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 /// NeedsExactSize - If the memory manager requires to know the size of the
66 /// objects to be emitted
67 bool NeedsExactSize() const {
71 //===--------------------------------------------------------------------===//
72 // Main Allocation Functions
73 //===--------------------------------------------------------------------===//
75 /// startFunctionBody - When we start JITing a function, the JIT calls this
76 /// method to allocate a block of free RWX memory, which returns a pointer to
77 /// it. The JIT doesn't know ahead of time how much space it will need to
78 /// emit the function, so it doesn't pass in the size. Instead, this method
79 /// is required to pass back a "valid size". The JIT will be careful to not
80 /// write more than the returned ActualSize bytes of memory.
81 virtual unsigned char *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 unsigned char *allocateStub(const GlobalValue* F, unsigned StubSize,
93 unsigned Alignment) =0;
96 /// endFunctionBody - This method is called when the JIT is done codegen'ing
97 /// the specified function. At this point we know the size of the JIT
98 /// compiled function. This passes in FunctionStart (which was returned by
99 /// the startFunctionBody method) and FunctionEnd which is a pointer to the
100 /// actual end of the function. This method should mark the space allocated
101 /// and remember where it is in case the client wants to deallocate it.
102 virtual void endFunctionBody(const Function *F, unsigned char *FunctionStart,
103 unsigned char *FunctionEnd) = 0;
105 /// allocateSpace - Allocate a memory block of the given size.
106 virtual unsigned char *allocateSpace(intptr_t Size, unsigned Alignment) = 0;
108 /// deallocateMemForFunction - Free JIT memory for the specified function.
109 /// This is never called when the JIT is currently emitting a function.
110 virtual void deallocateMemForFunction(const Function *F) = 0;
112 /// startExceptionTable - When we finished JITing the function, if exception
113 /// handling is set, we emit the exception table.
114 virtual unsigned char* startExceptionTable(const Function* F,
115 uintptr_t &ActualSize) = 0;
117 /// endExceptionTable - This method is called when the JIT is done emitting
118 /// the exception table.
119 virtual void endExceptionTable(const Function *F, unsigned char *TableStart,
120 unsigned char *TableEnd,
121 unsigned char* FrameRegister) = 0;
124 } // end namespace llvm.