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_CONSTANTPOOLS_H 16 #define LLVM_MC_CONSTANTPOOLS_H 17 18 #include "llvm/ADT/MapVector.h" 19 #include "llvm/ADT/SmallVector.h" 20 21 namespace llvm { 22 class MCContext; 23 class MCExpr; 24 class MCSection; 25 class MCStreamer; 26 class MCSymbol; 27 28 struct ConstantPoolEntry { 29 ConstantPoolEntry(MCSymbol *L, const MCExpr *Val, unsigned Sz) 30 : Label(L), Value(Val), Size(Sz) {} 31 MCSymbol *Label; 32 const MCExpr *Value; 33 unsigned Size; 34 }; 35 36 // A class to keep track of assembler-generated constant pools that are use to 37 // implement the ldr-pseudo. 38 class ConstantPool { 39 typedef SmallVector<ConstantPoolEntry, 4> EntryVecTy; 40 EntryVecTy Entries; 41 42 public: 43 // Initialize a new empty constant pool 44 ConstantPool() {} 45 46 // Add a new entry to the constant pool in the next slot. 47 // \param Value is the new entry to put in the constant pool. 48 // \param Size is the size in bytes of the entry 49 // 50 // \returns a MCExpr that references the newly inserted value 51 const MCExpr *addEntry(const MCExpr *Value, MCContext &Context, 52 unsigned Size); 53 54 // Emit the contents of the constant pool using the provided streamer. 55 void emitEntries(MCStreamer &Streamer); 56 57 // Return true if the constant pool is empty 58 bool empty(); 59 }; 60 61 class AssemblerConstantPools { 62 // Map type used to keep track of per-Section constant pools used by the 63 // ldr-pseudo opcode. The map associates a section to its constant pool. The 64 // constant pool is a vector of (label, value) pairs. When the ldr 65 // pseudo is parsed we insert a new (label, value) pair into the constant pool 66 // for the current section and add MCSymbolRefExpr to the new label as 67 // an opcode to the ldr. After we have parsed all the user input we 68 // output the (label, value) pairs in each constant pool at the end of the 69 // section. 70 // 71 // We use the MapVector for the map type to ensure stable iteration of 72 // the sections at the end of the parse. We need to iterate over the 73 // sections in a stable order to ensure that we have print the 74 // constant pools in a deterministic order when printing an assembly 75 // file. 76 typedef MapVector<const MCSection *, ConstantPool> ConstantPoolMapTy; 77 ConstantPoolMapTy ConstantPools; 78 79 public: 80 void emitAll(MCStreamer &Streamer); 81 void emitForCurrentSection(MCStreamer &Streamer); 82 const MCExpr *addEntry(MCStreamer &Streamer, const MCExpr *Expr, 83 unsigned Size); 84 85 private: 86 ConstantPool *getConstantPool(const MCSection *Section); 87 ConstantPool &getOrCreateConstantPool(const MCSection *Section); 88 }; 89 } // end namespace llvm 90 91 #endif 92
