MCContext.h revision c28cc093e3b5b8601cb5024a5365a6f31f49839a
1//===- MCContext.h - Machine Code Context -----------------------*- 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#ifndef LLVM_MC_MCCONTEXT_H 11#define LLVM_MC_MCCONTEXT_H 12 13#include "llvm/ADT/DenseMap.h" 14#include "llvm/ADT/StringMap.h" 15#include "llvm/Support/Allocator.h" 16 17namespace llvm { 18 class MCAsmInfo; 19 class MCExpr; 20 class MCSection; 21 class MCSymbol; 22 class StringRef; 23 class Twine; 24 25 /// MCContext - Context object for machine code objects. This class owns all 26 /// of the sections that it creates. 27 /// 28 class MCContext { 29 MCContext(const MCContext&); // DO NOT IMPLEMENT 30 MCContext &operator=(const MCContext&); // DO NOT IMPLEMENT 31 32 /// The MCAsmInfo for this target. 33 const MCAsmInfo &MAI; 34 35 /// Sections - Bindings of names to allocated sections. 36 StringMap<MCSection*> Sections; 37 38 /// Symbols - Bindings of names to symbols. 39 StringMap<MCSymbol*> Symbols; 40 41 /// NextUniqueID - The next ID to dole out to an unnamed assembler temporary 42 /// symbol. 43 unsigned NextUniqueID; 44 45 /// Allocator - Allocator object used for creating machine code objects. 46 /// 47 /// We use a bump pointer allocator to avoid the need to track all allocated 48 /// objects. 49 BumpPtrAllocator Allocator; 50 public: 51 explicit MCContext(const MCAsmInfo &MAI); 52 ~MCContext(); 53 54 const MCAsmInfo &getAsmInfo() const { return MAI; } 55 56 /// @name Symbol Managment 57 /// @{ 58 59 /// CreateTempSymbol - Create and return a new assembler temporary symbol 60 /// with a unique but unspecified name. 61 MCSymbol *CreateTempSymbol(); 62 63 /// GetOrCreateSymbol - Lookup the symbol inside with the specified 64 /// @p Name. If it exists, return it. If not, create a forward 65 /// reference and return it. 66 /// 67 /// @param Name - The symbol name, which must be unique across all symbols. 68 MCSymbol *GetOrCreateSymbol(StringRef Name, bool isTemporary = false); 69 MCSymbol *GetOrCreateSymbol(const Twine &Name, bool isTemporary = false); 70 71 /// GetOrCreateTemporarySymbol - Create a new assembler temporary symbol 72 /// with the specified @p Name if it doesn't exist or return the existing 73 /// one if it does. 74 /// 75 /// @param Name - The symbol name, for debugging purposes only, temporary 76 /// symbols do not surive assembly. If non-empty the name must be unique 77 /// across all symbols. 78 MCSymbol *GetOrCreateTemporarySymbol(StringRef Name = ""); 79 MCSymbol *GetOrCreateTemporarySymbol(const Twine &Name); 80 81 /// LookupSymbol - Get the symbol for \p Name, or null. 82 MCSymbol *LookupSymbol(StringRef Name) const; 83 84 /// @} 85 86 void *Allocate(unsigned Size, unsigned Align = 8) { 87 return Allocator.Allocate(Size, Align); 88 } 89 void Deallocate(void *Ptr) { 90 } 91 }; 92 93} // end namespace llvm 94 95// operator new and delete aren't allowed inside namespaces. 96// The throw specifications are mandated by the standard. 97/// @brief Placement new for using the MCContext's allocator. 98/// 99/// This placement form of operator new uses the MCContext's allocator for 100/// obtaining memory. It is a non-throwing new, which means that it returns 101/// null on error. (If that is what the allocator does. The current does, so if 102/// this ever changes, this operator will have to be changed, too.) 103/// Usage looks like this (assuming there's an MCContext 'Context' in scope): 104/// @code 105/// // Default alignment (16) 106/// IntegerLiteral *Ex = new (Context) IntegerLiteral(arguments); 107/// // Specific alignment 108/// IntegerLiteral *Ex2 = new (Context, 8) IntegerLiteral(arguments); 109/// @endcode 110/// Please note that you cannot use delete on the pointer; it must be 111/// deallocated using an explicit destructor call followed by 112/// @c Context.Deallocate(Ptr). 113/// 114/// @param Bytes The number of bytes to allocate. Calculated by the compiler. 115/// @param C The MCContext that provides the allocator. 116/// @param Alignment The alignment of the allocated memory (if the underlying 117/// allocator supports it). 118/// @return The allocated memory. Could be NULL. 119inline void *operator new(size_t Bytes, llvm::MCContext &C, 120 size_t Alignment = 16) throw () { 121 return C.Allocate(Bytes, Alignment); 122} 123/// @brief Placement delete companion to the new above. 124/// 125/// This operator is just a companion to the new above. There is no way of 126/// invoking it directly; see the new operator for more details. This operator 127/// is called implicitly by the compiler if a placement new expression using 128/// the MCContext throws in the object constructor. 129inline void operator delete(void *Ptr, llvm::MCContext &C, size_t) 130 throw () { 131 C.Deallocate(Ptr); 132} 133 134/// This placement form of operator new[] uses the MCContext's allocator for 135/// obtaining memory. It is a non-throwing new[], which means that it returns 136/// null on error. 137/// Usage looks like this (assuming there's an MCContext 'Context' in scope): 138/// @code 139/// // Default alignment (16) 140/// char *data = new (Context) char[10]; 141/// // Specific alignment 142/// char *data = new (Context, 8) char[10]; 143/// @endcode 144/// Please note that you cannot use delete on the pointer; it must be 145/// deallocated using an explicit destructor call followed by 146/// @c Context.Deallocate(Ptr). 147/// 148/// @param Bytes The number of bytes to allocate. Calculated by the compiler. 149/// @param C The MCContext that provides the allocator. 150/// @param Alignment The alignment of the allocated memory (if the underlying 151/// allocator supports it). 152/// @return The allocated memory. Could be NULL. 153inline void *operator new[](size_t Bytes, llvm::MCContext& C, 154 size_t Alignment = 16) throw () { 155 return C.Allocate(Bytes, Alignment); 156} 157 158/// @brief Placement delete[] companion to the new[] above. 159/// 160/// This operator is just a companion to the new[] above. There is no way of 161/// invoking it directly; see the new[] operator for more details. This operator 162/// is called implicitly by the compiler if a placement new[] expression using 163/// the MCContext throws in the object constructor. 164inline void operator delete[](void *Ptr, llvm::MCContext &C) throw () { 165 C.Deallocate(Ptr); 166} 167 168#endif 169