| author |  Jay Petacat <jay@jayschwa.net> 2022-05-04 10:43:27-04:00 |
| committer |  GitHub <noreply@github.com> 2022-05-04 09:43:27-05:00 |
| log | 28ef79ea808fdb8e00b6d88d1565314a9e412768 |
| tree | ef5a6579b9154d18234dc4736ac75468da7e0ccf |
| parent | 3ed9ef3e6bed3fef6d6cad07920d08b28e20ec3e |
| signature |  Signed by PGP key 4AEE18F83AFDEB23 |
std: Single-threaded `panicImpl` sleep is unreachable (#11569)
Adding `unreachable` prevents the futex code from being inspected during
a single-threaded build. Without futex, first draft BYOS packages don't
need to implement `nanosleep` to get a single-threaded "hello world"
program working.
Use of `assert()` did not achieve the desired effect of avoiding futex
in a single-threaded build.1 files changed, 1 insertions(+), 0 deletions(-)
lib- std
lib/std/debug.zig+1
| ... | @@ -340,6 +340,7 @@ pub fn panicImpl(trace: ?*const std.builtin.StackTrace, first_trace_addr: ?usize | ... | @@ -340,6 +340,7 @@ pub fn panicImpl(trace: ?*const std.builtin.StackTrace, first_trace_addr: ?usize |
| 340 | if (panicking.fetchSub(1, .SeqCst) != 1) { | 340 | if (panicking.fetchSub(1, .SeqCst) != 1) { |
| 341 | // Another thread is panicking, wait for the last one to finish | 341 | // Another thread is panicking, wait for the last one to finish |
| 342 | // and call abort() | 342 | // and call abort() |
| 343 | if (builtin.single_threaded) unreachable; | ||
| 343 | 344 | ||
| 344 | // Sleep forever without hammering the CPU | 345 | // Sleep forever without hammering the CPU |
| 345 | var futex = std.atomic.Atomic(u32).init(0); | 346 | var futex = std.atomic.Atomic(u32).init(0); |