103 lines
2.5 KiB
Rust
103 lines
2.5 KiB
Rust
// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// check that we don't have linear stack usage with multiple calls to `push`
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// min-llvm-version 4.0
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#![feature(test)]
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extern crate test;
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use std::mem;
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fn meal() -> Big {
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if test::black_box(false) {
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panic!()
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}
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Big { drop_me: [
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None, None, None, None, None, None, None, None,
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None, None, None, None, None, None, None, None,
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None, None, None, None, None, None, None, None,
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None, None, None, None, None, None, None, None,
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None, None, None, None, None, None, None, None,
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None, None, None, None, None, None, None, None,
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]}
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}
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pub struct Big {
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drop_me: [Option<Box<u8>>; 48],
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}
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#[inline]
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fn push(out: &mut Vec<Big>) {
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out.push(meal());
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}
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#[inline(never)]
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pub fn supersize_me(out: &mut Vec<Big>) {
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out); // 16 calls to `push`
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verify_stack_usage(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out);
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push(out); // 16 calls to `push`
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}
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#[inline(never)]
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fn verify_stack_usage(before_ptr: *mut Vec<Big>) {
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// to check stack usage, create locals before and after
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// and check the difference in addresses between them.
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let mut stack_var: Vec<Big> = vec![];
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test::black_box(&mut stack_var);
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let stack_usage = isize::abs(
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(&mut stack_var as *mut _ as isize) -
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(before_ptr as isize)) as usize;
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// give space for 2 copies of `Big` + 128 "misc" bytes.
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if stack_usage > mem::size_of::<Big>() * 2 + 128 {
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panic!("used {} bytes of stack, but `struct Big` is only {} bytes",
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stack_usage, mem::size_of::<Big>());
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}
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}
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pub fn main() {
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let mut v = vec![];
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test::black_box(&mut v);
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supersize_me(&mut v);
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}
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