[OpenCL] Add global_device and global_host address spaces

This patch introduces 2 new address spaces in OpenCL: global_device and global_host
which are a subset of a global address space, so the address space scheme will be
looking like:

```
generic->global->host
                          ->device
             ->private
             ->local
constant
```

Justification: USM allocations may be associated with both host and device memory. We
want to give users a way to tell the compiler the allocation type of a USM pointer for
optimization purposes. (Link to the Unified Shared Memory extension:
https://github.com/intel/llvm/blob/sycl/sycl/doc/extensions/USM/cl_intel_unified_shared_memory.asciidoc)

Before this patch USM pointer could be only in opencl_global
address space, hence a device backend can't tell if a particular pointer
points to host or device memory. On FPGAs at least we can generate more
efficient hardware code if the user tells us where the pointer can point -
being able to distinguish between these types of pointers at compile time
allows us to instantiate simpler load-store units to perform memory
transactions.

Patch by Dmitry Sidorov.

Reviewed By: Anastasia

Differential Revision: https://reviews.llvm.org/D82174

1 files changed, 14 insertions, 4 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 4c79252..48a1ddd 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1324,10 +1324,18 @@ static void removeImageAccessQualifier(std::string& TyName) {
 // (basically all single AS CPUs).
 static unsigned ArgInfoAddressSpace(LangAS AS) {
   switch (AS) {
-  case LangAS::opencl_global:   return 1;
-  case LangAS::opencl_constant: return 2;
-  case LangAS::opencl_local:    return 3;
-  case LangAS::opencl_generic:  return 4; // Not in SPIR 2.0 specs.
+  case LangAS::opencl_global:
+    return 1;
+  case LangAS::opencl_constant:
+    return 2;
+  case LangAS::opencl_local:
+    return 3;
+  case LangAS::opencl_generic:
+    return 4; // Not in SPIR 2.0 specs.
+  case LangAS::opencl_global_device:
+    return 5;
+  case LangAS::opencl_global_host:
+    return 6;
   default:
     return 0; // Assume private.
   }
@@ -3792,6 +3800,8 @@ LangAS CodeGenModule::GetGlobalVarAddressSpace(const VarDecl *D) {
   if (LangOpts.OpenCL) {
     AddrSpace = D ? D->getType().getAddressSpace() : LangAS::opencl_global;
     assert(AddrSpace == LangAS::opencl_global ||
+           AddrSpace == LangAS::opencl_global_device ||
+           AddrSpace == LangAS::opencl_global_host ||
            AddrSpace == LangAS::opencl_constant ||
            AddrSpace == LangAS::opencl_local ||
            AddrSpace >= LangAS::FirstTargetAddressSpace);