Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//===- ConstantPools.h - Keep track of assembler-generated ------*- C++ -*-===//

//

// 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 declares the ConstantPool and AssemblerConstantPools classes.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_MC_CONSTANTPOOLS_H

#define LLVM_MC_CONSTANTPOOLS_H

#include "llvm/ADT/MapVector.h"

#include "llvm/ADT/SmallVector.h"

#include "llvm/Support/SMLoc.h"

#include <cstdint>

#include <map>

namespace llvm {

class MCContext;

class MCExpr;

class MCSection;

class MCStreamer;

class MCSymbol;

class MCSymbolRefExpr;

struct ConstantPoolEntry {

  ConstantPoolEntry(MCSymbol *L, const MCExpr *Val, unsigned Sz, SMLoc Loc_)

    : Label(L), Value(Val), Size(Sz), Loc(Loc_) {}

  MCSymbol *Label;

  const MCExpr *Value;

  unsigned Size;

  SMLoc Loc;

};

// A class to keep track of assembler-generated constant pools that are use to

// implement the ldr-pseudo.

class ConstantPool {

  using EntryVecTy = SmallVector<ConstantPoolEntry, 4>;

  EntryVecTy Entries;

  std::map<int64_t, const MCSymbolRefExpr *> CachedConstantEntries;

  DenseMap<const MCSymbol *, const MCSymbolRefExpr *> CachedSymbolEntries;

public:

  // Initialize a new empty constant pool

  ConstantPool() = default;

  // Add a new entry to the constant pool in the next slot.

  // \param Value is the new entry to put in the constant pool.

  // \param Size is the size in bytes of the entry

  //

  // \returns a MCExpr that references the newly inserted value

  const MCExpr *addEntry(const MCExpr *Value, MCContext &Context,

                         unsigned Size, SMLoc Loc);

  // Emit the contents of the constant pool using the provided streamer.

  void emitEntries(MCStreamer &Streamer);

  // Return true if the constant pool is empty

  bool empty();

  void clearCache();

};

class AssemblerConstantPools {

  // Map type used to keep track of per-Section constant pools used by the

  // ldr-pseudo opcode. The map associates a section to its constant pool. The

  // constant pool is a vector of (label, value) pairs. When the ldr

  // pseudo is parsed we insert a new (label, value) pair into the constant pool

  // for the current section and add MCSymbolRefExpr to the new label as

  // an opcode to the ldr. After we have parsed all the user input we

  // output the (label, value) pairs in each constant pool at the end of the

  // section.

  //

  // We use the MapVector for the map type to ensure stable iteration of

  // the sections at the end of the parse. We need to iterate over the

  // sections in a stable order to ensure that we have print the

  // constant pools in a deterministic order when printing an assembly

  // file.

  using ConstantPoolMapTy = MapVector<MCSection *, ConstantPool>;

  ConstantPoolMapTy ConstantPools;

public:

  void emitAll(MCStreamer &Streamer);

  void emitForCurrentSection(MCStreamer &Streamer);

  void clearCacheForCurrentSection(MCStreamer &Streamer);

  const MCExpr *addEntry(MCStreamer &Streamer, const MCExpr *Expr,

                         unsigned Size, SMLoc Loc);

private:

  ConstantPool *getConstantPool(MCSection *Section);

  ConstantPool &getOrCreateConstantPool(MCSection *Section);

};

} // end namespace llvm

#endif // LLVM_MC_CONSTANTPOOLS_H