[llvm] [clang] [coroutine] Implement llvm.coro.await.suspend intrinsic (PR #79712)

[Chuanqi Xu via cfe-commits]

================
@@ -79,6 +79,73 @@ using namespace llvm;
 
 namespace {
 
+// Created on demand if the coro-early pass has work to do.
+class Lowerer : public coro::LowererBase {
+  IRBuilder<> Builder;
+  void lowerAwaitSuspend(CoroAwaitSuspendInst *CB);
+
+public:
+  Lowerer(Module &M) : LowererBase(M), Builder(Context) {}
+
+  void lowerAwaitSuspends(Function &F);
+};
+
+void Lowerer::lowerAwaitSuspend(CoroAwaitSuspendInst *CB) {
+  auto Helper = CB->getHelperFunction();
+  auto Awaiter = CB->getAwaiter();
+  auto FramePtr = CB->getFrame();
+
+  Builder.SetInsertPoint(CB);
+
+  CallBase *NewCall = nullptr;
+  if (auto Invoke = dyn_cast<InvokeInst>(CB)) {
+    auto HelperInvoke =
+        Builder.CreateInvoke(Helper, Invoke->getNormalDest(),
+                             Invoke->getUnwindDest(), {Awaiter, FramePtr});
+
+    HelperInvoke->setCallingConv(Invoke->getCallingConv());
+    std::copy(Invoke->bundle_op_info_begin(), Invoke->bundle_op_info_end(),
+              HelperInvoke->bundle_op_info_begin());
+    AttributeList NewAttributes =
+        Invoke->getAttributes().removeParamAttributes(Context, 2);
+    HelperInvoke->setAttributes(NewAttributes);
+    HelperInvoke->setDebugLoc(Invoke->getDebugLoc());
+    NewCall = HelperInvoke;
+  } else if (auto Call = dyn_cast<CallInst>(CB)) {
+    auto HelperCall = Builder.CreateCall(Helper, {Awaiter, FramePtr});
+
+    AttributeList NewAttributes =
+        Call->getAttributes().removeParamAttributes(Context, 2);
+    HelperCall->setAttributes(NewAttributes);
+    HelperCall->setDebugLoc(Call->getDebugLoc());
+    NewCall = HelperCall;
+  }
+
+  CB->replaceAllUsesWith(NewCall);
+  CB->eraseFromParent();
+
+  InlineFunctionInfo FnInfo;
+  auto InlineRes = InlineFunction(*NewCall, FnInfo);
+  assert(InlineRes.isSuccess() && "Expected inlining to succeed");
+  (void)InlineRes;
+}
+
+void Lowerer::lowerAwaitSuspends(Function &F) {
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ChuanqiXu9 wrote:

We can collect CoroAwaitSuspendInst during the construction of Shape. So that we can save one iterations of the function.

https://github.com/llvm/llvm-project/pull/79712