[OPENMP] Codegen for local variables with the allocate pragma.

Added initial codegen for the local variables with the #pragma omp
allocate directive. Instead of allocating the variables on the stack,
__kmpc_alloc|__kmpc_free functions are used for memory (de-)allocation.

llvm-svn: 356472
diff --git a/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp b/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp
index ba23c49..d35f56e 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp
+++ b/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp
@@ -4746,6 +4746,9 @@
         return VDI->second.PrivateAddr;
     }
   }
+  // TODO: replace it with return
+  // CGOpenMPRuntime::getAddressOfLocalVariable(CGF, VD); when NVPTX libomp
+  // supports __kmpc_alloc|__kmpc_free.
   return Address::invalid();
 }