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

[Chuanqi Xu via llvm-commits]

================
@@ -232,16 +237,59 @@ static LValueOrRValue emitSuspendExpression(CodeGenFunction &CGF, CGCoroData &Co
   auto *NullPtr = llvm::ConstantPointerNull::get(CGF.CGM.Int8PtrTy);
   auto *SaveCall = Builder.CreateCall(CoroSave, {NullPtr});
 
-  CGF.CurCoro.InSuspendBlock = true;
-  auto *SuspendRet = CGF.EmitScalarExpr(S.getSuspendExpr());
-  CGF.CurCoro.InSuspendBlock = false;
+  const auto AwaitSuspendCanThrow =
+      AwaitSuspendStmtCanThrow(S.getSuspendExpr());
+
+  auto SuspendHelper = CodeGenFunction(CGF.CGM).generateAwaitSuspendHelper(
+      CGF.CurFn->getName(), Prefix, S, AwaitSuspendCanThrow);
 
-  if (SuspendRet != nullptr && SuspendRet->getType()->isIntegerTy(1)) {
-    // Veto suspension if requested by bool returning await_suspend.
-    BasicBlock *RealSuspendBlock =
-        CGF.createBasicBlock(Prefix + Twine(".suspend.bool"));
-    CGF.Builder.CreateCondBr(SuspendRet, RealSuspendBlock, ReadyBlock);
-    CGF.EmitBlock(RealSuspendBlock);
+  llvm::CallBase *SuspendRet = nullptr;
+
+  {
+    CGF.CurCoro.InSuspendBlock = true;
+
+    auto FramePtrBinder = CodeGenFunction::OpaqueValueMappingData::bind(
+        CGF, S.getOpaqueFramePtr(), S.getOpaqueFramePtr()->getSourceExpr());
+    auto UnbindFramePtrOnExit =
+        llvm::make_scope_exit([&] { FramePtrBinder.unbind(CGF); });
+
+    SmallVector<llvm::Value *, 3> SuspendHelperCallArgs;
+    SuspendHelperCallArgs.push_back(
+        CGF.getOrCreateOpaqueLValueMapping(S.getOpaqueValue()).getPointer(CGF));
+    SuspendHelperCallArgs.push_back(
+        CGF.getOrCreateOpaqueRValueMapping(S.getOpaqueFramePtr())
+            .getScalarVal());
+    SuspendHelperCallArgs.push_back(SuspendHelper);
+
+    auto IID = llvm::Intrinsic::coro_await_suspend;
+    if (S.getSuspendExpr()->getType()->isBooleanType())
+      IID = llvm::Intrinsic::coro_await_suspend_bool;
+    else if (S.getSuspendExpr()->getType()->isVoidPointerType())
+      IID = llvm::Intrinsic::coro_await_suspend_handle;
+
+    llvm::Function *AwaitSuspendIntrinsic = CGF.CGM.getIntrinsic(IID);
+    // FIXME: add call attributes?
+    if (AwaitSuspendCanThrow)
+      SuspendRet =
+          CGF.EmitCallOrInvoke(AwaitSuspendIntrinsic, SuspendHelperCallArgs);
+    else
+      SuspendRet = CGF.EmitNounwindRuntimeCall(AwaitSuspendIntrinsic,
+                                               SuspendHelperCallArgs);
+
+    CGF.CurCoro.InSuspendBlock = false;
+  }
+
+  if (SuspendRet != nullptr) {
+    if (SuspendRet->getType()->isIntegerTy(1)) {
+      // Veto suspension if requested by bool returning await_suspend.
+      BasicBlock *RealSuspendBlock =
+          CGF.createBasicBlock(Prefix + Twine(".suspend.bool"));
+      CGF.Builder.CreateCondBr(SuspendRet, RealSuspendBlock, ReadyBlock);
+      CGF.EmitBlock(RealSuspendBlock);
+    } else if (SuspendRet->getType()->isPointerTy()) {
+      auto ResumeIntrinsic = CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_resume);
+      Builder.CreateCall(ResumeIntrinsic, SuspendRet);
+    }
----------------
ChuanqiXu9 wrote:

```suggestion
    } else
         llvm_unreachable(...);
```

nit: personal interest.

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