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 "Utils.h" 18 #include "llvm/ADT/STLExtras.h" 19 #include "llvm/ADT/SetVector.h" 20 #include "llvm/Transforms/Utils/ModuleUtils.h" 21 #include <iterator> 22 #include <vector> 23 24 using namespace llvm; 25 26 /// Removes all the Defined Functions 27 /// that aren't inside any of the desired Chunks. 28 static void extractFunctionsFromModule(Oracle &O, ReducerWorkItem &WorkItem) { 29 Module &Program = WorkItem.getModule(); 30 31 // Record all out-of-chunk functions. 32 SmallPtrSet<Constant *, 8> FuncsToRemove; 33 for (Function &F : Program.functions()) { 34 // Intrinsics don't have function bodies that are useful to 35 // reduce. Additionally, intrinsics may have additional operand 36 // constraints. But, do drop intrinsics that are not referenced. 37 if ((!F.isIntrinsic() || F.use_empty()) && !hasAliasOrBlockAddressUse(F) && 38 !O.shouldKeep()) 39 FuncsToRemove.insert(&F); 40 } 41 42 removeFromUsedLists(Program, [&FuncsToRemove](Constant *C) { 43 return FuncsToRemove.count(C); 44 }); 45 46 // Then, drop body of each of them. We want to batch this and do nothing else 47 // here so that minimal number of remaining exteranal uses will remain. 48 for (Constant *F : FuncsToRemove) 49 F->dropAllReferences(); 50 51 // And finally, we can actually delete them. 52 for (Constant *F : FuncsToRemove) { 53 // Replace all *still* remaining uses with the default value. 54 F->replaceAllUsesWith(getDefaultValue(F->getType())); 55 // And finally, fully drop it. 56 cast<Function>(F)->eraseFromParent(); 57 } 58 } 59 60 void llvm::reduceFunctionsDeltaPass(TestRunner &Test) { 61 runDeltaPass(Test, extractFunctionsFromModule, "Reducing Functions"); 62 } 63