[test] Test __attribute__((noreturn)), _Noreturn, and [[return]] with conditional operator

Author: MaskRay

clang/test/CodeGen/attr-noreturn.c

@@ -1,4 +1,5 @@
-// RUN: %clang_cc1 -S -emit-llvm %s -o - | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm -std=c2x %s -o - | FileCheck %s
+// RUN: %clang_cc1 -triple %itanium_abi_triple -x c++ -emit-llvm %s -o - | FileCheck %s --check-prefix=CHECK-CXX
 
 typedef void (*fptrs_t[4])(void);
 fptrs_t p __attribute__((noreturn));
@@ -8,3 +9,47 @@ void __attribute__((noreturn)) f(void) {
 }
 // CHECK: call void
 // CHECK-NEXT: unreachable
+
+// CHECK-LABEL: @test_conditional_gnu(
+// CHECK:         %cond = select i1 %tobool, ptr @t1, ptr @t2
+// CHECK:         call void %cond(
+// CHECK-NEXT:    unreachable
+
+// CHECK-CXX-LABEL: @_Z20test_conditional_gnui(
+// CHECK-CXX:         %cond{{.*}} = phi ptr [ @_Z2t1i, %{{.*}} ], [ @_Z2t2i, %{{.*}} ]
+// CHECK-CXX:         call void %cond{{.*}}(
+// CHECK-CXX:         %cond{{.*}} = phi ptr [ @_Z2t1i, %{{.*}} ], [ @_Z2t1i, %{{.*}} ]
+// CHECK-CXX:         call void %cond{{.*}}(
+// CHECK-CXX-NEXT:    unreachable
+void t1(int) __attribute__((noreturn));
+void t2(int);
+__attribute__((noreturn)) void test_conditional_gnu(int a) {
+  // The conditional operator isn't noreturn because t2 isn't.
+  (a ? t1 : t2)(a);
+  // The conditional operator is noreturn.
+  (a ? t1 : t1)(a);
+}
+
+// CHECK-LABEL: @test_conditional_Noreturn(
+// CHECK:         %cond = select i1 %tobool, ptr @t3, ptr @t2
+// CHECK:         call void %cond(
+// CHECK:         %cond2 = select i1 %tobool1, ptr @t3, ptr @t3
+// CHECK:         call void %cond2(
+// CHECK-NEXT:    ret void
+_Noreturn void t3(int);
+_Noreturn void test_conditional_Noreturn(int a) {
+  (a ? t3 : t2)(a);
+  (a ? t3 : t3)(a);
+}
+
+// CHECK-LABEL: @test_conditional_std(
+// CHECK:         %cond = select i1 %tobool, ptr @t4, ptr @t2
+// CHECK:         call void %cond(
+// CHECK:         %cond2 = select i1 %tobool1, ptr @t4, ptr @t4
+// CHECK:         call void %cond2(
+// CHECK-NEXT:    ret void
+[[noreturn]] void t4(int);
+[[noreturn]] void test_conditional_std(int a) {
+  (a ? t4 : t2)(a);
+  (a ? t4 : t4)(a);
+}