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Re: m4-1.4.9b on HP-UX 11
From: |
Bruno Haible |
Subject: |
Re: m4-1.4.9b on HP-UX 11 |
Date: |
Mon, 4 Jun 2007 04:24:26 +0200 |
User-agent: |
KMail/1.5.4 |
Albert Chin wrote:
> From the cc(1) man page:
> +O[no]fltacc Disable [enable] floating-point optimizations that
> can result in numerical differences.
> ...
> So, +Onofltacc disables floating-point optimizations.
I interpret this differently:
+Ofltacc Disable floating-point optimizations that
can result in numerical differences.
+Onofltacc enable floating-point optimizations that
can result in numerical differences.
This is consistent with the other parts of the doc, combined:
> +Ofltacc is the same as +Ofltacc=strict.
> +Onofltacc is the same as +Ofltacc=relaxed.
> ...
> limited
> Like default, but also allows floating
> point optimizations which may affect the
> generation and propagation of
> infinities, NaNs, and the sign of zero.
>
>
> relaxed
> In addition to the optimizations allowed
> by limited, permits optimizations, such
> as reordering of expressions, even if
> parenthesized, that may affect rounding
> error. This is the same as +Onofltacc.
Hence, "limited" and "relaxed" are not IEEE-754-safe optimizations.
Bruno