| //===- ReduceGlobalVars.cpp - Specialized Delta Pass ----------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements a function which calls the Generic Delta pass in order |
| // to reduce Global Variables in the provided Module. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "ReduceGlobalVars.h" |
| #include "llvm/IR/Constants.h" |
| #include <set> |
| |
| using namespace llvm; |
| |
| /// Removes all the GVs that aren't inside the desired Chunks. |
| static void extractGVsFromModule(Oracle &O, Module &Program) { |
| // Get GVs inside desired chunks |
| std::vector<GlobalVariable *> InitGVsToKeep; |
| for (auto &GV : Program.globals()) |
| if (O.shouldKeep()) |
| InitGVsToKeep.push_back(&GV); |
| |
| // We create a vector first, then convert it to a set, so that we don't have |
| // to pay the cost of rebalancing the set frequently if the order we insert |
| // the elements doesn't match the order they should appear inside the set. |
| std::set<GlobalVariable *> GVsToKeep(InitGVsToKeep.begin(), |
| InitGVsToKeep.end()); |
| |
| // Delete out-of-chunk GVs and their uses |
| std::vector<GlobalVariable *> ToRemove; |
| std::vector<WeakVH> InstToRemove; |
| for (auto &GV : Program.globals()) |
| if (!GVsToKeep.count(&GV)) { |
| for (auto *U : GV.users()) |
| if (auto *Inst = dyn_cast<Instruction>(U)) |
| InstToRemove.push_back(Inst); |
| |
| GV.replaceAllUsesWith(UndefValue::get(GV.getType())); |
| ToRemove.push_back(&GV); |
| } |
| |
| // Delete (unique) Instruction uses of unwanted GVs |
| for (Value *V : InstToRemove) { |
| if (!V) |
| continue; |
| auto *Inst = cast<Instruction>(V); |
| Inst->replaceAllUsesWith(UndefValue::get(Inst->getType())); |
| Inst->eraseFromParent(); |
| } |
| |
| for (auto *GV : ToRemove) |
| GV->eraseFromParent(); |
| } |
| |
| void llvm::reduceGlobalsDeltaPass(TestRunner &Test) { |
| outs() << "*** Reducing GVs...\n"; |
| runDeltaPass(Test, extractGVsFromModule); |
| } |