CodeGen: Fix address space of global variable

Certain targets (e.g. amdgcn) require global variable to stay in global or constant address
space. In C or C++ global variables are emitted in the default (generic) address space.
This patch introduces virtual functions TargetCodeGenInfo::getGlobalVarAddressSpace
and TargetInfo::getConstantAddressSpace to handle this in a general approach.

It only affects IR generated for amdgcn target.

Differential Revision: https://reviews.llvm.org/D33842


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@307470 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 0 deletions

diff --git a/include/clang/Basic/TargetInfo.h b/include/clang/Basic/TargetInfo.h
index 9bdb288eef..5885532b91 100644
--- a/include/clang/Basic/TargetInfo.h
+++ b/include/clang/Basic/TargetInfo.h
@@ -23,6 +23,7 @@
 #include "clang/Basic/VersionTuple.h"
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/IntrusiveRefCntPtr.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
@@ -954,6 +955,14 @@ public:
     return *AddrSpaceMap;
   }
 
+  /// \brief Return an AST address space which can be used opportunistically
+  /// for constant global memory. It must be possible to convert pointers into
+  /// this address space to LangAS::Default. If no such address space exists,
+  /// this may return None, and such optimizations will be disabled.
+  virtual llvm::Optional<unsigned> getConstantAddressSpace() const {
+    return LangAS::Default;
+  }
+
   /// \brief Retrieve the name of the platform as it is used in the
   /// availability attribute.
   StringRef getPlatformName() const { return PlatformName; }