[OpenMP 6.0] Allow only byref arguments with need_device_addr modifier on adjust_args clause

If the `need_device_addr` adjust-op modifier is present, each list item
that appears in the clause must refer to an argument in the declaration of
the function variant that has a reference type.

Reference:
OpenMP 6.0 [Sec 9.6.2, page 332, line 31-33, adjust_args clause, Restrictions]

Author: mdfazlay

clang/include/clang/Basic/DiagnosticParseKinds.td

@@ -1594,6 +1594,9 @@ def err_omp_unknown_adjust_args_op
 def err_omp_declare_variant_wrong_clause : Error<
   "expected %select{'match'|'match', 'adjust_args', or 'append_args'}0 clause "
   "on 'omp declare variant' directive">;
+def err_omp_non_by_ref_need_device_addr_modifier_argument
+         : Error<"expected reference type argument on 'adjust_args' clause with "
+                 "'need_device_addr' modifier">;
 def err_omp_declare_variant_duplicate_nested_trait : Error<
   "nested OpenMP context selector contains duplicated trait '%0'"
   " in selector '%1' and set '%2' with different score">;

clang/lib/Sema/SemaOpenMP.cpp

@@ -7612,6 +7612,21 @@ void SemaOpenMP::ActOnOpenMPDeclareVariantDirective(
     return;
   }
 
+  // OpenMP 6.0 [9.6.2 (page 332, line 31-33, adjust_args clause, Restrictions]
+  // If the `need_device_addr` adjust-op modifier is present, each list item
+  // that appears in the clause must refer to an argument in the declaration of
+  // the function variant that has a reference type
+  for (Expr *E : AdjustArgsNeedDeviceAddr) {
+    E = E->IgnoreParenImpCasts();
+    if (const auto *DRE = dyn_cast<DeclRefExpr>(E)) {
+      if (const auto *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
+        if (!VD->getType()->isReferenceType())
+          Diag(E->getExprLoc(),
+               diag::err_omp_non_by_ref_need_device_addr_modifier_argument);
+      }
+    }
+  }
+
   auto *NewAttr = OMPDeclareVariantAttr::CreateImplicit(
       getASTContext(), VariantRef, &TI,
       const_cast<Expr **>(AdjustArgsNothing.data()), AdjustArgsNothing.size(),

clang/test/OpenMP/declare_variant_clauses_ast_print.cpp

@@ -38,11 +38,11 @@
 #ifndef HEADER
 #define HEADER
 
-void foo_v1(float *AAA, float *BBB, int *I) {return;}
-void foo_v2(float *AAA, float *BBB, int *I) {return;}
-void foo_v3(float *AAA, float *BBB, int *I) {return;}
+void foo_v1(float *AAA, float *BBB, int &CCC, int *I) {return;}
+void foo_v2(float *AAA, float *BBB, int &CCC, int *I) {return;}
+void foo_v3(float *AAA, float *BBB, int &CCC, int *I) {return;}
 
-//DUMP: FunctionDecl{{.*}} foo 'void (float *, float *, int *)'
+//DUMP: FunctionDecl{{.*}} foo 'void (float *, float *, int &, int *)'
 //DUMP: OMPDeclareVariantAttr{{.*}}device={arch(x86, x86_64)}
 //DUMP: DeclRefExpr{{.*}}Function{{.*}}foo_v3
 //DUMP: DeclRefExpr{{.*}}ParmVar{{.*}}'I'
@@ -54,9 +54,9 @@ void foo_v3(float *AAA, float *BBB, int *I) {return;}
 //DUMP: DeclRefExpr{{.*}}Function{{.*}}foo_v1
 //DUMP: DeclRefExpr{{.*}}ParmVar{{.*}}'AAA'
 //DUMP: DeclRefExpr{{.*}}ParmVar{{.*}}'BBB'
-//PRINT: #pragma omp declare variant(foo_v3) match(construct={dispatch}, device={arch(x86, x86_64)}) adjust_args(nothing:I) adjust_args(need_device_ptr:BBB) adjust_args(need_device_addr:AAA)
+//PRINT: #pragma omp declare variant(foo_v3) match(construct={dispatch}, device={arch(x86, x86_64)}) adjust_args(nothing:I) adjust_args(need_device_ptr:BBB) adjust_args(need_device_addr:CCC)
 
-//PRINT: #pragma omp declare variant(foo_v2) match(construct={dispatch}, device={arch(ppc)}) adjust_args(need_device_ptr:AAA) adjust_args(need_device_addr:BBB)
+//PRINT: #pragma omp declare variant(foo_v2) match(construct={dispatch}, device={arch(ppc)}) adjust_args(need_device_ptr:AAA) adjust_args(need_device_addr:CCC)
 
 //PRINT: omp declare variant(foo_v1) match(construct={dispatch}, device={arch(arm)}) adjust_args(need_device_ptr:AAA,BBB)
 
@@ -67,33 +67,33 @@ void foo_v3(float *AAA, float *BBB, int *I) {return;}
 #pragma omp declare variant(foo_v2)                        \
    match(construct={dispatch}, device={arch(ppc)}),        \
    adjust_args(need_device_ptr:AAA)                        \
-   adjust_args(need_device_addr:BBB)
+   adjust_args(need_device_addr:CCC)
 
 #pragma omp declare variant(foo_v3)                        \
    adjust_args(need_device_ptr:BBB) adjust_args(nothing:I) \
-   adjust_args(need_device_addr:AAA)                      \
+   adjust_args(need_device_addr:CCC)                       \
    match(construct={dispatch}, device={arch(x86,x86_64)})
 
-void foo(float *AAA, float *BBB, int *I) {return;}
+void foo(float *AAA, float *BBB, int &CCC, int *I) {return;}
 
-void Foo_Var(float *AAA, float *BBB, float *CCC) {return;}
+void Foo_Var(float *AAA, float *BBB, float *&CCC) {return;}
 
 #pragma omp declare variant(Foo_Var) \
    match(construct={dispatch}, device={arch(x86_64)}) \
    adjust_args(need_device_ptr:AAA) adjust_args(nothing:BBB) \
    adjust_args(need_device_addr:CCC)
 template<typename T>
-void Foo(T *AAA, T *BBB, T *CCC) {return;}
+void Foo(T *AAA, T *BBB, T *&CCC) {return;}
 
 //PRINT: #pragma omp declare variant(Foo_Var) match(construct={dispatch}, device={arch(x86_64)}) adjust_args(nothing:BBB) adjust_args(need_device_ptr:AAA) adjust_args(need_device_addr:CCC)
-//DUMP: FunctionDecl{{.*}} Foo 'void (T *, T *, T *)'
+//DUMP: FunctionDecl{{.*}} Foo 'void (T *, T *, T *&)'
 //DUMP: OMPDeclareVariantAttr{{.*}}device={arch(x86_64)}
 //DUMP: DeclRefExpr{{.*}}Function{{.*}}Foo_Var
 //DUMP: DeclRefExpr{{.*}}ParmVar{{.*}}'BBB'
 //DUMP: DeclRefExpr{{.*}}ParmVar{{.*}}'AAA'
 //DUMP: DeclRefExpr{{.*}}ParmVar{{.*}}'CCC'
 //
-//DUMP: FunctionDecl{{.*}} Foo 'void (float *, float *, float *)'
+//DUMP: FunctionDecl{{.*}} Foo 'void (float *, float *, float *&)'
 //DUMP: OMPDeclareVariantAttr{{.*}}device={arch(x86_64)}
 //DUMP: DeclRefExpr{{.*}}Function{{.*}}Foo_Var
 //DUMP: DeclRefExpr{{.*}}ParmVar{{.*}}'BBB'

clang/test/OpenMP/declare_variant_clauses_messages.cpp

@@ -91,6 +91,7 @@ void foo_v1(float *AAA, float *BBB, int *I) { return; }
 void foo_v2(float *AAA, float *BBB, int *I) { return; }
 void foo_v3(float *AAA, float *BBB, int *I) { return; }
 void foo_v4(float *AAA, float *BBB, int *I, omp_interop_t IOp) { return; }
+void foo_v5(float *AAA, float *BBB, int I) { return; }
 
 #if _OPENMP >= 202011 // At least OpenMP 5.1
 void vararg_foo(const char *fmt, omp_interop_t it, ...);
@@ -129,6 +130,11 @@ void vararg_bar2(const char *fmt) { return; }
    adjust_args(nothing:J)                                    \
    match(construct={dispatch}, device={arch(x86,x86_64)})
 
+// expected-error@+2 {{expected reference type argument on 'adjust_args' clause with 'need_device_addr' modifier}}
+#pragma omp declare variant(foo_v1)                          \
+   adjust_args(need_device_addr:AAA)                         \
+   match(construct={dispatch}, device={arch(x86,x86_64)})
+
 // expected-error@+2 {{expected reference to one of the parameters of function 'foo'}}
 #pragma omp declare variant(foo_v3)                          \
    adjust_args(nothing:Other)                                \
@@ -218,6 +224,12 @@ void vararg_bar2(const char *fmt) { return; }
 
 void foo(float *AAA, float *BBB, int *I) { return; }
 
+// expected-error@+2 {{expected reference type argument on 'adjust_args' clause with 'need_device_addr' modifier}}
+#pragma omp declare variant(foo_v5)                          \
+   adjust_args(need_device_addr:I)                         \
+   match(construct={dispatch}, device={arch(x86,x86_64)})
+void foo5(float *AAA, float *BBB, int I) { return; }
+
 #endif // NO_INTEROP_T_DEF
 
 #ifdef C