1 //===-- JITMemoryManager.h - Interface JIT uses to Allocate Mem -*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #ifndef LLVM_EXECUTION_ENGINE_JIT_MEMMANAGER_H
11 #define LLVM_EXECUTION_ENGINE_JIT_MEMMANAGER_H
13 #include "llvm/Support/DataTypes.h"
21 /// JITMemoryManager - This interface is used by the JIT to allocate and manage
22 /// memory for the code generated by the JIT. This can be reimplemented by
23 /// clients that have a strong desire to control how the layout of JIT'd memory
25 class JITMemoryManager {
30 JITMemoryManager() : HasGOT(false) {}
31 virtual ~JITMemoryManager();
33 /// CreateDefaultMemManager - This is used to create the default
34 /// JIT Memory Manager if the client does not provide one to the JIT.
35 static JITMemoryManager *CreateDefaultMemManager();
37 /// setMemoryWritable - When code generation is in progress,
38 /// the code pages may need permissions changed.
39 virtual void setMemoryWritable() = 0;
41 /// setMemoryExecutable - When code generation is done and we're ready to
42 /// start execution, the code pages may need permissions changed.
43 virtual void setMemoryExecutable() = 0;
45 /// setPoisonMemory - Setting this flag to true makes the memory manager
46 /// garbage values over freed memory. This is useful for testing and
47 /// debugging, and may be turned on by default in debug mode.
48 virtual void setPoisonMemory(bool poison) = 0;
50 //===--------------------------------------------------------------------===//
51 // Global Offset Table Management
52 //===--------------------------------------------------------------------===//
54 /// AllocateGOT - If the current table requires a Global Offset Table, this
55 /// method is invoked to allocate it. This method is required to set HasGOT
57 virtual void AllocateGOT() = 0;
59 /// isManagingGOT - Return true if the AllocateGOT method is called.
60 bool isManagingGOT() const {
64 /// getGOTBase - If this is managing a Global Offset Table, this method should
65 /// return a pointer to its base.
66 virtual uint8_t *getGOTBase() const = 0;
68 //===--------------------------------------------------------------------===//
69 // Main Allocation Functions
70 //===--------------------------------------------------------------------===//
72 /// startFunctionBody - When we start JITing a function, the JIT calls this
73 /// method to allocate a block of free RWX memory, which returns a pointer to
74 /// it. If the JIT wants to request a block of memory of at least a certain
75 /// size, it passes that value as ActualSize, and this method returns a block
76 /// with at least that much space. If the JIT doesn't know ahead of time how
77 /// much space it will need to emit the function, it passes 0 for the
78 /// ActualSize. In either case, this method is required to pass back the size
79 /// of the allocated block through ActualSize. The JIT will be careful to
80 /// not write more than the returned ActualSize bytes of memory.
81 virtual uint8_t *startFunctionBody(const Function *F,
82 uintptr_t &ActualSize) = 0;
84 /// allocateStub - This method is called by the JIT to allocate space for a
85 /// function stub (used to handle limited branch displacements) while it is
86 /// JIT compiling a function. For example, if foo calls bar, and if bar
87 /// either needs to be lazily compiled or is a native function that exists too
88 /// far away from the call site to work, this method will be used to make a
89 /// thunk for it. The stub should be "close" to the current function body,
90 /// but should not be included in the 'actualsize' returned by
91 /// startFunctionBody.
92 virtual uint8_t *allocateStub(const GlobalValue* F, unsigned StubSize,
93 unsigned Alignment) = 0;
95 /// endFunctionBody - This method is called when the JIT is done codegen'ing
96 /// the specified function. At this point we know the size of the JIT
97 /// compiled function. This passes in FunctionStart (which was returned by
98 /// the startFunctionBody method) and FunctionEnd which is a pointer to the
99 /// actual end of the function. This method should mark the space allocated
100 /// and remember where it is in case the client wants to deallocate it.
101 virtual void endFunctionBody(const Function *F, uint8_t *FunctionStart,
102 uint8_t *FunctionEnd) = 0;
104 /// allocateCodeSection - Allocate a memory block of (at least) the given
105 /// size suitable for executable code. The SectionID is a unique identifier
106 /// assigned by the JIT and passed through to the memory manager for
107 /// the instance class to use if it needs to communicate to the JIT about
108 /// a given section after the fact.
109 virtual uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
110 unsigned SectionID) = 0;
112 /// allocateDataSection - Allocate a memory block of (at least) the given
113 /// size suitable for data. The SectionID is a unique identifier
114 /// assigned by the JIT and passed through to the memory manager for
115 /// the instance class to use if it needs to communicate to the JIT about
116 /// a given section after the fact.
117 virtual uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
118 unsigned SectionID) = 0;
120 /// allocateSpace - Allocate a memory block of the given size. This method
121 /// cannot be called between calls to startFunctionBody and endFunctionBody.
122 virtual uint8_t *allocateSpace(intptr_t Size, unsigned Alignment) = 0;
124 /// allocateGlobal - Allocate memory for a global.
125 virtual uint8_t *allocateGlobal(uintptr_t Size, unsigned Alignment) = 0;
127 /// deallocateFunctionBody - Free the specified function body. The argument
128 /// must be the return value from a call to startFunctionBody() that hasn't
129 /// been deallocated yet. This is never called when the JIT is currently
130 /// emitting a function.
131 virtual void deallocateFunctionBody(void *Body) = 0;
133 /// startExceptionTable - When we finished JITing the function, if exception
134 /// handling is set, we emit the exception table.
135 virtual uint8_t* startExceptionTable(const Function* F,
136 uintptr_t &ActualSize) = 0;
138 /// endExceptionTable - This method is called when the JIT is done emitting
139 /// the exception table.
140 virtual void endExceptionTable(const Function *F, uint8_t *TableStart,
141 uint8_t *TableEnd, uint8_t* FrameRegister) = 0;
143 /// deallocateExceptionTable - Free the specified exception table's memory.
144 /// The argument must be the return value from a call to startExceptionTable()
145 /// that hasn't been deallocated yet. This is never called when the JIT is
146 /// currently emitting an exception table.
147 virtual void deallocateExceptionTable(void *ET) = 0;
149 /// CheckInvariants - For testing only. Return true if all internal
150 /// invariants are preserved, or return false and set ErrorStr to a helpful
152 virtual bool CheckInvariants(std::string &) {
156 /// GetDefaultCodeSlabSize - For testing only. Returns DefaultCodeSlabSize
157 /// from DefaultJITMemoryManager.
158 virtual size_t GetDefaultCodeSlabSize() {
162 /// GetDefaultDataSlabSize - For testing only. Returns DefaultCodeSlabSize
163 /// from DefaultJITMemoryManager.
164 virtual size_t GetDefaultDataSlabSize() {
168 /// GetDefaultStubSlabSize - For testing only. Returns DefaultCodeSlabSize
169 /// from DefaultJITMemoryManager.
170 virtual size_t GetDefaultStubSlabSize() {
174 /// GetNumCodeSlabs - For testing only. Returns the number of MemoryBlocks
175 /// allocated for code.
176 virtual unsigned GetNumCodeSlabs() {
180 /// GetNumDataSlabs - For testing only. Returns the number of MemoryBlocks
181 /// allocated for data.
182 virtual unsigned GetNumDataSlabs() {
186 /// GetNumStubSlabs - For testing only. Returns the number of MemoryBlocks
187 /// allocated for function stubs.
188 virtual unsigned GetNumStubSlabs() {
193 } // end namespace llvm.