[llvm-branch-commits] [llvm] [LLVM][Coroutines] Create `.noalloc` variant of switch ABI coroutine ramp functions during CoroSplit (PR #99283)

[Chuanqi Xu via llvm-branch-commits]

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@@ -1455,6 +1462,74 @@ struct SwitchCoroutineSplitter {
     setCoroInfo(F, Shape, Clones);
   }
 
+  // Create a variant of ramp function that does not perform heap allocation
+  // for a switch ABI coroutine.
+  //
+  // The newly split `.noalloc` ramp function has the following differences:
+  //  - Has one additional frame pointer parameter in lieu of dynamic
+  //  allocation.
+  //  - Suppressed allocations by replacing coro.alloc and coro.free.
+  static Function *createNoAllocVariant(Function &F, coro::Shape &Shape,
+                                        SmallVectorImpl<Function *> &Clones) {
+    auto *OrigFnTy = F.getFunctionType();
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ChuanqiXu9 wrote:

nit: I feel better with an assertion here that the ABI is switch ABI.

https://github.com/llvm/llvm-project/pull/99283