similar to: [RFC] LLVM Coroutines

Hi Eli: >> semantics of the fork intrinsic... thinking about it a bit more, I think >> you're going to run into problems with trying to keep around a return block >> through optimizations: How about this? Make all control flow explicit (duh). declare i8 coro.suspend([...]) returns: 0 - resume 1 - cleanup anything else - suspend Now we can get

On Fri, Jun 10, 2016 at 5:25 PM, Gor Nishanov <gornishanov at gmail.com> wrote: > Hi Eli: > > >> Naively, you would expect that it would be legal to hoist the store... > >> but that breaks your coroutine semantics because the global could be > mutated > >> between the first return and the resume. > > Hmmm... I don't see the problem. I think

Hi Eli: Thank you very much for your comments! >> If you need some sort of unusual control flow construct, make it a >> proper terminator instruction I would love to. I was going by the advice in "docs/ExtendingLLVM.rst": "WARNING: Adding instructions changes the bitcode format, and it will take some effort to maintain compatibility with the previous

On Fri, Jun 10, 2016 at 6:36 AM, Gor Nishanov <gornishanov at gmail.com> wrote: > >> If you're going down that route, that still leaves the question of the > >> semantics of the fork intrinsic... thinking about it a bit more, I think > >> you're going to run into problems with trying to keep around a return > block > >> through optimizations:

Hi Sanjoy, >> I'm not familiar with fiber-type APIs, but I assume fiber_fork is like >> setjmp, in that it can "return twice"? Yes, user-mode stack switching API are somewhat similar to setjmp. Here are links to a doc page and implementation, just in case you are curious: http://www.boost.org/doc/libs/1_59_0/libs/context/doc/html/context/context.html

Hi Eli: >> Block1: >> %0 = call i8 coro.suspend() >> switch i8 %0, label suspend1 [i8 0 %return] ; or icmp + br i1 >> Suspend1: >> switch i8 %0, label %resume1 [i8 1 %destroy1] ; or icmp + br i1 >> >> This doesn't look right: intuitively the suspend happens after the return >> block runs. Perhaps, but, that is not the intended

cc llvm-dev On Thu, Jul 21, 2016 at 9:57 AM, Vadim Chugunov <vadimcn at gmail.com> wrote: > Hi Gor, > Does you design support resumption with parameter(s)? (such as Python's > generator.send(x)). I suppose the "promise" could be used for passing data > both ways, but if that's the plan, please mention this explicitly in the > design doc. > Also, how is

(Dropped llvm-dev by accident. Putting it back) HI Eli: >> coro.barrier() doesn't work: if the address of the alloca doesn't escape, >> alias analysis will assume the barrier can't read or write the value of >> the alloca, so the barrier doesn't actually block code movement. Got it. I am new to this and learning a lot over the course of this thread. Thank you

Hi all: Below is a proposal to add experimental coroutine support to LLVM. Though this proposal is motivated primarily by the desire to support C++ Coroutines [1], the llvm representation is language neutral and can be used to support coroutines in other languages as well. Clang + llvm coroutines allows you to take this code: generator<int> range(int from, int to) { for(int i =

Hi all: I've included below a brief description of coroutine related optimization passes and some questions/thoughts related to them. Looking forward to your feedback, comments and questions. Thank you! Roadmap: ======== 1) Get agreement on coroutine representation and overall direction. .. repeat 1) until happy http://lists.llvm.org/pipermail/llvm-dev/2016-June/100838.html (Initial)

Hi Sanjoy: >> Now in the above CFG %val can be folded to 10, but in reality you need >> a PHI of 10 and 20 Quick answer: folding %val to 10 is OK, but, I would prefer it to be 'undef' or even catch it in the verifier as it is a programmer/frontend error. Details are in the second half of my reply. I would like to start with the thought experiment you suggested, as it might

Hi David: >> How do you deal with basic blocks which appear to be used by multiple parts >> of the coroutine? We handled this in WinEHPrepare by cloning any BBs which >> were shared. I experimented with several approaches, but, cloning ended up being the simplest and most reliable. Suspend points express three different control flows that can happen at the suspend point: a

I think I got it. Original model (with coro.fork and two-way coro.suspend) will work with a tiny tweak. In the original model, I was replacing coro.suspend with br %return in original function. The problem was coming from potential phi-nodes introduces into return block during optimizations. Let's make sure that there is only entry into the return block. In the original model, ReturnBB had

Hello all, It's been a month since my previous email on the topic, and since then I've done some initial work on porting the coroutines passes to the new pass manager. In total there are 6 patches -- that's a lot to review, so allow me to introduce the changes being made in each of them. # What's finished In these first 6 patches, I focused on lowering coroutine intrinsics

Hi, I would like to propose a potential solution to a bug that involves coroutine and pthread_self(). Description of the bug can be found in https://bugs.llvm.org/show_bug.cgi?id=47833. Below is a summary: pthread_self() from glibc is defined with "__attribute__ ((__const__))". The const attribute tells the compiler that it does not read nor write any global state and hence always

I have this input IR in the final cleanup block of my coroutine: // call the free function call fastcc void %22(%Allocator* %20, %"[]u8"* byval %4), !dbg !244 // based on whether this is an early return or a normal return, we want to // either return to the caller, or resume the handle of the awaiter br i1 %19, label %Resume, label %Return, !dbg !244 Resume:

Hello all! (+cc Vedant Kumar, who I've been told knows a lot about UBSan!) I am trying to fix an assert that occurs when the transforms in llvm/lib/Transforms/Coroutines are applied to LLVM IR that has been generated with UBSan enabled -- specifically, '-fsanitize=null'. You can see an example of the assert in this 26-line C++ file here: https://godbolt.org/g/Gw9UZq Note that

It makes sense that you would be able to do this: %save1 = llvm.coro.save() %unused = musttail call llvm.coro.resume(%some_handle) %x = llvm.coro.suspend() ... But the docs for musttail say: > The call must immediately precede a ret instruction, or a pointer bitcast followed by a ret instruction. Should this be amended to allow a musttail to be followed by llvm.coro.suspend() ? Regards,

> On Mar 19, 2018, at 3:44 PM, Brian Gesiak <modocache at gmail.com> wrote: > > Hello all! > (+cc Vedant Kumar, who I've been told knows a lot about UBSan!) > > I am trying to fix an assert that occurs when the transforms in llvm/lib/Transforms/Coroutines are applied to LLVM IR that has been generated with UBSan enabled -- specifically, '-fsanitize=null'. >

I'm going to show the same function, first normally, and then as a coroutine, and show how gdb can see the variable when it's a normal function, but not when it's a coroutine. I'd like to understand if this can be improved. I'm trying to debug a real world problem, but the lack of debug info on variables in coroutines is making it difficult. Should I file a bug? Is this a