[clang] [CIR] Add structured control flow for coroutine suspend points (PR #213191)

[Erich Keane via cfe-commits]

================
@@ -382,11 +381,25 @@ CIRGenFunction::emitCoroutineBody(const CoroutineBodyStmt &s) {
   // Handle allocation failure if 'ReturnStmtOnAllocFailure' was provided.
   if (s.getReturnStmtOnAllocFailure())
     cgm.errorNYI("handle coroutine return alloc failure");
-
+  cir::CoroRetPointOp coroRet = nullptr;
+  mlir::OpBuilder::InsertPoint coroRetRegion;
   {
     assert(!cir::MissingFeatures::generateDebugInfo());
     ParamReferenceReplacerRAII paramReplacer(localDeclMap);
     RunCleanupsScope resumeScope(*this);
+    mlir::OpBuilder::InsertPoint coroRetBody;
+    coroRet = cir::CoroRetPointOp::create(
+        builder, openCurlyLoc,
+        /*bodyBuilder=*/
+        [&](mlir::OpBuilder &b, mlir::Location) {
+          coroRetBody = b.saveInsertionPoint();
----------------
erichkeane wrote:

I'm not a huge fan of doing stuff like this, we've seen this strategy get fragile in the past.  Is it problematic to extract the regions of code that od this into a function we can call here instead? 

https://github.com/llvm/llvm-project/pull/213191