bjoernager/rust
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Prevent __rust_begin_short_backtrace frames from being tail-call optimised away

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This commit is contained in:
Alan Egerton 2020-08-04 22:18:20 +01:00
parent 4d4342347b
commit 5792840bf5
6 changed files with 74 additions and 12 deletions
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39
library/std/src/sys_common/backtrace.rs
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@ -74,6 +74,8 @@ unsafe fn _print_fmt(fmt: &mut fmt::Formatter<'_>, print_fmt: PrintFmt) -> fmt::
bt_fmt.add_context()?;
let mut idx = 0;
let mut res = Ok(());
// Start immediately if we're not using a short backtrace.
let mut start = print_fmt != PrintFmt::Short;
backtrace_rs::trace_unsynchronized(|frame| {
if print_fmt == PrintFmt::Short && idx > MAX_NB_FRAMES {
return false;
@ -89,16 +91,24 @@ unsafe fn _print_fmt(fmt: &mut fmt::Formatter<'_>, print_fmt: PrintFmt) -> fmt::
stop = true;
return;
}
if sym.contains("__rust_end_short_backtrace") {
start = true;
return;
}
}
}
res = bt_fmt.frame().symbol(frame, symbol);
if start {
res = bt_fmt.frame().symbol(frame, symbol);
}
});
if stop {
return false;
}
if !hit {
res = bt_fmt.frame().print_raw(frame.ip(), None, None, None);
if start {
res = bt_fmt.frame().print_raw(frame.ip(), None, None, None);
}
}
idx += 1;
@ -123,10 +133,29 @@ unsafe fn _print_fmt(fmt: &mut fmt::Formatter<'_>, print_fmt: PrintFmt) -> fmt::
pub fn __rust_begin_short_backtrace<F, T>(f: F) -> T
where
F: FnOnce() -> T,
F: Send,
T: Send,
{
f()
let result = f();
// prevent this frame from being tail-call optimised away
crate::hint::black_box(());
result
}
/// Fixed frame used to clean the backtrace with `RUST_BACKTRACE=1`. Note that
/// this is only inline(never) when backtraces in libstd are enabled, otherwise
/// it's fine to optimize away.
#[cfg_attr(feature = "backtrace", inline(never))]
pub fn __rust_end_short_backtrace<F, T>(f: F) -> T
where
F: FnOnce() -> T,
{
let result = f();
// prevent this frame from being tail-call optimised away
crate::hint::black_box(());
result
}
pub enum RustBacktrace {