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Re: [Qemu-devel] [PATCH 08/19] target-alpha: use new float64_unordered()
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH 08/19] target-alpha: use new float64_unordered() function |
Date: |
Thu, 14 Apr 2011 16:39:21 +0100 |
On 14 April 2011 16:14, Richard Henderson <address@hidden> wrote:
> On 04/14/2011 02:14 AM, Peter Maydell wrote:
>> While we're on the subject of Alpha and flush-to-zero modes,
>> do you know what exception bits should get set when Alpha
>> flushes a denormal output (not input) to zero?
> ...
>> I think Alpha should set Inexact and not Underflow, but
>> I'm not sure -- can you confirm/deny?
>
> Deny.
>
> Page B-8, Add Sub Output Exceptions,
>
> Exponent underflow and disabled:
> Supply +0, no exception delivered to user.
>
> Exponent underflow and enabled:
> Supply +-MIN denorm, Underflow delivered to user.
>
> Footnote 3, Overflow and Underflow have priority over Inexact.
Thanks. Does "no exception delivered to user" mean also
"and do not set FPCR bit UNF" ?
The reason I thought it might set Inexact is that I was looking
at page 4-79, which says:
"If both the UNFD (underflow disable) bit and the UNDZ (underflow
to zero) bit are set in the FPCR, the implementation sets the
result of an underflow operation to a true zero result. The
zeroing of a denormal result by UNDZ must also be treated as an
inexact result."
-- PMM
- Re: [Qemu-devel] [PATCH 15/19] target-arm: fix wrong usage of floatx80_eq_quiet(), (continued)
- [Qemu-devel] [PATCH 08/19] target-alpha: use new float64_unordered() function, Aurelien Jarno, 2011/04/12
- Re: [Qemu-devel] [PATCH 08/19] target-alpha: use new float64_unordered() function, Peter Maydell, 2011/04/14
- Re: [Qemu-devel] [PATCH 08/19] target-alpha: use new float64_unordered() function, Richard Henderson, 2011/04/14
- Re: [Qemu-devel] [PATCH 08/19] target-alpha: use new float64_unordered() function,
Peter Maydell <=
- Re: [Qemu-devel] [PATCH 08/19] target-alpha: use new float64_unordered() function, Richard Henderson, 2011/04/14
- Re: [Qemu-devel] [PATCH 08/19] target-alpha: use new float64_unordered() function, Peter Maydell, 2011/04/14
- Re: [Qemu-devel] [PATCH 08/19] target-alpha: use new float64_unordered() function, Richard Henderson, 2011/04/14
[Qemu-devel] [PATCH 11/19] softfloat: rename float*_eq() into float*_eq_quiet(), Aurelien Jarno, 2011/04/12
[Qemu-devel] [PATCH 19/19] target-mips: don't hardcode softfloat exception bits, Aurelien Jarno, 2011/04/12
[Qemu-devel] [PATCH 13/19] softfloat: move float*_eq and float*_eq_quiet, Aurelien Jarno, 2011/04/12
[Qemu-devel] [PATCH 18/19] target-mips: simplify FP comparisons, Aurelien Jarno, 2011/04/12
[Qemu-devel] [PATCH 09/19] target-mips: use new float*_unordered*() functions, Aurelien Jarno, 2011/04/12
[Qemu-devel] [PATCH 16/19] target-alpha: fix wrong usage of float64_eq_quiet(), Aurelien Jarno, 2011/04/12