similar to: Combining fast math flags with constrained intrinsics

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

----- Original Message ----- > From: "Sanjay Patel" <spatel at rotateright.com> > To: "Hal J. Finkel" <hfinkel at anl.gov> > Cc: "Mehdi Amini" <mehdi.amini at apple.com>, "llvm-dev" > <llvm-dev at lists.llvm.org>, "cfe-dev" <cfe-dev at lists.llvm.org>, > "andrew kaylor" <andrew.kaylor at

Sent from my Verizon Wireless 4G LTE DROID On Nov 17, 2016 5:53 PM, Mehdi Amini <mehdi.amini at apple.com<mailto:mehdi.amini at apple.com>> wrote: > > >> On Nov 17, 2016, at 4:33 PM, Hal Finkel <hfinkel at anl.gov<mailto:hfinkel at anl.gov>> wrote: >> >> >> ________________________________ >>> >>> From: "Warren

> On Mar 15, 2017, at 2:00 PM, Hal Finkel <hfinkel at anl.gov> wrote: > > > On 03/15/2017 01:47 PM, Adam Nemet wrote: >> >>> On Mar 15, 2017, at 11:36 AM, Mehdi Amini <mehdi.amini at apple.com <mailto:mehdi.amini at apple.com>> wrote: >>> >>> >>>> On Mar 15, 2017, at 10:13 AM, Hal Finkel via cfe-dev <cfe-dev at

> On Mar 15, 2017, at 2:30 PM, Hal Finkel <hfinkel at anl.gov> wrote: > > > On 03/15/2017 04:05 PM, Adam Nemet wrote: >> >>> On Mar 15, 2017, at 2:00 PM, Hal Finkel <hfinkel at anl.gov <mailto:hfinkel at anl.gov>> wrote: >>> >>> >>> On 03/15/2017 01:47 PM, Adam Nemet wrote: >>>> >>>>> On Mar

Hi Sanjay, You are right. I tried XL and gcc 4.8.2 for PPC and I also got multiply-and-add operations. I supported my statement on what I read in the gcc man page. -ffast-math is used in clang to set fp-contract to fast (default is standard) and in gcc it activates (among others) the flag -funsafe-math-optimizations whose description includes: "Allow optimizations for floating-point

On 05/23/2018 11:06 AM, Hubert Tong via llvm-dev wrote: > Hi Ulrich, > > I am interested in knowing if the current proposals also take into > account the FP_CONTRACT pragma We should already do this (we turn relevant operations into the @llvm.fmuladd. when FP_CONTRACT is set to on during IR generation). > and the ability to implement options that imply a specific value for >

On 03/16/2017 04:13 PM, Adam Nemet wrote: > >> On Mar 15, 2017, at 2:51 PM, Adam Nemet <anemet at apple.com >> <mailto:anemet at apple.com>> wrote: >> >>> >>> On Mar 15, 2017, at 2:30 PM, Hal Finkel <hfinkel at anl.gov >>> <mailto:hfinkel at anl.gov>> wrote: >>> >>> >>> On 03/15/2017 04:05 PM, Adam

On Wed, May 23, 2018 at 12:19 PM, Hal Finkel <hfinkel at anl.gov> wrote: > > On 05/23/2018 11:06 AM, Hubert Tong via llvm-dev wrote: > > Hi Ulrich, > > I am interested in knowing if the current proposals also take into account > the FP_CONTRACT pragma > > > We should already do this (we turn relevant operations into the > @llvm.fmuladd. when FP_CONTRACT is

> On Mar 15, 2017, at 11:36 AM, Mehdi Amini <mehdi.amini at apple.com> wrote: > > >> On Mar 15, 2017, at 10:13 AM, Hal Finkel via cfe-dev <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote: >> >> >> On 03/15/2017 12:10 PM, Adam Nemet via llvm-dev wrote: >>> Relevant to this discussion is

> On Mar 16, 2017, at 4:04 PM, Adam Nemet via cfe-dev <cfe-dev at lists.llvm.org> wrote: > >> >> On Mar 16, 2017, at 3:25 PM, Hal Finkel <hfinkel at anl.gov <mailto:hfinkel at anl.gov>> wrote: >> >> >> >> On 03/16/2017 04:13 PM, Adam Nemet wrote: >>> >>>> On Mar 15, 2017, at 2:51 PM, Adam Nemet <anemet at

A little background: The fmuladd intrinsic was introduced to support the FP_CONTRACT pragma in C. llvm.fmuladd.* is generated by clang when it sees an expression of the form 'a * b + c' within a single source statement. If you want to opportunistically form FMA target instructions my inclination would be to skip llvm.fmuladd.* and just form them from a*b+c expressions at isel time. I

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

Copying the list on a discussion of potentially general interest.... From: Kaylor, Andrew Sent: Friday, November 03, 2017 1:11 PM To: 'Ding, Wei' <Wei.Ding2 at amd.com>; Sumner, Brian <Brian.Sumner at amd.com>; Arsenault, Matthew <Matthew.Arsenault at amd.com> Subject: RE: clarification needed for the constrained fp implementation. Hi Wei, I've been meaning to

On 15 March 2017 at 14:58, Hal Finkel <hfinkel at anl.gov> wrote: > When you reverted r282259 in 282289, you also reverted the functional fix > to make the command-line option actually work. Right now it is broken. > Regardless of what else we do, we should fix this (we should probably > recommit r282259, with the default flipped, to pick up the fixes). We should run check-all

Folks, I've been asking around people about the state of FP contract, which seems to be "on" but it's not really behaving like it, at least not as I would expect: int foo(float a, float b, float c) { return a*b+c; } $ clang -target aarch64-linux-gnu -O2 -S fma.c -ffp-contract=on -o - (...) fmul s0, s0, s1 fadd s0, s0, s2 (...) $ clang -target aarch64-linux-gnu -O2 -S fma.c

Hi Ulrich, I am interested in knowing if the current proposals also take into account the FP_CONTRACT pragma and the ability to implement options that imply a specific value for the FLT_EVAL_METHOD macro. Additionally, I am not aware of the IR being able to represent the potentially deferred loss of precision that the C language semantics provide; in particular, applying such semantics to the

This is just paraphrasing from D26602, so credit to Nicolai for first raising the issue there. float foo(float x, float y) { return x * (y + 1); } $ ./clang -O2 xy1.c -S -o - -target aarch64 -ffp-contract=fast | grep fm fmadd s0, s1, s0, s0 Is this a bug? We transformed the original expression into: x * y + x When x=INF and y=0, the code returns INF if we don't reassociate. With

On 11/03/2017 05:26 PM, 陳韋任 via llvm-dev wrote: > > > 2017-11-04 4:29 GMT+08:00 Kaylor, Andrew via llvm-dev > <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>>: > > Copying the list on a discussion of potentially general interest…. > > *From:* Kaylor, Andrew > *Sent:* Friday, November 03, 2017 1:11 PM > *To:* 'Ding,

Hello, at the recent EuroLLVM developer meeting in Bristol I held a BoF session on the topic "Towards implementing #pragma STDC FENV_ACCESS". I've also had a number of follow-on discussions both on-site in Bristol and online since. This post is intended as a summary of my current understanding set of requirements and implementation details covering the overall topic. I'm