llvm/llvm/lib/Transforms/Scalar/JumpTableToSwitch.cpp

//===- JumpTableToSwitch.cpp ----------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

#include "llvm/Transforms/Scalar/JumpTableToSwitch.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/DomTreeUpdater.h"
#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/Analysis/PostDominators.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"

usingnamespacellvm;

static cl::opt<unsigned>
    JumpTableSizeThreshold("jump-table-to-switch-size-threshold", cl::Hidden,
                           cl::desc("Only split jump tables with size less or "
                                    "equal than JumpTableSizeThreshold."),
                           cl::init(10));

// TODO: Consider adding a cost model for profitability analysis of this
// transformation. Currently we replace a jump table with a switch if all the
// functions in the jump table are smaller than the provided threshold.
static cl::opt<unsigned> FunctionSizeThreshold(
    "jump-table-to-switch-function-size-threshold", cl::Hidden,
    cl::desc("Only split jump tables containing functions whose sizes are less "
             "or equal than this threshold."),
    cl::init(50));

#define DEBUG_TYPE …

namespace {
struct JumpTableTy { … };
} // anonymous namespace

static std::optional<JumpTableTy> parseJumpTable(GetElementPtrInst *GEP,
                                                 PointerType *PtrTy) { … }

static BasicBlock *expandToSwitch(CallBase *CB, const JumpTableTy &JT,
                                  DomTreeUpdater &DTU,
                                  OptimizationRemarkEmitter &ORE) { … }

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