//===-- JITMemoryManager.h - Interface JIT uses to Allocate Mem -*- C++ -*-===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file defines the JITMemoryManagerInterface // //===----------------------------------------------------------------------===// #ifndef LLVM_EXECUTION_ENGINE_JIT_MEMMANAGER_H #define LLVM_EXECUTION_ENGINE_JIT_MEMMANAGER_H #include "llvm/Support/DataTypes.h" namespace llvm { class Function; /// JITMemoryManager - This interface is used by the JIT to allocate and manage /// memory for the code generated by the JIT. This can be reimplemented by /// clients that have a strong desire to control how the layout of JIT'd memory /// works. class JITMemoryManager { protected: bool HasGOT; bool SizeRequired; public: JITMemoryManager() : HasGOT(false), SizeRequired(false) {} virtual ~JITMemoryManager(); /// CreateDefaultMemManager - This is used to create the default /// JIT Memory Manager if the client does not provide one to the JIT. static JITMemoryManager *CreateDefaultMemManager(); /// setMemoryWritable - When code generation is in progress, /// the code pages may need permissions changed. virtual void setMemoryWritable(void) = 0; /// setMemoryExecutable - When code generation is done and we're ready to /// start execution, the code pages may need permissions changed. virtual void setMemoryExecutable(void) = 0; //===--------------------------------------------------------------------===// // Global Offset Table Management //===--------------------------------------------------------------------===// /// AllocateGOT - If the current table requires a Global Offset Table, this /// method is invoked to allocate it. This method is required to set HasGOT /// to true. virtual void AllocateGOT() = 0; /// isManagingGOT - Return true if the AllocateGOT method is called. /// bool isManagingGOT() const { return HasGOT; } /// getGOTBase - If this is managing a Global Offset Table, this method should /// return a pointer to its base. virtual unsigned char *getGOTBase() const = 0; /// SetDlsymTable - If the JIT must be able to relocate stubs after they have /// been emitted, potentially because they are being copied to a process /// where external symbols live at different addresses than in the JITing /// process, allocate a table with sufficient information to do so. virtual void SetDlsymTable(void *ptr) = 0; /// getDlsymTable - If this is managing a table of entries so that stubs to /// external symbols can be later relocated, this method should return a /// pointer to it. virtual void *getDlsymTable() const = 0; /// NeedsExactSize - If the memory manager requires to know the size of the /// objects to be emitted bool NeedsExactSize() const { return SizeRequired; } //===--------------------------------------------------------------------===// // Main Allocation Functions //===--------------------------------------------------------------------===// /// startFunctionBody - When we start JITing a function, the JIT calls this /// method to allocate a block of free RWX memory, which returns a pointer to /// it. The JIT doesn't know ahead of time how much space it will need to /// emit the function, so it doesn't pass in the size. Instead, this method /// is required to pass back a "valid size". The JIT will be careful to not /// write more than the returned ActualSize bytes of memory. virtual unsigned char *startFunctionBody(const Function *F, uintptr_t &ActualSize) = 0; /// allocateStub - This method is called by the JIT to allocate space for a /// function stub (used to handle limited branch displacements) while it is /// JIT compiling a function. For example, if foo calls bar, and if bar /// either needs to be lazily compiled or is a native function that exists too /// far away from the call site to work, this method will be used to make a /// thunk for it. The stub should be "close" to the current function body, /// but should not be included in the 'actualsize' returned by /// startFunctionBody. virtual unsigned char *allocateStub(const GlobalValue* F, unsigned StubSize, unsigned Alignment) =0; /// endFunctionBody - This method is called when the JIT is done codegen'ing /// the specified function. At this point we know the size of the JIT /// compiled function. This passes in FunctionStart (which was returned by /// the startFunctionBody method) and FunctionEnd which is a pointer to the /// actual end of the function. This method should mark the space allocated /// and remember where it is in case the client wants to deallocate it. virtual void endFunctionBody(const Function *F, unsigned char *FunctionStart, unsigned char *FunctionEnd) = 0; /// allocateSpace - Allocate a memory block of the given size. virtual unsigned char *allocateSpace(intptr_t Size, unsigned Alignment) = 0; /// deallocateMemForFunction - Free JIT memory for the specified function. /// This is never called when the JIT is currently emitting a function. virtual void deallocateMemForFunction(const Function *F) = 0; /// startExceptionTable - When we finished JITing the function, if exception /// handling is set, we emit the exception table. virtual unsigned char* startExceptionTable(const Function* F, uintptr_t &ActualSize) = 0; /// endExceptionTable - This method is called when the JIT is done emitting /// the exception table. virtual void endExceptionTable(const Function *F, unsigned char *TableStart, unsigned char *TableEnd, unsigned char* FrameRegister) = 0; }; } // end namespace llvm. #endif