ChuanqiXu added a comment. In D100739#2700324 <https://reviews.llvm.org/D100739#2700324>, @ychen wrote:
> In D100739#2700273 <https://reviews.llvm.org/D100739#2700273>, @ChuanqiXu > wrote: > >> I hadn't looked into the details. I would try to make it. >> But from my understanding to this problem, the correct solution should >> remain the previous behavior if the end user doesn't specify `alignas` for >> `promise_type`. I mean, it shouldn't make so many test cases fail. > > The failures mostly are due to the `llvm.coro.size()` -> `llvm.coro.size(i1 > alloc)` intrinsic signature change. The rest are due to the `align` arg of > `llvm.coro.id` is illegal 0 in most of the tests. This patch would read that > value causing asssertions. > >>> The alloca of the raw frame pointer (suppose we insert it in the frontend) >>> would be included in the non-overaligned frame if we don't teach CoroFrame >>> how to elide it. >> >> It is confusing to me, maybe I need to look into the codes. First, the raw >> frame pointer isn't inserted in the frontend. Do you mean coro.begin? Then, >> what's the relationship between eliding and over-aligned? It also makes me >> confused. > > Since we don't know if the frame is overaligned or not until after the frame > type is decided in CoroFrame, *suppose* we do this (adding raw frame ptr > alloca in frontend regardless of the presence of overalignment or not) in the > frontend, the code generated from CGCoroutine would be like this: > > %1 = alloc i8* > %2 = malloc(x) > store %2, %1 > .. > .. > %11 = load %1 > free(%11) > > The alloca `%1` must be there even if the frame is not aligned. Then in the > CoroFrame, we have to check if the frame is really overaligned and if not, > reverse the above patterns. Otherwise, the alloca `%1` would be in the frame > needlessly and the following optimizations could not reliably remove it. > > This patch defers adding the alloca until CoroFrame where we know for sure > that the frame is aligned. The semantics of alloca and free in the example look similar with coro.begin and coro.end. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D100739/new/ https://reviews.llvm.org/D100739 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
