[CUDA] Rename CheckCUDATarget to IsAllowedCUDACall. NFC

[jlebar]

Summary

I want to reuse "CheckCUDAFoo" in a later patch. Also, I think
IsAllowedCUDACall gets the point across more clearly.

[tra]

LGTM.

clang/include/clang/Sema/Sema.h

   ///               nullptr in case of global context.
   /// \param Callee target function
   ///
   /// \returns preference value for particular Caller/Callee combination.
   CUDAFunctionPreference IdentifyCUDAPreference(const FunctionDecl *Caller,
                                                 const FunctionDecl *Callee);
 
   /// Determines whether Caller may invoke Callee, based on their CUDA
-  /// host/device attributes.  Returns true if the call is not allowed.
-  bool CheckCUDATarget(const FunctionDecl *Caller, const FunctionDecl *Callee) {
-    return IdentifyCUDAPreference(Caller, Callee) == CFP_Never;
+  /// host/device attributes.  Returns false if the call is not allowed.
+  ///
+  /// Note: Will return true for CFP_WrongSide calls.  These may appear in
+  /// semantically correct CUDA programs, but only if they're never codegen'ed.
+  bool IsAllowedCUDACall(const FunctionDecl *Caller,
+                         const FunctionDecl *Callee) {
+    return IdentifyCUDAPreference(Caller, Callee) != CFP_Never;
   }
 
   /// May add implicit CUDAHostAttr and CUDADeviceAttr attributes to FD,
   /// depending on FD and the current compilation settings.
   void maybeAddCUDAHostDeviceAttrs(Scope *S, FunctionDecl *FD,
                                    const LookupResult &Previous);
 
   /// Finds a function in \p Matches with highest calling priority

clang/lib/Sema/SemaExpr.cpp

 ExprResult
 Sema::BuildDeclRefExpr(ValueDecl *D, QualType Ty, ExprValueKind VK,
                        const DeclarationNameInfo &NameInfo,
                        const CXXScopeSpec *SS, NamedDecl *FoundD,
                        const TemplateArgumentListInfo *TemplateArgs) {
   if (getLangOpts().CUDA)
     if (const FunctionDecl *Caller = dyn_cast<FunctionDecl>(CurContext))
       if (const FunctionDecl *Callee = dyn_cast<FunctionDecl>(D)) {
-        if (CheckCUDATarget(Caller, Callee)) {
+        if (!IsAllowedCUDACall(Caller, Callee)) {
           Diag(NameInfo.getLoc(), diag::err_ref_bad_target)
             << IdentifyCUDATarget(Callee) << D->getIdentifier()
             << IdentifyCUDATarget(Caller);
           Diag(D->getLocation(), diag::note_previous_decl)
             << D->getIdentifier();
           return ExprError();
         }
       }

clang/lib/Sema/SemaOverload.cpp

Sema::AddOverloadCandidate(FunctionDecl *Function,
 
   // (CUDA B.1): Check for invalid calls between targets.
   if (getLangOpts().CUDA)
     if (const FunctionDecl *Caller = dyn_cast<FunctionDecl>(CurContext))
       // Skip the check for callers that are implicit members, because in this
       // case we may not yet know what the member's target is; the target is
       // inferred for the member automatically, based on the bases and fields of
       // the class.
-      if (!Caller->isImplicit() && CheckCUDATarget(Caller, Function)) {
+      if (!Caller->isImplicit() && !IsAllowedCUDACall(Caller, Function)) {
         Candidate.Viable = false;
         Candidate.FailureKind = ovl_fail_bad_target;
         return;
       }
 
   // Determine the implicit conversion sequences for each of the
   // arguments.
   for (unsigned ArgIdx = 0; ArgIdx < Args.size(); ++ArgIdx) {
if (Candidate.Conversions[0].isBad()) {
       Candidate.FailureKind = ovl_fail_bad_conversion;
       return;
     }
   }
 
   // (CUDA B.1): Check for invalid calls between targets.
   if (getLangOpts().CUDA)
     if (const FunctionDecl *Caller = dyn_cast<FunctionDecl>(CurContext))
-      if (CheckCUDATarget(Caller, Method)) {
+      if (!IsAllowedCUDACall(Caller, Method)) {
         Candidate.Viable = false;
         Candidate.FailureKind = ovl_fail_bad_target;
         return;
       }
 
   // Determine the implicit conversion sequences for each of the
   // arguments.
   for (unsigned ArgIdx = 0; ArgIdx < Args.size(); ++ArgIdx) {
if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Fn)) {
         return false;
     } 
     else if (TargetTypeIsNonStaticMemberFunction)
       return false;
 
     if (FunctionDecl *FunDecl = dyn_cast<FunctionDecl>(Fn)) {
       if (S.getLangOpts().CUDA)
         if (FunctionDecl *Caller = dyn_cast<FunctionDecl>(S.CurContext))
-          if (!Caller->isImplicit() && S.CheckCUDATarget(Caller, FunDecl))
+          if (!Caller->isImplicit() && !S.IsAllowedCUDACall(Caller, FunDecl))
             return false;
 
       // If any candidate has a placeholder return type, trigger its deduction
       // now.
       if (S.getLangOpts().CPlusPlus14 &&
           FunDecl->getReturnType()->isUndeducedType() &&
           S.DeduceReturnType(FunDecl, SourceExpr->getLocStart(), Complain)) {
         HasComplained |= Complain;
Sema::BuildCallToMemberFunction(Scope *S, Expr *MemExprE,
   assert(Method && "Member call to something that isn't a method?");
   CXXMemberCallExpr *TheCall =
     new (Context) CXXMemberCallExpr(Context, MemExprE, Args,
                                     ResultType, VK, RParenLoc);
 
   // (CUDA B.1): Check for invalid calls between targets.
   if (getLangOpts().CUDA) {
     if (const FunctionDecl *Caller = dyn_cast<FunctionDecl>(CurContext)) {
-      if (CheckCUDATarget(Caller, Method)) {
+      if (!IsAllowedCUDACall(Caller, Method)) {
         Diag(MemExpr->getMemberLoc(), diag::err_ref_bad_target)
             << IdentifyCUDATarget(Method) << Method->getIdentifier()
             << IdentifyCUDATarget(Caller);
         return ExprError();
       }
     }
   }