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       1             : //===- ConstantPool.h - Keep track of assembler-generated  ------*- C++ -*-===//
       2             : //
       3             : //                     The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : //
      10             : // This file declares the ConstantPool and AssemblerConstantPools classes.
      11             : //
      12             : //===----------------------------------------------------------------------===//
      13             : 
      14             : #ifndef LLVM_MC_CONSTANTPOOLS_H
      15             : #define LLVM_MC_CONSTANTPOOLS_H
      16             : 
      17             : #include "llvm/ADT/DenseMap.h"
      18             : #include "llvm/ADT/MapVector.h"
      19             : #include "llvm/ADT/SmallVector.h"
      20             : #include "llvm/Support/SMLoc.h"
      21             : #include <cstdint>
      22             : #include <map>
      23             : 
      24             : namespace llvm {
      25             : 
      26             : class MCContext;
      27             : class MCExpr;
      28             : class MCSection;
      29             : class MCStreamer;
      30             : class MCSymbol;
      31             : class MCSymbolRefExpr;
      32             : 
      33             : struct ConstantPoolEntry {
      34             :   ConstantPoolEntry(MCSymbol *L, const MCExpr *Val, unsigned Sz, SMLoc Loc_)
      35         304 :     : Label(L), Value(Val), Size(Sz), Loc(Loc_) {}
      36             : 
      37             :   MCSymbol *Label;
      38             :   const MCExpr *Value;
      39             :   unsigned Size;
      40             :   SMLoc Loc;
      41             : };
      42             : 
      43             : // A class to keep track of assembler-generated constant pools that are use to
      44             : // implement the ldr-pseudo.
      45             : class ConstantPool {
      46             :   using EntryVecTy = SmallVector<ConstantPoolEntry, 4>;
      47             :   EntryVecTy Entries;
      48             :   std::map<int64_t, const MCSymbolRefExpr *> CachedEntries;
      49             : 
      50             : public:
      51             :   // Initialize a new empty constant pool
      52             :   ConstantPool() = default;
      53             : 
      54             :   // Add a new entry to the constant pool in the next slot.
      55             :   // \param Value is the new entry to put in the constant pool.
      56             :   // \param Size is the size in bytes of the entry
      57             :   //
      58             :   // \returns a MCExpr that references the newly inserted value
      59             :   const MCExpr *addEntry(const MCExpr *Value, MCContext &Context,
      60             :                          unsigned Size, SMLoc Loc);
      61             : 
      62             :   // Emit the contents of the constant pool using the provided streamer.
      63             :   void emitEntries(MCStreamer &Streamer);
      64             : 
      65             :   // Return true if the constant pool is empty
      66             :   bool empty();
      67             : 
      68             :   void clearCache();
      69             : };
      70             : 
      71           0 : class AssemblerConstantPools {
      72             :   // Map type used to keep track of per-Section constant pools used by the
      73             :   // ldr-pseudo opcode. The map associates a section to its constant pool. The
      74             :   // constant pool is a vector of (label, value) pairs. When the ldr
      75             :   // pseudo is parsed we insert a new (label, value) pair into the constant pool
      76             :   // for the current section and add MCSymbolRefExpr to the new label as
      77             :   // an opcode to the ldr. After we have parsed all the user input we
      78             :   // output the (label, value) pairs in each constant pool at the end of the
      79             :   // section.
      80             :   //
      81             :   // We use the MapVector for the map type to ensure stable iteration of
      82             :   // the sections at the end of the parse. We need to iterate over the
      83             :   // sections in a stable order to ensure that we have print the
      84             :   // constant pools in a deterministic order when printing an assembly
      85             :   // file.
      86             :   using ConstantPoolMapTy = MapVector<MCSection *, ConstantPool>;
      87             :   ConstantPoolMapTy ConstantPools;
      88             : 
      89             : public:
      90             :   void emitAll(MCStreamer &Streamer);
      91             :   void emitForCurrentSection(MCStreamer &Streamer);
      92             :   void clearCacheForCurrentSection(MCStreamer &Streamer);
      93             :   const MCExpr *addEntry(MCStreamer &Streamer, const MCExpr *Expr,
      94             :                          unsigned Size, SMLoc Loc);
      95             : 
      96             : private:
      97             :   ConstantPool *getConstantPool(MCSection *Section);
      98             :   ConstantPool &getOrCreateConstantPool(MCSection *Section);
      99             : };
     100             : 
     101             : } // end namespace llvm
     102             : 
     103             : #endif // LLVM_MC_CONSTANTPOOLS_H