Mir: Add TerminatorKind::Abort and generate one for foreign functions

Fixes rust-lang#18510
diwic · Oct 7, 2017 · 729092c · 729092c
1 parent b167fc0
commit 729092c
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Showing 16 changed files with 62 additions and 3 deletions.
diff --git a/src/librustc/ich/impls_mir.rs b/src/librustc/ich/impls_mir.rs
@@ -54,6 +54,7 @@ for mir::Terminator<'gcx> {
             mir::TerminatorKind::Goto { .. } |
             mir::TerminatorKind::SwitchInt { .. } |
             mir::TerminatorKind::Resume |
+            mir::TerminatorKind::Abort |
             mir::TerminatorKind::Return |
             mir::TerminatorKind::GeneratorDrop |
             mir::TerminatorKind::Unreachable |
@@ -148,6 +149,7 @@ for mir::TerminatorKind<'gcx> {
                 targets.hash_stable(hcx, hasher);
             }
             mir::TerminatorKind::Resume |
+            mir::TerminatorKind::Abort |
             mir::TerminatorKind::Return |
             mir::TerminatorKind::GeneratorDrop |
             mir::TerminatorKind::Unreachable => {}

diff --git a/src/librustc/mir/mod.rs b/src/librustc/mir/mod.rs
@@ -575,6 +575,10 @@ pub enum TerminatorKind<'tcx> {
     /// continue. Emitted by build::scope::diverge_cleanup.
     Resume,
 
+    /// Indicates that the landing pad is finished and that the process
+    /// should abort. Used to prevent unwinding for foreign items.
+    Abort,
+
     /// Indicates a normal return. The return pointer lvalue should
     /// have been filled in by now. This should occur at most once.
     Return,
@@ -660,7 +664,7 @@ impl<'tcx> TerminatorKind<'tcx> {
         match *self {
             Goto { target: ref b } => slice::ref_slice(b).into_cow(),
             SwitchInt { targets: ref b, .. } => b[..].into_cow(),
-            Resume | GeneratorDrop => (&[]).into_cow(),
+            Resume | Abort | GeneratorDrop => (&[]).into_cow(),
             Return => (&[]).into_cow(),
             Unreachable => (&[]).into_cow(),
             Call { destination: Some((_, t)), cleanup: Some(c), .. } => vec![t, c].into_cow(),
@@ -690,7 +694,7 @@ impl<'tcx> TerminatorKind<'tcx> {
         match *self {
             Goto { target: ref mut b } => vec![b],
             SwitchInt { targets: ref mut b, .. } => b.iter_mut().collect(),
-            Resume | GeneratorDrop => Vec::new(),
+            Resume | Abort | GeneratorDrop => Vec::new(),
             Return => Vec::new(),
             Unreachable => Vec::new(),
             Call { destination: Some((_, ref mut t)), cleanup: Some(ref mut c), .. } => vec![t, c],
@@ -780,6 +784,7 @@ impl<'tcx> TerminatorKind<'tcx> {
             Return => write!(fmt, "return"),
             GeneratorDrop => write!(fmt, "generator_drop"),
             Resume => write!(fmt, "resume"),
+            Abort => write!(fmt, "abort"),
             Yield { ref value, .. } => write!(fmt, "_1 = suspend({:?})", value),
             Unreachable => write!(fmt, "unreachable"),
             Drop { ref location, .. } => write!(fmt, "drop({:?})", location),
@@ -831,7 +836,7 @@ impl<'tcx> TerminatorKind<'tcx> {
     pub fn fmt_successor_labels(&self) -> Vec<Cow<'static, str>> {
         use self::TerminatorKind::*;
         match *self {
-            Return | Resume | Unreachable | GeneratorDrop => vec![],
+            Return | Resume | Abort | Unreachable | GeneratorDrop => vec![],
             Goto { .. } => vec!["".into()],
             SwitchInt { ref values, .. } => {
                 values.iter()
@@ -1806,6 +1811,7 @@ impl<'tcx> TypeFoldable<'tcx> for Terminator<'tcx> {
             },
             GeneratorDrop => GeneratorDrop,
             Resume => Resume,
+            Abort => Abort,
             Return => Return,
             Unreachable => Unreachable,
         };
@@ -1845,6 +1851,7 @@ impl<'tcx> TypeFoldable<'tcx> for Terminator<'tcx> {
             },
             Goto { .. } |
             Resume |
+            Abort |
             Return |
             GeneratorDrop |
             Unreachable => false

diff --git a/src/librustc/mir/visit.rs b/src/librustc/mir/visit.rs
@@ -431,6 +431,7 @@ macro_rules! make_mir_visitor {
                     }
 
                     TerminatorKind::Resume |
+                    TerminatorKind::Abort |
                     TerminatorKind::Return |
                     TerminatorKind::GeneratorDrop |
                     TerminatorKind::Unreachable => {

diff --git a/src/librustc_mir/borrow_check.rs b/src/librustc_mir/borrow_check.rs
@@ -291,6 +291,7 @@ impl<'c, 'b, 'a: 'b+'c, 'gcx, 'tcx: 'a> DataflowResultsConsumer<'b, 'gcx>
 
             TerminatorKind::Goto { target: _ } |
             TerminatorKind::Resume |
+            TerminatorKind::Abort |
             TerminatorKind::Return |
             TerminatorKind::GeneratorDrop |
             TerminatorKind::Unreachable => {

diff --git a/src/librustc_mir/build/mod.rs b/src/librustc_mir/build/mod.rs
@@ -378,10 +378,27 @@ fn construct_fn<'a, 'gcx, 'tcx, A>(hir: Cx<'a, 'gcx, 'tcx>,
     let arg_scope = region::Scope::Arguments(body.value.hir_id.local_id);
     let mut block = START_BLOCK;
     let source_info = builder.source_info(span);
+
     unpack!(block = builder.in_scope((call_site_scope, source_info), block, |builder| {
+
+        // According to rustc_trans/callee we mark all foreign instances with nounwind,
+        // so let's make sure we don't unwind.
+        // Therefore generate an extra "Abort" landing pad.
+
+        // This does not work :-(
+        // let is_foreign = tcx.is_foreign_item(tcx.hir.local_def_id(fn_id));
+        let is_foreign = match abi {
+            Abi::Rust | Abi::RustCall | Abi::RustIntrinsic => false,
+            _ => true,
+        };
+        if is_foreign && !tcx.sess.no_landing_pads() {
+            builder.schedule_abort();
+        };
+
         unpack!(block = builder.in_scope((arg_scope, source_info), block, |builder| {
             builder.args_and_body(block, &arguments, arg_scope, &body.value)
         }));
+
         // Attribute epilogue to function's closing brace
         let fn_end = span.with_lo(span.hi());
         let source_info = builder.source_info(fn_end);

diff --git a/src/librustc_mir/build/scope.rs b/src/librustc_mir/build/scope.rs
@@ -563,6 +563,14 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
         }
     }
 
+    pub fn schedule_abort(&mut self) -> BasicBlock {
+        self.scopes[0].needs_cleanup = true;
+        let abortblk = self.cfg.start_new_cleanup_block();
+        self.cfg.terminate(abortblk, self.scopes[0].source_info(self.fn_span), TerminatorKind::Abort);
+        self.cached_resume_block = Some(abortblk);
+        abortblk
+    }
+
     // Scheduling drops
     // ================
     /// Indicates that `lvalue` should be dropped on exit from

diff --git a/src/librustc_mir/dataflow/mod.rs b/src/librustc_mir/dataflow/mod.rs
@@ -676,6 +676,7 @@ impl<'a, 'tcx: 'a, D> DataflowAnalysis<'a, 'tcx, D> where D: BitDenotation
     {
         match bb_data.terminator().kind {
             mir::TerminatorKind::Return |
+            mir::TerminatorKind::Abort |
             mir::TerminatorKind::Resume |
             mir::TerminatorKind::GeneratorDrop |
             mir::TerminatorKind::Unreachable => {}

diff --git a/src/librustc_mir/dataflow/move_paths/builder.rs b/src/librustc_mir/dataflow/move_paths/builder.rs
@@ -263,6 +263,7 @@ impl<'a, 'tcx> MoveDataBuilder<'a, 'tcx> {
         match term.kind {
             TerminatorKind::Goto { target: _ } |
             TerminatorKind::Resume |
+            TerminatorKind::Abort |
             TerminatorKind::GeneratorDrop |
             TerminatorKind::Unreachable => { }
 

diff --git a/src/librustc_mir/transform/inline.rs b/src/librustc_mir/transform/inline.rs
@@ -713,6 +713,9 @@ impl<'a, 'tcx> MutVisitor<'tcx> for Integrator<'a, 'tcx> {
                     *kind = TerminatorKind::Goto { target: tgt }
                 }
             }
+            TerminatorKind::Abort => {
+                unimplemented!("I assume here's where we're supposed to insert a call to intrinsics::abort?");
+            }
             TerminatorKind::Unreachable => { }
         }
     }

diff --git a/src/librustc_mir/transform/no_landing_pads.rs b/src/librustc_mir/transform/no_landing_pads.rs
@@ -41,6 +41,7 @@ impl<'tcx> MutVisitor<'tcx> for NoLandingPads {
         match terminator.kind {
             TerminatorKind::Goto { .. } |
             TerminatorKind::Resume |
+            TerminatorKind::Abort |
             TerminatorKind::Return |
             TerminatorKind::Unreachable |
             TerminatorKind::GeneratorDrop |

diff --git a/src/librustc_mir/transform/qualify_consts.rs b/src/librustc_mir/transform/qualify_consts.rs
@@ -315,6 +315,7 @@ impl<'a, 'tcx> Qualifier<'a, 'tcx, 'tcx> {
                 TerminatorKind::SwitchInt {..} |
                 TerminatorKind::DropAndReplace { .. } |
                 TerminatorKind::Resume |
+                TerminatorKind::Abort |
                 TerminatorKind::GeneratorDrop |
                 TerminatorKind::Yield { .. } |
                 TerminatorKind::Unreachable => None,

diff --git a/src/librustc_mir/transform/type_check.rs b/src/librustc_mir/transform/type_check.rs
@@ -438,6 +438,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
         match term.kind {
             TerminatorKind::Goto { .. } |
             TerminatorKind::Resume |
+            TerminatorKind::Abort |
             TerminatorKind::Return |
             TerminatorKind::GeneratorDrop |
             TerminatorKind::Unreachable |
@@ -643,6 +644,11 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
                     span_mirbug!(self, block, "resume on non-cleanup block!")
                 }
             }
+            TerminatorKind::Abort => {
+                if !is_cleanup {
+                    span_mirbug!(self, block, "abort on non-cleanup block!")
+                }
+            }
             TerminatorKind::Return => {
                 if is_cleanup {
                     span_mirbug!(self, block, "return on cleanup block")

diff --git a/src/librustc_passes/mir_stats.rs b/src/librustc_passes/mir_stats.rs
@@ -113,6 +113,7 @@ impl<'a, 'tcx> mir_visit::Visitor<'tcx> for StatCollector<'a, 'tcx> {
             TerminatorKind::Goto { .. } => "TerminatorKind::Goto",
             TerminatorKind::SwitchInt { .. } => "TerminatorKind::SwitchInt",
             TerminatorKind::Resume => "TerminatorKind::Resume",
+            TerminatorKind::Abort => "TerminatorKind::Abort",
             TerminatorKind::Return => "TerminatorKind::Return",
             TerminatorKind::Unreachable => "TerminatorKind::Unreachable",
             TerminatorKind::Drop { .. } => "TerminatorKind::Drop",

diff --git a/src/librustc_trans/collector.rs b/src/librustc_trans/collector.rs
@@ -615,6 +615,7 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirNeighborCollector<'a, 'tcx> {
             mir::TerminatorKind::Goto { .. } |
             mir::TerminatorKind::SwitchInt { .. } |
             mir::TerminatorKind::Resume |
+            mir::TerminatorKind::Abort |
             mir::TerminatorKind::Return |
             mir::TerminatorKind::Unreachable |
             mir::TerminatorKind::Assert { .. } => {}

diff --git a/src/librustc_trans/mir/analyze.rs b/src/librustc_trans/mir/analyze.rs
@@ -217,6 +217,7 @@ pub fn cleanup_kinds<'a, 'tcx>(mir: &mir::Mir<'tcx>) -> IndexVec<mir::BasicBlock
             match data.terminator().kind {
                 TerminatorKind::Goto { .. } |
                 TerminatorKind::Resume |
+                TerminatorKind::Abort |
                 TerminatorKind::Return |
                 TerminatorKind::GeneratorDrop |
                 TerminatorKind::Unreachable |

diff --git a/src/librustc_trans/mir/block.rs b/src/librustc_trans/mir/block.rs
@@ -170,6 +170,13 @@ impl<'a, 'tcx> MirContext<'a, 'tcx> {
 
         self.set_debug_loc(&bcx, terminator.source_info);
         match terminator.kind {
+            mir::TerminatorKind::Abort => {
+                // Call core::intrinsics::abort()
+                let fnname = bcx.ccx.get_intrinsic(&("llvm.trap"));
+                bcx.call(fnname, &[], None);
+                bcx.unreachable();
+            }
+
             mir::TerminatorKind::Resume => {
                 if let Some(cleanup_pad) = cleanup_pad {
                     bcx.cleanup_ret(cleanup_pad, None);