clang/test/CodeGenCXX/builtin-constant-p.cpp

   1 // RUN: %clang_cc1 -triple=x86_64-linux-gnu -emit-llvm -o - %s | FileCheck %s
   2
   3 // Don't crash if the argument to __builtin_constant_p isn't scalar.
   4 template <typename T>
   5 constexpr bool is_constant(const T v) {
   6   return __builtin_constant_p(v);
   7 }
   8
   9 template <typename T>
  10 class numeric {
  11  public:
  12   using type = T;
  13
  14   template <typename S>
  15   constexpr numeric(S value)
  16       : value_(static_cast<T>(value)) {}
  17
  18  private:
  19   const T value_;
  20 };
  21
  22 bool bcp() {
  23   return is_constant(numeric<int>(1));
  24 }
  25
  26 // PR45535
  27 struct with_dtor {
  28   ~with_dtor();
  29 };
  30 // CHECK: define {{.*}}bcp_stmt_expr_1
  31 bool bcp_stmt_expr_1() {
  32   // CHECK-NOT: call {{.*}}with_dtorD
  33   return __builtin_constant_p(({with_dtor wd; 123;}));
  34 }
  35
  36 int do_not_call();
  37 // CHECK: define {{.*}}bcp_stmt_expr_2
  38 bool bcp_stmt_expr_2(int n) {
  39   // CHECK-NOT: call {{.*}}do_not_call
  40   return __builtin_constant_p(({
  41     // This has a side-effect due to the VLA bound, so CodeGen should fold it
  42     // to false.
  43     typedef int arr[do_not_call()];
  44     n;
  45   }));
  46   // CHECK-NOT: }
  47   // CHECK: ret i1 false
  48 }