Mir: Abort on nounwind ABIs

Generate Abort instead of Resume terminators on nounwind ABIs.

#18510

Signed-off-by: David Henningsson <[email protected]>

Author: diwic

src/Cargo.lock

@@ -14,6 +14,7 @@ graphviz = { path = "../libgraphviz" }
 log = "0.3"
 log_settings = "0.1.1"
 rustc = { path = "../librustc" }
+rustc_back = { path = "../librustc_back" }
 rustc_const_eval = { path = "../librustc_const_eval" }
 rustc_const_math = { path = "../librustc_const_math" }
 rustc_data_structures = { path = "../librustc_data_structures" }

src/librustc_mir/Cargo.toml

@@ -20,6 +20,7 @@ use rustc::mir::visit::{MutVisitor, TyContext};
 use rustc::ty::{self, Ty, TyCtxt};
 use rustc::ty::subst::Substs;
 use rustc::util::nodemap::NodeMap;
+use rustc_back::PanicStrategy;
 use rustc_const_eval::pattern::{BindingMode, PatternKind};
 use rustc_data_structures::indexed_vec::{IndexVec, Idx};
 use shim;
@@ -353,6 +354,27 @@ macro_rules! unpack {
     };
 }
 
+fn needs_abort_block<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
+                                     fn_id: ast::NodeId,
+                                     abi: Abi)
+                                     -> bool {
+
+    // Not callable from C, so we can safely unwind through these
+    if abi == Abi::Rust || abi == Abi::RustCall { return false; }
+
+    // We never unwind, so it's not relevant to stop an unwind
+    if tcx.sess.panic_strategy() != PanicStrategy::Unwind { return false; }
+
+    // We cannot add landing pads, so don't add one
+    if tcx.sess.no_landing_pads() { return false; }
+
+    // This is a special case: some functions have a C abi but are meant to
+    // unwind anyway. Don't stop them.
+    if tcx.has_attr(tcx.hir.local_def_id(fn_id), "unwind") { return false; }
+
+    return true;
+}
+
 ///////////////////////////////////////////////////////////////////////////
 /// the main entry point for building MIR for a function
 
@@ -383,6 +405,11 @@ fn construct_fn<'a, 'gcx, 'tcx, A>(hir: Cx<'a, 'gcx, 'tcx>,
     let source_info = builder.source_info(span);
     let call_site_s = (call_site_scope, source_info);
     unpack!(block = builder.in_scope(call_site_s, LintLevel::Inherited, block, |builder| {
+
+        if needs_abort_block(tcx, fn_id, abi) {
+            builder.schedule_abort();
+        }
+
         let arg_scope_s = (arg_scope, source_info);
         unpack!(block = builder.in_scope(arg_scope_s, LintLevel::Inherited, block, |builder| {
             builder.args_and_body(block, &arguments, arg_scope, &body.value)

src/librustc_mir/build/mod.rs

@@ -612,6 +612,16 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
         }
     }
 
+    // Schedule an abort block - this is used for some ABIs that cannot unwind
+    pub fn schedule_abort(&mut self) -> BasicBlock {
+        self.scopes[0].needs_cleanup = true;
+        let abortblk = self.cfg.start_new_cleanup_block();
+        let source_info = self.scopes[0].source_info(self.fn_span);
+        self.cfg.terminate(abortblk, source_info, TerminatorKind::Abort);
+        self.cached_resume_block = Some(abortblk);
+        abortblk
+    }
+
     // Scheduling drops
     // ================
     /// Indicates that `place` should be dropped on exit from

src/librustc_mir/build/scope.rs

@@ -49,6 +49,7 @@ extern crate rustc_errors;
 #[macro_use]
 extern crate syntax;
 extern crate syntax_pos;
+extern crate rustc_back;
 extern crate rustc_const_math;
 extern crate rustc_const_eval;
 extern crate core; // for NonZero

src/librustc_mir/lib.rs

@@ -0,0 +1,43 @@
+// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Since we mark some ABIs as "nounwind" to LLVM, we must make sure that
+// we never unwind through them.
+
+// ignore-emscripten no processes
+
+use std::{env, panic};
+use std::io::prelude::*;
+use std::io;
+use std::process::{Command, Stdio};
+
+extern "C" fn panic_in_ffi() {
+    panic!("Test");
+}
+
+fn test() {
+    let _ = panic::catch_unwind(|| { panic_in_ffi(); });
+    // The process should have aborted by now.
+    io::stdout().write(b"This should never be printed.\n");
+    let _ = io::stdout().flush();
+}
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+    if args.len() > 1 && args[1] == "test" {
+        return test();
+    }
+
+    let mut p = Command::new(&args[0])
+                        .stdout(Stdio::piped())
+                        .stdin(Stdio::piped())
+                        .arg("test").spawn().unwrap();
+    assert!(!p.wait().unwrap().success());
+}