[OpenCL] Allow zero assignment and comparisons between queue_t type variables

This change allows for zero assignment and comparison of queue_t
type variables, and extends null_queue.cl to test this.

Patch by Alistair Davies.

Differential Revision: https://reviews.llvm.org/D51727


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@342968 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Sema/SemaExpr.cpp

@@ -8086,6 +8086,13 @@ Sema::CheckSingleAssignmentConstraints(QualType LHSType, ExprResult &CallerRHS,
     return Compatible;
   }
 
+  // OpenCL queue_t type assignment.
+  if (LHSType->isQueueT() && RHS.get()->isNullPointerConstant(
+                                 Context, Expr::NPC_ValueDependentIsNull)) {
+    RHS = ImpCastExprToType(RHS.get(), LHSType, CK_NullToPointer);
+    return Compatible;
+  }
+
   // This check seems unnatural, however it is necessary to ensure the proper
   // conversion of functions/arrays. If the conversion were done for all
   // DeclExpr's (created by ActOnIdExpression), it would mess up the unary
@@ -10423,6 +10430,10 @@ QualType Sema::CheckCompareOperands(ExprResult &LHS, ExprResult &RHS,
   }
 
   if (getLangOpts().OpenCLVersion >= 200) {
+    if (LHSType->isQueueT() && RHSType->isQueueT()) {
+      return computeResultTy();
+    }
+
     if (LHSIsNull && RHSType->isQueueT()) {
       LHS = ImpCastExprToType(LHS.get(), RHSType, CK_NullToPointer);
       return computeResultTy();

test/SemaOpenCL/null_queue.cl

@@ -1,12 +1,30 @@
 // RUN: %clang_cc1 %s -cl-std=CL2.0 -verify -pedantic -fsyntax-only
 extern queue_t get_default_queue();
 
-bool compare() {
-  return 1 == get_default_queue() && // expected-error{{invalid operands to binary expression ('int' and 'queue_t')}}
-         get_default_queue() == 1; // expected-error{{invalid operands to binary expression ('queue_t' and 'int')}}
-}
+void queue_arg(queue_t); // expected-note {{passing argument to parameter here}}
 
 void init() {
   queue_t q1 = 1; // expected-error{{initializing 'queue_t' with an expression of incompatible type 'int'}}
   queue_t q = 0;
 }
+
+void assign() {
+  queue_t q2, q3;
+  q2 = 5; // expected-error{{assigning to 'queue_t' from incompatible type 'int'}}
+  q3 = 0;
+  q2 = q3 = 0;
+}
+
+bool compare() {
+  queue_t q4, q5;
+  return 1 == get_default_queue() && // expected-error{{invalid operands to binary expression ('int' and 'queue_t')}}
+         get_default_queue() == 1 && // expected-error{{invalid operands to binary expression ('queue_t' and 'int')}}
+	     q4 == q5 &&
+	     q4 != 0 &&
+	     q4 != 0.0f; // expected-error{{invalid operands to binary expression ('queue_t' and 'float')}}
+}
+
+void call() {
+  queue_arg(5); // expected-error {{passing 'int' to parameter of incompatible type 'queue_t'}}
+  queue_arg(0);
+}