llvm/llvm/lib/Transforms/Utils/MoveAutoInit.cpp

//===-- MoveAutoInit.cpp - move auto-init inst closer to their use site----===//
//
// 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 pass moves instruction maked as auto-init closer to the basic block that
// use it, eventually removing it from some control path of the function.
//
//===----------------------------------------------------------------------===//

#include "llvm/Transforms/Utils/MoveAutoInit.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/MemorySSA.h"
#include "llvm/Analysis/MemorySSAUpdater.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Transforms/Utils.h"
#include "llvm/Transforms/Utils/LoopUtils.h"

usingnamespacellvm;

#define DEBUG_TYPE …

STATISTIC(NumMoved, "Number of instructions moved");

static cl::opt<unsigned> MoveAutoInitThreshold(
    "move-auto-init-threshold", cl::Hidden, cl::init(128),
    cl::desc("Maximum instructions to analyze per moved initialization"));

static bool hasAutoInitMetadata(const Instruction &I) { … }

static std::optional<MemoryLocation> writeToAlloca(const Instruction &I) { … }

/// Finds a BasicBlock in the CFG where instruction `I` can be moved to while
/// not changing the Memory SSA ordering and being guarded by at least one
/// condition.
static BasicBlock *usersDominator(const MemoryLocation &ML, Instruction *I,
                                  DominatorTree &DT, MemorySSA &MSSA) { … }

static bool runMoveAutoInit(Function &F, DominatorTree &DT, MemorySSA &MSSA) { … }

PreservedAnalyses MoveAutoInitPass::run(Function &F,
                                        FunctionAnalysisManager &AM) { … }