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//===- ReduceInstructions.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 uninteresting Instructions from defined functions.
//
//===----------------------------------------------------------------------===//
#include "ReduceInstructions.h"
#include "Utils.h"
#include "llvm/IR/Constants.h"
using namespace llvm;
/// Filter out cases where deleting the instruction will likely cause the
/// user/def of the instruction to fail the verifier.
//
// TODO: Technically the verifier only enforces preallocated token usage and
// there is a none token.
static bool shouldAlwaysKeep(const Instruction &I) {
return I.isEHPad() || I.getType()->isTokenTy() || I.isSwiftError();
}
/// Removes out-of-chunk arguments from functions, and modifies their calls
/// accordingly. It also removes allocations of out-of-chunk arguments.
static void extractInstrFromModule(Oracle &O, ReducerWorkItem &WorkItem) {
Module &Program = WorkItem.getModule();
std::vector<Instruction *> InitInstToKeep;
for (auto &F : Program)
for (auto &BB : F) {
// Removing the terminator would make the block invalid. Only iterate over
// instructions before the terminator.
InitInstToKeep.push_back(BB.getTerminator());
for (auto &Inst : make_range(BB.begin(), std::prev(BB.end()))) {
if (shouldAlwaysKeep(Inst) || O.shouldKeep())
InitInstToKeep.push_back(&Inst);
}
}
// 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<Instruction *> InstToKeep(InitInstToKeep.begin(),
InitInstToKeep.end());
std::vector<Instruction *> InstToDelete;
for (auto &F : Program)
for (auto &BB : F)
for (auto &Inst : BB)
if (!InstToKeep.count(&Inst)) {
Inst.replaceAllUsesWith(getDefaultValue(Inst.getType()));
InstToDelete.push_back(&Inst);
}
for (auto &I : InstToDelete)
I->eraseFromParent();
}
void llvm::reduceInstructionsDeltaPass(TestRunner &Test) {
runDeltaPass(Test, extractInstrFromModule, "Reducing Instructions");
}
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