
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      : ShouldHackArguments(ShouldHackArguments_) {}
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  PreservedAnalyses run(Module &M, ModuleAnalysisManager &);
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  /// Convenience wrapper
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  RetOrArg CreateRet(const Function *F, unsigned Idx) {
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    return RetOrArg(F, Idx, false);
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  }
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  /// Convenience wrapper
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  RetOrArg CreateArg(const Function *F, unsigned Idx) {
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    return RetOrArg(F, Idx, true);
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  }
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  using UseMap = std::multimap<RetOrArg, RetOrArg>;
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  /// This maps a return value or argument to any MaybeLive return values or
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  /// arguments it uses. This allows the MaybeLive values to be marked live
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  /// when any of its users is marked live.
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  /// For example (indices are left out for clarity):
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  ///  - Uses[ret F] = ret G
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  ///    This means that F calls G, and F returns the value returned by G.
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  ///  - Uses[arg F] = ret G
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  ///    This means that some function calls G and passes its result as an
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  ///    argument to F.
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  ///  - Uses[ret F] = arg F
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  ///    This means that F returns one of its own arguments.
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  ///  - Uses[arg F] = arg G
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  ///    This means that G calls F and passes one of its own (G's) arguments
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  ///    directly to F.
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  UseMap Uses;
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  using LiveSet = std::set<RetOrArg>;
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  using LiveFuncSet = std::set<const Function *>;
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  /// This set contains all values that have been determined to be live.
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  LiveSet LiveValues;
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  /// This set contains all values that are cannot be changed in any way.
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  LiveFuncSet LiveFunctions;
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  using UseVector = SmallVector<RetOrArg, 5>;
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  /// This allows this pass to do double-duty as the dead arg hacking pass
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  /// (used only by bugpoint).
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  bool ShouldHackArguments = false;
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private:
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  Liveness MarkIfNotLive(RetOrArg Use, UseVector &MaybeLiveUses);
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  Liveness SurveyUse(const Use *U, UseVector &MaybeLiveUses,
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                     unsigned RetValNum = -1U);
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  Liveness SurveyUses(const Value *V, UseVector &MaybeLiveUses);
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  void SurveyFunction(const Function &F);
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  void MarkValue(const RetOrArg &RA, Liveness L,
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                 const UseVector &MaybeLiveUses);
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  void MarkLive(const RetOrArg &RA);
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  void MarkLive(const Function &F);
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  void PropagateLiveness(const RetOrArg &RA);
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  bool RemoveDeadStuffFromFunction(Function *F);
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  bool DeleteDeadVarargs(Function &Fn);
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  bool RemoveDeadArgumentsFromCallers(Function &Fn);
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};
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} // end namespace llvm
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#endif // LLVM_TRANSFORMS_IPO_DEADARGUMENTELIMINATION_H