Add asm label support to AST and HIR

compiler/rustc_hir/src/hir.rs

@@ -2645,6 +2645,9 @@ pub enum InlineAsmOperand<'hir> {
         path: QPath<'hir>,
         def_id: DefId,
     },
+    Label {
+        block: &'hir Block<'hir>,
+    },
 }
 
 impl<'hir> InlineAsmOperand<'hir> {
@@ -2654,7 +2657,10 @@ impl<'hir> InlineAsmOperand<'hir> {
             | Self::Out { reg, .. }
             | Self::InOut { reg, .. }
             | Self::SplitInOut { reg, .. } => Some(reg),
-            Self::Const { .. } | Self::SymFn { .. } | Self::SymStatic { .. } => None,
+            Self::Const { .. }
+            | Self::SymFn { .. }
+            | Self::SymStatic { .. }
+            | Self::Label { .. } => None,
         }
     }
 
@@ -2675,6 +2681,12 @@ pub struct InlineAsm<'hir> {
     pub line_spans: &'hir [Span],
 }
 
+impl InlineAsm<'_> {
+    pub fn contains_label(&self) -> bool {
+        self.operands.iter().any(|x| matches!(x.0, InlineAsmOperand::Label { .. }))
+    }
+}
+
 /// Represents a parameter in a function header.
 #[derive(Debug, Clone, Copy, HashStable_Generic)]
 pub struct Param<'hir> {