Rollup merge of rust-lang#105194 - tmiasko:cleanup-kinds, r=davidtwco

Add comment to cleanup_kinds based on the original commit message 1ae7ae0
JohnTitor · Jan 11, 2023 · 8d7a06a · 8d7a06a
2 parents bf7ea0d + 836ef61
commit 8d7a06a
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/compiler/rustc_codegen_ssa/src/mir/analyze.rs b/compiler/rustc_codegen_ssa/src/mir/analyze.rs
@@ -261,6 +261,9 @@ impl CleanupKind {
     }
 }
 
+/// MSVC requires unwinding code to be split to a tree of *funclets*, where each funclet can only
+/// branch to itself or to its parent. Luckily, the code we generates matches this pattern.
+/// Recover that structure in an analyze pass.
 pub fn cleanup_kinds(mir: &mir::Body<'_>) -> IndexVec<mir::BasicBlock, CleanupKind> {
     fn discover_masters<'tcx>(
         result: &mut IndexVec<mir::BasicBlock, CleanupKind>,