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 {
34 JITMemoryManager() : HasGOT(false) {}
35 virtual ~JITMemoryManager();
37 /// CreateDefaultMemManager - This is used to create the default
38 /// JIT Memory Manager if the client does not provide one to the JIT.
39 static JITMemoryManager *CreateDefaultMemManager();
41 /// setMemoryWritable - When code generation is in progress,
42 /// the code pages may need permissions changed.
43 virtual void setMemoryWritable() = 0;
45 /// setMemoryExecutable - When code generation is done and we're ready to
46 /// start execution, the code pages may need permissions changed.
47 virtual void setMemoryExecutable() = 0;
49 /// setPoisonMemory - Setting this flag to true makes the memory manager
50 /// garbage values over freed memory. This is useful for testing and
51 /// debugging, and is be turned on by default in debug mode.
52 virtual void setPoisonMemory(bool poison) = 0;
54 //===--------------------------------------------------------------------===//
55 // Global Offset Table Management
56 //===--------------------------------------------------------------------===//
58 /// AllocateGOT - If the current table requires a Global Offset Table, this
59 /// method is invoked to allocate it. This method is required to set HasGOT
61 virtual void AllocateGOT() = 0;
63 /// isManagingGOT - Return true if the AllocateGOT method is called.
65 bool isManagingGOT() const {
69 /// getGOTBase - If this is managing a Global Offset Table, this method should
70 /// return a pointer to its base.
71 virtual uint8_t *getGOTBase() const = 0;
73 //===--------------------------------------------------------------------===//
74 // Main Allocation Functions
75 //===--------------------------------------------------------------------===//
77 /// startFunctionBody - When we start JITing a function, the JIT calls this
78 /// method to allocate a block of free RWX memory, which returns a pointer to
79 /// it. If the JIT wants to request a block of memory of at least a certain
80 /// size, it passes that value as ActualSize, and this method returns a block
81 /// with at least that much space. If the JIT doesn't know ahead of time how
82 /// much space it will need to emit the function, it passes 0 for the
83 /// ActualSize. In either case, this method is required to pass back the size
84 /// of the allocated block through ActualSize. The JIT will be careful to
85 /// not write more than the returned ActualSize bytes of memory.
86 virtual uint8_t *startFunctionBody(const Function *F,
87 uintptr_t &ActualSize) = 0;
89 /// allocateStub - This method is called by the JIT to allocate space for a
90 /// function stub (used to handle limited branch displacements) while it is
91 /// JIT compiling a function. For example, if foo calls bar, and if bar
92 /// either needs to be lazily compiled or is a native function that exists too
93 /// far away from the call site to work, this method will be used to make a
94 /// thunk for it. The stub should be "close" to the current function body,
95 /// but should not be included in the 'actualsize' returned by
96 /// startFunctionBody.
97 virtual uint8_t *allocateStub(const GlobalValue* F, unsigned StubSize,
98 unsigned Alignment) = 0;
100 /// endFunctionBody - This method is called when the JIT is done codegen'ing
101 /// the specified function. At this point we know the size of the JIT
102 /// compiled function. This passes in FunctionStart (which was returned by
103 /// the startFunctionBody method) and FunctionEnd which is a pointer to the
104 /// actual end of the function. This method should mark the space allocated
105 /// and remember where it is in case the client wants to deallocate it.
106 virtual void endFunctionBody(const Function *F, uint8_t *FunctionStart,
107 uint8_t *FunctionEnd) = 0;
109 /// allocateSpace - Allocate a memory block of the given size. This method
110 /// cannot be called between calls to startFunctionBody and endFunctionBody.
111 virtual uint8_t *allocateSpace(intptr_t Size, unsigned Alignment) = 0;
113 /// allocateGlobal - Allocate memory for a global.
115 virtual uint8_t *allocateGlobal(uintptr_t Size, unsigned Alignment) = 0;
117 /// deallocateFunctionBody - Free the specified function body. The argument
118 /// must be the return value from a call to startFunctionBody() that hasn't
119 /// been deallocated yet. This is never called when the JIT is currently
120 /// emitting a function.
121 virtual void deallocateFunctionBody(void *Body) = 0;
123 /// startExceptionTable - When we finished JITing the function, if exception
124 /// handling is set, we emit the exception table.
125 virtual uint8_t* startExceptionTable(const Function* F,
126 uintptr_t &ActualSize) = 0;
128 /// endExceptionTable - This method is called when the JIT is done emitting
129 /// the exception table.
130 virtual void endExceptionTable(const Function *F, uint8_t *TableStart,
131 uint8_t *TableEnd, uint8_t* FrameRegister) = 0;
133 /// deallocateExceptionTable - Free the specified exception table's memory.
134 /// The argument must be the return value from a call to startExceptionTable()
135 /// that hasn't been deallocated yet. This is never called when the JIT is
136 /// currently emitting an exception table.
137 virtual void deallocateExceptionTable(void *ET) = 0;
139 /// CheckInvariants - For testing only. Return true if all internal
140 /// invariants are preserved, or return false and set ErrorStr to a helpful
142 virtual bool CheckInvariants(std::string &) {
146 /// GetDefaultCodeSlabSize - For testing only. Returns DefaultCodeSlabSize
147 /// from DefaultJITMemoryManager.
148 virtual size_t GetDefaultCodeSlabSize() {
152 /// GetDefaultDataSlabSize - For testing only. Returns DefaultCodeSlabSize
153 /// from DefaultJITMemoryManager.
154 virtual size_t GetDefaultDataSlabSize() {
158 /// GetDefaultStubSlabSize - For testing only. Returns DefaultCodeSlabSize
159 /// from DefaultJITMemoryManager.
160 virtual size_t GetDefaultStubSlabSize() {
164 /// GetNumCodeSlabs - For testing only. Returns the number of MemoryBlocks
165 /// allocated for code.
166 virtual unsigned GetNumCodeSlabs() {
170 /// GetNumDataSlabs - For testing only. Returns the number of MemoryBlocks
171 /// allocated for data.
172 virtual unsigned GetNumDataSlabs() {
176 /// GetNumStubSlabs - For testing only. Returns the number of MemoryBlocks
177 /// allocated for function stubs.
178 virtual unsigned GetNumStubSlabs() {
183 } // end namespace llvm.