split the JIT memory management code out from the main JIT logic into its

own JITMemoryManager interface.  There is no functionality change with 
this patch.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44640 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 96 insertions, 0 deletions

diff --git a/include/llvm/ExecutionEngine/JITMemoryManager.h b/include/llvm/ExecutionEngine/JITMemoryManager.h
new file mode 100644
index 0000000000..ba7c8bdc2e
--- /dev/null
+++ b/include/llvm/ExecutionEngine/JITMemoryManager.h
@@ -0,0 +1,96 @@
+//===-- 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_H
+#define LLVM_EXECUTION_ENGINE_JIT_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