similar to: [cfe-dev] Why is #pragma STDC FENV_ACCESS not supported?

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 }

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

Ulrich Weigand/Germany/IBM wrote on 06.03.2018 16:07:34: > So it appears to me that if we need a chain (or control register > dependencies etc.), it would be easier on the back-end anyway to > have a different ISD node, in which case it just might be the easiest > to pass the STRICT_ nodes through to the back-end if it wants ... > > I'll try and go ahead with the SystemZ

> On Jan 9, 2018, at 11:04 AM, Kevin P. Neal via cfe-dev <cfe-dev at lists.llvm.org> wrote: > >> On 01/08/2018 07:06 PM, Richard Smith via llvm-dev wrote: >> >> On 8 January 2018 at 11:15, Kaylor, Andrew via llvm-dev >> <[1]llvm-dev at lists.llvm.org> wrote: >> >> Hi Kevin, >> Thanks for reaching out about this, and

I know next to nothing about the AST, so I'll leave commentary on that to someone who does except to say that I don't believe there is a strong connection between Richard's suggestion and Hal's. An IRBuilder can be created anywhere (and is frequently used in the optimizer). When the front end support is implemented it may use an IRBuilder that leverages the state Hal is suggesting,

APFloat is derived from C code using fixed width storage for the matntissa. When converting to C++ I changed it to variable- width storage for space efficiency and generality reasons. Unfortunately this leads to a complication during float->float conversions that I missed that isn't present when using fixed width storage. Dale - I think this solves the issue correctly whilst preserving

Oh, and other thing: Are you planning to attend the upcoming LLVM developer's meeting in Bristol? I thought it might be good idea to get all parties interested in this feature together in person, if we're at the same meeting anyway. So I was thinking of submitting a proposal for a BoF session on this topic ... Mit freundlichen Gruessen / Best Regards Ulrich Weigand -- Dr. Ulrich

We use .note descriptors with ELF on OpenVMS.  We have self-describing entries with tags and lengths.  The compiler encodes stuff for the linker such as compiler version, compilation date-time, module name, final severity of the compilation, etc.  The linker itself then adds/modifies the .note entries to insert linker version, link date/time, etc.  We also use .notes to record floating point

> ... 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

I'm working with Andrew on D43515 right now, and some of these unanswered questions are directly relevant to that patch. So.... On Fri, Feb 09, 2018 at 03:42:20PM +0100, Ulrich Weigand wrote: > C) Floating-point exceptions > If a mask bit in the floating-point status register is set, then all FP > instructions will *trap* whenever an IEEE exception condition is >

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 Andrew, sorry for the delay, I only now got some time to look into this a bit more. But I still have a number of questions of how to actually implement this in the back end. Looking at this bottom-up, starting with the behavior of the actual machine instructions, we have (at least on SystemZ) the following things to consider: A) Rounding mode Most FP arithmetic instructions use the

On Tue, Jan 09, 2018 at 06:53:51PM +0000, Kaylor, Andrew via cfe-dev wrote: > I think we're going to need to create a new mechanism to communicate > strict FP modes to the backend. I think we need to avoid doing anything > that will require re-inventing or duplicating all of the pattern > matching that goes on in instruction selection (which is the reason >

On 8 January 2018 at 11:15, Kaylor, Andrew via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Hi Kevin, > > Thanks for reaching out about this, and thanks especially for offering to > help. I've had some other priorities that have prevented me from making > progress on this recently. > > As far as I know, there is no support at all in clang for handling the >

On 8 Jan 2018 19:50, "Hal Finkel via cfe-dev" <cfe-dev at lists.llvm.org> wrote: On 01/08/2018 07:06 PM, Richard Smith via llvm-dev wrote: On 8 January 2018 at 11:15, Kaylor, Andrew via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Hi Kevin, > > Thanks for reaching out about this, and thanks especially for offering to > help. I've had some other

>The standard argument against trying to introduce "scope-like" mechanisms to LLVM IR is inlining; >unless you're going to prevent functions that use stricter/laxer FP rules from being inlined >into >each other (which sounds disastrous), you're going to need to communicate strictness on an >instruction-by-instruction basis. If the backend wants to handle that by

On 9 Jan 2018 22:55, "John McCall via llvm-dev" <llvm-dev at lists.llvm.org> wrote: On Jan 9, 2018, at 3:50 PM, Kaylor, Andrew <andrew.kaylor at intel.com> wrote: >The standard argument against trying to introduce "scope-like" mechanisms to LLVM IR is inlining; >unless you're going to prevent functions that use stricter/laxer FP rules from being inlined

I think we're going to need to create a new mechanism to communicate strict FP modes to the backend. I think we need to avoid doing anything that will require re-inventing or duplicating all of the pattern matching that goes on in instruction selection (which is the reason we're currently dropping that information). I'm out of my depth on this transition, but I think maybe we could

Hi All, APFloat::fusedMultiplyAdd currently computes the wrong signed zero when small negative results are truncated back to zero in standard precision. The following snippet handles the signedness in fusedMultiplyAdd: /* If two numbers add (exactly) to zero, IEEE 754 decrees it is a positive zero unless rounding to minus infinity, except that adding two like-signed zeroes gives that

Hi Mehdi, Thanks for the feedback. I think the comment is fine - the problem is just that the original conditional didn't exactly match it. With the addition of the underflow check I believe the condition now matches the comment: The sign is only tweaked if the result of the addition is exactly zero, rather than a small result that truncates to zero. CC'ing llvm-commits, where this email