llvm/llvm/lib/CodeGen/UnreachableBlockElim.cpp

//===-- UnreachableBlockElim.cpp - Remove unreachable blocks for codegen --===//
//
// 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 is an extremely simple version of the SimplifyCFG pass.  Its sole
// job is to delete LLVM basic blocks that are not reachable from the entry
// node.  To do this, it performs a simple depth first traversal of the CFG,
// then deletes any unvisited nodes.
//
// Note that this pass is really a hack.  In particular, the instruction
// selectors for various targets should just not generate code for unreachable
// blocks.  Until LLVM has a more systematic way of defining instruction
// selectors, however, we cannot really expect them to handle additional
// complexity.
//
//===----------------------------------------------------------------------===//

#include "llvm/CodeGen/UnreachableBlockElim.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/IR/Dominators.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
usingnamespacellvm;

namespace {
class UnreachableBlockElimLegacyPass : public FunctionPass { … };
}
char UnreachableBlockElimLegacyPass::ID = …;
INITIALIZE_PASS(…)

FunctionPass *llvm::createUnreachableBlockEliminationPass() { … }

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

namespace {
  class UnreachableMachineBlockElim : public MachineFunctionPass { … };
}
char UnreachableMachineBlockElim::ID = …;

INITIALIZE_PASS(…)

char &llvm::UnreachableMachineBlockElimID = …;

void UnreachableMachineBlockElim::getAnalysisUsage(AnalysisUsage &AU) const { … }

bool UnreachableMachineBlockElim::runOnMachineFunction(MachineFunction &F) { … }