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/Support/DataTypes.h"
22 /// JITMemoryManager - This interface is used by the JIT to allocate and manage
23 /// memory for the code generated by the JIT. This can be reimplemented by
24 /// clients that have a strong desire to control how the layout of JIT'd memory
26 class JITMemoryManager {
31 JITMemoryManager() : HasGOT(false), SizeRequired(false) {}
32 virtual ~JITMemoryManager();
34 /// CreateDefaultMemManager - This is used to create the default
35 /// JIT Memory Manager if the client does not provide one to the JIT.
36 static JITMemoryManager *CreateDefaultMemManager();
38 /// setMemoryWritable - When code generation is in progress,
39 /// the code pages may need permissions changed.
40 virtual void setMemoryWritable(void) = 0;
42 /// setMemoryExecutable - When code generation is done and we're ready to
43 /// start execution, the code pages may need permissions changed.
44 virtual void setMemoryExecutable(void) = 0;
46 //===--------------------------------------------------------------------===//
47 // Global Offset Table Management
48 //===--------------------------------------------------------------------===//
50 /// AllocateGOT - If the current table requires a Global Offset Table, this
51 /// method is invoked to allocate it. This method is required to set HasGOT
53 virtual void AllocateGOT() = 0;
55 /// isManagingGOT - Return true if the AllocateGOT method is called.
57 bool isManagingGOT() const {
61 /// getGOTBase - If this is managing a Global Offset Table, this method should
62 /// return a pointer to its base.
63 virtual unsigned char *getGOTBase() const = 0;
65 /// SetDlsymTable - If the JIT must be able to relocate stubs after they have
66 /// been emitted, potentially because they are being copied to a process
67 /// where external symbols live at different addresses than in the JITing
68 /// process, allocate a table with sufficient information to do so.
69 virtual void SetDlsymTable(void *ptr) = 0;
71 /// getDlsymTable - If this is managing a table of entries so that stubs to
72 /// external symbols can be later relocated, this method should return a
74 virtual void *getDlsymTable() const = 0;
76 /// NeedsExactSize - If the memory manager requires to know the size of the
77 /// objects to be emitted
78 bool NeedsExactSize() const {
82 //===--------------------------------------------------------------------===//
83 // Main Allocation Functions
84 //===--------------------------------------------------------------------===//
86 /// startFunctionBody - When we start JITing a function, the JIT calls this
87 /// method to allocate a block of free RWX memory, which returns a pointer to
88 /// it. The JIT doesn't know ahead of time how much space it will need to
89 /// emit the function, so it doesn't pass in the size. Instead, this method
90 /// is required to pass back a "valid size". The JIT will be careful to not
91 /// write more than the returned ActualSize bytes of memory.
92 virtual unsigned char *startFunctionBody(const Function *F,
93 uintptr_t &ActualSize) = 0;
95 /// allocateStub - This method is called by the JIT to allocate space for a
96 /// function stub (used to handle limited branch displacements) while it is
97 /// JIT compiling a function. For example, if foo calls bar, and if bar
98 /// either needs to be lazily compiled or is a native function that exists too
99 /// far away from the call site to work, this method will be used to make a
100 /// thunk for it. The stub should be "close" to the current function body,
101 /// but should not be included in the 'actualsize' returned by
102 /// startFunctionBody.
103 virtual unsigned char *allocateStub(const GlobalValue* F, unsigned StubSize,
104 unsigned Alignment) =0;
107 /// endFunctionBody - This method is called when the JIT is done codegen'ing
108 /// the specified function. At this point we know the size of the JIT
109 /// compiled function. This passes in FunctionStart (which was returned by
110 /// the startFunctionBody method) and FunctionEnd which is a pointer to the
111 /// actual end of the function. This method should mark the space allocated
112 /// and remember where it is in case the client wants to deallocate it.
113 virtual void endFunctionBody(const Function *F, unsigned char *FunctionStart,
114 unsigned char *FunctionEnd) = 0;
116 /// allocateSpace - Allocate a memory block of the given size.
117 virtual unsigned char *allocateSpace(intptr_t Size, unsigned Alignment) = 0;
119 /// deallocateMemForFunction - Free JIT memory for the specified function.
120 /// This is never called when the JIT is currently emitting a function.
121 virtual void deallocateMemForFunction(const Function *F) = 0;
123 /// startExceptionTable - When we finished JITing the function, if exception
124 /// handling is set, we emit the exception table.
125 virtual unsigned char* 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, unsigned char *TableStart,
131 unsigned char *TableEnd,
132 unsigned char* FrameRegister) = 0;
135 } // end namespace llvm.