[llvm-commits] CVS: llvm/include/llvm/System/Memory.h

[Chris Lattner]

On Fri, 29 Jul 2005, Reid Spencer wrote:
>> support near allocations for the JIT
>>        /// This method allocates a block of Read/Write/Execute memory that is
>>        /// suitable for executing dynamically generated code (e.g. JIT). An
>>        /// attempt to allocate \p NumBytes bytes of virtual memory is made.
>> +      /// \p NearBlock may point to an existing allocation in which case
>> +      /// an attempt is made to allocate more memory near the existing block.
>>        /// @throws std::string if an error occurred.
>>        /// @brief Allocate Read/Write/Execute memory.
>> -      static MemoryBlock AllocateRWX(unsigned NumBytes);
>> +      static MemoryBlock AllocateRWX(unsigned NumBytes, const MemoryBlock* NearBlock);
>
> What if one does NOT want to allocate something near another block?
> Shouldn't the second argument be initialized to zero in order to retain
> the existing API? A zero value would indicate that the "NearBlock"
> constraint should be ignored and the function is permitted to allocate
> memory anywhere available. Furthermore, this needs to be "hint" as is
> done with the mmap(2) system call.

The implementation already does this (treats it as a hint, and ignores the 
argument if it's not 0).  If you want, it would be easy to make the second 
argument default to zero if not specified.

-Chris

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