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