On Thu, 26 Nov 2020, Roger Sayle wrote:
> NaNs have a sign-bit, so copyexpr (and negate and ABS_EXPR) are
> well-defined, and it's reasonable for nonnegative_p to reflect this.
> IMHO, the true bug is that we can't fold away (any) comparisons against
> NaN when flag_trapping_math, irrespective
On Thu, 26 Nov 2020, Richard Biener wrote:
> Is copysign (x, NaN) supposed to be well-defined? We'd stop folding
copysign with NaN arguments (including sNaN) is well-defined and copies
the sign bit without raising any exceptions.
> this then, no? I think the ABS_EXPR < 0 to false folding is
>
Doh! Wrong patch2.txt file. Sorry.
-Original Message-
From: Roger Sayle
Sent: 27 November 2020 10:52
To: 'Jakub Jelinek' ; 'Joseph S. Myers'
Cc: 'Richard Biener' ; 'gcc-patches@gcc.gnu.org'
Subject: RE: [PATCH] fold-const: Don't c
Hi Jakub,
Technically, PR97965 doesn't explicitly mention equality/inequality, but
you're
right, it makes sense to tackle this missed optimization at the same time as
we
fix the wrong-code.
On Thu, Nov 26, 2020, Jakub Jelinek wrote:
>On Thu, Nov 26, 2020 at 01:56:03PM -, Roger Sayle wrote:
>>
On Thu, Nov 26, 2020 at 01:56:03PM -, Roger Sayle wrote:
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -3998,7 +3998,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> (cmp @0 { build_real (TREE_TYPE (@1), dconst0); }))
> /* x != NaN is always true, other ops are always false. */
> (if
On Thu, Nov 26, 2020 at 03:13:22PM +0100, Jakub Jelinek via Gcc-patches wrote:
> On Thu, Nov 26, 2020 at 01:56:03PM -, Roger Sayle wrote:
> > My completely untested solution is the attached patch. My apologies, I'm
> > not
> > even set up to compile things on the laptop that I'm composing this
On Thu, Nov 26, 2020 at 01:56:03PM -, Roger Sayle wrote:
> My completely untested solution is the attached patch. My apologies, I'm
> not
> even set up to compile things on the laptop that I'm composing this e-mail
> on,
> but my notes/proposals on tackling PR97965 are easier expressed as the
From: Richard Biener
Sent: 26 November 2020 10:04
To: Jakub Jelinek
Cc: Joseph S. Myers ; Jason Merrill
; gcc-patches@gcc.gnu.org; ro...@nextmovesoftware.com
Subject: Re: [PATCH] fold-const: Don't consider NaN non-negative [PR97965]
On Thu, 26 Nov 2020, Jakub Jelinek wrote:
> On Thu, N
On Thu, 26 Nov 2020, Jakub Jelinek wrote:
> On Thu, Nov 26, 2020 at 09:16:29AM +, Richard Biener wrote:
> > > So, I really don't know if we want this or not, posting it for
> > > discussions.
> >
> > Is copysign (x, NaN) supposed to be well-defined? We'd stop folding
> > this then, no?
>
>
On Thu, Nov 26, 2020 at 09:16:29AM +, Richard Biener wrote:
> > So, I really don't know if we want this or not, posting it for discussions.
>
> Is copysign (x, NaN) supposed to be well-defined? We'd stop folding
> this then, no?
Yes, we'd stop folding several cases with NaNs.
> I think the
On Thu, 26 Nov 2020, Jakub Jelinek wrote:
> Hi!
>
> The testcase in the PR
> constexpr bool a = __builtin_nan ("") > 0.0;
> constexpr bool b = __builtin_nans ("") > 0.0;
> constexpr bool c = __builtin_nan ("") < 0.0;
> constexpr bool d = __builtin_nans ("") < 0.0;
> constexpr bool e = __builtin_n
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