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60 lines
2.1 KiB
C++
60 lines
2.1 KiB
C++
//===- ReduceGlobalVars.cpp - Specialized Delta Pass ----------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements a function which calls the Generic Delta pass in order
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// to reduce Global Variables in the provided Module.
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//
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//===----------------------------------------------------------------------===//
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#include "ReduceGlobalVars.h"
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#include "Utils.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/Transforms/Utils/ModuleUtils.h"
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using namespace llvm;
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static bool shouldAlwaysKeep(const GlobalVariable &GV) {
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return GV.getName() == "llvm.used" || GV.getName() == "llvm.compiler.used";
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}
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/// Removes all the GVs that aren't inside the desired Chunks.
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static void extractGVsFromModule(Oracle &O, ReducerWorkItem &WorkItem) {
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Module &Program = WorkItem.getModule();
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// Get GVs inside desired chunks
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std::vector<Constant *> InitGVsToKeep;
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for (auto &GV : Program.globals()) {
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if (shouldAlwaysKeep(GV) || O.shouldKeep())
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InitGVsToKeep.push_back(&GV);
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}
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// We create a vector first, then convert it to a set, so that we don't have
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// to pay the cost of rebalancing the set frequently if the order we insert
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// the elements doesn't match the order they should appear inside the set.
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DenseSet<Constant *> GVsToKeep(InitGVsToKeep.begin(), InitGVsToKeep.end());
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// Delete out-of-chunk GVs and their uses
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DenseSet<Constant *> ToRemove;
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for (auto &GV : Program.globals()) {
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if (!GVsToKeep.count(&GV))
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ToRemove.insert(&GV);
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}
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removeFromUsedLists(Program,
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[&ToRemove](Constant *C) { return ToRemove.count(C); });
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for (auto *GV : ToRemove) {
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GV->replaceAllUsesWith(getDefaultValue(GV->getType()));
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cast<GlobalVariable>(GV)->eraseFromParent();
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}
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}
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void llvm::reduceGlobalsDeltaPass(TestRunner &Test) {
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runDeltaPass(Test, extractGVsFromModule, "Reducing GlobalVariables");
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}
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