llvm/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp

//===- LocalStackSlotAllocation.cpp - Pre-allocate locals to stack slots --===//
//
// 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 assigns local frame indices to stack slots relative to one another
// and allocates additional base registers to access them when the target
// estimates they are likely to be out of range of stack pointer and frame
// pointer relative addressing.
//
//===----------------------------------------------------------------------===//

#include "llvm/CodeGen/LocalStackSlotAllocation.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/TargetFrameLowering.h"
#include "llvm/CodeGen/TargetOpcodes.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <tuple>

usingnamespacellvm;

#define DEBUG_TYPE …

STATISTIC(NumAllocations, "Number of frame indices allocated into local block");
STATISTIC(NumBaseRegisters, "Number of virtual frame base registers allocated");
STATISTIC(NumReplacements, "Number of frame indices references replaced");

namespace {

  class FrameRef { … };

  class LocalStackSlotImpl { … };

  class LocalStackSlotPass : public MachineFunctionPass { … };

} // end anonymous namespace

PreservedAnalyses
LocalStackSlotAllocationPass::run(MachineFunction &MF,
                                  MachineFunctionAnalysisManager &) { … }

char LocalStackSlotPass::ID = …;

char &llvm::LocalStackSlotAllocationID = …;
INITIALIZE_PASS(…)

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

/// AdjustStackOffset - Helper function used to adjust the stack frame offset.
void LocalStackSlotImpl::AdjustStackOffset(MachineFrameInfo &MFI, int FrameIdx,
                                           int64_t &Offset, bool StackGrowsDown,
                                           Align &MaxAlign) { … }

/// AssignProtectedObjSet - Helper function to assign large stack objects (i.e.,
/// those required to be close to the Stack Protector) to stack offsets.
void LocalStackSlotImpl::AssignProtectedObjSet(
    const StackObjSet &UnassignedObjs, SmallSet<int, 16> &ProtectedObjs,
    MachineFrameInfo &MFI, bool StackGrowsDown, int64_t &Offset,
    Align &MaxAlign) { … }

/// calculateFrameObjectOffsets - Calculate actual frame offsets for all of the
/// abstract stack objects.
void LocalStackSlotImpl::calculateFrameObjectOffsets(MachineFunction &Fn) { … }

static inline bool
lookupCandidateBaseReg(unsigned BaseReg,
                       int64_t BaseOffset,
                       int64_t FrameSizeAdjust,
                       int64_t LocalFrameOffset,
                       const MachineInstr &MI,
                       const TargetRegisterInfo *TRI) { … }

bool LocalStackSlotImpl::insertFrameReferenceRegisters(MachineFunction &Fn) { … }