similar to: [RFC] Add support for options -fp-model= and -fp-speculation= : specify floating point behavior

About ftrapping-math: I think we should eliminate ftrapping-math, a boolean option, because it overlaps with ffp-exception-behavior, a 3 valued option. Or we can keep it in the clang driver for compatibility, but it should be rewritten by clang driver into ffp-exception-behavior=ignore and ffp-exception-behavior=strict. There are various fields in llvm and/or clang that maintain Boolean

> ... math errno ... I wouldn't recommend to anyone that they should rely on math errno (because I don't trust libraries to correctly support it). My goal here was to incorporate our existing support for it into the rest of what I'm trying to document. My understanding is that for clang this primarily controls whether or not we feel free to substitute intrinsics for recognized

Hi all, I'm trying to put together a set of rules for how the various floating point semantic modes should be handled in clang. A lot of this information will be relevant to other front ends, but the details are necessarily bound to a front end implementation so I'm framing the discussion here in terms of clang. Other front ends can choose to follow clang or not. The existence of this set

Hi, this is an RFC for optional, named parameter tuples for intrinsics. The proposed syntax is: %z = call @llvm.some.intrinsic(%a, %b) optional_tuple(%x, %y, %z) where from the perspective of the call site %x, %y and %z are simply additional parameters. Optional parameter tuples would be very useful for constrained fp intrinsics and vector predication. Some examples: ; Default fpenv fadd

Let me clarify. These aren’t intended to be exposed to the user. The user code that leads to the generation of these intrinsics will be normal floating point operations combined with either pragmas (such as “STDC FENV_ACCESS ON”) or command line options (such as the recently introduced “-fp-model=strict”). The reason I’ve been avoiding normal constant values is that it provides no information when

Hello everyone, I've just uploaded a patch (https://reviews.llvm.org/D70261) to introduce a could of new token types to be used with constrained floating point intrinsics and, optionally, vector predicated intrinsics. These intrinsics may not be of interest to many of you, but I have a more general question. I would like some general feedback on the way I am proposing to use token arguments

I've got a ticket open where I would very much like some input from maintainers of other languages that rely on llvm and use the IRBuilder. See: Teach the IRBuilder about constrained fadd and friends: https://reviews.llvm.org/D53157 I'm adding support to functions like CreateFAdd() the ability to optionally emit the constrained math intrinsics required to support strict floating point

Hi: I am trying to implement interval arithmetic through llvm. I have a problem with the rounding mode with llvm.experimental.constrained.cos I have two pieces of codes: ; Function Attrs: norecurse nounwind readnone ssp uwtable define double @cosine_down(double returned) local_unnamed_addr #0 {   ; call the llvm intrinsic to perform downward cosine

Hi All, Ok, just for the matter of providing feedback that may be useful for others, I figured out one way to do it based on the setup that I described earlier. It can be something like this git checkout patchbranch # checkout to the patch branch, this is the one containing the differential patch code git checkout -b tmp # checkout to a new tmp branch git reset —soft master

Hi Craig: I tried that, now the function is like this: ; Function Attrs: norecurse nounwind readnone ssp uwtable define { double, double } @add(double, double, double, double) local_unnamed_addr #0 {   %5 = call double @llvm.experimental.constrained.fadd(double %0, double %2, metadata !"round.downward", metadata !"fpexcept.ignore")   %6 = fadd double %1, %3

We really have been trying to keep in mind that LLVM needs to support multiple front ends, which may be implementing different language standards. As much as possible, I’ve been trying to let the IEEE 754 spec drive my thinking about this, though I’ll admit that on a few points I’ve use the C99 spec as a sort of reference interpretation of IEEE 754. LLVM’s IRBuilder has been recently updated to

Hi Craig: It’s llvm 10.1 I think, I did the same thing, removing everything except the code block but still failed with llvm-as. Thank you Xuan Tang On Sep 3, 2020, 20:14 -0500, Craig Topper <craig.topper at gmail.com>, wrote: > I just pasted that code and ran it through llc, opt, and llvm-as. All passed without issue. What version of llvm are you using? > > ~Craig > > >

Hi: Sorry I need to send email directly. I am new to llvm and trying to write interval arithmetic, which requires changing rounding mode during computation. The document I found https://llvm.org/docs/LangRef.html#constrained-floating-point-intrinsics, seems to be doing the trick. Here is the piece of code that I did:

Yes, you’re probably right about this. I was originally thinking of FENV_ACCESS as a fully strict mode of operation, but what you’re suggesting aligns with what Cameron suggested and even some of my own reasoning on other points. So, let me amend my previous proposal to say: STDC FENV_ACCESS {ON|OFF} Patch in progress. I think ON should force the following: except_behavior { strict }

Some clarification after getting feedback from Craig Topper…. It’s probably best to say in the documentation that the llvm.nearbyint and llvm.rint functions “assume the default rounding mode, roundToNearest”. This will allow the optimizer to transform them as if they were rounding to nearest without requiring backends to use an encoding that enforces roundToNearest as the rounding mode for these

On Fri, Jan 17, 2020 at 8:09 PM Finkel, Hal J. <hfinkel at anl.gov> wrote: > Andy, thanks for writing this up. A few thoughts: > > 1. The mental model that I have is that there is always an FP_CONTRACT pragma: there's some default (implicit) pragma at the beginning, and what it says (off/on/fast) is controlled by the command-line flags (or the driver's default if no flags

> > The only issue I see is that since we also assume FP operations have no > side effects by default there is no difference between llvm.rint and > llvm.nearbyint. I wouldn’t have a problem with dropping llvm.rint > completely. The forthcoming C standard ( http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2454.pdf, 7.12.9.8) defines new function, `roundeven`, which implements

Hi, The ComputeSpeculationCost() function in Transforms/Utils/SimplifyCFG.cpp uses a higher speculation cost for Select than other instructions. Does anyone know why this is? I would like SimplifyCFG to be able to speculatively execute Select instructions. Which of these solutions makes the most sense: 1. Change speculation cost of Select from 2 to 1. 2. Add a TargetTransformInfo callback

>What situations are they common in? ICC Vectorizer made a paradigm shift a while ago. If there aren’t a clear reason why something can’t be vectorized, we should try our best to vectorize. The rest is a performance modeling (and priority to implement) question, not a capability question. We believe this is a good paradigm to follow in a vectorizer development. It was a big departure from

> > One concern with replacing llvm.rint and llvm.nearbyint with > llvm.roundeven makes it difficult to turn back into a libcall if the > backend doesn't have an instruction for it. You can't just call the > roundeven library function since that wouldn't exist in older libm > implementations. So ideally you would know which function was originally > used in the