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After writing a simple FPRange, I've hit a stumbling block. I don't know what LLVM code should be extended to use it. I was initially thinking of extending LazyValueInfo, but it appears to be used for passes that don’t address the case that I need for Julia. I’m now wondering if I’m better off extending SimplifyFCmpI...

Yes, the modeling of floating-point is trickier. The wrap-around trick used by ConstantRange seems less applicable, and there are the unordered NaNs. Though in all cases, the key abstraction is a lattice of values, so an instance of FPRange should be thought of as a point on a lattice, not an interval. The lattice needs to be complicated enough the cover the cases of interest, but not so complicated that it gobbles up excessive time and space. My guess is that most of the cases of practical interest are eliminating domain checks an...

...;>> class, like our constant range, and go from there? >> That's certainly another way to go. My worry is that a more >> complicated lattice gets us deeper into rounding-mode issues and >> considerably more work for smaller gain. I like the idea of >> creating an FPRange class. We could start with a simple one and >> extend it as experience warrants. > I worry about that too ;) -- I think creating a simple one and extending from there makes sense. > > -Hal > >> - Arch >> >> -----Original Message----- >> From: Hal Finkel...

...are also common. Why not just add a FP range class, like our constant range, and go from there? That's certainly another way to go. My worry is that a more complicated lattice gets us deeper into rounding-mode issues and considerably more work for smaller gain. I like the idea of creating an FPRange class. We could start with a simple one and extend it as experience warrants. - Arch -----Original Message----- From: Hal Finkel [mailto:hfinkel at anl.gov] Sent: Thursday, January 8, 2015 1:03 PM To: Robison, Arch Cc: Philip Reames; llvmdev at cs.uiuc.edu Subject: Re: [LLVMdev] Floating-point...

Thanks for the pointers. Looks like LazyValueInfo has the sort of infrastructure I had in mind. LVILatticeVal could be extended to floating point. (The comment "this can be made a lot more rich in the future" is an invitation :-). I'm thinking a simple lattice would address most cases of interest for floating-point checks. The lattice points for floating-point could be all