[clang] [clang][dataflow] Check for backedges directly (instead of loop statements). (PR #68923)

[via cfe-commits]

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@@ -53,19 +52,8 @@ static int blockIndexInPredecessor(const CFGBlock &Pred,
   return BlockPos - Pred.succ_begin();
 }
 
-static bool isLoopHead(const CFGBlock &B) {
-  if (const auto *T = B.getTerminatorStmt())
-    switch (T->getStmtClass()) {
-      case Stmt::WhileStmtClass:
-      case Stmt::DoStmtClass:
-      case Stmt::ForStmtClass:
-      case Stmt::CXXForRangeStmtClass:
-        return true;
-      default:
-        return false;
-    }
-
-  return false;
+static bool isBackedgeNode(const CFGBlock &B) {
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martinboehme wrote:

Yes, but

* It still requires work (not everyone has an IDE with great cross-linking, so this could be multiple clicks), and
* 
* We're introducing a new term here ("backedge node"), and it's not clear without an explanation whether a) we intend for this to be a synonym for "has loop target" (but then why aren't we reusing that term -- is it because we think "backedge node" is clearer?), or b) `getLoopTarget() != nullptr` happens to be the right implementation today, but we think it might change in the future, so we're wrapping this check in a function?

https://github.com/llvm/llvm-project/pull/68923