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 #include "llvm/Support/SMLoc.h" 21 22 namespace llvm { 23 class MCContext; 24 class MCExpr; 25 class MCSection; 26 class MCStreamer; 27 class MCSymbol; 28 29 struct ConstantPoolEntry { 30 ConstantPoolEntry(MCSymbol *L, const MCExpr *Val, unsigned Sz, SMLoc Loc_) 31 : Label(L), Value(Val), Size(Sz), Loc(Loc_) {} 32 MCSymbol *Label; 33 const MCExpr *Value; 34 unsigned Size; 35 SMLoc Loc; 36 }; 37 38 // A class to keep track of assembler-generated constant pools that are use to 39 // implement the ldr-pseudo. 40 class ConstantPool { 41 typedef SmallVector<ConstantPoolEntry, 4> EntryVecTy; 42 EntryVecTy Entries; 43 44 public: 45 // Initialize a new empty constant pool 46 ConstantPool() {} 47 48 // Add a new entry to the constant pool in the next slot. 49 // \param Value is the new entry to put in the constant pool. 50 // \param Size is the size in bytes of the entry 51 // 52 // \returns a MCExpr that references the newly inserted value 53 const MCExpr *addEntry(const MCExpr *Value, MCContext &Context, 54 unsigned Size, SMLoc Loc); 55 56 // Emit the contents of the constant pool using the provided streamer. 57 void emitEntries(MCStreamer &Streamer); 58 59 // Return true if the constant pool is empty 60 bool empty(); 61 }; 62 63 class AssemblerConstantPools { 64 // Map type used to keep track of per-Section constant pools used by the 65 // ldr-pseudo opcode. The map associates a section to its constant pool. The 66 // constant pool is a vector of (label, value) pairs. When the ldr 67 // pseudo is parsed we insert a new (label, value) pair into the constant pool 68 // for the current section and add MCSymbolRefExpr to the new label as 69 // an opcode to the ldr. After we have parsed all the user input we 70 // output the (label, value) pairs in each constant pool at the end of the 71 // section. 72 // 73 // We use the MapVector for the map type to ensure stable iteration of 74 // the sections at the end of the parse. We need to iterate over the 75 // sections in a stable order to ensure that we have print the 76 // constant pools in a deterministic order when printing an assembly 77 // file. 78 typedef MapVector<MCSection *, ConstantPool> ConstantPoolMapTy; 79 ConstantPoolMapTy ConstantPools; 80 81 public: 82 void emitAll(MCStreamer &Streamer); 83 void emitForCurrentSection(MCStreamer &Streamer); 84 const MCExpr *addEntry(MCStreamer &Streamer, const MCExpr *Expr, 85 unsigned Size, SMLoc Loc); 86 87 private: 88 ConstantPool *getConstantPool(MCSection *Section); 89 ConstantPool &getOrCreateConstantPool(MCSection *Section); 90 }; 91 } // end namespace llvm 92 93 #endif 94
