[Patch soft-fp] Add support for various half-precision conversion routines

James Greenhalgh james.greenhalgh@arm.com
Fri Sep 16 10:28:00 GMT 2016


On Wed, Sep 07, 2016 at 04:35:25PM +0000, Joseph Myers wrote:
> On Wed, 7 Sep 2016, James Greenhalgh wrote:
> 
> > 2016-09-07  James Greenhalgh  <james.greenhalgh@arm.com>
> > 
> > 	* soft-fp/extendhftf2.c: New.
> > 	* soft-fp/fixhfti.c: Likewise.
> > 	* soft-fp/fixunshfti.c: Likewise.
> > 	* soft-fp/floattihf.c: Likewise.
> > 	* soft-fp/floatuntihf.c: Likewise.
> > 	* soft-fp/half.h: Likewise.
> 
> This ChangeLog entry is missing trunctfhf2.c.
> 
> Your patch description refers to conversions to and from DImode, but they 
> aren't in the patch.  One might also wonder whether a direct truncation 
> from DFmode is relevant to avoid double rounding (and for that matter a 
> conversion from SImode, to avoid going via DFmode; going via SFmode would 
> involve double rounding).

Hi Joseph,

An initial draft of this patch did implement these conversions. I thought
I had updated the ChangeLog, but clearly didn't. I pulled them out to get
the minimum number of new functions I needed for AArch64 support. After
https://gcc.gnu.org/ml/gcc-patches/2016-09/msg00704.html is approved,
the DI to HF conversion routines will not require a libgcc call (for AArch64).
Likewise DF to HF is handled by GCC proper.

However, as you've observed I will need to add more of these when I get on
to enabling _Float16 for AArch32, so if proposing them now would be prefered,
I'm happy to do that.

Thanks,
James 



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