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//===- 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;
// Caches of entries that already exist, indexed by their contents
// and also the size of the constant.
std::map<std::pair<int64_t, unsigned>, const MCSymbolRefExpr *>
CachedConstantEntries;
DenseMap<std::pair<const MCSymbol *, unsigned>, 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
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