The HSA Foundation together with AMD and Microsoft recently announced an open source C++ AMP compiler implementation they have been working on, using the Clang/LLVM C++ compiler as a base but currently separate from Clang/LLVM. The implementation targets OpenCL, HSAIL, and SPIR 1.2 on Linux and other non-Windows platforms. When the work is finished, the intention is to approach the LLVM community to offer this work as a contribution back to the official Clang/LLVM code base if there is interest.
C++ AMP is an open specification from Microsoft that enables STL-like C++ extensions for massively parallel computation using GPUs and vector units, and is part of the basis for the Parallel STL proposal now under consideration for standardized parallel computations on multicore and vector hardware.
AMD released on Nov 12, 2013 a fully open sourced C++ AMP compiler based on CLANG/LLVM with outputs to OpenCL and Khronos Group SPIR 1.2 initially. This compiler will have HSAIL support in early 2014 for HSA platforms. This initial focus is bring about Linux support for C++AMP, complete with GPU acceleration. AMD is also bringing their BOLT Standard Template library over to be qualified with this tool chain.
Microsoft is engaged with AMD and MultiCoreWare, by providing design and validation inputs to help drive the success of this project.