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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(std::vector<Chunk> ChunksToKeep,
Module *Program) {
Oracle O(ChunksToKeep);
// Get GVs inside desired chunks
std::set<GlobalVariable *> GVsToKeep;
for (auto &GV : Program->globals())
if (O.shouldKeep())
GVsToKeep.insert(&GV);
// 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();
}
/// Counts the amount of GVs and displays their
/// respective name & index
static int countGVs(Module *Program) {
// TODO: Silence index with --quiet flag
outs() << "----------------------------\n";
outs() << "GlobalVariable Index Reference:\n";
int GVCount = 0;
for (auto &GV : Program->globals())
outs() << "\t" << ++GVCount << ": " << GV.getName() << "\n";
outs() << "----------------------------\n";
return GVCount;
}
void llvm::reduceGlobalsDeltaPass(TestRunner &Test) {
outs() << "*** Reducing GVs...\n";
int GVCount = countGVs(Test.getProgram());
runDeltaPass(Test, GVCount, extractGVsFromModule);
}
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