[clang] [Clang][OpenCL] Mark scalar loads from constant address space invariant (PR #218356)

[Matt Arsenault via cfe-commits]

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@@ -3500,10 +3503,14 @@ static LValue EmitGlobalVarDeclLValue(CodeGenFunction &CGF,
     return EmitThreadPrivateVarDeclLValue(CGF, VD, T, Addr, RealVarTy,
                                           E->getExprLoc());
   }
-  LValue LV = VD->getType()->isReferenceType() ?
-      CGF.EmitLoadOfReferenceLValue(Addr, VD->getType(),
-                                    AlignmentSource::Decl) :
-      CGF.MakeAddrLValue(Addr, T, AlignmentSource::Decl);
+  const bool IsReference = VD->getType()->isReferenceType();
+  LValue LV = IsReference ? CGF.EmitLoadOfReferenceLValue(Addr, VD->getType(),
+                                                          AlignmentSource::Decl)
+                          : CGF.MakeAddrLValue(Addr, T, AlignmentSource::Decl);
+  // Preserve CUDA constant storage information from the AST declaration.
+  if (!IsReference && CGF.getLangOpts().CUDAIsDevice &&
+      CGF.CGM.GetGlobalVarAddressSpace(VD) == LangAS::cuda_constant)
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arsenm wrote:

Special casing an address space, there should be some predicate function that tells you the global is invariant, not spread the language and address space check here 

https://github.com/llvm/llvm-project/pull/218356