llvm/llvm/tools/llvm-reduce/deltas/Delta.cpp

//===- Delta.cpp - Delta Debugging Algorithm Implementation ---------------===//
//
// 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 contains the implementation for the Delta Debugging Algorithm:
// it splits a given set of Targets (i.e. Functions, Instructions, BBs, etc.)
// into chunks and tries to reduce the number chunks that are interesting.
//
//===----------------------------------------------------------------------===//

#include "Delta.h"
#include "ReducerWorkItem.h"
#include "TestRunner.h"
#include "Utils.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Analysis/ModuleSummaryAnalysis.h"
#include "llvm/Analysis/ProfileSummaryInfo.h"
#include "llvm/Bitcode/BitcodeReader.h"
#include "llvm/Bitcode/BitcodeWriter.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/Config/llvm-config.h" // for LLVM_ENABLE_THREADS
#include "llvm/IR/Module.h"
#include "llvm/IR/Verifier.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/MemoryBufferRef.h"
#include "llvm/Support/ThreadPool.h"
#include <fstream>

usingnamespacellvm;

extern cl::OptionCategory LLVMReduceOptions;

static cl::opt<bool> AbortOnInvalidReduction(
    "abort-on-invalid-reduction",
    cl::desc("Abort if any reduction results in invalid IR"),
    cl::cat(LLVMReduceOptions));

static cl::opt<unsigned int> StartingGranularityLevel(
    "starting-granularity-level",
    cl::desc("Number of times to divide chunks prior to first test"),
    cl::cat(LLVMReduceOptions));

#ifdef LLVM_ENABLE_THREADS
static cl::opt<unsigned> NumJobs(
    "j",
    cl::desc("Maximum number of threads to use to process chunks. Set to 1 to "
             "disable parallelism."),
    cl::init(1), cl::cat(LLVMReduceOptions));
#else
unsigned NumJobs = 1;
#endif

/// Splits Chunks in half and prints them.
/// If unable to split (when chunk size is 1) returns false.
static bool increaseGranularity(std::vector<Chunk> &Chunks) { … }

// Check if \p ChunkToCheckForUninterestingness is interesting. Returns the
// modified module if the chunk resulted in a reduction.
static std::unique_ptr<ReducerWorkItem>
CheckChunk(const Chunk ChunkToCheckForUninterestingness,
           std::unique_ptr<ReducerWorkItem> Clone, const TestRunner &Test,
           ReductionFunc ExtractChunksFromModule,
           const DenseSet<Chunk> &UninterestingChunks,
           const std::vector<Chunk> &ChunksStillConsideredInteresting) { … }

static SmallString<0> ProcessChunkFromSerializedBitcode(
    const Chunk ChunkToCheckForUninterestingness, const TestRunner &Test,
    ReductionFunc ExtractChunksFromModule,
    const DenseSet<Chunk> &UninterestingChunks,
    ArrayRef<Chunk> ChunksStillConsideredInteresting, StringRef OriginalBC,
    std::atomic<bool> &AnyReduced) { … }

SharedTaskQueue;

/// Runs the Delta Debugging algorithm, splits the code into chunks and
/// reduces the amount of chunks that are considered interesting by the
/// given test. The number of chunks is determined by a preliminary run of the
/// reduction pass where no change must be made to the module.
void llvm::runDeltaPass(TestRunner &Test, ReductionFunc ExtractChunksFromModule,
                        StringRef Message) { … }