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----- Original Message ----- > From: "Andrew Trick" <atrick at apple.com> > To: "Sanjoy Das" <sanjoy at playingwithpointers.com> > Cc: "Daniel Berlin" <dberlin at dberlin.org>, "llvm-dev" <llvm-dev at lists.llvm.org>, "Joseph Tremoulet" > <jotrem at microsoft.com>, "Oscar Blumberg"

2017-04-01 15:59 GMT+02:00 Piotr Padlewski <piotr.padlewski at gmail.com>: > > > 2017-03-31 23:20 GMT+02:00 Sanjoy Das <sanjoy at playingwithpointers.com>: > >> Hi Piotr, >> >> On March 31, 2017 at 1:07:12 PM, Piotr Padlewski >> (piotr.padlewski at gmail.com) wrote: >> > [snip] >> > Do I understand it correctly, that it is legal to

...and dereferenceable. > >> > >> What do you think about this idea? > > I'm sorry for being *this* annoying, but I'm not on board with this. :) > > I think this will run into the same dead-code-can-affect-behavior > issue discussed in https://reviews.llvm.org/D20116. > > Specifically, if your program is: > > if (false) { > ptr = load i8*, i8** %ptrptr, !dereferenceable !{i64 8, !"GlobalProperty} > // ptr is not actually dereferenceable, even the load above has UB > // (since the metadata is "wrong"), but it is never ex...

...parallel with all this, I'll try to come up with a concrete notion > of how the nospeculate attributes on loads and function calls will > look like, how it would interact with optimizations like mem2reg etc. > I'll consider potential interactions with > https://reviews.llvm.org/D20116 "Add speculatable function attribute" > and generally just kick it around to see if the idea holds up and > gives us all of the constraints we need. > > Sounds good? > -- Sanjoy > _______________________________________________ > LLVM Developers mailing list > llvm...