Re: [PATCH] libgcc/m68k: More fixes for soft float

[Jeff Law <jeffreyalaw@gmail.com>]

On 1/1/25 2:16 PM, Keith Packard wrote:
> I thought I had sent all of my m68k soft float fixes along last year,
> but it looks like I managed to leave some out. I had been building
> my toolchain from a private repo (oops), which masked my mistake. We're
> fixing that by automatically building toolchains from upstream source
> with a list of patches now, so this "shouldn't" happen again. Now to
> drive that list of patches to zero.
> 
> 
> 0001-libgcc-m68k-Fixes-for-soft-float.patch
> 
>  From 1a3e403603f5a687724c7e2f6625debc3d23d934 Mon Sep 17 00:00:00 2001
> From: Keith Packard<keithp@keithp.com>
> Date: Sun, 29 Dec 2024 01:42:29 -0800
> Subject: [PATCH] libgcc/m68k: Fixes for soft float
> 
> Fix __extenddfxf2:
> 
>    * Remove bogus denorm handling block which would never execute --
>      the converted exp value is always positive as EXCESSX > EXCESSD.
> 
>    * Compute the whole significand in dl instead of doing part of it in
>      ldl.
> 
>      * Mask off exponent from dl.l.upper so the denorm shift test
>        works.
> 
>      * Insert the hidden one bit into dl.l.upper as needed.
> 
> Fix __truncxfdf2 denorm handling. All that is required is to shift the
> significand right by the correct amount; it already has all of the
> necessary bits set including the explicit one. Compute the shift
> amount, then perform the wide shift across both elements of the
> significand.
> 
> Fix __fixxfsi:
> 
>    * The value  was off by a factor of two as the significand contains
>      32 bits, not 31 so we need to shift by one more than the equivalent
>      code in __fixdfsi.
> 
>    * Simplify the code having realized that the lower 32 bits of the
>      significand can never appear in the results.
> 
> Return positive qNaN instead of negative. For floats, qNaN is 0x7fff_ffff. For
> doubles, qNaN is 0x7fff_ffff_ffff_ffff.
> 
> Return correctly signed zero on float and double divide underflow. This means
> that Ld$underflow now expects d7 to contain the sign bit, just like the other
> return paths.
> 
> Signed-off-by: Keith Packard<keithp@keithp.com>
Thanks.  I pushed this to the trunk.

jeff