================ @@ -1744,6 +1744,273 @@ a call to ``llvm.coro.suspend.retcon`` after resuming abnormally. In a yield-once coroutine, it is undefined behavior if the coroutine executes a call to ``llvm.coro.suspend.retcon`` after resuming in any way. +.. _coro.await.suspend: + +'llvm.coro.await.suspend' Intrinsic +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +:: + + declare void @llvm.coro.await.suspend( + ptr <awaiter>, + ptr <handle>, + ptr <await_suspend_function>) + +Overview: +""""""""" + +The '``llvm.coro.await.suspend``' intrinsic hides C++ `await-suspend` +block code from optimizations on presplit coroutine body +to avoid miscompilations. This version of intrinsic corresponds to +'``void awaiter.await_suspend(...)``' variant. + +Arguments: +"""""""""" + +The first argument is a pointer to `awaiter` object. + +The second argument is a pointer to the current coroutine's frame. + +The third argument is a pointer to the helper function encapsulating +`await-suspend` logic. Its signature must be + +.. code-block:: llvm + + declare void @await_suspend_function(ptr %awaiter, ptr %hdl) + +Semantics: +"""""""""" + +The intrinsic must be used between corresponding `coro.save`_ and +`coro.suspend`_ calls. It is lowered to an inlined +`await_suspend_function` call during `CoroSplit`_ pass. + +Example: +"""""""" + +.. code-block:: llvm + + ; before lowering + await.suspend: + %save = call token @llvm.coro.save(ptr %hdl) + call void @llvm.coro.await.suspend( + ptr %awaiter, + ptr %hdl, + ptr @await_suspend_function) + %suspend = call i8 @llvm.coro.suspend(token %save, i1 false) + ... + + ; after lowering + await.suspend: + %save = call token @llvm.coro.save(ptr %hdl) + ; the call to await_suspend_function is inlined + call void @await_suspend_function( + ptr %awaiter, + ptr %hdl) + %suspend = call i8 @llvm.coro.suspend(token %save, i1 false) + ... + + ; helper function example + define void @await_suspend_function(ptr %awaiter, ptr %hdl) + entry: + %hdl.tmp = alloca %"struct.std::coroutine_handle" + %hdl.result.tmp = alloca %"struct.std::coroutine_handle" + %hdl.promise.tmp = alloca %"struct.std::coroutine_handle.0" + %hdl.promise = call ptr @"std::corouine_handle<promise_type>::from_address"(ptr %hdl) + %hdl.promise.tmp.dive = getelementptr inbounds %"struct.std::coroutine_handle.0", + ptr %hdl.promise.tmp, i32 0, i32 0 + %hdl.promise.tmp.dive2 = getelementptr inbounds %"struct.std::coroutine_handle", + ptr %hdl.promise.tmp.dive, i32 0, i32 0 + store ptr %hdl.promise, ptr %hdl.promise.tmp.dive2 + call void @llvm.memcpy.p0.p0.i64(ptr %hdl.tmp, ptr %hdl.promise.tmp, i64 8, i1 false) + %hdl.tmp.dive = getelementptr inbounds %"struct.std::coroutine_handle", + ptr %hdl.tmp, i32 0, i32 0 + %hdl.arg = load ptr, ptr %hdl.tmp.dive ---------------- fpasserby wrote:
Reduced the amount of IR https://github.com/llvm/llvm-project/pull/79712 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
