Add `#[loop_match]` for improved DFA codegen

Co-authored-by: Folkert de Vries <folkert@folkertdev.nl>

1 files changed, 32 insertions, 0 deletions

diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index c2a58b4cd7d..3c40b597f41 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -132,6 +132,12 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 Attribute::Parsed(AttributeKind::Optimize(_, attr_span)) => {
                     self.check_optimize(hir_id, *attr_span, span, target)
                 }
+                Attribute::Parsed(AttributeKind::LoopMatch(attr_span)) => {
+                    self.check_loop_match(hir_id, *attr_span, target)
+                }
+                Attribute::Parsed(AttributeKind::ConstContinue(attr_span)) => {
+                    self.check_const_continue(hir_id, *attr_span, target)
+                }
                 Attribute::Parsed(AttributeKind::AllowInternalUnstable(syms)) => self
                     .check_allow_internal_unstable(
                         hir_id,
@@ -2630,6 +2636,32 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
             }
         }
     }
+
+    fn check_loop_match(&self, hir_id: HirId, attr_span: Span, target: Target) {
+        let node_span = self.tcx.hir_span(hir_id);
+
+        if !matches!(target, Target::Expression) {
+            self.dcx().emit_err(errors::LoopMatchAttr { attr_span, node_span });
+            return;
+        }
+
+        if !matches!(self.tcx.hir_expect_expr(hir_id).kind, hir::ExprKind::Loop(..)) {
+            self.dcx().emit_err(errors::LoopMatchAttr { attr_span, node_span });
+        };
+    }
+
+    fn check_const_continue(&self, hir_id: HirId, attr_span: Span, target: Target) {
+        let node_span = self.tcx.hir_span(hir_id);
+
+        if !matches!(target, Target::Expression) {
+            self.dcx().emit_err(errors::ConstContinueAttr { attr_span, node_span });
+            return;
+        }
+
+        if !matches!(self.tcx.hir_expect_expr(hir_id).kind, hir::ExprKind::Break(..)) {
+            self.dcx().emit_err(errors::ConstContinueAttr { attr_span, node_span });
+        };
+    }
 }
 
 impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {