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(const std::vector<Chunk> & ChunksToKeep,Module * Program)30extractSpecialGlobalsFromModule(const std::vector<Chunk> &ChunksToKeep, 31 Module *Program) { 32 Oracle O(ChunksToKeep); 33 34 for (StringRef Name : SpecialGlobalNames) { 35 if (auto *Used = Program->getNamedGlobal(Name)) { 36 Used->replaceAllUsesWith(UndefValue::get(Used->getType())); 37 Used->eraseFromParent(); 38 } 39 } 40 } 41 42 /// Counts the amount of special globals and prints their 43 /// respective name & index countSpecialGlobals(Module * Program)44static int countSpecialGlobals(Module *Program) { 45 // TODO: Silence index with --quiet flag 46 errs() << "----------------------------\n"; 47 errs() << "Special Globals Index Reference:\n"; 48 int Count = 0; 49 for (StringRef Name : SpecialGlobalNames) { 50 if (auto *Used = Program->getNamedGlobal(Name)) 51 errs() << "\t" << ++Count << ": " << Used->getName() << "\n"; 52 } 53 errs() << "----------------------------\n"; 54 return Count; 55 } 56 reduceSpecialGlobalsDeltaPass(TestRunner & Test)57void llvm::reduceSpecialGlobalsDeltaPass(TestRunner &Test) { 58 errs() << "*** Reducing Special Globals ...\n"; 59 int Functions = countSpecialGlobals(Test.getProgram()); 60 runDeltaPass(Test, Functions, extractSpecialGlobalsFromModule); 61 errs() << "----------------------------\n"; 62 } 63