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From: Joseph Myers <>
To: Xi Ruoyao <>
Cc: Lulu Cheng <>, <>,
	Wang Xuerui <>, Chenghua Xu <>,
	Xiaolin Tang <>
Subject: Re: [PATCH v2 2/4] LoongArch: Add ftint{,rm,rp}.{w,l}.{s,d} instructions
Date: Fri, 11 Nov 2022 00:07:04 +0000	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

[-- Attachment #1: Type: text/plain, Size: 1450 bytes --]

On Thu, 10 Nov 2022, Xi Ruoyao via Gcc-patches wrote:

> Joseph: can you confirm that -ftrapping-math allows floor and ceil to
> raise inexact exception?  The man page currently says:
> The default is -ffp-int-builtin-inexact, allowing the exception to be
> raised, unless C2X or a later C standard is selected.  This option does 
>                                                        ^^^^^^^^^^^
> nothing unless -ftrapping-math is in effect.
> To me it's not very clear that "this option" stands for -fno-fp-int-
> builtin-inexact or -ffp-int-builtin-inexact.

The -ftrapping-math option (which is on by default) means that we care 
about whether operations raise exceptions: they should raise exceptions if 
and only if the relevant standard permit them to do so.

The combination of -ftrapping-math with -fno-fp-int-builtin-inexact means 
the listed built-in functions must not raise "inexact".

If -fno-trapping-math is used, then we don't care about whether exceptions 
are raised or not (for any floating-point operations, not just those 
functions).  So given -fno-trapping-math, there is no difference between 
-fno-fp-int-builtin-inexact and -ffp-int-builtin-inexact.

If -ffp-int-builtin-inexact (default before C2X), we don't care about 
whether those functions raise "inexact" (but still care about other 
exceptions and exceptions for other operations, unless 

Joseph S. Myers

  reply	other threads:[~2022-11-11  0:07 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-09 13:53 [PATCH v2 0/4] LoongArch: Add some floating-point operations Xi Ruoyao
2022-11-09 13:53 ` [PATCH v2 1/4] LoongArch: Rename frint_<fmt> to rint<mode>2 Xi Ruoyao
2022-11-10  8:15   ` Lulu Cheng
2022-11-09 13:53 ` [PATCH v2 2/4] LoongArch: Add ftint{,rm,rp}.{w,l}.{s,d} instructions Xi Ruoyao
2022-11-10  6:41   ` Lulu Cheng
2022-11-10  8:49     ` Xi Ruoyao
2022-11-11  0:07       ` Joseph Myers [this message]
2022-11-11  5:29         ` Xi Ruoyao
2022-11-12  1:58           ` Lulu Cheng
2022-11-09 13:53 ` [PATCH v2 3/4] LoongArch: Add fscaleb.{s,d} instructions as ldexp{sf,df}3 Xi Ruoyao
2022-11-12  3:54   ` Lulu Cheng
2022-11-12  4:40     ` Xi Ruoyao
2022-11-12  6:52       ` Lulu Cheng
2022-11-09 13:53 ` [PATCH v2 4/4] LoongArch: Add flogb.{s,d} instructions and expand logb{sf,df}2 Xi Ruoyao
2022-11-12  6:51   ` Lulu Cheng
2022-11-12  7:08 ` [PATCH v2 0/4] LoongArch: Add some floating-point operations Xi Ruoyao
2022-11-12  7:14   ` Lulu Cheng
2022-11-14  2:41   ` tangxiaolin

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