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//===- 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);
}
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