From 0ec321f7b541fcbfbf20286beb497e6d9d3352b2 Mon Sep 17 00:00:00 2001 From: Alex Crichton Date: Fri, 8 Apr 2016 16:18:40 -0700 Subject: rustc: Implement custom panic runtimes This commit is an implementation of [RFC 1513] which allows applications to alter the behavior of panics at compile time. A new compiler flag, `-C panic`, is added and accepts the values `unwind` or `panic`, with the default being `unwind`. This model affects how code is generated for the local crate, skipping generation of landing pads with `-C panic=abort`. [RFC 1513]: https://github.com/rust-lang/rfcs/blob/master/text/1513-less-unwinding.md Panic implementations are then provided by crates tagged with `#![panic_runtime]` and lazily required by crates with `#![needs_panic_runtime]`. The panic strategy (`-C panic` value) of the panic runtime must match the final product, and if the panic strategy is not `abort` then the entire DAG must have the same panic strategy. With the `-C panic=abort` strategy, users can expect a stable method to disable generation of landing pads, improving optimization in niche scenarios, decreasing compile time, and decreasing output binary size. With the `-C panic=unwind` strategy users can expect the existing ability to isolate failure in Rust code from the outside world. Organizationally, this commit dismantles the `sys_common::unwind` module in favor of some bits moving part of it to `libpanic_unwind` and the rest into the `panicking` module in libstd. The custom panic runtime support is pretty similar to the custom allocator support with the only major difference being how the panic runtime is injected (takes the `-C panic` flag into account). --- src/libsyntax/ext/build.rs | 2 +- src/libsyntax/feature_gate.rs | 11 +++++++++++ 2 files changed, 12 insertions(+), 1 deletion(-) (limited to 'src/libsyntax') diff --git a/src/libsyntax/ext/build.rs b/src/libsyntax/ext/build.rs index 67bce440d4d..7958162986c 100644 --- a/src/libsyntax/ext/build.rs +++ b/src/libsyntax/ext/build.rs @@ -755,7 +755,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> { let expr_file_line_ptr = self.expr_addr_of(span, expr_file_line_tuple); self.expr_call_global( span, - self.std_path(&["rt", "begin_unwind"]), + self.std_path(&["rt", "begin_panic"]), vec!( self.expr_str(span, msg), expr_file_line_ptr)) diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs index 7f01821b004..dbe4d9bb6f7 100644 --- a/src/libsyntax/feature_gate.rs +++ b/src/libsyntax/feature_gate.rs @@ -141,6 +141,8 @@ declare_features! ( (active, simd_ffi, "1.0.0", Some(27731)), (active, start, "1.0.0", Some(29633)), (active, structural_match, "1.8.0", Some(31434)), + (active, panic_runtime, "1.10.0", Some(32837)), + (active, needs_panic_runtime, "1.10.0", Some(32837)), // OIBIT specific features (active, optin_builtin_traits, "1.0.0", Some(13231)), @@ -435,6 +437,15 @@ pub const KNOWN_ATTRIBUTES: &'static [(&'static str, AttributeType, AttributeGat attribute is an experimental \ feature", cfg_fn!(needs_allocator))), + ("panic_runtime", Whitelisted, Gated("panic_runtime", + "the `#[panic_runtime]` attribute is \ + an experimental feature", + cfg_fn!(panic_runtime))), + ("needs_panic_runtime", Whitelisted, Gated("needs_panic_runtime", + "the `#[needs_panic_runtime]` \ + attribute is an experimental \ + feature", + cfg_fn!(needs_panic_runtime))), ("rustc_variance", Normal, Gated("rustc_attrs", "the `#[rustc_variance]` attribute \ is just used for rustc unit tests \ -- cgit 1.4.1-3-g733a5