tests/codegen/issue-69101-bounds-check.rs

   1 // no-system-llvm
   2 // compile-flags: -O
   3 // ignore-debug: the debug assertions get in the way
   4 #![crate_type = "lib"]
   5
   6 // Make sure no bounds checks are emitted in the loop when upfront slicing
   7 // ensures that the slices are big enough.
   8 // In particular, bounds checks were not always optimized out if the upfront
   9 // check was for a greater len than the loop requires.
  10 // (i.e. `already_sliced_no_bounds_check` was not always optimized even when
  11 // `already_sliced_no_bounds_check_exact` was)
  12 // CHECK-LABEL: @already_sliced_no_bounds_check
  13 #[no_mangle]
  14 pub fn already_sliced_no_bounds_check(a: &[u8], b: &[u8], c: &mut [u8]) {
  15     // CHECK: slice_end_index_len_fail
  16     // CHECK-NOT: panic_bounds_check
  17     let _ = (&a[..2048], &b[..2048], &mut c[..2048]);
  18     for i in 0..1024 {
  19         c[i] = a[i] ^ b[i];
  20     }
  21 }
  22
  23 // CHECK-LABEL: @already_sliced_no_bounds_check_exact
  24 #[no_mangle]
  25 pub fn already_sliced_no_bounds_check_exact(a: &[u8], b: &[u8], c: &mut [u8]) {
  26     // CHECK: slice_end_index_len_fail
  27     // CHECK-NOT: panic_bounds_check
  28     let _ = (&a[..1024], &b[..1024], &mut c[..1024]);
  29     for i in 0..1024 {
  30         c[i] = a[i] ^ b[i];
  31     }
  32 }
  33
  34 // Make sure we're checking for the right thing: there can be a panic if the slice is too small.
  35 // CHECK-LABEL: @already_sliced_bounds_check
  36 #[no_mangle]
  37 pub fn already_sliced_bounds_check(a: &[u8], b: &[u8], c: &mut [u8]) {
  38     // CHECK: slice_end_index_len_fail
  39     // CHECK: panic_bounds_check
  40     let _ = (&a[..1023], &b[..2048], &mut c[..2048]);
  41     for i in 0..1024 {
  42         c[i] = a[i] ^ b[i];
  43     }
  44 }