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 // This file defines the JITMemoryManagerInterface
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_EXECUTION_ENGINE_JIT_MEMMANAGER_H
15 #define LLVM_EXECUTION_ENGINE_JIT_MEMMANAGER_H
17 #include "llvm/System/DataTypes.h"
25 /// JITMemoryManager - This interface is used by the JIT to allocate and manage
26 /// memory for the code generated by the JIT. This can be reimplemented by
27 /// clients that have a strong desire to control how the layout of JIT'd memory
29 class JITMemoryManager {
35 JITMemoryManager() : HasGOT(false), SizeRequired(false) {}
36 virtual ~JITMemoryManager();
38 /// CreateDefaultMemManager - This is used to create the default
39 /// JIT Memory Manager if the client does not provide one to the JIT.
40 static JITMemoryManager *CreateDefaultMemManager();
42 /// setMemoryWritable - When code generation is in progress,
43 /// the code pages may need permissions changed.
44 virtual void setMemoryWritable() = 0;
46 /// setMemoryExecutable - When code generation is done and we're ready to
47 /// start execution, the code pages may need permissions changed.
48 virtual void setMemoryExecutable() = 0;
50 /// setPoisonMemory - Setting this flag to true makes the memory manager
51 /// garbage values over freed memory. This is useful for testing and
52 /// debugging, and is be turned on by default in debug mode.
53 virtual void setPoisonMemory(bool poison) = 0;
55 //===--------------------------------------------------------------------===//
56 // Global Offset Table Management
57 //===--------------------------------------------------------------------===//
59 /// AllocateGOT - If the current table requires a Global Offset Table, this
60 /// method is invoked to allocate it. This method is required to set HasGOT
62 virtual void AllocateGOT() = 0;
64 /// isManagingGOT - Return true if the AllocateGOT method is called.
66 bool isManagingGOT() const {
70 /// getGOTBase - If this is managing a Global Offset Table, this method should
71 /// return a pointer to its base.
72 virtual uint8_t *getGOTBase() const = 0;
74 /// SetDlsymTable - If the JIT must be able to relocate stubs after they have
75 /// been emitted, potentially because they are being copied to a process
76 /// where external symbols live at different addresses than in the JITing
77 /// process, allocate a table with sufficient information to do so.
78 virtual void SetDlsymTable(void *ptr) = 0;
80 /// getDlsymTable - If this is managing a table of entries so that stubs to
81 /// external symbols can be later relocated, this method should return a
83 virtual void *getDlsymTable() const = 0;
85 /// NeedsExactSize - If the memory manager requires to know the size of the
86 /// objects to be emitted
87 bool NeedsExactSize() const {
91 //===--------------------------------------------------------------------===//
92 // Main Allocation Functions
93 //===--------------------------------------------------------------------===//
95 /// startFunctionBody - When we start JITing a function, the JIT calls this
96 /// method to allocate a block of free RWX memory, which returns a pointer to
97 /// it. If the JIT wants to request a block of memory of at least a certain
98 /// size, it passes that value as ActualSize, and this method returns a block
99 /// with at least that much space. If the JIT doesn't know ahead of time how
100 /// much space it will need to emit the function, it passes 0 for the
101 /// ActualSize. In either case, this method is required to pass back the size
102 /// of the allocated block through ActualSize. The JIT will be careful to
103 /// not write more than the returned ActualSize bytes of memory.
104 virtual uint8_t *startFunctionBody(const Function *F,
105 uintptr_t &ActualSize) = 0;
107 /// allocateStub - This method is called by the JIT to allocate space for a
108 /// function stub (used to handle limited branch displacements) while it is
109 /// JIT compiling a function. For example, if foo calls bar, and if bar
110 /// either needs to be lazily compiled or is a native function that exists too
111 /// far away from the call site to work, this method will be used to make a
112 /// thunk for it. The stub should be "close" to the current function body,
113 /// but should not be included in the 'actualsize' returned by
114 /// startFunctionBody.
115 virtual uint8_t *allocateStub(const GlobalValue* F, unsigned StubSize,
116 unsigned Alignment) = 0;
118 /// endFunctionBody - This method is called when the JIT is done codegen'ing
119 /// the specified function. At this point we know the size of the JIT
120 /// compiled function. This passes in FunctionStart (which was returned by
121 /// the startFunctionBody method) and FunctionEnd which is a pointer to the
122 /// actual end of the function. This method should mark the space allocated
123 /// and remember where it is in case the client wants to deallocate it.
124 virtual void endFunctionBody(const Function *F, uint8_t *FunctionStart,
125 uint8_t *FunctionEnd) = 0;
127 /// allocateSpace - Allocate a memory block of the given size. This method
128 /// cannot be called between calls to startFunctionBody and endFunctionBody.
129 virtual uint8_t *allocateSpace(intptr_t Size, unsigned Alignment) = 0;
131 /// allocateGlobal - Allocate memory for a global.
133 virtual uint8_t *allocateGlobal(uintptr_t Size, unsigned Alignment) = 0;
135 /// deallocateFunctionBody - Free the specified function body. The argument
136 /// must be the return value from a call to startFunctionBody() that hasn't
137 /// been deallocated yet. This is never called when the JIT is currently
138 /// emitting a function.
139 virtual void deallocateFunctionBody(void *Body) = 0;
141 /// startExceptionTable - When we finished JITing the function, if exception
142 /// handling is set, we emit the exception table.
143 virtual uint8_t* startExceptionTable(const Function* F,
144 uintptr_t &ActualSize) = 0;
146 /// endExceptionTable - This method is called when the JIT is done emitting
147 /// the exception table.
148 virtual void endExceptionTable(const Function *F, uint8_t *TableStart,
149 uint8_t *TableEnd, uint8_t* FrameRegister) = 0;
151 /// deallocateExceptionTable - Free the specified exception table's memory.
152 /// The argument must be the return value from a call to startExceptionTable()
153 /// that hasn't been deallocated yet. This is never called when the JIT is
154 /// currently emitting an exception table.
155 virtual void deallocateExceptionTable(void *ET) = 0;
157 /// CheckInvariants - For testing only. Return true if all internal
158 /// invariants are preserved, or return false and set ErrorStr to a helpful
160 virtual bool CheckInvariants(std::string &) {
164 /// GetDefaultCodeSlabSize - For testing only. Returns DefaultCodeSlabSize
165 /// from DefaultJITMemoryManager.
166 virtual size_t GetDefaultCodeSlabSize() {
170 /// GetDefaultDataSlabSize - For testing only. Returns DefaultCodeSlabSize
171 /// from DefaultJITMemoryManager.
172 virtual size_t GetDefaultDataSlabSize() {
176 /// GetDefaultStubSlabSize - For testing only. Returns DefaultCodeSlabSize
177 /// from DefaultJITMemoryManager.
178 virtual size_t GetDefaultStubSlabSize() {
182 /// GetNumCodeSlabs - For testing only. Returns the number of MemoryBlocks
183 /// allocated for code.
184 virtual unsigned GetNumCodeSlabs() {
188 /// GetNumDataSlabs - For testing only. Returns the number of MemoryBlocks
189 /// allocated for data.
190 virtual unsigned GetNumDataSlabs() {
194 /// GetNumStubSlabs - For testing only. Returns the number of MemoryBlocks
195 /// allocated for function stubs.
196 virtual unsigned GetNumStubSlabs() {
201 } // end namespace llvm.