Add document README.md

Change-Id: Ib186c1b55663e397b562ec53fca2d476de0c96b3

rocclr/README.md

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+# ROCclr - Radeon Open Compute Common Language Runtime
+ROCclr is a virtual device interface that compute runtimes interact with to different backends such as ROCr or PAL
+This abstraction allows runtimes to work on Windows as well as on Linux without much effort.
+
+## Repository branches
+The repository maintains several branches. The branches that are of importance are:
+
+-   master: This is the default branch.
+
+## Building
+
+### Prerequisites
+
+-   Install mesa-common-dev
+-   Either build or install [COMGR](https://github.com/RadeonOpenCompute/ROCm-CompilerSupport), [CLANG](https://github.com/RadeonOpenCompute/llvm-project) and [Device Library](https://github.com/RadeonOpenCompute/ROCm-Device-Libs)
+
+### Getting the source code
+
+```bash
+git clone https://github.com/ROCm-Developer-Tools/ROCclr.git
+git clone -b master-next https://github.com/RadeonOpenCompute/ROCm-OpenCL-Runtime.git
+```
+
+### Set the environment variables
+
+```bash
+export ROCclr_DIR="$(readlink -f ROCclr)"
+export OPENCL_DIR="$(readlink -f ROCm-OpenCL-Runtime)"
+```
+
+### Build ROCclr
+Here is command to build ROCclr:
+
+```bash
+cd "$ROCclr_DIR"
+mkdir -p build; cd build
+cmake -DOPENCL_DIR="$OPENCL_DIR" -DCMAKE_INSTALL_PREFIX=/opt/rocm/rocclr ..
+make -j$(nproc)
+```
+
+### Optional steps to build HIP runtime
+Enter the directory where git cloned the ROCClr and OpenCL. Run the following commands:
+
+```bash
+git clone -b master-next https://github.com/ROCm-Developer-Tools/HIP.git
+export HIP_DIR="$(readlink -f HIP)"
+cd "$HIP_DIR"
+mkdir -p build; cd build
+cmake -DHIP_COMPILER=clang -DHIP_PLATFORM=rocclr -DCMAKE_PREFIX_PATH="$ROCclr_DIR/build" ..
+make -j$(nproc)
+```
+
+### Release build
+For release build, add "-DCMAKE_BUILD_TYPE=Release" to the cmake command line.