llvm/llvm/lib/Target/MSP430/MSP430BranchSelector.cpp

//===-- MSP430BranchSelector.cpp - Emit long conditional branches ---------===//
//
// 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 a pass that scans a machine function to determine which
// conditional branches need more than 10 bits of displacement to reach their
// target basic block.  It does this in two passes; a calculation of basic block
// positions pass, and a branch pseudo op to machine branch opcode pass.  This
// pass should be run last, just before the assembly printer.
//
//===----------------------------------------------------------------------===//

#include "MSP430.h"
#include "MSP430InstrInfo.h"
#include "MSP430Subtarget.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Target/TargetMachine.h"
usingnamespacellvm;

#define DEBUG_TYPE …

static cl::opt<bool>
    BranchSelectEnabled("msp430-branch-select", cl::Hidden, cl::init(true),
                        cl::desc("Expand out of range branches"));

STATISTIC(NumSplit, "Number of machine basic blocks split");
STATISTIC(NumExpanded, "Number of branches expanded to long format");

namespace {
class MSP430BSel : public MachineFunctionPass { … };
char MSP430BSel::ID = …;
}

static bool isInRage(int DistanceInBytes) { … }

/// Measure each basic block, fill the BlockOffsets, and return the size of
/// the function, starting with BB
unsigned MSP430BSel::measureFunction(OffsetVector &BlockOffsets,
                                     MachineBasicBlock *FromBB) { … }

/// Do expand branches and split the basic blocks if necessary.
/// Returns true if made any change.
bool MSP430BSel::expandBranches(OffsetVector &BlockOffsets) { … }

bool MSP430BSel::runOnMachineFunction(MachineFunction &mf) { … }

/// Returns an instance of the Branch Selection Pass
FunctionPass *llvm::createMSP430BranchSelectionPass() { … }