gcc/testsuite/g++.dg/opt/temp1.C

   1 // PR c++/16405
   2 // { dg-options "-O2" }
   3 // { dg-do run }
   4
   5 // There should be exactly one temporary generated for the code in "f"
   6 // below when optimizing -- for the result of "b + c".  We have no
   7 // easy way of checking that directly, so we count the number of calls
   8 // to "memcpy", which is used on (some?) targets to copy temporaries.
   9 // If there is more than two calls (one for coping "*this" to "t", and
  10 // one for copying the temporary to "a"), then there are too many
  11 // temporaries.
  12
  13 int i;
  14
  15 extern "C"
  16 void *memcpy (void *dest, const void *src, __SIZE_TYPE__ n)
  17 {
  18   ++i;
  19 }
  20
  21 struct T {
  22   int a[128];
  23   T &operator+=(T const &v) __attribute__((noinline));
  24   T operator+(T const &v) const { T t = *this; t += v; return t; }
  25 };
  26
  27 T &T::operator+=(T const &v) {
  28   return *this;
  29 }
  30
  31 T a, b, c;
  32
  33 void f() { a = b + c; }
  34
  35 int main () {
  36   i = 0;
  37   f();
  38   if (i > 2)
  39     return 1;
  40 }