Revert "Insert random noops to increase security against ROP attacks (llvm)"

This reverts commit:
http://reviews.llvm.org/D3392

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225948 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/CommandFlags.h

@@ -207,12 +207,6 @@ FunctionSections("function-sections",
                  cl::desc("Emit functions into separate sections"),
                  cl::init(false));
 
-cl::opt<bool>
-NoopInsertion("noop-insertion",
-             cl::desc("Randomly add Noop instructions to create fine-grained "
-                      "code layout diversity."),
-             cl::init(false));
-
 cl::opt<llvm::JumpTable::JumpTableType>
 JTableType("jump-table-type",
           cl::desc("Choose the type of Jump-Instruction Table for jumptable."),
@@ -290,7 +284,6 @@ static inline TargetOptions InitTargetOptionsFromCodeGenFlags() {
   Options.UseInitArray = !UseCtors;
   Options.DataSections = DataSections;
   Options.FunctionSections = FunctionSections;
-  Options.NoopInsertion = NoopInsertion;
 
   Options.MCOptions = InitMCTargetOptionsFromFlags();
   Options.JTType = JTableType;

include/llvm/CodeGen/NoopInsertion.h

@@ -1,44 +0,0 @@
-//===-- NoopInsertion.h - Noop Insertion ------------------------*- C++ -*-===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This pass adds fine-grained diversity by displacing code using randomly
-// placed (optionally target supplied) Noop instructions.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_CODEGEN_NOOPINSERTION_H
-#define LLVM_CODEGEN_NOOPINSERTION_H
-
-#include "llvm/CodeGen/MachineFunctionPass.h"
-#include <random>
-
-namespace llvm {
-
-class RandomNumberGenerator;
-
-class NoopInsertion : public MachineFunctionPass {
-public:
-  static char ID;
-
-  NoopInsertion();
-
-private:
-  bool runOnMachineFunction(MachineFunction &MF) override;
-
-  void getAnalysisUsage(AnalysisUsage &AU) const override;
-
-  std::unique_ptr<RandomNumberGenerator> RNG;
-
-  // Uniform real distribution from 0 to 100
-  std::uniform_real_distribution<double> Distribution =
-      std::uniform_real_distribution<double>(0, 100);
-};
-}
-
-#endif // LLVM_CODEGEN_NOOPINSERTION_H

include/llvm/CodeGen/Passes.h

@@ -603,10 +603,6 @@ namespace llvm {
   /// the intrinsic for later emission to the StackMap.
   extern char &StackMapLivenessID;
 
-  /// NoopInsertion - This pass adds fine-grained diversity by displacing code
-  /// using randomly placed (optionally target supplied) Noop instructions.
-  extern char &NoopInsertionID;
-
   /// createJumpInstrTables - This pass creates jump-instruction tables.
   ModulePass *createJumpInstrTablesPass();