gnu / gcc / 1f16a020acbea0af26209478990b83b1a1ba3a2b / . / gcc / testsuite / gcc.dg / tree-ssa / pr19210-1.c

/* { dg-do compile } */ | |

/* { dg-options "-O2 -fno-tree-vectorize -fopt-info-loop-missed" } */ | |

extern void g(void); | |

void | |

f (unsigned n) | |

{ | |

unsigned k; | |

for(k = 0;k <= n;k++) /* { dg-missed "missed loop optimization: niters analysis .*" } */ | |

g(); | |

for(k = 0;k <= n;k += 4) /* { dg-missed "missed loop optimization: niters analysis .*" } */ | |

g(); | |

/* We used to get warning for this loop. However, since then # of iterations | |

analysis improved, and we can now prove that this loop does not verflow. | |

This is because the only case when it would overflow is if n = ~0 (since | |

~0 is divisible by 5), and this cannot be the case, since when we got | |

here, the previous loop exited, thus there exists k > n. */ | |

for(k = 5;k <= n;k += 5) | |

g(); | |

/* So we need the following loop, instead. */ | |

for(k = 4;k <= n;k += 5) /* { dg-missed "missed loop optimization: niters analysis .*" } */ | |

g(); | |

for(k = 15;k >= n;k--) /* { dg-missed "missed loop optimization: niters analysis .*" } */ | |

g(); | |

} |