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//===-- JITMemoryManager.h - Interface JIT uses to Allocate Mem -*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Chris Lattner and 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;
public:
JITMemoryManager() : HasGOT(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();
//===--------------------------------------------------------------------===//
// 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;
//===--------------------------------------------------------------------===//
// 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(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;
/// 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;
};
} // end namespace llvm.
#endif
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