Auto merge of #142546 - cjgillot:reachable-jump, r=compiler-errors

Only traverse reachable blocks in JumpThreading.

Fixes https://github.com/rust-lang/rust/issues/131451

We only compute loop headers for reachable blocks. We shouldn't try to perform an opt on unreachable blocks anyway.

1 files changed, 1 insertions, 1 deletions

diff --git a/compiler/rustc_mir_transform/src/jump_threading.rs b/compiler/rustc_mir_transform/src/jump_threading.rs
index 48db536c122..b45bff2af44 100644
--- a/compiler/rustc_mir_transform/src/jump_threading.rs
+++ b/compiler/rustc_mir_transform/src/jump_threading.rs
@@ -89,7 +89,7 @@ impl<'tcx> crate::MirPass<'tcx> for JumpThreading {
             opportunities: Vec::new(),
         };
 
-        for bb in body.basic_blocks.indices() {
+        for (bb, _) in traversal::preorder(body) {
             finder.start_from_switch(bb);
         }