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From: "joseph at codesourcery dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/107370] long double sqrtl constant folding is wrong
Date: Mon, 24 Oct 2022 20:00:02 +0000	[thread overview]
Message-ID: <bug-107370-4-qcIZCLR8Q0@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-107370-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107370

--- Comment #8 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
On Mon, 24 Oct 2022, jacob at jacob dot remcomp.fr via Gcc-bugs wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107370
> 
> --- Comment #3 from jacob navia <jacob at jacob dot remcomp.fr> ---
>   1 trunk gcc:
>   2 .LC1:
>   3        .word   325511829  # 0x1366EA95 <<<--- SHOULD BE 325508205
>   4        .word   -922176773 # 0xC908B2FB OK
>   5        .word   -429395012 # 0xE667F3BC OK
>   6        .word   1073703433 # 0x3FFF6A09 OK
> 
> This data is wrong, I repeat, the first number (line 3) should be 325508205 or 
> 0x1366DC6D.

Why do you think that number is wrong?  If I compute the square root of 
2**225 using GMP (so not involving MPFR at all, just integer square root 
in GMP), I get 1366ea95 as the low 32 bits (and the next bit is a 0, so 
rounding toward 0 is correct in this case).

  parent reply	other threads:[~2022-10-24 20:00 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-24  6:11 [Bug c/107370] New: long double precision is wrong in ARM 64 jacob at jacob dot remcomp.fr
2022-10-24  6:22 ` [Bug c/107370] " jacob at jacob dot remcomp.fr
2022-10-24 15:19 ` [Bug target/107370] " pinskia at gcc dot gnu.org
2022-10-24 18:33 ` jacob at jacob dot remcomp.fr
2022-10-24 18:40 ` [Bug middle-end/107370] long double sqrtl constant folding is wrong pinskia at gcc dot gnu.org
2022-10-24 19:27 ` jakub at gcc dot gnu.org
2022-10-24 19:53 ` jacob at jacob dot remcomp.fr
2022-10-24 19:56 ` jacob at jacob dot remcomp.fr
2022-10-24 20:00 ` joseph at codesourcery dot com [this message]
2022-10-24 20:01 ` jacob at jacob dot remcomp.fr
2022-10-24 20:08 ` jacob at jacob dot remcomp.fr
2022-10-24 20:09 ` jacob at jacob dot remcomp.fr
2022-10-24 20:21 ` jakub at gcc dot gnu.org
2022-10-24 20:25 ` jakub at gcc dot gnu.org
2022-10-24 20:32 ` jakub at gcc dot gnu.org
2022-10-24 20:50 ` jacob at jacob dot remcomp.fr
2022-10-24 20:51 ` jacob at jacob dot remcomp.fr
2022-10-24 20:56 ` jacob at jacob dot remcomp.fr
2022-10-24 20:59 ` jacob at jacob dot remcomp.fr
2022-10-24 21:01 ` jacob at jacob dot remcomp.fr
2022-10-24 21:02 ` jakub at gcc dot gnu.org
2022-10-24 21:03 ` jacob at jacob dot remcomp.fr
2022-10-24 21:06 ` jacob at jacob dot remcomp.fr
2022-10-24 21:09 ` jakub at gcc dot gnu.org
2022-10-24 21:26 ` jacob at jacob dot remcomp.fr
2022-10-24 21:29 ` pinskia at gcc dot gnu.org
2022-10-24 21:31 ` pinskia at gcc dot gnu.org

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