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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:18:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:18:58 +0000 |
commit | a4b7ed7a42c716ab9f05e351f003d589124fd55d (patch) | |
tree | b620cd3f223850b28716e474e80c58059dca5dd4 /tests/codegen/issue-96497-slice-size-nowrap.rs | |
parent | Adding upstream version 1.67.1+dfsg1. (diff) | |
download | rustc-a4b7ed7a42c716ab9f05e351f003d589124fd55d.tar.xz rustc-a4b7ed7a42c716ab9f05e351f003d589124fd55d.zip |
Adding upstream version 1.68.2+dfsg1.upstream/1.68.2+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'tests/codegen/issue-96497-slice-size-nowrap.rs')
-rw-r--r-- | tests/codegen/issue-96497-slice-size-nowrap.rs | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/tests/codegen/issue-96497-slice-size-nowrap.rs b/tests/codegen/issue-96497-slice-size-nowrap.rs new file mode 100644 index 000000000..0413ed6b2 --- /dev/null +++ b/tests/codegen/issue-96497-slice-size-nowrap.rs @@ -0,0 +1,29 @@ +// This test case checks that LLVM is aware that computing the size of a slice cannot wrap. +// The possibility of wrapping results in an additional branch when dropping boxed slices +// in some situations, see https://github.com/rust-lang/rust/issues/96497#issuecomment-1112865218 + +// compile-flags: -O +// min-llvm-version: 15.0 + +#![crate_type="lib"] + +// CHECK-LABEL: @simple_size_of_nowrap +#[no_mangle] +pub fn simple_size_of_nowrap(x: &[u32]) -> usize { + // Make sure the shift used to compute the size has a nowrap flag. + + // CHECK: [[A:%.*]] = shl nsw {{.*}}, 2 + // CHECK-NEXT: ret {{.*}} [[A]] + core::mem::size_of_val(x) +} + +// CHECK-LABEL: @drop_write +#[no_mangle] +pub fn drop_write(mut x: Box<[u32]>) { + // Check that this write is optimized out. + // This depends on the size calculation not wrapping, + // since otherwise LLVM can't tell that the memory is always deallocated if the slice len > 0. + + // CHECK-NOT: store i32 42 + x[1] = 42; +} |