[llvm] [NFC] CoroElide: Refactor `Lowerer` into `CoroIdElider` (PR #91539)

[Chuanqi Xu via llvm-commits]

================
@@ -33,24 +33,46 @@ static cl::opt<std::string> CoroElideInfoOutputFilename(
 
 namespace {
 // Created on demand if the coro-elide pass has work to do.
-struct Lowerer : coro::LowererBase {
+class FunctionElideManager {
+public:
+  FunctionElideManager(Function *F) : ContainingFunction(F) {
+    this->collectPostSplitCoroIds();
+  }
+
+  bool isElideNecessary() const { return !CoroIds.empty(); }
+
+  const SmallVectorImpl<CoroIdInst *> &getCoroIds() const { return CoroIds; }
+
+private:
+  Function *ContainingFunction;
   SmallVector<CoroIdInst *, 4> CoroIds;
+  SmallPtrSet<const SwitchInst *, 4> CoroSuspendSwitches;
+
+  void collectPostSplitCoroIds();
+  friend class CoroIdElider;
+};
+
+class CoroIdElider {
+public:
+  CoroIdElider(CoroIdInst *CoroId, FunctionElideManager &FEM, AAResults &AA,
+               DominatorTree &DT, OptimizationRemarkEmitter &ORE);
+  void elideHeapAllocations(uint64_t FrameSize, Align FrameAlign);
+  bool lifetimeEligibleForElide() const;
+  bool attemptElide();
+  bool CoroBeginCanEscape(const CoroBeginInst *,
----------------
ChuanqiXu9 wrote:

```suggestion
  bool canCoroBeginEscape(const CoroBeginInst *,
```

nit

https://github.com/llvm/llvm-project/pull/91539