[OpenCL] Add LangAS::opencl_private to represent private address space in AST

Currently Clang uses default address space (0) to represent private address space for OpenCL
in AST. There are two issues with this:

Multiple address spaces including private address space cannot be diagnosed.
There is no mangling for default address space. For example, if private int* is emitted as
i32 addrspace(5)* in IR. It is supposed to be mangled as PUAS5i but it is mangled as
Pi instead.

This patch attempts to represent OpenCL private address space explicitly in AST. It adds
a new enum LangAS::opencl_private and adds it to the variable types which are implicitly
private:

automatic variables without address space qualifier

function parameter

pointee type without address space qualifier (OpenCL 1.2 and below)

Differential Revision: https://reviews.llvm.org/D35082

llvm-svn: 315668

1 files changed, 14 insertions, 14 deletions

diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 9181176bbd9..e8aa8f3d33d 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -3293,20 +3293,20 @@ Expr::isNullPointerConstant(ASTContext &Ctx,
       // Check that it is a cast to void*.
       if (const PointerType *PT = CE->getType()->getAs<PointerType>()) {
         QualType Pointee = PT->getPointeeType();
-        Qualifiers Q = Pointee.getQualifiers();
-        // In OpenCL v2.0 generic address space acts as a placeholder
-        // and should be ignored.
-        bool IsASValid = true;
-        if (Ctx.getLangOpts().OpenCLVersion >= 200) {
-          if (Pointee.getAddressSpace() == LangAS::opencl_generic)
-            Q.removeAddressSpace();
-          else
-            IsASValid = false;
-        }
-
-        if (IsASValid && !Q.hasQualifiers() &&
-            Pointee->isVoidType() &&                      // to void*
-            CE->getSubExpr()->getType()->isIntegerType()) // from int.
+        // Only (void*)0 or equivalent are treated as nullptr. If pointee type
+        // has non-default address space it is not treated as nullptr.
+        // (__generic void*)0 in OpenCL 2.0 should not be treated as nullptr
+        // since it cannot be assigned to a pointer to constant address space.
+        bool PointeeHasDefaultAS =
+            Pointee.getAddressSpace() == LangAS::Default ||
+            (Ctx.getLangOpts().OpenCLVersion >= 200 &&
+             Pointee.getAddressSpace() == LangAS::opencl_generic) ||
+            (Ctx.getLangOpts().OpenCL &&
+             Ctx.getLangOpts().OpenCLVersion < 200 &&
+             Pointee.getAddressSpace() == LangAS::opencl_private);
+
+        if (PointeeHasDefaultAS && Pointee->isVoidType() && // to void*
+            CE->getSubExpr()->getType()->isIntegerType())   // from int.
           return CE->getSubExpr()->isNullPointerConstant(Ctx, NPC);
       }
     }