llvm/tools/llvm-reduce/deltas/ReduceSpecialGlobals.cpp

   1 //===- ReduceSpecialGlobals.cpp - Specialized Delta Pass ------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements a function which calls the Generic Delta pass in order
  10 // to reduce special globals, like @llvm.used, in the provided Module.
  11 //
  12 // For more details about special globals, see
  13 // https://llvm.org/docs/LangRef.html#intrinsic-global-variables
  14 //
  15 //===----------------------------------------------------------------------===//
  16
  17 #include "ReduceSpecialGlobals.h"
  18 #include "Delta.h"
  19 #include "Utils.h"
  20 #include "llvm/ADT/StringRef.h"
  21 #include "llvm/IR/Constants.h"
  22 #include "llvm/IR/GlobalValue.h"
  23
  24 using namespace llvm;
  25
  26 static StringRef SpecialGlobalNames[] = {"llvm.used", "llvm.compiler.used"};
  27
  28 /// Removes all special globals aren't inside any of the
  29 /// desired Chunks.
  30 static void extractSpecialGlobalsFromModule(Oracle &O,
  31                                             ReducerWorkItem &WorkItem) {
  32   Module &Program = WorkItem.getModule();
  33
  34   for (StringRef Name : SpecialGlobalNames) {
  35     if (auto *Used = Program.getNamedGlobal(Name)) {
  36       if (!O.shouldKeep()) {
  37         Used->replaceAllUsesWith(getDefaultValue(Used->getType()));
  38         Used->eraseFromParent();
  39       }
  40     }
  41   }
  42 }
  43
  44 void llvm::reduceSpecialGlobalsDeltaPass(TestRunner &Test) {
  45   runDeltaPass(Test, extractSpecialGlobalsFromModule,
  46                "Reducing Special Globals");
  47 }