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Re: [Patch-86512]: Subnormal float support in armv7(with -msoft-float) for intrinsics
- From: Umesh Kalappa <umesh dot kalappa0 at gmail dot com>
- To: Wilco Dijkstra <Wilco dot Dijkstra at arm dot com>
- Cc: gcc-patches at gcc dot gnu dot org, nd <nd at arm dot com>, Szabolcs Nagy <Szabolcs dot Nagy at arm dot com>, Ramana Radhakrishnan <Ramana dot Radhakrishnan at arm dot com>
- Date: Fri, 20 Jul 2018 21:30:10 +0530
- Subject: Re: [Patch-86512]: Subnormal float support in armv7(with -msoft-float) for intrinsics
- References: <DB5PR08MB10300230C683B33FB0297BDF83510@DB5PR08MB1030.eurprd08.prod.outlook.com>
Thank you all for your comments .
We tried some of the normalisation numbers and the fix works and please
could you help us with the input ,where if you see that fix breaks down.
Thank you again
On Fri, Jul 20, 2018, 7:07 PM Wilco Dijkstra <Wilco.Dijkstra@arm.com> wrote:
> Hi Umesh,
> Looking at your patch, this would break all results which need to be
> Index: libgcc/config/arm/ieee754-df.S
> --- libgcc/config/arm/ieee754-df.S (revision 262850)
> +++ libgcc/config/arm/ieee754-df.S (working copy)
> @@ -203,8 +203,11 @@
> @ Determine how to normalize the result.
> + @ if result is denormal i.e (exp)=0,then don't normalise the
> cmp xh, #0x00100000
> + blt LSYM(Lad_e)
> + cmp xh, #0x00100000
> bcc LSYM(Lad_a)
> cmp xh, #0x00200000
> bcc LSYM(Lad_e)
> It seems Lad_a doesn't correctly handle the case where the result is a
> denormal. For this case
> the result is correct so nothing else needs to be done. This requires an
> explicit test that the
> exponent is zero - other cases still need to be renormalized as usual.
> This code looks overly
> complex so any change will require extensive testing of all the corner