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Re: Architecture floating-point underflow information wanted
- From: Andreas Schwab <schwab at linux-m68k dot org>
- To: "Joseph S. Myers" <joseph at codesourcery dot com>
- Cc: <libc-alpha at sourceware dot org>, <libc-ports at sourceware dot org>, Andreas Krebbel <krebbel at linux dot vnet dot ibm dot com>, Richard Henderson <rth at twiddle dot net>, Mark Salter <msalter at redhat dot com>, Carlos O'Donell <carlos at systemhalted dot org>, Mike Frysinger <vapier at gentoo dot org>
- Date: Tue, 25 Sep 2012 20:10:47 +0200
- Subject: Re: Architecture floating-point underflow information wanted
- References: <Pine.LNX.4.64.1209251238230.12872@digraph.polyomino.org.uk>
"Joseph S. Myers" <joseph@codesourcery.com> writes:
> #include <fenv.h>
> #include <stdio.h>
>
> volatile float a = 0x1.fffp-126;
> volatile float b = 0x1.0008p-1;
> volatile float c;
>
> int
> main (void)
> {
> feclearexcept (FE_ALL_EXCEPT);
> c = a * b;
> if (fetestexcept (FE_UNDERFLOW))
Does this really give the correct result for FLT_EVAL_METHOD != 0? I
think for those archs you have to set the rounding mode to float to be
accurate.
Andreas.
--
Andreas Schwab, schwab@linux-m68k.org
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