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Diffstat (limited to '')
-rw-r--r-- | src/test/ui/issues/issue-40883.rs | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/src/test/ui/issues/issue-40883.rs b/src/test/ui/issues/issue-40883.rs new file mode 100644 index 000000000..8a4aef46d --- /dev/null +++ b/src/test/ui/issues/issue-40883.rs @@ -0,0 +1,94 @@ +// run-pass +#![allow(dead_code)] +// check that we don't have linear stack usage with multiple calls to `push` + +#![feature(test)] + +extern crate test; +use std::mem; + +fn meal() -> Big { + if test::black_box(false) { + panic!() + } + Big { drop_me: [ + None, None, None, None, None, None, None, None, + None, None, None, None, None, None, None, None, + None, None, None, None, None, None, None, None, + None, None, None, None, None, None, None, None, + None, None, None, None, None, None, None, None, + None, None, None, None, None, None, None, None, + ]} +} + +pub struct Big { + drop_me: [Option<Box<u8>>; 48], +} + +#[inline] +fn push(out: &mut Vec<Big>) { + out.push(meal()); +} + +#[inline(never)] +pub fn supersize_me(out: &mut Vec<Big>) { + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); // 16 calls to `push` + + verify_stack_usage(out); + + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); + push(out); // 16 calls to `push` +} + +#[inline(never)] +fn verify_stack_usage(before_ptr: *mut Vec<Big>) { + // To check stack usage, create locals before and after + // and check the difference in addresses between them. + let mut stack_var: Vec<Big> = vec![]; + test::black_box(&mut stack_var); + let stack_usage = isize::abs( + (&mut stack_var as *mut _ as isize) - + (before_ptr as isize)) as usize; + // Give space for 2 copies of `Big` + 272 "misc" bytes + // (value observed on x86_64-pc-windows-gnu). + if stack_usage > mem::size_of::<Big>() * 2 + 272 { + panic!("used {} bytes of stack, but `struct Big` is only {} bytes", + stack_usage, mem::size_of::<Big>()); + } + +} + +pub fn main() { + let mut v = vec![]; + test::black_box(&mut v); + supersize_me(&mut v); +} |