llvm/llvm/lib/CodeGen/RegUsageInfoCollector.cpp

//===-- RegUsageInfoCollector.cpp - Register Usage Information Collector --===//
//
// 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 required to take advantage of the interprocedural register
/// allocation infrastructure.
///
/// This pass is simple MachineFunction pass which collects register usage
/// details by iterating through each physical registers and checking
/// MRI::isPhysRegUsed() then creates a RegMask based on this details.
/// The pass then stores this RegMask in PhysicalRegisterUsageInfo.cpp
///
//===----------------------------------------------------------------------===//

#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/RegisterUsageInfo.h"
#include "llvm/CodeGen/TargetFrameLowering.h"
#include "llvm/IR/Function.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"

usingnamespacellvm;

#define DEBUG_TYPE …

STATISTIC(NumCSROpt,
          "Number of functions optimized for callee saved registers");

namespace {

class RegUsageInfoCollector : public MachineFunctionPass { … };

} // end of anonymous namespace

char RegUsageInfoCollector::ID = …;

INITIALIZE_PASS_BEGIN(RegUsageInfoCollector, "RegUsageInfoCollector",
                      "Register Usage Information Collector", false, false)
INITIALIZE_PASS_DEPENDENCY(PhysicalRegisterUsageInfo)
INITIALIZE_PASS_END(RegUsageInfoCollector, "RegUsageInfoCollector",
                    "Register Usage Information Collector", false, false)

FunctionPass *llvm::createRegUsageInfoCollector() { … }

// TODO: Move to hook somwehere?

// Return true if it is useful to track the used registers for IPRA / no CSR
// optimizations. This is not useful for entry points, and computing the
// register usage information is expensive.
static bool isCallableFunction(const MachineFunction &MF) { … }

bool RegUsageInfoCollector::runOnMachineFunction(MachineFunction &MF) { … }

void RegUsageInfoCollector::
computeCalleeSavedRegs(BitVector &SavedRegs, MachineFunction &MF) { … }