[coro][NFC] Move switch basic block to beginning of coroutine

[vogelsgesang]

This makes the code flow when reading the LLVM IR of a split coroutine a bit more natural. It does not change anything from an end-user perspective but makes debugging the CoroSplit pass slightly easier.

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

@llvm/pr-subscribers-coroutines

Author: Adrian Vogelsgesang (vogelsgesang)

Changes

This makes the code flow a bit more natural when reading the LLVM IR of a split coroutine. It does not change anything from an end-user perspective but makes debugging the CoroSplit pass slightly easier.

---

Full diff: https://github.com/llvm/llvm-project/pull/143626.diff

1 Files Affected:

• (modified) llvm/lib/Transforms/Coroutines/CoroSplit.cpp (+1)

diff --git a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
index f9a6c70fedc2d..cebe44581b061 100644
--- a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
@@ -703,6 +703,7 @@ void coro::BaseCloner::replaceEntryBlock() {
     auto *SwitchBB =
         cast<BasicBlock>(VMap[Shape.SwitchLowering.ResumeEntryBlock]);
     Builder.CreateBr(SwitchBB);
+    SwitchBB->moveAfter(Entry);
     break;
   }
   case coro::ABI::Async: