Add initial AST and MIR support for unwinding from inline assembly

compiler/rustc_mir_transform/src/check_unsafety.rs

@@ -208,6 +208,7 @@ impl<'a, 'tcx> Visitor<'tcx> for UnsafetyChecker<'a, 'tcx> {
                             MutatingUseContext::Store
                                 | MutatingUseContext::Drop
                                 | MutatingUseContext::AsmOutput
+                                | MutatingUseContext::LlvmAsmOutput
                         )
                     );
                 // If this is just an assignment, determine if the assigned type needs dropping.

compiler/rustc_mir_transform/src/const_prop.rs

@@ -1022,6 +1022,7 @@ impl<'tcx> Visitor<'tcx> for CanConstProp {
             // These are just stores, where the storing is not propagatable, but there may be later
             // mutations of the same local via `Store`
             | MutatingUse(MutatingUseContext::Call)
+            | MutatingUse(MutatingUseContext::AsmOutput)
             // Actual store that can possibly even propagate a value
             | MutatingUse(MutatingUseContext::Store) => {
                 if !self.found_assignment.insert(local) {
@@ -1052,7 +1053,7 @@ impl<'tcx> Visitor<'tcx> for CanConstProp {
 
             // These could be propagated with a smarter analysis or just some careful thinking about
             // whether they'd be fine right now.
-            MutatingUse(MutatingUseContext::AsmOutput)
+            MutatingUse(MutatingUseContext::LlvmAsmOutput)
             | MutatingUse(MutatingUseContext::Yield)
             | MutatingUse(MutatingUseContext::Drop)
             | MutatingUse(MutatingUseContext::Retag)

compiler/rustc_mir_transform/src/dest_prop.rs

@@ -624,6 +624,7 @@ impl Conflicts<'a> {
                 options: _,
                 line_spans: _,
                 destination: _,
+                cleanup: _,
             } => {
                 // The intended semantics here aren't documented, we just assume that nothing that
                 // could be written to by the assembly may overlap with any other operands.

compiler/rustc_mir_transform/src/inline.rs

@@ -441,6 +441,13 @@ impl Inliner<'tcx> {
                     }
                 }
                 TerminatorKind::Resume => cost += RESUME_PENALTY,
+                TerminatorKind::InlineAsm { cleanup, .. } => {
+                    cost += INSTR_COST;
+
+                    if cleanup.is_some() {
+                        cost += LANDINGPAD_PENALTY;
+                    }
+                }
                 _ => cost += INSTR_COST,
             }
 
@@ -954,9 +961,13 @@ impl<'a, 'tcx> MutVisitor<'tcx> for Integrator<'a, 'tcx> {
             {
                 bug!("False unwinds should have been removed before inlining")
             }
-            TerminatorKind::InlineAsm { ref mut destination, .. } => {
+            TerminatorKind::InlineAsm { ref mut destination, ref mut cleanup, .. } => {
                 if let Some(ref mut tgt) = *destination {
                     *tgt = self.map_block(*tgt);
+                } else if !self.in_cleanup_block {
+                    // Unless this inline asm is in a cleanup block, add an unwind edge to
+                    // the original call's cleanup block
+                    *cleanup = self.cleanup_block;
                 }
             }
         }