From e0975b9b0150118d376ea19908cc9bfdf400bfd5 Mon Sep 17 00:00:00 2001 From: Erik Desjardins Date: Mon, 15 Jun 2020 18:19:54 -0400 Subject: [PATCH] elaborate, add check for exact bounds --- src/test/codegen/issue-69101-bounds-check.rs | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/src/test/codegen/issue-69101-bounds-check.rs b/src/test/codegen/issue-69101-bounds-check.rs index cdbe51da03cc2..cf062b6ad7588 100644 --- a/src/test/codegen/issue-69101-bounds-check.rs +++ b/src/test/codegen/issue-69101-bounds-check.rs @@ -2,6 +2,12 @@ // compile-flags: -O #![crate_type = "lib"] +// Make sure no bounds checks are emitted in the loop when upfront slicing +// ensures that the slices are big enough. +// In particular, bounds checks were not always optimized out if the upfront +// check was for a greater len than the loop requires. +// (i.e. `already_sliced_no_bounds_check` was not always optimized even when +// `already_sliced_no_bounds_check_exact` was) // CHECK-LABEL: @already_sliced_no_bounds_check #[no_mangle] pub fn already_sliced_no_bounds_check(a: &[u8], b: &[u8], c: &mut [u8]) { @@ -13,7 +19,18 @@ pub fn already_sliced_no_bounds_check(a: &[u8], b: &[u8], c: &mut [u8]) { } } -// make sure we're checking for the right thing: there can be a panic if the slice is too small +// CHECK-LABEL: @already_sliced_no_bounds_check_exact +#[no_mangle] +pub fn already_sliced_no_bounds_check_exact(a: &[u8], b: &[u8], c: &mut [u8]) { + // CHECK: slice_index_len_fail + // CHECK-NOT: panic_bounds_check + let _ = (&a[..1024], &b[..1024], &mut c[..1024]); + for i in 0..1024 { + c[i] = a[i] ^ b[i]; + } +} + +// Make sure we're checking for the right thing: there can be a panic if the slice is too small. // CHECK-LABEL: @already_sliced_bounds_check #[no_mangle] pub fn already_sliced_bounds_check(a: &[u8], b: &[u8], c: &mut [u8]) {