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 //===--------------------------------------------------------------------===//
39 // Global Offset Table Management
40 //===--------------------------------------------------------------------===//
42 /// AllocateGOT - If the current table requires a Global Offset Table, this
43 /// method is invoked to allocate it. This method is required to set HasGOT
45 virtual void AllocateGOT() = 0;
47 /// isManagingGOT - Return true if the AllocateGOT method is called.
49 bool isManagingGOT() const {
53 /// getGOTBase - If this is managing a Global Offset Table, this method should
54 /// return a pointer to its base.
55 virtual unsigned char *getGOTBase() const = 0;
57 /// NeedsExactSize - If the memory manager requires to know the size of the
58 /// objects to be emitted
59 bool NeedsExactSize() const {
63 //===--------------------------------------------------------------------===//
64 // Main Allocation Functions
65 //===--------------------------------------------------------------------===//
67 /// startFunctionBody - When we start JITing a function, the JIT calls this
68 /// method to allocate a block of free RWX memory, which returns a pointer to
69 /// it. The JIT doesn't know ahead of time how much space it will need to
70 /// emit the function, so it doesn't pass in the size. Instead, this method
71 /// is required to pass back a "valid size". The JIT will be careful to not
72 /// write more than the returned ActualSize bytes of memory.
73 virtual unsigned char *startFunctionBody(const Function *F,
74 uintptr_t &ActualSize) = 0;
76 /// allocateStub - This method is called by the JIT to allocate space for a
77 /// function stub (used to handle limited branch displacements) while it is
78 /// JIT compiling a function. For example, if foo calls bar, and if bar
79 /// either needs to be lazily compiled or is a native function that exists too
80 /// far away from the call site to work, this method will be used to make a
81 /// thunk for it. The stub should be "close" to the current function body,
82 /// but should not be included in the 'actualsize' returned by
83 /// startFunctionBody.
84 virtual unsigned char *allocateStub(const GlobalValue* F, unsigned StubSize,
85 unsigned Alignment) =0;
88 /// endFunctionBody - This method is called when the JIT is done codegen'ing
89 /// the specified function. At this point we know the size of the JIT
90 /// compiled function. This passes in FunctionStart (which was returned by
91 /// the startFunctionBody method) and FunctionEnd which is a pointer to the
92 /// actual end of the function. This method should mark the space allocated
93 /// and remember where it is in case the client wants to deallocate it.
94 virtual void endFunctionBody(const Function *F, unsigned char *FunctionStart,
95 unsigned char *FunctionEnd) = 0;
97 /// deallocateMemForFunction - Free JIT memory for the specified function.
98 /// This is never called when the JIT is currently emitting a function.
99 virtual void deallocateMemForFunction(const Function *F) = 0;
101 /// startExceptionTable - When we finished JITing the function, if exception
102 /// handling is set, we emit the exception table.
103 virtual unsigned char* startExceptionTable(const Function* F,
104 uintptr_t &ActualSize) = 0;
106 /// endExceptionTable - This method is called when the JIT is done emitting
107 /// the exception table.
108 virtual void endExceptionTable(const Function *F, unsigned char *TableStart,
109 unsigned char *TableEnd,
110 unsigned char* FrameRegister) = 0;
113 } // end namespace llvm.