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 "llvm/ADT/StringRef.h"
  20 #include "llvm/IR/Constants.h"
  21 #include "llvm/IR/GlobalValue.h"
  22
  23 using namespace llvm;
  24
  25 static StringRef SpecialGlobalNames[] = {"llvm.used", "llvm.compiler.used"};
  26
  27 /// Removes all special globals aren't inside any of the
  28 /// desired Chunks.
  29 static void extractSpecialGlobalsFromModule(Oracle &O, Module &Program) {
  30   for (StringRef Name : SpecialGlobalNames) {
  31     if (auto *Used = Program.getNamedGlobal(Name)) {
  32       Used->replaceAllUsesWith(UndefValue::get(Used->getType()));
  33       Used->eraseFromParent();
  34     }
  35   }
  36 }
  37
  38 void llvm::reduceSpecialGlobalsDeltaPass(TestRunner &Test) {
  39   errs() << "*** Reducing Special Globals ...\n";
  40   runDeltaPass(Test, extractSpecialGlobalsFromModule);
  41   errs() << "----------------------------\n";
  42 }