Extend RTDyld API to enable optionally precomputing the total amount of memory

required for all sections in a module. This can be useful when targets or
code-models place strict requirements on how sections must be laid out
in memory.

If RTDyldMemoryManger::needsToReserveAllocationSpace() is overridden to return
true then the JIT will call the following method on the memory manager, which
can be used to preallocate the necessary memory.

void RTDyldMemoryManager::reserveAllocationSpace(uintptr_t CodeSize,
                                                 uintptr_t DataSizeRO,
                                                 uintptr_t DataSizeRW)

Patch by Vaidas Gasiunas. Thanks very much Viadas!



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201259 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 14 insertions, 0 deletions

diff --git a/include/llvm/ExecutionEngine/RTDyldMemoryManager.h b/include/llvm/ExecutionEngine/RTDyldMemoryManager.h
index 38a7606cde..70dd1cbe71 100644
--- a/include/llvm/ExecutionEngine/RTDyldMemoryManager.h
+++ b/include/llvm/ExecutionEngine/RTDyldMemoryManager.h
@@ -52,6 +52,20 @@ public:
     uintptr_t Size, unsigned Alignment, unsigned SectionID,
     StringRef SectionName, bool IsReadOnly) = 0;
 
+  /// Inform the memory manager about the total amount of memory required to
+  /// allocate all sections to be loaded:
+  /// \p CodeSize - the total size of all code sections
+  /// \p DataSizeRO - the total size of all read-only data sections
+  /// \p DataSizeRW - the total size of all read-write data sections
+  /// 
+  /// Note that by default the callback is disabled. To enable it
+  /// redefine the method needsToReserveAllocationSpace to return true.
+  virtual void reserveAllocationSpace(
+    uintptr_t CodeSize, uintptr_t DataSizeRO, uintptr_t DataSizeRW) { }
+  
+  /// Override to return true to enable the reserveAllocationSpace callback.
+  virtual bool needsToReserveAllocationSpace() { return false; }
+
   /// Register the EH frames with the runtime so that c++ exceptions work.
   ///
   /// \p Addr parameter provides the local address of the EH frame section