Auto merge of #102906 - nbdd0121:mir, r=wesleywiser,tmiasko

Refactor unwind in MIR

This makes unwinding from current `Option<BasicBlock>` into
```rust
enum UnwindAction {
	Continue,
	Cleanup(BasicBlock),
	Unreachable,
	Terminate,
}
```

cc `@JakobDegen` `@RalfJung` `@Amanieu`

Author: bors

compiler/rustc_borrowck/src/diagnostics/find_use.rs

@@ -11,7 +11,7 @@ use crate::{
 };
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_middle::mir::visit::{MirVisitable, PlaceContext, Visitor};
-use rustc_middle::mir::{Body, Local, Location};
+use rustc_middle::mir::{self, Body, Local, Location};
 use rustc_middle::ty::{RegionVid, TyCtxt};
 
 pub(crate) fn find<'tcx>(
@@ -70,7 +70,10 @@ impl<'cx, 'tcx> UseFinder<'cx, 'tcx> {
                             block_data
                                 .terminator()
                                 .successors()
-                                .filter(|&bb| Some(&Some(bb)) != block_data.terminator().unwind())
+                                .filter(|&bb| {
+                                    Some(&mir::UnwindAction::Cleanup(bb))
+                                        != block_data.terminator().unwind()
+                                })
                                 .map(|bb| Location { statement_index: 0, block: bb }),
                         );
                     }

compiler/rustc_borrowck/src/invalidation.rs

@@ -125,7 +125,7 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
                 args,
                 destination,
                 target: _,
-                cleanup: _,
+                unwind: _,
                 from_hir_call: _,
                 fn_span: _,
             } => {
@@ -135,7 +135,7 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
                 }
                 self.mutate_place(location, *destination, Deep);
             }
-            TerminatorKind::Assert { cond, expected: _, msg, target: _, cleanup: _ } => {
+            TerminatorKind::Assert { cond, expected: _, msg, target: _, unwind: _ } => {
                 self.consume_operand(location, cond);
                 use rustc_middle::mir::AssertKind;
                 if let AssertKind::BoundsCheck { len, index } = msg {
@@ -173,7 +173,7 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
                 options: _,
                 line_spans: _,
                 destination: _,
-                cleanup: _,
+                unwind: _,
             } => {
                 for op in operands {
                     match op {
@@ -198,7 +198,7 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
                 }
             }
             TerminatorKind::Goto { target: _ }
-            | TerminatorKind::Abort
+            | TerminatorKind::Terminate
             | TerminatorKind::Unreachable
             | TerminatorKind::FalseEdge { real_target: _, imaginary_target: _ }
             | TerminatorKind::FalseUnwind { real_target: _, unwind: _ } => {

compiler/rustc_borrowck/src/lib.rs

@@ -740,7 +740,7 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
                 args,
                 destination,
                 target: _,
-                cleanup: _,
+                unwind: _,
                 from_hir_call: _,
                 fn_span: _,
             } => {
@@ -750,7 +750,7 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
                 }
                 self.mutate_place(loc, (*destination, span), Deep, flow_state);
             }
-            TerminatorKind::Assert { cond, expected: _, msg, target: _, cleanup: _ } => {
+            TerminatorKind::Assert { cond, expected: _, msg, target: _, unwind: _ } => {
                 self.consume_operand(loc, (cond, span), flow_state);
                 use rustc_middle::mir::AssertKind;
                 if let AssertKind::BoundsCheck { len, index } = msg {
@@ -770,7 +770,7 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
                 options: _,
                 line_spans: _,
                 destination: _,
-                cleanup: _,
+                unwind: _,
             } => {
                 for op in operands {
                     match op {
@@ -801,7 +801,7 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
             }
 
             TerminatorKind::Goto { target: _ }
-            | TerminatorKind::Abort
+            | TerminatorKind::Terminate
             | TerminatorKind::Unreachable
             | TerminatorKind::Resume
             | TerminatorKind::Return
@@ -845,7 +845,7 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
                 }
             }
 
-            TerminatorKind::Abort
+            TerminatorKind::Terminate
             | TerminatorKind::Assert { .. }
             | TerminatorKind::Call { .. }
             | TerminatorKind::Drop { .. }

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -1300,7 +1300,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         match &term.kind {
             TerminatorKind::Goto { .. }
             | TerminatorKind::Resume
-            | TerminatorKind::Abort
+            | TerminatorKind::Terminate
             | TerminatorKind::Return
             | TerminatorKind::GeneratorDrop
             | TerminatorKind::Unreachable
@@ -1584,7 +1584,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     span_mirbug!(self, block_data, "resume on non-cleanup block!")
                 }
             }
-            TerminatorKind::Abort => {
+            TerminatorKind::Terminate => {
                 if !is_cleanup {
                     span_mirbug!(self, block_data, "abort on non-cleanup block!")
                 }
@@ -1610,49 +1610,29 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             }
             TerminatorKind::Unreachable => {}
             TerminatorKind::Drop { target, unwind, .. }
-            | TerminatorKind::Assert { target, cleanup: unwind, .. } => {
+            | TerminatorKind::Assert { target, unwind, .. } => {
                 self.assert_iscleanup(body, block_data, target, is_cleanup);
-                if let Some(unwind) = unwind {
-                    if is_cleanup {
-                        span_mirbug!(self, block_data, "unwind on cleanup block")
-                    }
-                    self.assert_iscleanup(body, block_data, unwind, true);
-                }
+                self.assert_iscleanup_unwind(body, block_data, unwind, is_cleanup);
             }
-            TerminatorKind::Call { ref target, cleanup, .. } => {
+            TerminatorKind::Call { ref target, unwind, .. } => {
                 if let &Some(target) = target {
                     self.assert_iscleanup(body, block_data, target, is_cleanup);
                 }
-                if let Some(cleanup) = cleanup {
-                    if is_cleanup {
-                        span_mirbug!(self, block_data, "cleanup on cleanup block")
-                    }
-                    self.assert_iscleanup(body, block_data, cleanup, true);
-                }
+                self.assert_iscleanup_unwind(body, block_data, unwind, is_cleanup);
             }
             TerminatorKind::FalseEdge { real_target, imaginary_target } => {
                 self.assert_iscleanup(body, block_data, real_target, is_cleanup);
                 self.assert_iscleanup(body, block_data, imaginary_target, is_cleanup);
             }
             TerminatorKind::FalseUnwind { real_target, unwind } => {
                 self.assert_iscleanup(body, block_data, real_target, is_cleanup);
-                if let Some(unwind) = unwind {
-                    if is_cleanup {
-                        span_mirbug!(self, block_data, "cleanup in cleanup block via false unwind");
-                    }
-                    self.assert_iscleanup(body, block_data, unwind, true);
-                }
+                self.assert_iscleanup_unwind(body, block_data, unwind, is_cleanup);
             }
-            TerminatorKind::InlineAsm { destination, cleanup, .. } => {
+            TerminatorKind::InlineAsm { destination, unwind, .. } => {
                 if let Some(target) = destination {
                     self.assert_iscleanup(body, block_data, target, is_cleanup);
                 }
-                if let Some(cleanup) = cleanup {
-                    if is_cleanup {
-                        span_mirbug!(self, block_data, "cleanup on cleanup block")
-                    }
-                    self.assert_iscleanup(body, block_data, cleanup, true);
-                }
+                self.assert_iscleanup_unwind(body, block_data, unwind, is_cleanup);
             }
         }
     }
@@ -1669,6 +1649,29 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         }
     }
 
+    fn assert_iscleanup_unwind(
+        &mut self,
+        body: &Body<'tcx>,
+        ctxt: &dyn fmt::Debug,
+        unwind: UnwindAction,
+        is_cleanup: bool,
+    ) {
+        match unwind {
+            UnwindAction::Cleanup(unwind) => {
+                if is_cleanup {
+                    span_mirbug!(self, ctxt, "unwind on cleanup block")
+                }
+                self.assert_iscleanup(body, ctxt, unwind, true);
+            }
+            UnwindAction::Continue => {
+                if is_cleanup {
+                    span_mirbug!(self, ctxt, "unwind on cleanup block")
+                }
+            }
+            UnwindAction::Unreachable | UnwindAction::Terminate => (),
+        }
+    }
+
     fn check_local(&mut self, body: &Body<'tcx>, local: Local, local_decl: &LocalDecl<'tcx>) {
         match body.local_kind(local) {
             LocalKind::ReturnPointer | LocalKind::Arg => {

compiler/rustc_codegen_cranelift/src/base.rs

@@ -345,7 +345,7 @@ fn codegen_fn_body(fx: &mut FunctionCx<'_, '_, '_>, start_block: Block) {
             TerminatorKind::Return => {
                 crate::abi::codegen_return(fx);
             }
-            TerminatorKind::Assert { cond, expected, msg, target, cleanup: _ } => {
+            TerminatorKind::Assert { cond, expected, msg, target, unwind: _ } => {
                 if !fx.tcx.sess.overflow_checks() && msg.is_optional_overflow_check() {
                     let target = fx.get_block(*target);
                     fx.bcx.ins().jump(target, &[]);
@@ -450,7 +450,7 @@ fn codegen_fn_body(fx: &mut FunctionCx<'_, '_, '_>, start_block: Block) {
                 destination,
                 target,
                 fn_span,
-                cleanup: _,
+                unwind: _,
                 from_hir_call: _,
             } => {
                 fx.tcx.prof.generic_activity("codegen call").run(|| {
@@ -470,7 +470,7 @@ fn codegen_fn_body(fx: &mut FunctionCx<'_, '_, '_>, start_block: Block) {
                 options,
                 destination,
                 line_spans: _,
-                cleanup: _,
+                unwind: _,
             } => {
                 if options.contains(InlineAsmOptions::MAY_UNWIND) {
                     fx.tcx.sess.span_fatal(
@@ -488,7 +488,7 @@ fn codegen_fn_body(fx: &mut FunctionCx<'_, '_, '_>, start_block: Block) {
                     *destination,
                 );
             }
-            TerminatorKind::Abort => {
+            TerminatorKind::Terminate => {
                 codegen_panic_cannot_unwind(fx, source_info);
             }
             TerminatorKind::Resume => {

compiler/rustc_codegen_cranelift/src/constant.rs

@@ -549,7 +549,7 @@ pub(crate) fn mir_operand_get_const_val<'tcx>(
                     TerminatorKind::Goto { .. }
                     | TerminatorKind::SwitchInt { .. }
                     | TerminatorKind::Resume
-                    | TerminatorKind::Abort
+                    | TerminatorKind::Terminate
                     | TerminatorKind::Return
                     | TerminatorKind::Unreachable
                     | TerminatorKind::Drop { .. }

compiler/rustc_codegen_ssa/src/mir/analyze.rs

@@ -284,19 +284,19 @@ pub fn cleanup_kinds(mir: &mir::Body<'_>) -> IndexVec<mir::BasicBlock, CleanupKi
             match data.terminator().kind {
                 TerminatorKind::Goto { .. }
                 | TerminatorKind::Resume
-                | TerminatorKind::Abort
+                | TerminatorKind::Terminate
                 | TerminatorKind::Return
                 | TerminatorKind::GeneratorDrop
                 | TerminatorKind::Unreachable
                 | TerminatorKind::SwitchInt { .. }
                 | TerminatorKind::Yield { .. }
                 | TerminatorKind::FalseEdge { .. }
                 | TerminatorKind::FalseUnwind { .. } => { /* nothing to do */ }
-                TerminatorKind::Call { cleanup: unwind, .. }
-                | TerminatorKind::InlineAsm { cleanup: unwind, .. }
-                | TerminatorKind::Assert { cleanup: unwind, .. }
+                TerminatorKind::Call { unwind, .. }
+                | TerminatorKind::InlineAsm { unwind, .. }
+                | TerminatorKind::Assert { unwind, .. }
                 | TerminatorKind::Drop { unwind, .. } => {
-                    if let Some(unwind) = unwind {
+                    if let mir::UnwindAction::Cleanup(unwind) = unwind {
                         debug!(
                             "cleanup_kinds: {:?}/{:?} registering {:?} as funclet",
                             bb, data, unwind