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 15 #ifndef LLVM_MC_CONSTANTPOOL_H 16 #define LLVM_MC_CONSTANTPOOL_H 17 18 #include "llvm/ADT/SmallVector.h" 19 namespace llvm { 20 class MCContext; 21 class MCExpr; 22 class MCSection; 23 class MCStreamer; 24 class MCSymbol; 25 // A class to keep track of assembler-generated constant pools that are use to 26 // implement the ldr-pseudo. 27 class ConstantPool { 28 typedef SmallVector<std::pair<MCSymbol *, const MCExpr *>, 4> EntryVecTy; 29 EntryVecTy Entries; 30 31 public: 32 // Initialize a new empty constant pool 33 ConstantPool() {} 34 35 // Add a new entry to the constant pool in the next slot. 36 // \param Value is the new entry to put in the constant pool. 37 // 38 // \returns a MCExpr that references the newly inserted value 39 const MCExpr *addEntry(const MCExpr *Value, MCContext &Context); 40 41 // Emit the contents of the constant pool using the provided streamer. 42 void emitEntries(MCStreamer &Streamer); 43 44 // Return true if the constant pool is empty 45 bool empty(); 46 }; 47 48 class AssemblerConstantPools { 49 // Map type used to keep track of per-Section constant pools used by the 50 // ldr-pseudo opcode. The map associates a section to its constant pool. The 51 // constant pool is a vector of (label, value) pairs. When the ldr 52 // pseudo is parsed we insert a new (label, value) pair into the constant pool 53 // for the current section and add MCSymbolRefExpr to the new label as 54 // an opcode to the ldr. After we have parsed all the user input we 55 // output the (label, value) pairs in each constant pool at the end of the 56 // section. 57 // 58 // We use the MapVector for the map type to ensure stable iteration of 59 // the sections at the end of the parse. We need to iterate over the 60 // sections in a stable order to ensure that we have print the 61 // constant pools in a deterministic order when printing an assembly 62 // file. 63 typedef MapVector<const MCSection *, ConstantPool> ConstantPoolMapTy; 64 ConstantPoolMapTy ConstantPools; 65 66 public: 67 AssemblerConstantPools() {} 68 ~AssemblerConstantPools() {} 69 70 void emitAll(MCStreamer &Streamer); 71 void emitForCurrentSection(MCStreamer &Streamer); 72 const MCExpr *addEntry(MCStreamer &Streamer, const MCExpr *Expr); 73 74 private: 75 ConstantPool *getConstantPool(const MCSection *Section); 76 ConstantPool &getOrCreateConstantPool(const MCSection *Section); 77 }; 78 } // end namespace llvm 79 80 #endif 81
