1 //===- ReduceFunctions.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 functions (and any instruction that calls it) in the provided 11 // Module. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "ReduceFunctions.h" 16 #include "Delta.h" 17 #include "llvm/ADT/STLExtras.h" 18 #include "llvm/IR/Instructions.h" 19 #include <iterator> 20 #include <vector> 21 22 using namespace llvm; 23 24 /// Removes all the Defined Functions 25 /// that aren't inside any of the desired Chunks. 26 static void extractFunctionsFromModule(const std::vector<Chunk> &ChunksToKeep, 27 Module *Program) { 28 Oracle O(ChunksToKeep); 29 30 // Record all out-of-chunk functions. 31 std::vector<std::reference_wrapper<Function>> FuncsToRemove; 32 copy_if(Program->functions(), std::back_inserter(FuncsToRemove), 33 [&O](auto &unused) { return !O.shouldKeep(); }); 34 35 // Then, drop body of each of them. We want to batch this and do nothing else 36 // here so that minimal number of remaining exteranal uses will remain. 37 for (Function &F : FuncsToRemove) 38 F.dropAllReferences(); 39 40 // And finally, we can actually delete them. 41 for (Function &F : FuncsToRemove) { 42 // Replace all *still* remaining uses with undef. 43 F.replaceAllUsesWith(UndefValue::get(F.getType())); 44 // And finally, fully drop it. 45 F.eraseFromParent(); 46 } 47 } 48 49 /// Counts the amount of non-declaration functions and prints their 50 /// respective name & index 51 static int countFunctions(Module *Program) { 52 // TODO: Silence index with --quiet flag 53 errs() << "----------------------------\n"; 54 errs() << "Function Index Reference:\n"; 55 int FunctionCount = 0; 56 for (auto &F : *Program) 57 errs() << "\t" << ++FunctionCount << ": " << F.getName() << "\n"; 58 59 errs() << "----------------------------\n"; 60 return FunctionCount; 61 } 62 63 void llvm::reduceFunctionsDeltaPass(TestRunner &Test) { 64 errs() << "*** Reducing Functions...\n"; 65 int Functions = countFunctions(Test.getProgram()); 66 runDeltaPass(Test, Functions, extractFunctionsFromModule); 67 errs() << "----------------------------\n"; 68 } 69